Processing, Analysis, Modelling and Mechanics of Materials and Structures

In order to explore the evolution of physical and mechanical properties and acoustic emission (AE) characteristics of aluminum foam under fatigue and quasi-static compression from a microscopic point of view, the AE monitoring technology was used to analyze the deformation, hardening, and energy absorption characteristics of open-cell aluminum foam under quasi-static compression at different rates (2, 10 and 50 mm/min) and fatigue loading tests with different peak stress ratios k (k = maximum stress/yield stress) by means of MTS fatigue testing machine and CCD camera. The results indicated that under different compression rates, the AE ring down count had the same trend as the engineering stress–strain response of the specimens, the AE ring down count rate at the plastic deformation stage showed the same performance as the work hardening rate, and the AE energy absorption efficiency corresponded well to the experimental results. The specimen entered the densification stage with the stability of AE count and the decrease in energy absorption efficiency. During the fatigue tests of different k values, the change trend of strain was consistent with the response of acoustic emission characteristic parameters, and the fatigue compression damage caused by the deformation process of the specimen can be monitored by the change in AE characteristics. The AE characteristics can dynamically monitor the compression process and provide a new research method and idea for the study of mechanical properties of aluminum foam. Full article

Because of the high hardness, brittleness, and anisotropy of reaction-bonded silicon carbide composites (RB-SiC), it is challenging to process high-quality textures on their surfaces. With the advantages of high processing accuracy and low processing damage, femtosecond laser processing is the preferred technology for the precision processing of difficult-to-process materials. The present work used a femtosecond laser with a linear scanning path and a spot diameter of 18 µm to process microgrooves on RB-SiC. The influence of different processing parameters on the microgroove profile, dimensions, and ablation rate (AR) was investigated. The ablation width W_a and average ablation depth D_a of microgrooves were evaluated, and the various patterns of varying processing parameters were obtained. A model for W_a prediction was developed based on the laser fluence within the finite length (F_L). As a result, the experimental values were distributed near the prediction curve with a maximum error of 20.4%, showing an upward trend of gradually decreasing increments. For a single pass, the AR value was mainly determined by the laser energy, which could reach the scale of 10⁶ μm³/s when the laser energy was greater than 50 μJ. For multiple passes, the AR value decreased as the number of passes increased and it finally stabilized. The above research will provide theoretical and experimental support for the high-quality and efficient processing of RB-SiC surface textures. Full article

In the present work, we take the influences of activated slip systems and the orientation spread into account to predict the cup height using analytical earing models and compare the predicted results with experimental results. The effect of boundary conditions of the various stress states and the work hardening exponents are compared and discussed for profile of single crystals. A stress ratio of −0.3 and a hardening exponent of 0.3 are selected for the prediction of earing profiles. The combination of activation of the single slip systems and orientation spread provides the best prediction of deep-drawing profiles. With further consideration of the orientation spread, an increase in the total orientation leads to peak-broadening, i.e., broad and smooth ears. Furthermore, the difference of the height between the maximum and minimum value of cup profiles is reduced because of the orientation spread. The profile for C is found with single ear at 45°, while the other components individually reveal double ears at 35° and 50° for S, at 15° and 45° for B, at 0° and 90° for Cube, at 5° and 90° for r-Cube, and at 15° and 90° for G. Herein, simple analytical earing models are proposed to understand the effects of slip systems and the orientation spread. The deep-drawing profiles are predicted with six major texture components. Full article

This study aims to develop combined methods with dual and triple use of different non-destructive test (NDT) methods and to examine the effectiveness of these methods. For this purpose, nine different high-strength concrete series were produced, and destructive and NDT methods were applied to these samples on the 3rd and 90th days. Surface hardness, ultrasonic pulse velocity, and penetration resistance were considered from NDT methods. Analyses were made on the response surface method using the NDT measurements and compressive strength values obtained, and four different mathematical models were developed. Models 1, 2, and 3 were designed with dual use of NDT methods, and model 4 was designed with triple use. The absolute relative deviation values for all the developed models’ early and final-age strengths were below 10%. It is of great importance to determine concrete quality with high accuracy and practicality, especially in places like Elazig, where there are thousands of newly constructed buildings since the Sivrice-Elazig earthquake, and rapid production is required. Therefore, it is thought that determining the strength values with high accuracy using the developed combined methods without damaging the building element will provide benefits in terms of time, labor, and cost. Full article

The P-S-N curve is a vital tool for dealing with fatigue life analysis, and its fitting under the condition of small samples is always concerned. In the view that the three parameters of the P-S-N curve equation can better describe the relationship between stress and fatigue life in the middle- and long-life range, this paper proposes an improved maximum likelihood method (IMLM). The backward statistical inference method (BSIM) recently proposed has been proven to be a good solution to the two-parameter P-S-N curve fitting problem under the condition of small samples. Because of the addition of an unknown parameter, the problem exists in the search for the optimal solution to the three-parameter P-S-N curve fitting. Considering that the maximum likelihood estimation is a commonly used P-S-N curve fitting method, and the rationality of its search for the optimal solution is better than that of BSIM, a new method combining BSIM and the maximum likelihood estimation is proposed. In addition to the BSIM advantage of expanding the sample information, the IMLM also has the advantage of more reasonable optimal solution search criteria, which improves the disadvantage of BSIM in parameter search. Finally, through the simulation tests and the fatigue test, the P-S-N curve fitting was carried out by using the traditional group method (GM), BSIM, and IMLM, respectively. The results show that the IMLM has the highest fitting accuracy. A test arrangement method is proposed accordingly. Full article

The coordination number (CN) is an important structure property of liquid metals. A simple yet extremely precise method for calculating CN is proposed, the classical CN methods are evaluated systematically, and the mathematical forms of the symmetry method are corrected. Using the Gaussian function construct, the first coordination shell of the pair distribution function (PDF), the right-hand side of the first peak of the pair distribution function is extrapolated, and the CN expression is simplified with a Gaussian function to obtain its non-integral form. The first coordination shell is used to explain the Tao coordination number model (Tao CN) and obtain a Modified Tao CN. The Gaussian function is combined with the Tao CN, obtaining the function expression for the peak with peak position. These are important for the structural research of liquid metals. The CN of 27 liquid metals is calculated by these methods. The average relative deviation of the Gaussian function extrapolation method is ±6.46%, of the Modified Tao CN is ± 18.51%; those of the four classical methods range from ±15% to ±42%. The Modified Tao CN and extrapolation methods to calculate CN are more accurate for calculating CN than the classical method; they are more suitable for use in quantitative applications of CN. The equations derived in this work can be applied to the problem of integration of distribution functions to obtain simple mathematical models. Full article

The compression and compressive creep behavior of target shipping containers, which are material properties based on finite element analysis, and the lifetime and load-sharing rate, were analyzed in this study to develop a computer-aided engineering prediction technology for predicting the multi-stage compression behavior of three target packages with different logistics conditions. In the experiment performed in the study, the relative humidity levels were 50%, 70%, and 90%, with creep measurements performed for 12 h for a combination of three levels of applied load and relative humidity. Using the nonlinear model of the stress–strain and creep behavior of the target shipping container, the lifetime was analyzed by estimating the average creep rate of the target shipping container. The load-sharing rate for each logistics situation of the target packages was also analyzed. The reduction rate of the compression strength of the container with respect to the increase in relative humidity was greater in the ‘horizontal long’ container than in the ‘vertical long’ container. As the applied load increased, the rate of increase in the average creep rate increased, i.e., the higher the applied load, the larger the difference in the average creep rate with respect to the relative humidity. The lifetime estimated from the failure strain and average creep rate of the container gradually decreased as the applied load increased at all relative humidity levels. However, as the applied load increased, the difference with respect to the relative humidity tended to decrease. In the target packages used in this study, the ratio of the load-sharing rate between the shipping container and an expanded polystyrene cushioning material was determined to be 2%:98%, with most of the stacking load applied to the product through the cushioning material. Full article

The mechanized resource utilization of domestic waste is the development trend in the field of waste treatment. The difficulty of bag breaking and the easy entanglement of domestic waste are the factors restricting the mechanization of waste separation and recycling. In response to the above problems, an internal blowing anti-tangle bag-breaking device for domestic waste was developed by combining the arc-type cutter and the internal flow field of the rotary. In addition, the motion trajectory of the cutters and the support rods were theoretically analyzed, as well as the force during the bag-breaking process of domestic waste. A three-factor, five-level orthogonal test was carried out to complete the regression ANOVA, and a relationship model was constructed between the test factors such as the cutting–support speed ratio, the center distance, the inlet flow rate and the response indicators such as the bag film length–perimeter ratio and bag film winding specific gravity. The key parameters and their significant interactions with the bag-breaking efficiency were analyzed to obtain the optimal combination of parameters for the device. Under the same conditions, the errors between the physical test and model predictions for the two response indicators were 5.46% and 7.90%, respectively, indicating that the verification test results were basically consistent with the model prediction results. Full article

The large difference in mechanical properties and plastic deformation ability of each layer will have a great impact on the overall performance of a composite sheet prepared by cold-roll bonding. The effect of rolling and material variables on the stress distribution and bonding state in the rolling deformation zone should be studied. In this work, an accurate cold-rolling deformation model considering the anisotropic effect and position-dependent friction model is established using the slab method. Effects of different process and material variables are analyzed. Related experiments were performed on Ti-Al clads and calculation results from the deformation model were compared with the experimental results. This model can well predict the Ti/Al thickness ratio after rolling, and the smaller the initial aluminum strength, the more accurate the predicted value; the minimum error is within 1%. The deformation coordination between the titanium and aluminum layers becomes better with the increase in rolling reduction and initial aluminum strength. At 50% reduction, the deformation ratio of titanium and aluminum increases from 93.8% to 98.1%, which is consistent with the trend of the results calculated using this model. Full article

The article presents a theoretical study of the regimes of high-pressure torsion (HPT) for which slippage of the deforming material on the interfaces with anvils is possible. The approach taken is a generalisation of the currently accepted view of the HPT process. It enables a rational explanation of its salient features and the effects observed experimentally. These include a lag in the rotation angle of the specimen behind that of the anvils, an outflow of the material from the deformation zone, enhancement in gripping the specimen with anvils with increasing axial pressure, etc. A generalised condition for gripping the specimen with anvils, providing a basis for an analytical investigation of the HPT deformation at a qualitative level, is established. The results of the analytical modelling are supported by finite-element calculations. It is shown that for friction stress below the shear stress of the specimen material (i.e., for the friction factor m < 1), plastic deformation is furnished by non-shear flows, which expands the range of possible process regimes. The potential of these flow modes is impressive, which is reflected in the second meaning of the word “gripping” in the title of the article. Non-shear flows manifest themselves in the spreading of the material over the anvil surfaces whose cessation signifies the end of deformation and the beginning of slippage of the specimen as a whole. The model shows that for m < 1 such a finale is inevitable at any axial pressure. It predicts, however, that the highest achievable strain is increased when the axial pressure is raised in the course of the HPT process. Unlimited deformation of the specimen is only possible for m = 1, when slippage of the deforming material relative to the anvils is suppressed. Full article

In this paper, the eigenfunction expansion method combined with local contact models are presented to analyze the repeated impact behaviors between the sphere and the beam. The simulations are verified with the experimental results of a simply-supported beam struck 91 times by a sphere. In order to clarify the validity of the eigenfunction expansion method to solve the repeated transverse impacts on beams, the simulation results of the spring-mass method are also compared with the experiments. It shows that with appropriate contact models, the eigenfunction expansion method can predict agreeable results with the experimental results, especially the impact behaviors (including the accumulated permanent indentation, the coefficient of restitution and the separation velocity of the sphere) representing energy dissipations, due to the consideration of structural vibrations, local impact behaviors, as well as the wave propagations. The comparisons between the eigenfunction expansion method and the spring-mass model show that the wave propagations are important for energy dissipations, which cannot be neglected in flexible structure impacts. The studies are important for the analysis of repeated impact response of beam structures. Full article

The research provides an innovative contribution to the interpretation of three-point and four-point bending tests on mortars by employing a bi-modulus material model, which assumes an asymmetric constitutive law, i.e., different elastic moduli in tension and in compression. To this aim, Euler–Bernoulli and Timoshenko bi-modulus beam models are defined, and the related displacement fields are reported for three-point loading, and provided for the first time for the four-point bending layout. A wide experimental campaign, including uni-axial tensile and compressive tests, three-point and four-point bending tests, and on notched specimens three-point tests for mode-I fracture energy, has been carried out on lime mortar specimens exploiting traditional contact (CE-DT) and contactless (DIC) measurement systems. Experimental results provided the values of tensile and compressive mechanical characteristics, which are employed to validate estimations of the analytical model. The tension-to-compression moduli ratio experimentally observed is on average 0.52. Experimental outcomes of the DIC analysis proved the bi-modulus behaviour during the four-point bending tests showing visible shifting of the neutral axis. The bi-modulus analytical model provides closer results to the experimental ones for the slender specimens subjected to four-point bending. Full article

