Search Results (273)

Deep-sea oil and gas pipelines undergo significant plastic strain during reel-lay installation. Additionally, the static strain aging phenomenon that occurs during service can further deteriorate the mechanical properties of the pipelines. This study investigates the plastic deformation mechanism of reel-lay pipeline steel by subjecting the test steel to 5% pre-strain followed by aging treatment at 250 °C for 1 h. The present study systematically correlates the evolution of mechanical properties with microstructural changes through microstructural characterization techniques such as EBSD, TEM, and XRD. The results demonstrate that after pre-straining, the yield strength of the experimental steel increases due to dislocation strengthening and residual stress generation, while its uniform elongation decreases. Although no significant changes in grain size are observed macroscopically, microstructural characterization reveals a substantial increase in dislocation density within the matrix, forming dislocation cells and walls. These substructures lead to a deterioration of the material’s work hardening capacity. Following aging treatment, the tested steel exhibits further increased yield strength and reduced uniform elongation. After aging treatment, although the dislocation density in the matrix slightly decreases and dislocation tangles are somewhat reduced, the Cottrell atmosphere pinning effect leads to a further decline in work hardening capability, ultimately resulting in the deterioration of plasticity in reel-lay pipeline steel. The instantaneous hardening exponent curve shows that the work hardening phenomenon becomes more pronounced in the tested steel after strain aging as the tempering temperature increases. Full article

This research developed a complex physical and mathematical model of the flat rolling theory problem. This model takes into account the influence of many parameters affecting the roll’s gripping capacity and the overall stability of the entire rolling process. It is important to emphasize that the method of the argument of functions of a complex variable does not rely on simplifying assumptions commonly associated with: the linearized theory of plasticity; or the decoupled solution of stress and strain fields. Furthermore, it does not utilize the rigid-plastic material model. Within this method, solutions are developed based on the complete formulation of the system of equations in terms of stresses and strains, incorporating constitutive relations, thermal effects, and boundary conditions that define a well-posed problem in the theory of plasticity. The presented applied problem is closed in nature, yet it accounts for the effects of mechanical loading and satisfies the system of equation. For this purpose, such factors as roll geometry, physical and mechanical properties of the rolled metal (including its fluidity, hardness, plasticity, and structure heterogeneity), rolling speed, metal temperature, roll lubrication, and many other parameters that can influence the process have been taken into account. Based on the developed mathematical model, a new, previously undescribed force factor significantly affecting the capture of metal by rolls and the stability of the rolling process was identified and investigated in detail. This factor is associated with force stretching of metal in the lagging zone—the area behind the rolls, where the metal has already left the deformation zone, but continues to experience residual stress. It was shown that this stretching, depending on the process parameters, can both contribute to the rolling stability and, on the contrary, destabilize it, causing oscillations and non-uniformity of deformation. The qualitative indicators of transient regime stability have been determined for various values of the parameter α. Specifically, for α = 0.077, the ratio f/α ranges from 1.10 to 1.95; for α = 0.129, the ratio f/α ranges from 1.19 to 1.95; and for α = 0.168, the ratio f/α ranges from 1.28 to 1.95. Full article

In this paper, we propose the use of burnishing internal cylindrical surfaces with a hard tool in a mandrel shape. The burnishing force is exerted mainly by the press slide, which has pushing properties, moving the burnisher through the hollow tube. The burnishing of hollow surfaces is used as the finishing step for elements such as tubes. The purpose of using the burnishing method may be, for example, to increase the smoothness and accuracy of the object, for the improvement of its functional and operational properties, for economic reasons, or to increase its resistance to corrosion and fatigue. The depth of plastic deformation and the accuracy of processing are the main differences in the machining effects for individual burnishing methods. The selection of the burnishing conditions depends on the method of exerting pressure from the burnishing elements on the machined surface, which can be elastic or rigid. Computer simulations of the burnishing process were performed in FORGE^® NxT 2.1 software. A numerical analysis was performed using a three-dimensional triangular mesh. The theoretical and experimental research was determined to have very good compatibility, as determined by the numerically calculated results and by the mean deviation of residual stress method. This research analyzed the stress and strain state after the burnishing process, and a depth of deformation of approximately 20 μm to 30 μm in the material was determined. Full article

African swine fever virus (ASFV), the causative agent of African swine fever (ASF), poses a catastrophic threat to global swine industries through its capacity for immune subversion and rapid evolution. Multigene family genes (MGFs)-encoded proteins serve as molecular hubs governing viral evolution, immune evasion, cell tropism, and disease pathogenesis. This review synthesizes structural and functional evidence demonstrating that MGFs-encoded proteins suppress both interferon signaling and inflammasome activation, while their genomic plasticity in variable terminal regions drives strain diversification and adaptation. Translationally, targeted deletion of immunomodulatory MGFs enables the rational design of live attenuated vaccines that improve protective efficacy while minimizing residual virulence. Moreover, hypervariable MGFs provide strain-specific signatures for PCR-based diagnostics and phylogeographic tracking, directly addressing outbreak surveillance challenges. By unifying virology with translational innovation, this review establishes MGFs as priority targets for next-generation ASF countermeasures. Full article

The Tankou area is a vital production capacity replacement area in the Jianghan oilfield. The recovery of the amount of erosion in Qianjiang Formation and Jinghezhen Formation is significant for studying this area’s tectonic evolution and geothermal history. The target layer, characterised by well-developed plastic materials, intense tectonic deformation, and insufficient well data, fails to meet the applicability criteria of the conventional denudation estimation methods. This study proposes a novel approach based on the structural strain characteristics. The method estimates the stratigraphic denudation by analysing residual formation features and fault characteristics. First, a stress analysis is performed using the fault characteristics, and the change law for the thickness of the target layer is summarised based on the characteristics of the residual strata to recover the amount of erosion in the profile. Second, a grid of the stratigraphic lines in the profiles of the main line and the tie line is used to complete the recovery of the amount of erosion in the plane through interpolation, and the results of the profile recovery are corrected again. Finally, the evolution results of the geological equilibrium method and the stress–strain analysis are compared to analyse the reasonableness of their differences and verify the accuracy of the erosion recovery results. The area of erosion in each layer increases from bottom to top. The amount of denudation in each layer gradually increases from the denudation area near the southern slope to the surrounding area. It converges to 0 at the boundary of the denudation area. The maximum amount of erosion is distributed in the erosion area close to the side of the