Air-rib tents are widely used because they are lightweight and site adaptable, but the large deformation of these tents reduces their effective space. It is important to reduce the displacement of the air-rib tent by parameter optimization. The influences of external factors on the tent are studied in this paper. Four parameters of the tent’s wind ropes are the angle of the wind ropes, the number of the wind ropes, and the initial prestress of the wind ropes on the side or end faces. The influence of the angle of the wind ropes and the number of the wind ropes on the displacement is larger than the other two parameters. The closer the wind ropes are to the center of the tarpaulin, the greater the displacement of the tent. Based on an analysis using response surface methodology, the optimal parameters are as follows: the angle of the wind ropes is 41°, the number of the wind ropes on the side is two, the initial prestress of the wind ropes on the end face is 800 Pa, and the initial prestress of the wind ropes on the side is 0 Pa. Under these optimal parameters, the maximum displacement decreases by 10.2%, and the maximum stress barely changes. Full article

The creep strain resistance of expanded polystyrene (EPS) is important; thus, time-dependent creep properties of EPS have been of significant interest. This study is a part of the computer-aided engineering (CAE) prediction-technology development for the inclination of unitized loads of packaged appliances applied to EPS-based cushioning systems. Creep properties are validated to ensure finite element analysis (FEA) reliability regarding the creep behavior of EPS-based cushioning systems. The elastic modulus and Poisson’s ratio (EPS elastic properties) as well as creep properties (plastic properties) were measured. The EPS density range was 16–30 kg/m³, and the temperature range was 0–60 °C. Because the measured mechanical properties were not temperature-dependent, only their density dependence was analyzed. The EPS behavior, measured over 12 h, exhibited a significant creep amount and rate, depending on the applied stress level. FEA was performed on 7-day-long EPS creep, using the measured EPS elastic and plastic properties. The FEA and experimental results were strongly concordant. These EPS creep validation results are expected to improve the reliability of FEA for creep behavior studies of EPS-based cushioning systems. Full article

As giant magnetostrictive material, TbDyFe is regarded as a promising choice for magnetic sensing due to its excellent sensitivity to changes in magnetic fields. To satisfy the requirements of high sensitivity and the stability of magnetic sensors, TbDyFe thin films were successfully deposited on single-crystal diamond (SCD) substrate with a Young’s modulus over 1000 GPa and an ultra-stable performance by radio-frequency magnetron sputtering at room temperature. The sputtering power and deposition time effects of TbDyFe thin films on phase composition, microstructure, and magnetic properties were investigated. Amorphous TbDyFe thin films were achieved under various conditions of sputtering power and deposition time. TbDyFe films appeared as an obvious boundary to SCD substrate as sputtering power exceeded 100 W and deposition time exceeded 2 h, and the thickness of the films was basically linear with the sputtering power and deposition time based on a scanning electron microscope (SEM). The film roughness ranged from 0.15 nm to 0.35 nm, which was measured by an atomic force microscope (AFM). The TbDyFe film prepared under a sputtering power of 100 W and a deposition time of 3 h possessed the coercivity of 48 Oe and a remanence ratio of 0.53, with a giant magnetostriction and Young’s modulus effect, suggesting attractive magnetic sensitivity. The realization of TbDyFe/SCD magnetic material demonstrates a foreseeable potential in the application of high-performance sensors. Full article

Admittedly, the design requirements of compactness, low frequency, and broadband seem to constitute an impossible trinity, hindering the further development of elastic metamaterials (EMMs) in wave shielding engineering. To break through these constraints, we propose theoretical combinations of effective parameters for wave isolation based on the propagation properties of Lamb waves in the EMM layer. Accordingly, we design compact EMMs with a novel ultralow-frequency bandgap, and the role of auxeticity in the dissociation between the dipole mode and the toroidal dipole mode is clearly revealed. Finally, under the guidance of the improved gradient design, we integrate multiple bandgaps to assemble metamaterial barriers (MMBs) for broadband wave isolation. In particular, the original configuration is further optimized and its ultralow-frequency and broadband performance are proven by transmission tests. It is foreseeable that our work will provide a meaningful reference for the application of the new EMMs in disaster prevention and protection engineering. Full article

High temperature and strain will occur in the cutting area during dry milling of contour bevel gears, which causes plastic deformation of the workpiece, resulting in changes in the physical properties of the machined surface’s metamorphic layer, reducing the quality of the workpiece’s machined surface. Therefore, it is necessary to investigate the properties of the metamorphic layer and the work hardening behavior of the machined surfaces of contour bevel gears. The paper first establishes a single-tooth finite element simulation model for a contour bevel gear and extracts the temperature field, strain field and strain rate at different depths from the machined surface. Then, based on the simulation results, the experiment of milling contour bevel gears is carried out, the microscopic properties of the machined metamorphic layer are studied using XRD diffractometer and ultra-deep field microscopy, and the work hardening behavior of the machined metamorphic layer under different cutting parameters is studied. Finally, the influence of the cutting parameters on the thickness of the metamorphic layer of the machined surface is investigated by scanning electron microscopy. The research results can not only improve the surface quality and machinability of the workpiece, but are also significant for increasing the fatigue strength of the workpiece. Full article

In this study, the effects of Si on the microstructure and tensile properties of weathering bridge steel were elucidated. The thermal mechanical control process (TMCP), containing two stages of controlled rolling and accelerated cooling process, was simulated using a thermo-mechanical simulator for four experimental steels with varying Si contents (0.15–0.77 wt.%). Micro-tensile tests were performed, and the microstructures were observed via optical microscope (OM), scanning electron microscope (SEM), transmission electron microscope (TEM), and electron back-scattered diffraction (EBSD). Furthermore, the tensile properties and microstructures of these steels were analyzed. The results show that a mixed microstructure comprising granular bainitic ferrite (GBF), quasi-polygonal ferrite (QF), and martensite/austenite (M/A) constituent was formed in each sample. With an increase in Si content, the GBF content decreased, QF content increased, mean equivalent diameter (MED) of the QF+GBF matrix increased, and the fraction and average size of the M/A constituent increased. With a rise in Si content from 0.15 to 0.77 wt.%, the contributions of dislocation strengthening, grain boundary strengthening, and precipitation strengthening decreased from 149, 220, and 21 MPa to 126, 179, and 19 MPa, respectively. However, the combined contribution of solution strengthening, lattice strengthening, and M/A strengthening increased from 41 to 175 MPa, which augmented the final yield strength from 431 to 499 MPa. The decreasing yield ratio shows that strain hardening capacity is enhanced due to an increase in the fraction of the M/A constituent as well as in the MED of the QF+GBF matrix. Furthermore, the mechanisms by which Si content controls the microstructure and mechanical properties of weathering bridge steel were also discussed. Full article

The microbiological purity of textiles plays a pivotal role in the use of textiles, especially in hospitals and other medical facilities. Microbiological purity of cotton fabric was achieved by a new disinfection method using tetrabutyloammonium OXONE (TBA-OXONE) before washing. As a result of the disinfection, the cotton fabric became microbiologically pure, despite the markedly decreased washing time with respect to the widely used standard procedure. Shortening of the washing time allowed for significant energy savings. In addition, the effect of the number of disinfection and washing cycles on the tensile properties and tearing force of the fabric was examined. After 120 disinfection and washing cycles the mechanical properties of cotton fabric were only slightly worsened. Full article

The advantageous implications of the microstructure and volume fraction of reversed austenite for the tensile properties of super 13Cr martensitic stainless steel (13Cr SMSS) in an experiment with quenching and double-step tempering treatment in the temperature range of 550–750 °C were investigated. The results show that, with increases in one-step tempering temperature, the content of reversed austenite was enhanced considerably from 0.9% to 13.3%. The reversed austenite distributed in the martensitic lath boundary conformed to the (1$\overline{1}$1)_γ//(011)_α’ and [011]_γ//[$\overline{1}\overline{1}$1]_α’ Kurdjumov–Sachs orientation relationship with the matrix. When tempered at 675 °C for 3 h for the first stage and 600 °C for 2 h for the second stage, the maximum volume fraction of reversed austenite was approximately 13.3%, achieving uniform elongation of 10.4% and total elongation of 27.2%. Moreover, the product of strength and elongation (PSE) was 23.5 GPa·% higher than other samples. The outstanding combination of high strength and commendable plasticity was due to the phase transformation of the reversed austenite into secondary martensite during tensile straining. The reversed austenite consumed the plastic energy at the tip of the microcrack and made the crack tip blunt, which hindered the further propagation of the crack, consequently increasing the total elongation and improving toughness. Full article

Liquid ammonia as a non-aqueous medium has many physical properties close to water, such as small molecular weight and strong permeability. It has been widely used for the ecological processing of cellulosic fibers to improve their luster, softness and dyeing properties. However, there are few reports on the dyeing of wool treated with liquid ammonia, especially at a lower temperature. Herein, a continuous liquid ammonia finishing machine was used to batch process wool followed by dyeing in a commonly-used wool dyeing machine. The results showed that many scale flakes and some cuticle cracking were seen on the fiber surface, and the disulfide bonds of cystine were broken down after liquid ammonia treatment, which promoted the diffusion of dyestuff into the fiber. Moreover, the uptakes and K/S value of wool dyed with Lanaset and Lanasol CE dyes were higher than the untreated wool, and the dyeing temperature could decrease to 85 °C, while the degree of fiber strength reduction merely decreased by 3–5%. Furthermore, for the reactive dyes, the dyeing temperature can reduce to 70 °C with the chemical auxiliaries Miralan LTD, while the degree of strength reduction decrease by 8–10%. Liquid ammonia treatment can be used for dyeing at a lower temperature than boiling temperature (100 °C), reduce energy consumption and reduce the degree of fiber strength reduction of wool. The method shows considerable to great value and is significant in providing a feasible approach for the industrial application of low-temperature dyeing technology. Full article

In the Ruhrstahl–Heraeus (RH) vacuum degassing process, we propose a real-time prediction model for the carbon content in molten steel, and show that the decarburization endpoint can be accurately determined using this model. Firstly, we applied a novel off-gas analyzer that can measure the carbon oxide concentration produced in the decarburization reaction faster and more accurately. Next, we generate decarburization curves using the off-gas components measured by the new analyzer. The decarburization curve describes the carbon content profile well during operation, and shows good agreement with the actual carbon content. In order to predict the carbon content during operation in real time, we create an artificial neural network (ANN) using the decarburization curves and operation data. By comparing the endpoint carbon content measured at the end of the operation with the predicted values, we confirmed the excellent predictive performance of the ANN model. Finally, we show that it is possible to accurately determine the decarburization endpoint using the prediction model. We expect that the proposed real-time prediction model can increase the productivity of the RH process. Full article

The production of catalysts such as zeolites is a complex multiscale and multi-step process. Various material properties, such as particle size or moisture content, as well as operating parameters—e.g., temperature or amount and composition of input material flows—significantly affect the outcome of each process step, and hence determine the properties of the final product. Therefore, the design and optimization of such processes is a complex task, which can be greatly facilitated with the help of numerical simulations. This contribution presents a modeling framework for the dynamic flowsheet simulation of a zeolite production sequence consisting of four stages: precipitation in a batch reactor; concentration and washing in a block of centrifuges; formation of droplets and drying in a spray dryer; and burning organic residues in a chain of rotary kilns. Various techniques and methods were used to develop the applied models. For the synthesis in the reactor, a multistage strategy was used, comprising discrete element method simulations, data-driven surrogate modeling, and population balance modeling. The concentration and washing stage consisted of several multicompartment decanter centrifuges alternating with water mixers. The drying is described by a co–current spray dryer model developed by applying a two-dimensional population balance approach. For the rotary kilns, a multi-compartment model was used, which describes the gas–solid reaction in the counter–current solids and gas flows. Full article

For the numerical simulation of components made of short fiber-reinforced composites, the correct prediction of the deformation including the elastic and plastic behavior and its spatial distribution is essential. When using purely deterministic modeling approaches, the information of the probabilistic microstructure is not included in the simulation process. One possible approach for the integration of stochastic information is the use of random fields. In this study, numerical simulations of tensile test specimens were conducted utilizing a finite deformation elastic–ideal plastic material model. A selection of the material parameters covering the elastic and plastic domain are represented by cross-correlated second-order Gaussian random fields to incorporate the probabilistic nature of the material parameters. To validate the modeling approach, tensile tests until failure were carried out experimentally, which confirmed the assumption of the spatially distributed material behavior in both the elastic and plastic domain. Since the correlation lengths of the random fields cannot be determined by pure analytic treatments, additionally numerical simulations were performed for different values of the correlation length. The numerical simulations endorsed the influence of the correlation length on the overall behavior. For a correlation length of 5 $\mathrm{m}$$\mathrm{m}$, a good conformity with the experimental results was obtained. Therefore, it was concluded that the presented modeling approach was suitable to predict the elastic and plastic deformation of a set of tensile test specimens made of short fiber-reinforced composite sufficiently. Full article

Orthotropic steel deck (OSD) bridges are lightweight constructions which are convenient, especially for the achievement of long spans. Conversely, due to the stress concentration in correspondence to the numerous and unavoidable welded construction details, this bridge typology is prone to fatigue cracking under the effect of cyclic loading with high-stress amplitudes. Existing OSD bridges are particularly vulnerable to fatigue damage accumulation because of the dated standards adopted at the time of their design and the fact that heavy lorries have increased in travel frequency and weight. In the present paper, a case study of a northern Italian existing highway viaduct, built in the 1990s, is presented and analyzed. The fatigue damage accumulation was carried out according to the fatigue load models for road bridges reported in Eurocode EN 1991-2 and the assessment criteria indicated in EN 1993-1-9. The stress amplitude, in correspondence to the critical details of the bridge, is assessed by means of detailed finite-element calculations carried out with the software MIDAS GEN^®. The amplitude and frequency of the travelling weights are assessed based on real traffic monitoring from the highway. Moreover, an automatic “rain-flow” algorithm is implemented, which is able to detect each nominal stress variation above the fatigue limit. In general, the bridge is not fully compliant with today’s standards when considering the entire duration of the prescribed life of the design. Countermeasures, like lane number reductions and lane reshaping, are critically analyzed since their effectiveness is questionable as far as the reduction in heavy traffic is concerned. Other interventions, like the replacement of the pavement in order to improve the stress redistribution upon the connection details below the wheel footprint, and continuous bridge inspections or monitoring, look more promising. Full article

The solidification of heavy metal Cr has always been a challenge in the treatment of Cr-containing wastes, due to its high mobility in alkaline environments. In addition, the solidification mechanism of Cr has not been fully investigated. In this study, blast furnace slag (BFS)-based cementitious materials were used as binders for the immobilization of heavy metal Cr to investigate the solidification mechanism of Cr in different hydration products. From XRD, FTIR, XPS, and XANES analyses, it could be seen that SO₄²⁻ in ettringite was replaced by Cr in the form of CrO₄²⁻, making SO₄²⁻ re-dissolve in the liquid phase. The SO₄²⁻ in the solution would compete with CrO₄²⁻ ions, leading to the direct influence of SO₄²⁻ content on the solidification efficiency of Cr. In ettringite, Cr mainly existed in the form of Cr⁶⁺, accounting for more than 84% however, Cr was solidified in Friedel’s salt under two coexisting valence states (Cr⁶⁺ and Cr³⁺). This resulted not only from the slow excitation rate of the BFS in the cementitious system that did not contain sulfate, but also from the existence of a certain amount of reducing substances in the BFS, such as Fe²⁺ and S²⁻, which could reduce some of Cr⁶⁺ to Cr³⁺. In Friedel’s salt, the residual Cr⁶⁺ replaced Cl⁻ in the form of CrO₄²⁻, whereas the Cr³⁺ replaced Al³⁺. The binding energies of Cr 2p3/1 and Cr 2p3/2 decreased with the addition of Cr, indicating that the coordination numbers of Cr³⁺ and Cr⁶⁺ increased, and that the binding energies of Cr³⁺ and Cr⁶⁺ decreased after entering the structure of Friedel’s salt. Full article

Lightweight structural alloys have broad application prospects in aerospace, energy, and transportation fields, and it is crucial to understand the hot deformation behavior of novel alloys for subsequent applications. The deformation behavior and microstructure evolution of a new Al-Zn-Mg-Li-Cu alloy was studied by hot compression experiments at temperatures ranging from 300 °C to 420 °C and strain rates ranging from 0.01 s⁻¹ to 10 s⁻¹. The as-cast Al-Zn-Mg-Li-Cu alloy is composed of an α-Al phase, an Al₂Cu phase, a T phase, an η phase, and an η′ phase. The constitutive relationship between flow stress, temperature, and strain rate, represented by Zener–Hollomon parameters including Arrhenius terms, was established. Microstructure observations show that the grain size and the fraction of DRX increases with increasing deformation temperature. The grain size of DRX decreases with increasing strain rates, while the fraction of DRX first increases and then decreases. A certain amount of medium-angle grain boundaries (MAGBs) was present at both lower and higher deformation temperatures, suggesting the existence of continuous dynamic recrystallization (CDRX). The cumulative misorientation from intragranular to grain boundary proves that the CDRX mechanism of the alloy occurs through progressive subgrain rotation. This paper provides a basis for the deformation process of a new Al-Zn-Mg-Li-Cu alloy. Full article

Ti alloys contemplating the simultaneous addition of Fe and Nb are available in the literature as Fe enhances the strength and Nb improves the biological behaviour of Ti. Nevertheless, casting has been the main manufacturing process, the Nb content is normally ≥10 wt.%, and no tensile properties are available. In this study, Ti-5Fe-xNb alloys (x = 2, 6, and 9 wt.%) were produced via powder metallurgy, which is more energy efficient than casting, with the aim of understanding the relationship between the mechanical behaviour and the microstructural changes brought about by the progressive addition of a greater amount of Nb. This study shows that the increment of the Nb content reduces the densification of the alloys, as the relative density decreases from 98.2% to 95.0%, but remarkably increases the volume fraction of the stabilised β phase (14→36%). Accordingly, the Ti-5Fe-xNb alloys are characterised by Widmanstätten microstructures, which become finer for higher Nb contents, and progressively higher mechanical properties including yield stress (725–949 MPa), ultimate tensile strength (828–995 MPa), and hardness (66.5–67.6 HRA), but lower elongation to fracture (4.0–5.1%). It is found that the ductility is much more influenced by the presence of the residual pores, whereas the strength greatly depends on the microstructural changes brought about by the addition of the alloying elements. Full article

Studies have been steadily conducted on the forming process of the bending pipe that enables the transport of underground resources. Recently, it has been suggested that bent pipes for transport withstand high pressure during the forming process, but it is judged that the research on methods able to overcome the limitations of non-uniform dimensional distribution due to the difference in the mechanical properties and thickness of the outer and inner pipes is insufficient. This study proposes a new precision forging method called the cut-forged-joint process (CFJP) for the manufacture of bent pipe containing bi-metal. The initial billet and mandrel were designed considering the standard dimensions of bent pipes, and pre-simulation was performed applied to the designed models. The results of dimensional accuracy obtained by forging experiments and the computational forming simulation were compared with each other to verify the reliability. As a final outcome, it was confirmed that it is possible to secure the dimensional accuracy of bi-metal bent pipes by applying the newly proposed CFJP. Full article

The failure of a 101.6 mm drill pipe was studied by combining experimental testing and finite element simulation. The macro analysis, metallographic structure and energy spectrum, chemical composition and a mechanical property test of the failed drill pipe sample were firstly carried out. Then, a three-dimensional finite element model of drill pipe failure was established based on the experimental results. Finally, the failure mechanism of drill pipe was analyzed and the mitigation measures were put forward. The results showed that solids settling sticking was the direct cause of fracture failure of the drill pipe joint. Due to the violent friction and wear between the drill pipe joint and the settled sand, the large amount of heat generated caused the microstructure of the joint material to undergo phase transformation and the bearing capacity to be reduced. Finally, fracture occurs under tensile and torsional loads. Full article

Laser polishing (LP) is a process that allows a significant reduction of the surface roughness of a metal workpiece via re-melting a shallow layer of material. However, the practical use of LP is limited due to the difficulty of satisfying the high surface polishing quality for industries such as jewelry. Hence, this study presents a thermal model based on the Chernoff formula for fixed and moving LP processes. The model was validated via a sensitivity analysis of the coefficient of absorption of the solid and liquid phase and through comparing the results with the corresponding experimental observations of the melt pools produced. In this investigation, a continuous wave, high power diode laser (980 nm wavelength, Ø 0.9 mm spot size with a flat top distribution) was coupled to a fixed focusing head. The material was a hardened tool steel (X38CrMVo5-1 steel-1.2343) with an initial surface state obtained by electrical discharge machining (EDM) of CH30 on the Charmilles scale for EDM, which corresponds to a roughness Ra of 3.15 µm. The results show that the model is able to represent the thermal behavior of the tool steel during LP. The best results are obtained with two constant coefficients, one for the solid based on the measurement at room temperature (a_s = 35%) and one for the liquid fixed so that the model fits the experiment data (a_l = 25%). Full article

Chemical–mechanical polishing (CMP) is widely adopted as a key bridge between fine rotation grinding and ion beam figuring in super-smooth monocrystalline silicon mirror manufacturing. However, controlling mid- to short-spatial-period errors during CMP is a challenge owing to the complex chemical–mechanical material removal process during surface morphology formation. In this study, the nature of chemical and mechanical material removal during CMP is theoretically studied based on a three-system elastic–plastic model and wet chemical etching behavior. The effect of the applied load, material properties, abrasive size distribution, and chemical reaction rate on the polishing surface morphology is evaluated. A microscale material removal model is established to numerically predict the silicon surface morphology and to explain the surface roughness evolution and the source of nanoscale intrinsic polishing scratches. The simulated surface morphology is consistent with the experimental results obtained by using the same polishing parameters tested by employing profilometry and atomic force microscopy. The PSD curve for both simulated surface and experimental results by profilometry and atomic force microscopy follows linear relation with double-logarithmic coordinates. This model can be used to adjust the polishing parameters for surface quality optimization, which facilitates CMP manufacturing. Full article

Brittleness is an essential parameter to determine the deformation and failure behavior of rocks, and it is useful to quantify the brittleness of rocks in numerus engineering practices. A novel energy-based brittleness evaluation index is proposed in this study, which redefines the dissipated proportion of ultimate elastic strain energy relative to post-peak failure energy and residual elastic strain energy. A series of conventional triaxial compression (CTC) tests were performed on shale rock to verify the reliability and accuracy of the brittleness index. The results show that the proposed index can precisely reflect the deformation and failure characteristic of rocks under different confining pressures. Based on the testing data from six types of rocks in previous studies, the universality of the novel index was verified. According to comparison with existing brittleness indices, the new brittleness index can more precisely characterize the brittleness of rock. Full article

With the need of developing new materials, exploring new phenomenon, and discovering new mechanisms under extreme conditions, the response of materials to high-pressure compression attract more attention. However, the high-pressure state deviating from the Hugoniot line is difficult to realize by conventional experiments. Gas gun launching graded materials could reach the state. In our work, the corresponding Al-Cu composites and graded materials are prepared by tape casting and hot-pressing sintering. The microstructure and the acoustic impedance of the corresponding Al-Cu composites are analyzed to explain the impact behavior of Al-Cu graded materials. Computed tomographic testing and three-dimension surface profilometry machine results demonstrated well-graded structure and parallelism of the graded material. Al-Cu GMs with good parallelism are used to impact the Al-LiF target at 2.3 km/s using a two-stage light-gas gun, with an initial shock impact of 20.6 GPa and ramping until 27.2 GPa, deviating from the Hugoniot line. Full article

Existing concrete random aggregate modeling methods (CRAMMs) have deficiencies in in the parameterization of the mesoscale pore structure. A novel CRAMM is proposed, whose pore structure is determined by the pore gradation, total porosity, sub-porosity, and pore size of each pore gradation segment. To study the influence of pore structure on the mechanical properties of concrete, 25 mesoscopic concrete specimens with the same aggregate structure but different meso-scale pore structures are constructed and subjected to uniaxial compression tests. For the first time, the influence of sub-porosity of each pore gradation segment, average pore radius (APR), pore specific surface area (PSSA), and total porosity on concrete failure process, compressive strength, peak strain, and elastic modulus were quantitatively and qualitatively analyzed. Results indicate that the pore structure makes the germination and propagation of the damage in cement mortar show obvious locality and affects the formation and expansion of macroscopic cracks. However, it does not accelerate the propagation of the damage in cement mortar from the periphery to the center of the specimen, nor does it change the phenomenon that the ITZ is more damaged than other meso-components of concrete before peak stress. Macroscopic cracks occur in the descending section of the stress–strain curve, and the sudden drops in the descending section of the stress–strain curve are often accompanied by the generation and expansion of macroscopic cracks. The quadratic polynomial, exponential, and power functions can well fit the relationship between total porosity and compressive strength and the relationship between PSSA and compressive strength. The linear, exponential, and power functions can well reflect the relationship between total porosity and compressive modulus and the relationship between compressive modulus and PSSA. For concrete specimens with the same total porosity, the elastic modulus and strength show randomness with the increase in the sub-porosity of macropores and are basically not affected by the APR. Based on the grey relational analysis, the effects of pore structure parameters on the elastic modulus and compressive strength are in the same order: total porosity > T [k₁,k₂] > T [k₂,k₃] > T [k₃,k₄] > T [k₄,k₅] > AVR > PSSA. The order of influence of the pore structure parameters on the peak strain is: T [k₂,k₃] > T [k₁,k₂] > T [k₃,k₄] > T [k₄,k₅] > APR > PSSA > total porosity. Full article

The machined-surface integrity plays a critical role in corrosion resistance and fatigue properties of ultra-high-strength steels. This work develops a multiphysics model for predicting the microstructure changes and microhardness of machined AerMet100 steel. The variations of stress, strain and temperature of the machined workpiece are evaluated by constructing a finite-element model of the orthogonal cutting process. Based on the multiphysics fields, the analytical models of phase transformation and dislocation density evolution are built up. The white layer is modeled according to the phase-transformation mechanism and the effects of stress and plastic strain on real phase-transformation temperature are taken into consideration. The microhardness changes are predicted by a model that accounts for both dislocation density and phase-transformation evolution processes. Experimental tests are carried out for model validation. The predicted results of cutting force, white-layer thickness and microhardness are in good agreement with the measured data. Additionally, from the proposed model, the correlation between the machined-surface characteristics and processing parameters is established. Full article

In order to effectively prevent and control the rutting problem of asphalt pavement in the deep loess area of Eastern Gansu and reduce road diseases, diatomite was added into the asphalt mixture for laboratory tests. Through Marshall test and rutting test, the optimum mix proportion of the diatomite asphalt mixture, and the optimal mix amount of the diatomite in this area were determined. The pavement performance of activated diatomite asphalt pavement and SBS asphalt pavement in this area is compared and analyzed through laboratory tests and on-site road paving. The test results show that under the same ambient temperature, the activated diatomite asphalt pavement has the advantages of lower surface temperature, high stability, and low-water permeability coefficient than SBS modified asphalt pavement. In addition, by fitting the fatigue test data of these two asphalt pavements, it is found that the fatigue life of diatomite asphalt mixture is more sensitive to the change in stress level and has better fatigue resistance. Therefore, it is concluded that the use of diatomite modified asphalt pavement in the loess area can improve the temperature stability of the pavement, prolong the service life, and reduce the cost of construction, which can be popularized. Full article

Based on the nonlinear piezomagnetic equation, the piezomagnetic effect of prismatic iron-cobalt alloy is analyzed by using the ANSYS finite element simulation platform. The variation of the dynamic piezomagnetic coefficient of the iron-cobalt alloy under different bias magnetic fields and different stress was studied through simulation. Referring to the working condition of the tractor force sensor and according to the principle of magnetic circuit superposition, a piezomagnetic force sensor was designed and manufactured using iron-cobalt alloy. According to the electromagnetic theory and piezomagnetic effect, the three-dimensional model and magnetic circuit mathematical model of the sensor are established, and the system simulation model of the piezomagnetic sensor was established based on the MATLAB/Simulink module. The experimental platform of the magnetostrictive force sensor was built to verify the correctness of the simulation model, and the effects of bias magnetic field and force on the output characteristics are studied. The simulation and experimental results show that the maximum piezomagnetic coefficient was 9.2 T/GPA when the bias magnetic field intensity was 14.74 kA/m. The force measuring range of the sensor is 0–120 kN, and the sensor has high sensitivity within 0–80 kN. The sensor has a simple structure, is suitable for the force measurement and control of an electro-hydraulic lifter under heavy load, and can better adapt to the harsh working environment. Full article

Collisions between ships and offshore platforms frequently occur, with severe consequences. Predicting the collision depth under different conditions is very important to evaluate the severity of the consequences. Considering the time-consuming numerical simulation problem and the accuracy problems of existing approximation algorithms, this paper proposes a comprehensive approach to estimating penetration depths by obtaining two collision coefficients for specific collision structures based on the partial results of numerical simulations and simplified theoretical analysis. In this study, the collision process between a supply ship with a transverse framing stern and an offshore semi-platform was first numerically simulated based on the explicit dynamic method. The changes in ship velocity, impact force, and energy conversion before and after the collision processes were obtained through numerical simulations of the collisions with different speeds and angles. Then, by combining the external dynamics and numerical results, the analytical results of dissipated energy under other collision conditions were obtained using a simulated restitution coefficient. For the following internal dynamics analysis, according to the failure modes of specific structural components in different regions, an appropriate structural energy absorption formula was combined to obtain the relationship between the penetrations and energy absorption in a particular collision area. According to the friction energy ratio derived by the simulation, the penetration depths in the offshore platform were calculated. The results showed that the deviations between the proposed method and direct simulation results were less than 15% in the cases of a medium- to high-energy collision. It can be concluded that the restitution coefficient and friction energy ratio in different collision conditions can be approximately determined for a specific collision system by typical numerical simulations, thus quickly calculating the penetration depths of other conditions. Full article

In this study, a functional relationship between the solid particle density $({\rho }_s)$, void ratio $\left(e\right)$, and dry density $({\rho }_d)$ of mechanically and biologically treated (MBT) municipal solid waste (MSW) was examined. In total, 60 waste specimens were tested with an air pycnometer device and corresponding triplets $(e, {\rho }_d,\mathrm{and}{\rho }_s)$ of values were obtained. In addition, a long-term oedometer test with an allowed decomposition process was also conducted. Based on the obtained results, the variability in the solid particle density caused by heterogeneity and decomposition, as well as its influence on the corresponding void ratio and dry density values, were critically evaluated. The obtained results showed that the variability in the solid particle density caused by waste heterogeneity had a significant influence on the initial void ratio value. Furthermore, the obtained results also showed that the change in the solid particle density, caused by the degradation process, had a significant impact on the final void ratio and dry density values. In addition, an empirical relationship, ${\rho }_d=f\left(e\right),$ was proposed. The proposed function allows a landfill operator to establish the corresponding dry density at an arbitrary chosen void ratio, and vice versa, without having the exact knowledge of the corresponding solid particle density value. Full article

The ammonothermal method is considered the most promising method of fabricating bulk gallium nitride (GaN) crystals. This paper improves the ammonothermal growth model by replacing the heater-long fixed temperature boundary with two resistance heaters and considering the real thermal boundary outside the shell. The relationship between power values and temperatures of dissolution and crystallization is expressed by the backpropagation (BP) neural network, and the optimal power values for specific systems are found using the non-dominated sorting genetic algorithm (NSGAII). Simulation results show that there are several discrepancies between updated and simplified models. It is necessary to build an ammonothermal system model with resistance heaters as a heat source. Then large-sized GaN crystal growth is analyzed based on the well-developed numerical model. According to the simulation results, both the increasing rate and maximum stable values of the metastable GaN concentration gradient are reduced for a larger-sized system, which is caused by the inhomogeneity of heat transfer in the autoclave. Full article

Ceramic foam filters (CFFs) are used to remove inclusions and/or solid particles from molten metal. In general, the molten metal poured on the top of a CFF should reach a certain height to form the pressure (metal head) required to prime the filter. For estimating the required metal head and obtaining the permeability coefficients of the CFFs, permeability experiments are essential. Recently, electromagnetic priming and filtration of molten aluminum with low and high grades of CFF, i.e., 30, 50 and 80 pore per inch (PPI) CFFs, have been introduced. Since then, there has been interest in exploring the possibility of obtaining further inclusion entrapment and aluminum refinement by using electromagnetic force to prime and filter with stacked CFFs. The successful execution of such trials requires a profound understanding concerning the permeability parameters of the stacked filters. Such data were deemed not to exist prior to this study. As a result, this study presents experimental findings of permeability measurements for stacks of three 30, three 50 and three 80 PPI commercial alumina CFFs from different industrial batches and compares the findings to numerically modelled data as well as previous research works. Both experimental and numerical findings showed a good agreement with previous results. The deviation between the experimentally and numerically obtained data lies in the range of 0.4 to 6.3%. Full article

This paper focuses on the frequency domain fluid–structure interaction (FSI) vibration characteristics of aircraft hydraulic pipe with complex constraints. The linear partial differential fourteen-equation model is applied to describe the nonlinear FSI dynamics of pipes conveying fluid with high-speed, high-pressure, a wide Reynolds number, and the vibration frequency range. The excitation, complex boundary, and middle constraint models of liquid-filled pipes are analytically established and added into the global model of the pipe system. These resulting models are solved by the improved Laplace transform transfer matrix method (LTTMM) in the frequency domain. Then, the dynamic response characteristics of an aircraft hydraulic pipe containing diverse constraints are investigated numerically and experimentally under four types of working conditions, and the improvement conditions for the numerical instabilities are presented. In general, the present method is highly efficient and convenient for rapid model parameter modifications, in order to be fully applicable to different pipe systems and analysis cases. The results reveal the complex resonant laws regarding aircraft hydraulic pipes with complex constraints in the broad frequency band, which can also provide theoretical reference and technical support for FSI vibration analysis and the control of aircraft hydraulic pipes. Full article

Compliant foil gas seal is a non-contact and high-efficiency sealing technology. The dynamic performance of compliant foil gas seal with different structure parameters was analyzed in this paper. These parameters include the seal diameter, gas film thickness and the ratio of groove. Compared with the rigid film, the advantage of compliant film is analyzed. The stability performance and dynamic performance with the different structures are obtained. The results show that the larger diameter is a disadvantage for the stability performance. However, the increase of seal length can decrease the leakage. Otherwise, the increase of gas thickness improves the dynamic characteristics with the leakage rising and gas force dramatically decreasing. While the groove length ratio is around 0.6, the seal performance and dynamic characteristics are best. The compliant structure benefits the improvement of the sealing performance. Full article

Natural gas hydrate (NGH) is a kind of unique resource among hydrocarbon fuels. It is stable within its sedimentary hosts and will only convert to its constituent gas and water phases relatively quickly if reservoir pressure-temperature conditions are artificially disturbed. The unwanted vibrations from the drill string with the complex external environment and excitation usually cause instability in the NGH. In this paper, a nonlinear mathematical model is presented taking into account the fluid–solid coupling vibration caused by the drilling fluid inside and outside the drill string, the non-smooth rub-impact between the drill string and borehole wall, and the influence of centralizer setting interval on nonlinear resonant vibration of the drill string. The relationship between the variable parameters of the drill string and the complex dynamics of the drill string is analyzed. Finally, the bifurcation diagram is given. The results show that the system response exhibits complex dynamic behavior due to rub-impact and nonlinear effects. However, there is always a suitable parameter in the bifurcation diagram of each parameter change, so that the amplitude of the system is small and the failure probability of the drill string is reduced. The research results have reference significance for exploring the nonlinear dynamic mechanism of a drill string under complex working conditions and reasonably optimizing drilling parameters. Full article

The use of corrugated webs in steel beams has become one of the most practical ways to increase the efficiency of beams in resisting loads, natural frequencies, and their resulting displacements. Such a practice has the benefit of achieving the same efficiency as beams with a flat web with a greater thickness. Consequently, the effect of the types of corrugated webs on the flexure mode shapes and natural frequencies in the steel beams has been investigated by analyzing 23 beams with flat and corrugated webs using the finite element (FE) numerical analysis technique. Hence, two flat web steel beams with and without stiffeners were experimentally tested and compared to FE numerical modeling results. Moreover, three types (trapezoidal, rectangular, triangular) of corrugated webs were tested and studied in addition to other parameters such as thickness, width, length, and angle. The investigation results show that FE numerical analysis is very highly accurate in predicting the natural frequencies and flexure mode shape changes of beams with corrugated webs. Accordingly, a saving of at least 33% in thickness could be realized as compared to the flat type. The triangular corrugated web is more efficient in the 1st mode shape, while rectangular is better for the other modes. The effectiveness of the angle for the triangular type in resisting mode shape and frequencies was clearly noticed, and decreases of 0.60 and 0.78, respectively, were recorded. It is also perceived that the effect of thickness and angle is linear for specified cases. Full article

The main aim of this research is to mathematically describe the influence of the processing parameters of metal foam production from machining chip waste. Using this method, metal foams were produced without a remelting step, which should be both economically and environmentally effective. Firstly, expensive metal powders were replaced with waste in the form of machining chips. Secondly, machining chip waste was recycled without any significant material losses, which usually occurs during conventional recycling (using the melting process). To describe the innovative process and to relate metal foam properties to foaming temperature, the blowing agent weight percentage, and foam density (controlled by foaming height), response surface methodology, and the design of experiments were used. The quality of the produced metal foams was evaluated by determination of density, yield strength, compression strength, plateau stress, energy absorption, pore perimeter, and pore inhomogeneity for specimens obtained following the experimental plan. It was proven that pore inhomogeneity increased in the range from 1.41 to 4.81 mm with a higher temperature and the addition of a foaming agent. However, higher energy absorption and yield strength were obtained with a higher temperature but a lower percentage of TiH₂. Despite the production from machining chips, pores were homogenous without significant cracks. These kinds of metal foams are comparable to commercial foams made of metal powders. Full article

A high sintering temperature is usually required to acquire excellent performance in the ceramic industry, but it results in high fuel consumption and high pollution. To reduce the sintering temperature and to toughen the porcelain, a self-produced sintering additive of citric acid activated kaolinite was added to the raw material; X-ray powder diffraction (XRD), transmission electron microscope (TEM), scanning electron microscope (SEM), and thermal gravity analysis and differential scanning calorimetry (TG-DSC) were used to characterize the samples, and the toughening mechanism was discussed. The citric acid activated kaolinite obtained high activity and a large specific surface area. After introducing the activated kaolinite, the bending strength of porcelain at 1270 °C increased from 100.08 MPa to 124.04 Mpa, which was 11.45% higher than that of porcelain without activated kaolinite at 1350 °C. The results of XRD revealed that the content of mullite increased and the quartz decreased at 1270 °C, and the well-distributed needle-like mullite was observed in the images of SEM with the addition of citric acid activated kaolinite. The TG-DSC results indicated adding activated kaolinite to porcelain raw materials reduced the formation of mullite to 994.6 °C. The formation of mullite in a lower temperature served as mullite seeds in a green body during firing, and it enhanced the growth of mullite. These contributed to the appropriate phase composition and the excellent microstructure of porcelain. Thus, the distinguished mechanical performance of porcelain was obtained. Moreover, the sintering additive had no adverse effect on the porcelain body as citric acid-activated kaolinite was one of the main components of the porcelain raw material. Full article

Charpy impact energy/impact toughness is closely related to external factors such as specimen size. However, when the sample size is small, the linear conversion relationship between the Charpy impact energy of the sub-size and full-size Charpy specimens does not hold; the Charpy impact toughness varies with the size of the specimen and other factors. This indicates that studying the internal influence of external factors on impact energy or impact toughness is the key to accurately understanding and evaluating the toughness and brittleness of materials. In this paper, the effects of strain rate on the flow behavior and the effects of stress triaxiality on the fracture behavior of 30CrMnSiNi2A high-strength steel were investigated using quasi-static smooth bar and notched bar uniaxial tensile tests and Split Hopkinson Tensile Bar (SHTP). Based on the flow behavior and strain rate dependences of the yield behavior, a modified JC model was established to describe the flow behavior and strain rate behavior. Charpy impact tests were simulated using the modified JC model and JC failure model with the determined parameters. Reasonable agreements between the simulation and experimental results have been achieved, and the validity of the model was proved. According to the simulation results, the impact energy was divided into crack initiation energy, crack stability propagation energy and crack instability propagation energy. On this basis, the effects of striker velocity and specimen width on the energy and characteristic load of each part were studied. The results show that each part of the impact energy has a negligible dependence on the hammer velocity, but there is a significantly different positive linear relationship with the width of the sample. The energy increment of each part also showed an inverse correlation with the increase in the sample width. The findings reveal that the internal mechanism of Charpy impact toughness decreases with the increase in sample width; to a certain extent, it also reveals the internal reason why the linear transformation relationship of Charpy impact energy between sub-size specimens and standard specimens is not established when the specimens are small. The analytical method and results presented in this paper can provide a reference for the study of the dynamic behavior of high-strength steel, the relationship between material properties and sample size, and the elastic–plastic impact dynamic design. Full article

A pressure-controlled jet crushing tool (PJCT) for the exploitation of deep-sea natural gas hydrate (NGH) was invented to achieve sediment crushing and cavity creation. The opening and closing of tool is controlled by changing the internal flow rate remotely. It can realize the controllable continuous switching of the working state between horizontal well drilling and cavity creation. A dynamic simulation model of the sliding core was established based on the innovative design scheme of the PJCT and the motion law of its slide core was analyzed under the influence of spring stiffness, friction coefficient, and flow rate loading scheme. Moreover, an engineering prototype of the PJCT was manufactured so that a sliding core motion experiment of the prototype was carried out. When the drilling fluid flow rate reaches 455 L/min, the PJCT can stably complete the self-locking and unlocking functions. Its sliding core needs more time to stabilize with an increase in spring stiffness. Meanwhile, the PJCT could achieve continuous fast switching between the mechanical drilling state and the jet crushing state within a cycle of continuous flow changes. Finally, the kinematic and dynamic working mechanism of the PJCT is verified by the combination of the numerical simulation and the experimental analysis above. Full article

A reactive sintering technique with a small addition of carbon (up to 1.9 wt.%) has been used for tungsten powder consolidation. The process allowed procurement of the nonporous and fully densified material at 1300 °C and 30 MPa in 12 min. The SEM and EDX analysis showed that the milling of 5 μm tungsten powder with 0.6, 1.3, and 1.9 wt.% of carbon in a planetary mill led to the formation of the nanostructured mix, which appears to be W-C nanopowder surrounding tungsten grains. X-Ray Diffractometry data indicated tungsten hemicarbide (W₂C) nucleation during the hot pressing of the milled powders. The exothermic reaction 2W + C → W₂C occurs during the sintering process and promotes charge densification. The Vickers hardness and indentation toughness of W-1.3 wt.%C composition reached 5.7 GPa and 12.6 MPa∙m^1/2, respectively. High toughness and high material densification allow proposing the W-WC₂ for use as a plasma-facing material in fusion applications. Full article

Products are manufactured as printed electronics through electro-conductive ink having properties suitable for flexible substrates. As printing process conditions affect the quality of the electronic properties of the final devices, it is essential to understand how the parameters of each process affect print quality. Spray printing, one of several printing processes, suits flexible large-area substrates and continuous processes with a uniform layer for electro-conductive aqueous ink. This study adopted the spray printing process for cellulose nanofiber (CNF)/carbon nanotube (CNT) composite conductive printing. Five spray parameters (nozzle diameter, spray speed, amount of sprayed ink, distance of nozzle to substrate, and nozzle pressure) were chosen to investigate the effects between process parameters and electrical properties relating to the morphology of the printing products. This study observed the controlling morphology through parameter adjustment and confirmed how it affects the final electrical conductivity. It means that the quality of the electronic properties can be modified by adjusting several spray process parameters. Full article

A numerical simulation was carried out to investigate the blood flow behavior (i.e., flow rate and pressure) and coupling of a renal vascular network and the myogenic response to various conditions. A vascular segment and an entire kidney vascular network were modeled by assuming one single vessel as a straight pipe whose diameter was determined by Murray’s law. The myogenic response was tested on individual AA (afferent artery)–GC (glomerular capillaries)–EA (efferent artery) systems, thereby regulating blood flow throughout the vascular network. Blood flow in the vascular structure was calculated by network analysis based on Hagen–Poiseuille’s law to various boundary conditions. Simulation results demonstrated that, in the vascular segment, the inlet pressure $P_{\mathrm{inlet}}$ and the vascular structure act together on the myogenic response of each individual AA–GC–EA subsystem, such that the early-branching subsystems in the vascular network reached the well-regulated state first, with an interval of the inlet as $P_{\mathrm{inlet}}$ = 10.5–21.0 kPa, whereas the one that branched last exhibited a later interval with $P_{\mathrm{inlet}}$ = 13.0–24.0 kPa. In the entire vascular network, in contrast to the $P_{\mathrm{inlet}}$ interval (13.0–20.0 kPa) of the unified well-regulated state for all AA–GC–EA subsystems of the symmetric model, the asymmetric model exhibited the differences among subsystems with $P_{\mathrm{inlet}}$ ranging from 12.0–17.0 to 16.0–20.0 kPa, eventually achieving a well-regulated state of 13.0–18.5 kPa for the entire kidney. Furthermore, when $P_{\mathrm{inlet}}$ continued to rise (e.g., 21.0 kPa) beyond the vasoconstriction range of the myogenic response, high glomerular pressure was also related to vascular structure, where $P_{\mathrm{GC}}$ of early-branching subsystems was 9.0 kPa and of late-branching one was 7.5 kPa. These findings demonstrate how the myogenic response regulates renal blood flow in vascular network system that comprises a large number of vessel elements. Full article

The integrated electric-hydraulic pump has the advantages of no leakage, compact structure, and low noise. Here, we propose a novel integrated electric-hydraulic vane pump (IEHVP) to solve the problem of low reliability of the existing ordinary axially arranged hydraulic oil source in the harsh deep-sea environments. IEVP combines an external-rotor brushless motor and a balanced vane pump. In order to obtain the external characteristic curve of the designed IEHVP, the theoretical analysis of coupling analysis between the operating characteristics of the electric motor and the vane pump is designed. The results reveal that the output flow of the proposed IEHVP increases linearly with the increase of the input voltage and decreases non-linearly as the outlet pressure increase. Finally, the proposed IEHVP is tested. The relationship between the output flow and volumetric efficiency and its outlet pressure and input voltage is obtained. The experimental results verify the characteristics of the proposed IEHVP design. Full article

Polyhydroxyalkanoates are a promising class of biopolymers that can allow the production of sustainable plastic materials. The mechanical properties of such materials are very important for possible industrial applications, but the amount of polymer required for common mechanical testing can be orders of magnitude more than what is possible to achieve with a lab-scale process. Nanoindentation with the Atomic Force Microscope allows an estimation of the Elastic Modulus that can be used as a preliminary measurement on PHA when only a limited amount of material is available. Poly(hydroxybutyrate-co-hydroxyvalerate) copolymers were analyzed, with moduli ranging from 528 ± 62 MPa to 1623 ± 172 MPa, according to both the composition and the crystallization kinetics. Full article

The aim of the present study is to investigate the role of Ti on corrosion and the wear properties of Mg-5Sn-xTi (x = 0, 0.15, 0.75, 1.5 wt.%) alloys. The samples were fabricated by conventional casting followed by hot extrusion, and the studies were examined by means of a pin-on-disc tribometer at various loads of 6, 10, and 20 N with constant sliding velocities of 0.04 m/s at ambient temperature. The corrosion performance, using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS), was studied in a basic solution containing 3.5 wt.% NaCl. The observation indicated a drop in the wear rate with an increase in Ti, while the average coefficient of friction was raised in higher Ti contents compared to the base material. The sample with 0.75 wt.% Ti exhibited superior wear properties at 6 and 10 N of normal force, while the sample with 0.15 wt.% Ti presented better wear resistance for 20 N. Electrochemical test observations demonstrated that the Ti deteriorated the corrosion features of the Mg-5Sn alloy, owing to the galvanic effects of Ti. The Mg-5Sn alloy exhibited excellent corrosion behavior (corrosion potential (E_corr) = −1.45V and current density (I_corr) = 43.92 A/cm²). The results indicated the significant role of Ti content in modulating wear and corrosion resistance of the Mg-5Sn alloy. Full article

Precipitate evolution during high temperature annealing plays an important role in the magnetic property of grain-oriented silicon steel but was rarely studied. Aluminum was one of the important components of precipitates. Grain-oriented silicon steels with three levels of aluminum content were prepared and the interrupted extraction experiments were carried out. The results showed that during high temperature annealing, the precipitates were polygonal with the main composition of (Al,Si)N. Both the distribution density and volume fraction of precipitates showed first increasing and then decreasing tendencies, while the precipitate size remained approximately constant at first and then increased. Aluminum had a significant effect on the density and volume fraction of precipitates, which resulted in different secondary recrystallization structures. A small amount of aluminum with 0.015 wt.% led to low precipitate density, resulting in a low onset secondary recrystallization temperature as well as a Goss texture with large deviation angles. With the aluminum content of 0.025 wt.%, the secondary recrystallization was developed exactly right in the optimum temperature range, resulting in a perfect magnetic property. When the aluminum content was overcommitted to 0.035 wt.%, Goss grains could not show the preferential growth advantage and the secondary recrystallization structure could not be well developed. Full article

A numerical simulation method is proposed to study the deformation and failure rule of granite with multi-directional tensile stress, based on the importance of the rock tension. This investigation took into consideration the fact that the current experimental equipment cannot complete multi-directional tension experiments for rock. The deformation and failure rule of the granite material model with biaxial and triaxial tensile stress are studied using the numerical simulation software CASRock. The results show that in a biaxial tensile stress state, the tensile strength of granite decreases with the increase in the confining pressure, but the influence of the compression confining pressure on the strength reduction is greater than the tensile confining pressure. The number of cracks generated during failure decreases with the increase in the compressive confining pressure, and the inclination angle of the failure surface increases with the increase in the compressive confining pressure. In the three-direction tension stress state, the tensile strength of granite decreases slightly with the increase in the compressive confining pressure. However, when the compressive confining pressure in one direction is close to the uniaxial tensile strength, the tensile strength of granite will decrease quickly, and the failure result is similar to that of the uniaxial tensile failure. Full article

The effect of grain size on the mechanical properties and creep rupture of 253 microalloyed (MA) austenitic stainless steel (ASS) was investigated. The cold rolling process with a 53% reduction in thickness was applied to the steel followed by annealing at 1100 °C over 0, 900, 1800, and 3600 s to obtain grain sizes of 32.4, 34.88, 40.35, and 43.77 µm, respectively. Uniaxial tensile and micro-Vickers hardness tests were carried out to study the effect of grain size on mechanical properties at room temperature. The creep rupture test was performed at 700 °C under a load of 150 MPa. The results showed that there was a correlation between grain size, mechanical properties, and creep rupture time. The fine initial grain size showed relatively good mechanical properties with a short creep rupture time, while the coarse initial grain size produced low mechanical properties with a long creep rupture time. The initial grain size of 40.35 µm was the optimum grain size for a high value of creep rupture time due to the low hardness and elongation values at room temperature and low creep ductility value. The intergranular fracture was found on the initial grain size below 40.35 µm, and a mixed mode of intergranular and transgranular fracture was found on the initial grain size above 40.35 µm after the creep rupture test. Full article

Bending deformation gives rise to interwire slippage for spiral strands subjected to multi-axial loads, and further induces wear or fatigue phenomena in practice. The interwire friction would resist bending deformation and lead to uneven tension distribution of individual constituent wires but little research has quantified these effects. To figure out this issue, a beam finite element (FE) is established, into which a penalty stiffness algorithm and a Coulomb friction model are incorporated. A series of free bending simulations are developed for parametric study on deflection near the terminations and tension distribution of individual wire for strands with different levels of length and friction coefficient as well as external loads. Based on the simulation results, it is found that strand length has little influence on bending deformation and tension distribution if the strand length exceeds six times the pitch length. A deflection formula extended from the classical Euler beam model well predicts the sag deflections and the relative error with respect to experimental measurements is less than 10%. Furthermore, additional axial tension induced by the friction is clearly characterized and an approximate expression is proposed to estimate tension distribution for outer layer wires. Its predictions are encouraging for longer strands. Full article

The vibration characteristics induced by radial hydraulic force on the fire turbopump have been investigated by numerical simulations in this paper. The numerical model was validated with corresponding experimental measurements. The turbopump has the special structure with two hydraulic machineries of a turbine and a pump. The hydraulic force characteristics on the separate turbine and the separate pump were first studied. There is one period in the force variation for one cycle of impeller rotation, and pressure fluctuations are observed in 15 times and 30 times the shaft rotating frequency of the turbine. Meanwhile, there are five periods in the force fluctuation in one full working cycle, and obvious fluctuation amplitudes on 5 times, 10 times and 15 times the shaft rotating frequency of the pump are found. Then, the coupled effect of force fluctuations on the turbine and pump was explored. For the turbopump, the periodicity of force fluctuation in the time domain and force characteristics in the frequency domain are dominated by pump structure. The hydraulic force fluctuation on the impeller is enhanced, while that on the housing is damped by counteracting the forces between turbine suction and pump volute. Full article

In order to explore the reasonable ore blending of low-silicon magnetite in sintering, it I necessary to realize the efficient utilization of low-silicon ore, further reduce cost, and increase yield. In this study, based on the high-temperature basic characteristics of iron ore powder used in the experiment, sinter pot tests were carried out with different low-silicon ore ratios, and the microstructure of the sinter was observed by scanning electron microscopy (SEM) and energy spectrum analysis (EDS) to determine the optimal matching law of low-silicon ore. The result showed that SiO₂, Al₂O₃, and burning loss in iron ore powder composition were positively correlated with its assimilation, whereas MgO and basicity R₂ were negatively correlated with the assimilation of iron ore powder. When the ratio of low-silicon ore was not more than 35%, increasing the ratio of hematite improved the liquid production and increased the production of acicular calcium ferrite. Therefore, the optimization of ore blending based on assimilation can improve the quality of sinter and strengthen the sintering process. This study has certain reference significance for the industrial production of low-silica sintering. Full article

The effect of Nb-content and heat input rate on the mechanical properties and microstructure of simulated coarse-grained heat-affected zone (CGHAZ) of high-strength low-alloy steel (HSLA) was investigated. While using a low heat input (20 kJ/cm), the toughness of simulated CGHAZ was improved by increasing the Nb-content. The maximum toughness was obtained when the Nb-content was 0.110 wt.% and the heat input was 20 kJ/cm. The samples made at this condition had fine martensite/austenite (M/A-constituent), acicular ferrite and refined austenite grains. As the heat input was increased to 200 kJ/cm, the toughness of simulated CGHAZ was significantly decreased irrespective of the Nb-content because of the formation of coarse austenite grains, low angle grain boundaries, and massive M/A-constituents. Full article

The investigation into the circumferential mechanical properties of tubular materials has been receiving increasing attention, since the tube hydroforming process has been used in the tubular materials forming field, because the circumferential mechanical properties have a significant effect on the hydroformability of the tubular materials. In the present study, a method for evaluation of the circumferential mechanical properties of the tubular materials with the flaring test was proposed. The expressions for the yield stress, strain hardening coefficient and exponent values of the tube were successfully derived based on the geometrical and mechanical relationships in the tube flaring test. To verify the reliability of this method, the calculated results of the yield stress, strain hardening coefficient and exponent values, obtained from the newly proposed method, were compared to the ones obtained with the conventional tensile tests. It was found that the method proposed in the current study is reliable, with high accuracy. The method is appropriate to evaluate the circumferential mechanical properties of the tubular materials. Full article

Under irradiation, dispersion nuclear fuel meat consists of a three-phase composite of fuel particles surrounded by an interaction layer dispersed within a metal matrix. Nonuniform swelling pressures are exerted on the matrix, generated by irradiation swelling of the fuel particles. As these are considerable, they can cause matrix failure, but they are difficult to calculate. In this paper, taking into account thermal expansion, nonuniform fission pores and the interaction layer, nonuniform irradiation swelling pressure has been formulated, based on the equivalent inclusion method. By means of doubly equivalent transformations, a porous fuel particle, surrounded by an interaction layer, which is under irradiation, can be simplified as a homogeneous particle with the eigenstrain. With the aid of Green’s function, nonuniform irradiation swelling pressure can be numerically analyzed. The simulation results of swelling pressures are in good agreement with numerical calculations. Furthermore, several simplified examples have been given to investigate the factors of influence and the impact mechanisms. Conclusions are drawn that nonuniform irradiation swelling pressure can be analyzed numerically and adopted to explore matrix failure. It is identified that the number and locations of fission pores inside a fuel particle are key factors for nonuniformity of swelling pressures. The volatility of swelling pressures is aggravated by burnup, while the average values of swelling pressures are intensely affected by temperature. This work provides a perspective to investigate the strength and integrity of dispersion fuel meat under high burnup. Full article

Emergency generators normally use diesel engines. The generators need to conduct weekly no-load operation inspections to ensure stable performance in emergency situations. In particular, the generators with large diesel engines mainly use rectangle-type filter substrates. To minimize hazardous emissions generated by generators, optimizing the reduction efficiency through computational fluid dynamics (CFD) analysis of flow characteristics of particulate matter (PM)/NO_X reduction system is important. In this study, we analyzed internal flow by CFD, which is difficult to confirm by experimental method. The main factors in our numerical study are the changes of flow uniformity and back pressure. As a result, the flow distribution characteristics according to the cross-sectional shape are similar at high engine loads. Spraying urea in the reverse direction increases static pressure, greatly improving flow uniformity. Raising the selective catalyst reduction (SCR) diffuser angle to 30 degrees improves both back pressure and flow uniformity characteristics, and when the porosity increases, both flow uniformity and back pressure decrease. Full article

The Qinghai–Tibet railway is the plateau permafrost railway with the highest altitude and the longest line in the world. The natural conditions along the line are harsh, with many unfavorable factors such as low temperature, strong ultraviolet radiation, and large changes in daily temperature, resulting in frequent bridge damage. In order to study the bridge temperature field and its effect in the permafrost region of the Qinghai–Tibet railway, a long-term field test was carried out, and a calculation model of sunshine temperature field of concrete two-piece T-beam was established based on the principle of meteorology and heat transfer. On this basis, the beam temperature difference load mode, beam section temperature distribution law, and temperature effect were obtained. As revealed, the daily temperature difference of the Qinghai–Tibet railway bridge is large in winter, which is related to the ground’s effective radiation and surface reflectivity, and the maximum value has exceeded the current codes. The beam section temperature field shows “internal heat and external cold” in the morning and “internal cold and external heat” from noon to evening. Under the action of strong radiation and large temperature difference, bridge displacement occurs frequently, by which it is easy to cause damage to rail fasteners and bridge bearings. Based on the field test and finite element analysis, the bridge temperature difference load mode was proposed, which makes up for the deficiency that the relevant codes do not consider the plateau’s special climatic conditions and can provide a reference for the construction of plateau railways such as the Sichuan–Tibet railway. Full article

Hardenability is one of the most basic criteria influencing the formulation of the heat treatment process and steel selection. Therefore, it is of great engineering value to calculate the hardenability curves rapidly and accurately without resorting to any laborious and costly experiments. However, generating a high-precision computational model for steels with different hardenability remains a challenge. In this study, a combined machine learning (CML) model including k-nearest neighbor and random forest is established to predict the hardenability curves of non-boron steels solely on the basis of chemical compositions: (i) random forest is first applied to classify steel into low- and high-hardenability steel; (ii) k-nearest neighbor and random forest models are then developed to predict the hardenability of low- and high-hardenability steel. Model validation is carried out by calculating and comparing the hardenability curves of five steels using different models. The results reveal that the CML model works well for its distinguished prediction performance with precise classification accuracy (100%), high correlation coefficient (≥0.981), and low mean absolute errors (≤3.6 HRC) and root-mean-square errors (≤3.9 HRC); it performs better than JMatPro and empirical formulas including the ideal critical diameter method and modified nonlinear equation. Therefore, this study demonstrates that the CML model combining material informatics and data-driven machine learning can rapidly and efficiently predict the hardenability curves of non-boron steel, with high prediction accuracy and a wide application range. It can guide process design and machine part selection, reducing the cost of trial and error and accelerating the development of new materials. Full article

The physical and chemical properties of the CaO–SiO₂–Al₂O₃–MgO slag system depend on structure evolution caused by the synergistic mechanism among the components at high temperature, especially the structural complexity of the anion group. In this study, Si–O, Al–O, and Al–Si–O anion groups were found in the high-temperature slag systems at 1773 K. The [Si₂O₅]²⁻ (Q₃) structural unit of the silicate polymer changed to [Si₂O₆]⁴⁻ (Q₂), [Si₂O₇]⁶⁻ (Q₁), and [SiO₄]⁴⁻ (Q₀) as the binary basicity (R₂) and ω(MgO)/ω(Al₂O₃) increased, while there was a trend toward a simplified structure. That is, the stability of each structural unit weakened, and the relative content of non-bridging oxygen increased. As a result, the degree of polymerization of slag decreased, and the experimental results of the relative content of non-bridge oxygen can be fitted well with the calculations from the reference documents. At the same time, the number of Si–O–Al structural units gradually decreased. The ²⁷Al-MAS-NMR spectroscopy results showed that the structure of aluminate changed from [AlO₄]⁵⁻ tetrahedral structure to [AlO₅]⁷⁻ pentahedral and [AlO₆]⁹⁻ octahedral structure, and the degree of polymerization of the slag decreased. Comprehensive analysis showed that basicity controlled within 1.2 with the ω(MgO)/ω(Al₂O₃) ratio; less than 0.55 allows for suitable fluidity and energy-saving ability, which is beneficial for the stable and smooth production of the blast furnace. Full article

Young’s modulus is a key parameter of materials. The method of its calculation in the current paper is concerned with the mismatch of the mechanical impedance at the bar/specimen interface for a compression SHPB (split Hopkinson pressure bar) test. By using long and thin specimens, the signal recorded in the transmission bar presents itself as a multistep signal. The ratio between the heights of two successive steps represents the experimental data that are considered in the formula of the elastic modulus this article is devoted to. The oscillatory nature of the real signals on the horizontal or quasi-horizontal segments prevents a precise determination of the two successive step heights ratio. A fine tuning of this value is made based on the characteristic time necessary for the signal to rise from one level to the next one. The FEM (Finite Element Method) simulations are also used in calculation of the Poisson coefficient of the tested complex concentrated alloy. Full article

This paper investigated the influence of deep cryogenic treatments (DCT) on the tensile strength, elongation to fracture and conductivity of a deformation-processed Cu-Ni-Co-Si alloy. The tensile properties were measured using a mechanical testing machine. The conductivity was evaluated using a low-resistance tester. The microstructure and precipitated phases were analyzed using scanning electron microscopy (SEM), transmission electron microscopy (TEM), an energy dispersive spectrometer (EDS) and an X-ray diffractometer (XRD). The tensile strength, elongation to fracture and conductivity of the Cu-1.34Ni-1.02Co-0.61Si alloy before and after cold rolling at 47% reduction increased with increasing DCT time and tended to be stable at about 36 h. The microstructure became more uniform after the DCT. The grain size was refined and was smallest after DCT for 48 h. The DCT promoted the precipitation of the solid solution elements Ni, Co and Si from the Cu matrix to form many fine and evenly distributed 20–70 nm spherical second-phase particles in the grains and grain boundaries. Full article

Silicon carbide (SiC) is a promising structural and cladding material for accident tolerant fuel cladding of nuclear reactor due to its excellent properties. However, when exposed to severe environments (e.g., during neutron irradiation), lattice defects are created in amounts significantly greater than normal concentrations. Then, a series of radiation damage behaviors (e.g., radiation swelling) appear. Accurate understanding of radiation damage of nuclear materials is the key to the design of new fuel cladding materials. Multi-scale computational simulations are often required to understand the physical mechanism of radiation damage. In this work, the effect of neutron irradiation on the volume swelling of cubic-SiC film with 0.3 mm was studied by using the combination of molecular dynamics (MD) and rate theory (RT). It was found that for C-vacancy (C_V), C-interstitial (C_I), Si-vacancy (Si_V), Si-interstitial (Si_I), and Si-antisite (Si_C), the volume of supercell increases linearly with the increase of concentration of these defects, while the volume of supercell decreases linearly with the increase of defect concentration for C-antisite (C_Si). Furthermore, according to the neutron spectrum of a certain reactor, one RT model was constructed to simulate the evolution of point defect under neutron irradiation. Then, the relationship between the volume swelling and the dose of neutrons can be obtained through the results of MD and RT. It was found that swelling typically increases logarithmically with radiation dose and saturates at relatively low doses, and that the critical dose for abrupt transition of volume is consistent with the available experimental data, which indicates that the rate theory model can effectively describe the radiation damage evolution process of SiC. This work not only presents a systematic study on the relationship between various point defect and excess volume, but also gives a good example of multi-scale modelling through coupling the results of binary collision, MD and RT methods, etc., regardless of the multi-scale modelling only focus on the evolution of primary point defects. Full article

Considering the effect of the bridge deck’s bending stiffness and the indirect effect of adjacent cables (CEB), this paper aims to propose a refined model to reliably analyze the complex internal resonance mechanism of the tower–multicable–beam coupled system (MCS) under nonlinear geometric conditions. To accurately analyze the dynamic behavior, the shear difference effect is applied to simulate the continuous rigidity of the single beam. The dynamic equations of the whole resonance system are derived based on the D’Alembert Principle and the Finite Difference Method, the Galerkin Method and verified by the case study. The results of the numerical simulation based on the Fourth Runge–Kutta Method show that the dynamic parameter of each component is closely related to the coupled resonance of the system. The dynamic behavior under two conditions, tower–cable 1:1 resonance (TCR) or cable–beam 1:2 resonance (CBR), is deeply analyzed. Additionally, the excitation effect of the maximum amplitude by two excitation approaches, the initial displacement or initial velocity, both show a linear increase. The mutual transmission process of vibration excitation on the cable through the bridge beam or the tower as the medium is also further discussed. Full article

In this paper, an improved rotor structure with cross-shaped flux-barriers was proposed to improve the torque output capacity and reduce the torque ripple of the synchronous reluctance motor (SynRM). Firstly, an improved rotor structure of synchronous reluctance motor with cross-shaped flux-barriers, which can be described by two main parameters, is presented. Second, the improved motor is qualitatively analyzed by using magnetic equivalent circuit (MEC), and then the effects of the main parameters of the improved flux-barriers on the distribution of air-gap flux density, average torque, and torque ripple were analyzed by using the finite element method. Based on the above analysis, the rotor structure parameters of the proposed cross-shaped flux-barriers were obtained, and the performance was compared with that of the initial motor. The results show that the proposed rotor structure with cross-shaped flux-barriers can significantly reduce the torque ripple and increase the average torque. Full article

An in situ tensile test of the ring-rolled GH4169 alloy is performed to investigate the plastic deformation behavior at the micro level. Slip system activations are identified by slip traces captured by a scanning electron microscope and lattice orientation data acquired by electron backscattered diffraction. Our results demonstrated that the fraction of low-angle grain boundaries gradually increased upon tensile deformation, and the misorientation evolution in the grain interior was severely inhomogeneous. The Schmid factors at the grains of interest are calculated for comparison with the actual activated slip systems. Most of the slip system activation coincides with the Schmid law, as opposed to the initiation of other potential slip systems at some grains. Full article

The zigzag (ZZ) classifier is a sorting and classification device with a wide range of applications (e.g. recycling, food industry). Due to the possible variation of geometry and process settings, the apparatus is used for various windows of operation due to the specifications of the separation (e.g. cut sizes from 100 µm to several decimetres, compact and fluffy materials as well as foils). Since the ZZ classifier gains more and more interest in recycling applications, it is discussed in this paper, with regards to its design, mode of operation, influencing parameters and the research to date. Research on the ZZ-classifier has been ongoing on for more than 50 years and can be divided into mainly experimental studies and modelling approaches. Full article

This paper investigates the effects of disc deformation on the tilting-induced vibration of a splined spinning disc with axial-fixed boundaries.The purpose is to provide an intuitive interpretation of the vibration variance of the wet clutch system with different deformed discs. First, tilting models of flat and deformed discs are derived by introducing distinctive shape functions. Additionally, the inner spline interface is chosen as the friction boundary. Then, an impact model between friction pairs and the rigid boundary is established by adopting Hertz’s contact theory. Finally, the dynamic equations are solved via numerical methods, and the responses are analyzed in both time and frequency domains. The deformation can increase the nonlinearity of the dynamic response of the spinning disc. Moreover, the effects of increasing the impulse force and reducing the boundary distance are quite similar; they both increase the motion intensity. Full article

Non-thermal endovenous ablations, due to the lowest probability of complications, are the new method of treating chronic venous insufficiency—one of the most common diseases globally. The Flebogrif system (Balton Sp. z o.o., Warsaw, Poland) is a new mechano-chemical ablation system causing the mechanical damage of endothelium that allows for better sclerosant penetration into its wall. The purpose of the article is to provide mechanical characteristics in the form of force–displacement dependence for a single cutting element, and a bundle of cutting elements of Flebogrif as a whole for different levels of protrusion of the bundle of cutting elements. A TA.HD plus (Stable Micro Systems, Godalming, UK) analyzer equipped with special handles, was used for characteristics testing. The head movement speed used was 5 mm·s⁻¹. The Flebogrif system was tested for three cutting element protrusion levels: L = L_max, L = 0.9·L_max, and L = 0.8·L_max. Before testing, geometric measurement of the spacing of the cutting elements for three proposed protrusions was performed. It was established that decreasing the working length of the cutting elements will increase their rigidity, and, as a result, increase the force exerted on the internal surface of the vein wall. The obtained characteristics will allow for specifying contact force variability ranges and the corresponding diameter ranges of operated veins. Full article

During the thermal sintering of metal nanoparticles (NPs) the process temperature plays the most important role in the outcome of the sintering results and the selection of a suitable substrate. Here, temperature calculation during pulsed laser sintering of silver (Ag) nanoparticles (NPs) inkjet-printed on glass substrates is presented. During the pulsed laser sintering of Ag NPs, a minimum line resistivity less than twice the bulk silver resistivity was obtained within around 52 s under a laser power of 276 mW. The temperature field during the pulsed laser sintering of Ag NPs was estimated via a three-dimensional numerical model in which a temperature-dependent thermal conductivity of Ag NPs was adopted. An algorithm for treating the thermal conductivity of the heated Ag NPs in a region by a previous laser shot was devised for the improvement of the temperature field estimation. A maximum temperature of approximately 204 °C over the Ag NPs line was obtained with a 276 mW laser power and a scanning speed of 135 μm/s. Full article

Axial extrusion-connection technology is one of the important connection technologies for hydraulic piping systems, with high sealing performance and mechanical strength. In this paper, the finite-element-modeling method is used to simulate the experimental process of the connection strength of the axial extrusion joint. The generation mechanism and calculation method of the connection strength are analyzed. To optimize the joint strength, orthogonal testing and grey correlation analysis are used to analyze the influencing factors of joint strength. The key factors affecting joint strength are obtained as the friction coefficient ${\mu }_1$, ${\mu }_2$ between joint components and the groove angle ${\theta }_1$ of the fittings body. The back-propagation (BP) neural-network algorithm is used to establish the connection-strength model of the joint and the genetic algorithm is used to optimize it. The optimal connection strength is 8.237 kN and the optimal combination of influencing factors is 0.2, 0.4 and 76.8°. Compared with the prediction results of the neural-network genetic algorithm, the relative error of the finite-element results is 3.9%, indicating that the method has high accuracy. The results show that the extrusion-based joining process offers significant advantages in the manufacture of high-strength titanium tubular joints. Full article

As is well known, hydrotalcite-like compounds, such as layered-double-hydroxide (LDH) materials, have shown great potential applications in many fields owing to their unique characteristics, including a higher anion exchange capacity, a structure memory effect, low costs, and remarkable recyclability. While the lower surface area and leaching of metal ions from LDH composites reduce the process efficiency of the catalyst, combining LDH materials with other materials can improve the surface properties of the composites and enhance the catalytic performance. Among organic compounds, carbon materials can be used as synergistic materials to overcome the defects of LDHs and provide better performance for environmental functional materials, including adsorption materials, electrode materials, photocatalytic materials, and separation materials. Therefore, this article comprehensively reviews recent works on the preparation and application of layered double-hydroxide-based carbon (LDH–C) composites as synergistic materials in the field of environmental remediation. In addition, their corresponding mechanisms are discussed in depth. Finally, some perspectives are proposed for further research directions on exploring efficient and low-cost clay composite materials. Full article

Glass-fiber reinforced polymer (GFRP) bars are increasingly widely used in slope support instead of steel bars or steel pipes. GFRP Bars are generally connected with the slope by combining conical nut and tray, but the tray stress still lacks corresponding theoretical calculation and strength verification methods. Therefore, assuming that the tray is an equal thickness thin plate, the internal force distribution of the tray is calculated using the thin plate bending and cavity expansion theory, and compared with the finite element numerical analysis results of the tray. The calculation and analysis show that the elastic theoretical solution of internal force distribution of equal thickness tray is basically the same as the numerical simulation solution of variable thickness tray. The tray loading and free surface are controlled by hoop tensile and radial compressive stress, respectively. The inner wall of the free surface of the tray is the weakest part of the tray, and the ultimate strength of a GFRP tray is 35.81–53.00% of the standard tensile strength of Φ20 GFRP bars by distortion energy density. This theoretical method can be used for stress analysis of variable thickness trays and has played technical support for promoting the application of GFRP bars in slope support. Full article

As a typical third-generation semiconductor material, silicon carbide (SiC) has been increasingly used in recent years. However, the outstanding performance of SiC component can only be obtained when it has a high-quality surface and low-damage subsurface. Due to the hard–brittle property of SiC, it remains a challenge to investigate the ductile machining mechanism, especially at the nano scale. In this study, a three-dimensional molecular dynamics (MD) simulation model of nanometric cutting on monocrystalline 3C-SiC was established based on the ABOP Tersoff potential. Multi-group MD simulations were performed to study the removal mechanism of SiC at the nano scale. The effects of both cutting speed and undeformed cutting thickness on the material removal mechanism were considered. The ductile machining mechanism, cutting force, hydrostatic pressure, and tool wear was analyzed in depth. It was determined that the chip formation was dominated by the extrusion action rather than the shear theory during the nanocutting process. The performance and service life of the diamond tool can be effectively improved by properly increasing the cutting speed and reducing the undeformed cutting thickness. Additionally, the nanometric cutting at a higher cutting speed was able to improve the material removal rate but reduced the quality of machined surface and enlarged the subsurface damage of SiC. It is believed that the results can promote the level of ultraprecision machining technology. Full article

Gear transmission system dynamic responses under high-speed and heavy-duty working conditions were obviously affected by support structures, especially in lightweight design. However, web thicknesses and angles were usually ignored in dynamic modeling process. Therefore, a full mesh model with web structure was built and its dynamic characteristics were analyzed by a modified vector form intrinsic finite element (VFIFE), which is proposed to solve high-speed dynamic problems with good efficiency. For spiral bevel gear pair dynamic characteristics, the impacts of web thicknesses and angles were simulated and discussed. Simulation results showed that web support angles will affect gear meshing performance and dynamic characteristics more remarkable than web thickness did. In addition, the good performance of the proposed modified VFIFE method was proved, which showed good computing efficiency. Full article

During the process of deep drawing of cylindrical thin-walled products from aluminum sheets, the occurrence of product defects in the form of breaking the material continuity is observed. This has a very large impact on the efficiency of production lines and the number of generated scraps. The number of defects depends on many factors, including the material and the process properties. Because the problem appears after changing one material to another, while the process parameters do not change, it was assumed that the material has the main influence on the number of defects. To reduce the number of defects, a tool is needed to predict threats to the process. Decision tree models were used for this purpose. Using the tree interaction algorithms, the influence of the chemical composition and strength parameters of the 3xxx series aluminum alloy on the number of generated defects was investigated. Increased Silicon (Si) and Iron (Fe) values generated a higher number of defects. Increased yield strength (YS) and decreased elongation (E) also generated a higher number of defects. Based on the results, a defect prediction tool was created, where after entering the parameters of the material, it is possible to predict production hazards. Full article

Cu-0.4Cr (wt.%) alloys with the microalloying of Hf elements were subjected to a modified rolling–aging process to achieve high strength, high electrical conductivity and high ductility simultaneously. Transmission electron microscopy and X-ray line broadening analysis were conducted to characterize the microstructures of these alloys. Deformation twins and high-density dislocations were introduced into the copper alloys via the modified rolling–aging process and the microalloying of Hf, improving the mechanical properties of copper alloys. The Cu-Cr-Hf alloy with a reduced Hf content performed well in terms of strength, electrical conductivity and ductility. The microalloying of 0.4 wt.% Hf in the Cu-0.4Cr alloy was sufficient to achieve a good combination of high tensile strength (593 MPa), high uniform elongation (~5%) and high electrical conductivity (80.51% IACS). Full article

Claw pole machines (CPMs) have the advantages of a simple structure and low cost; therefore, they are commonly used in electric vehicles (EV). However, the methods to improve reliability and efficiency should be studied. So, a new type of hybrid excitation claw pole machine (HE-CPM) for EV is proposed. The permanent magnet (PM) is inserted in the rotor, and the field winding is placed on the front and back ending cover. Because the hybrid flux path of the proposed machine is three-dimensional (3D) and 3D finite element analysis (FEA) is time-consuming, a 3D magnet equivalent circuit (MEC) method considering rotor position is proposed and results between 3D MEC and FEA are compared. Particle swarm optimization (PSO) and 3D MEC are combined in the optimization design of HE-CPM. The optimized results prove the effectiveness of the optimization method. Finally, the flux density distribution, electromagnetic characteristics of HE-CPM are evaluated. The thermal analysis and mechanical stress analysis are carried out. The HE-CPM prototype was manufactured. The direct current (DC) bus voltages under different excitation currents and load currents are measured and compared with those of FEA. When the armature current and the excitation current are 7 A and 4 A, respectively, the rated power and rated speed of HE-CPM are 10.28 kW and 3000 rpm, respectively. The maximum efficiency is 89%. FEA results are basically consistent with the experimental results. Accurate results and time savings can be achieved by combining PSO and 3D MEC. Full article

Voronoi tessellations are shown to be statistically representative of polycrystalline microstructures, which have been widely accepted for the modeling of microstructures of metallurgic and ceramic materials. In this paper, a new implementation of the Voronoi diagram in Laguerre geometry is presented for the generation of numerical models of polycrystalline microstructures, where the size and shape of the grains can be controlled, and the 3D grain boundaries can be modeled with a specified thickness. The distribution of grain sizes in the models is fitted to a lognormal distribution, compared with the normal distribution in the Voronoi tessellation methods. Finally, statistical analyses of grain face and grain size distribution are performed with the models, and the macroscopic elastic properties of polycrystalline ceramic materials are simulated to verify the capability of the presented method. Full article

Due to the high density of grain boundaries (GBs), nanocrystalline metals possess superior properties, including enhanced strength, work hardening, and fatigue resistance, in comparison to their conventional counterparts. The expectation of GB migration is critical for grain coarsening and GB annihilation in these materials, significantly affecting the polycrystalline network and mechanical behavior. Here, we perform molecular dynamics (MD) simulations on gold (Au) nanocrystals containing multiple parallelly arranged GBs, with a focus on the investigation of annihilation mechanisms of low-angle grain boundaries (LAGBs). It is observed that the shear-coupled motion of LAGBs, consisting of dislocations, gives rise to their preliminary migration with the reduced separation distance between GBs. With subsequent GB motion, the LAGBs encountered with neighboring GBs, and can be annihilated by various mechanisms, including dislocations interpenetration, dislocations interaction, or dislocations absorption, depending on the specific configuration of the neighboring GB. These findings enhance our understanding of GB interactions and shed light on the controlled fabrication of high-performance nanocrystalline metals. Full article

In the present paper, the medium-C Si-rich steel with a quenched martensite microstructure was heated to intercritical annealing temperatures at 750 °C, 760 °C and 770 °C after warm rolling deformation to obtain ferrite with varying volume fractions. Subsequently, bainite/ferrite multiphase microstructures were attained via austempering near Ms temperature. The microstructures of the test steel after different heat treatments were characterized by scanning electron microscopy, transmission electron microscopy and electron backscatter diffraction, and corresponding tensile and impact properties were tested. The results showed that, with the increase of intercritical annealing temperature, the austenite content increased, which limited the growth of ferrite grains, and the grain size decreased from ~1.6 μm to ~1.4 μm. In addition, the degree of ferrite recrystallization was almost complete. At the same intercritical annealing temperature, compared with austempering above Ms, prior athermal martensite (PAM) was obtained after austempering below Ms, which effectively refined the size of bainite ferrite lath. Moreover, with the increase of intercritical annealing temperature, the bainite content of the test steel increased after austempering, resulting in the increase of yield strength, tensile strength and impact energy. In contrast, while the decrease in ferrite content led to a significant decrease in uniform elongation. At constant intercritical annealing temperature, the tensile strength decreased slightly, and the impact property improved after austempering above Ms. Full article

The nonlinear deformation, visco-elasto-plasticity and other macroscopic properties of soil are the concentrated manifestations of its microstructural state. In order to study the microstructural characteristics and variations of the clay under the action of additional stress caused by groundwater exploitation, borehole sampling was carried out on the clay layers at different depths in a typical land subsidence area. Consolidation tests, freeze-drying, ion sputtering, and scanning electron microscope (SEM) were conducted in order to scan and analyze the microstructure of the test samples at different scales. The Particles and Cracks Analysis System (PCAS) was used to quantify the microscopic parameters, the variations of the microstructural parameters with consolidation loads at different sizes were revealed, and the correlation between the macroscopic and microscopic parameters were discussed. The results show that: (1) the microstructural characteristics of soils with different buried depths have directivity, to a certain extent; (2) as the consolidation load increases, the average unit area and average form factor of the soil microstructure generally decrease, the structural arrangement of the unit gradually tends to be orderly, and the average pore area, apparent void ratio and the number of pores generally show a decreasing trend; (3) under the action of a consolidation load, when the microstructure at a relatively large scale is basically stable, the microstructure at a smaller scale will continue to adjust; (4) the apparent void ratio has a good linear regression relationship with the conventional void ratio, and the apparent void ratio has a good exponential growth relationship with the compressibility. Full article

Very high fluence implantation of ${}^{14}$N${}^{+}$ ions was used to promote the formation of a nitride layer on the surface of steel coinage dies used by the Portuguese Mint. Die steel samples were studied before and after implantation at 90 keV plus 30 keV for two nominal fluences, 5.0 × 10${}^{17}$ at/cm${}^2$ and 1.0 × 10${}^{18}$ at/cm${}^2$, and for two implantation temperatures, room and liquid nitrogen temperature. Surface characterization was carried out by ultramicrohardness indentation, Atomic Force Microscopy (AFM), and Rutherford Backscattering Spectrometry (RBS). A significant increase (factor two) in depth reached by the implanted nitrogen was observed for LN2 implantations, which, to our knowledge, was never reported before. Results point out the benefit of nitrogen implantation at room temperature with a nominal fluence of 5.0 × 10${}^{17}$ at/cm${}^2$, which raised the hardness of the dies by ∼40% (from 6.2 ± 0.5 to 8.7 ± 0.7 GPa). Nitrogen implanted dies were used to mint circulating two cents euro coins and their performance was assessed, showing that when compared to Vautrol coated dies (standard coating used by the Portuguese Mint), the crack density was lower and similar wear resistance was observed. Full article

Honeycomb aluminum structures are used in energy-absorbing constructions in military, automotive, aerospace and space industries. Especially, the protection against explosives in military vehicles is very important. The paper deals with the study of selected aluminum honeycomb sandwich materials subjected to static and dynamic compressive loading. The used equipment includes: static strength machine, drop hammer and Split Hopkinson Pressure Bar (SHPB). The results show the influence of applied strain rate on the strength properties, especially Plateau stress, of the tested material. In each of the discussed cases, an increase in the value of plateau stresses in the entire strain range was noted with an increase in the strain rate, with an average of 10 to 19%. This increase is mostly visible in the final phase of structure destruction, and considering the geometrical parameters of the samples, the plateau stress increase was about 0.3 MPa between samples with the smallest and largest cell size for the SHPB test and about 0.15 MPa for the drop hammer test. Full article

Drive and conveyor belts are widely used in the mining and processing industry. One of the types often used is the belt with a cross-section and a diameter of several millimeters, made of weldable thermoplastic elastomer. Their production process requires the joining of the ends to obtain a closed loop. This operation is often performed by butt welding using the hot plate method. Taking into account the industrial requirements, the authors made an effort to design the automated welding machine for this type of belt. The work that had been conducted was finished with the implementation of the device for serial belt production. One of the stages of the design process of the welding machine consisted of developing a solution for the electromechanical drive system. The paper presents a design and the selection of the key components of the drive system, in particular, the electrical executive elements. Firstly, on the basis of the functional requirements of individual working mechanisms, the kinematic structure of the drives was developed, and the influence of the workload on power consumption was described. Then, using known technological parameters, experimental research of the plasticization operation was performed. On the basis of the results obtained, a mathematical model of the correlation between the plasticization force and technological parameters was derived. Using the derived model, the optimization of the technological parameters was made by using a genetic algorithm. The work led to the choice of an effective electric motor, which is the main component of the designed drive system. Full article

The electronic, mechanical and transport properties of the In substitution in GaAs are investigated by the TB-mBJ potential, BoltzTraP code and Charpin tensor matrix analysis using Wien2k code. The formation energies of the alloys Ga_1−xIn_xAs (x = 0.0, 0.25, 0.50, 0.75 and 1.0) confirm that they are thermodynamically favorable. The directional symmetry changes when increasing the In concentration and reduces the bandgap from 1.55 eV (GaAs) to 0.57 eV (InAs), as well as reducing the electrical conductivity and increasing the Seebeck coefficient. The thermoelectric performance is depicted by the power factor without including lattice vibration. The elastic properties’ analysis shows mechanical stability, and elastic moduli decrease with an increasing In in GaAs, which converts the brittle nature to ductile. The Debye temperature, hardness and thermal conductivity decrease, thus, increasing their importance for device fabrications. Full article

When the film is under no stress, it does not show any stiffness or capability to withstand loads. Therefore, with the help of ANSYS motion, the author applied pre-stress, controlled point coordinates and the equation of equivalent stress surface and used form-finding conditions to explore the equilibrium state of the films in different depths. The author established curve fitting equations and designed a new membrane-removing mulch film recovery machine. The author also analyzed key components and separately established regression equations between recovery rate, damage rate, release rate and the working angle of film picking mechanism, as well as the regression equation between the depth of picking mechanism into the soil and the working angle of clamping conveyor. Then the author conducted the variance analysis on these regression equations. By using Design Expert 8.0.6 to optimize the solution, when the working angle of the pick-up mechanism is 27.31°, the depth of the pick-up mechanism is 73.0 mm. The working angle of the clamping and conveying device is 38.33°, the recovery rate is 93.9% and the damage rate is 89.3%. The test result shows that when parameters are set as above values, the recovery rate of residual film is 92.5%, the release rate is 87.6% and the error values of damage rate and release rate are both lower than 1.5%, which have verified the feasibility of the optimization solution. The experimental result can work as a reference for the optimum working parameters of the new membrane-removing mulch film recovery machine. Full article

Sinter-hardening is an emerging powder metallurgy process by which the consolidation of powder and the hardening of dense bulk samples are integrated into one step. In this study, to understand the complex effects of sinter-hardening parameters on the properties of the Fe-Cr-Ni (Cu)-C alloy, an artificial neural network (ANN) with the topology of a nonlinear multi-layered perceptron was designed to predict the ultimate tensile strength and elongation, considering parameters including chemical composition, sintering temperature, and cooling rate. The predictability of the ANN was verified by experiments, indicating that this method is adequate to quantitatively ascribe steel properties to powder metallurgy parameters in the view of improving process robustness. Full article

To prepare wrought magnesium alloys with excellent plastic deformation properties, Mg-3Sn-2Al-1Zn-0.6Nd alloys were prepared. A hot compression test of Mg-3Sn-2Al-1Zn-0.6Nd alloy was carried out on a thermo-mechanical simulator. The hot deformation behavior of the alloys was studied, and the constitutive equations and the processing map at the strain of 0.8 were established. The processing map exhibited the stable domain (temperature range of 320–350 °C and strain rate range of 0.001–0.04 s⁻¹) with the high power dissipation efficiency (>30%). A large number of fine dynamic recrystallization (DRX) grains and deformed twinning existed in the alloy after the hot deformation. The dominant texture of the Mg-3Sn-2Al-1Zn-0.6Nd alloy is <0001>//CD texture after the hot deformation. The continuous dynamic recrystallization (CDRX) and discontinuous dynamic recrystallization (DDRX) were the dominant recrystallization mechanisms, and {10$\overline{1}$2} extension twinning also occurred in the alloy during the hot deformation. Full article

Thin-walled plates subjected to transverse loading undergoing large deflection have been the topic of a large number of studies. However, there is still a lack of information about the nature and the distribution membrane stresses generated under large deflections. The purpose of this paper is to calculate and display the distribution of the generated stresses and the respective deflections on the entire rectangular plate area. Finite element analysis results for thin-walled plates with aspect ratios of 1, 2 and 5, on movable and immovable edges simply supported and clamped boundary conditions are clearly visualized. The distribution of the normal and shear stresses enables a good understanding of the plate critical points locations. It was found that strong tensile and compressive membrane stresses exist at various points near the plate edges, creating potential failure hazards. Full article

In a thermal simulator of Gleeble-3500, isothermal hot compression tests were performed on a Ni-Cr-Co-based superalloy at deformation temperatures ranging from 1323 K to 1423 K and with strain rates of 0.01, 0.1, 1, and 5 s⁻¹. We obtained the true stress–strain curves, and the microstructures of deformed samples were analyzed by electron backscatter diffraction (EBSD) technique. The segmented constitutive models were developed to predict the flow stress, and the dynamic recrystallization grain size model was established to evaluate the microstructure evolution for a Ni-Cr-Co-based superalloy. It is found that discontinuous dynamic recrystallization (DDRX) and continuous dynamic recrystallization (CDRX) appear simultaneously in the Ni-Cr-Co-based superalloy during hot deformation, with the latter not being active. Comparison between the experimental and predicted results indicates that the proposed models can describe and interpret the work-hardening and dynamic softening behaviors as well as the evolution characteristic of dynamic recrystallization grain size of the Ni-Cr-Co-based superalloy. In the error analysis of the segmented constitutive models, correlation coefficient (R) is 0.988 and average absolute relative error (AARE) is 6.94%, and for the AGS of DRX, R is 0.974 and AARE is 5.83%, which both have good accuracy. Full article

Base-isolated frames supported by stepped foundation in mountainous areas possess their own particularity, so its progressive collapse dynamic response performance and dynamic effect propagation path are very different from those of ordinary flat ground-isolated structural systems. In order to study the progressive collapse performance of the base-isolated frames supported by stepped foundation in mountainous areas under two-directional coupled dynamic excitation, a four-span three-story plane frame demolition column test was simulated to verify the reliability of the computing platform. The common ground motion and three types of long-period ground motions were selected, and the two-dimensional dynamic coupling of the ordinary flat ground isolation structure and the base-isolated frames supported by stepped foundation in mountainous areas was obtained based on the demolition method. First, the seismic isolation structure was subjected to the collapse dynamic response under the vertical unbalanced load, then the collapse dynamic response under the vertical unbalanced load and the horizontal seismic coupling excitation was made; the two were compared and analyzed. It can be used as a reference for the design of progressive collapse of the frame structure of the base-isolated frames supported by stepped foundation in mountainous areas. Full article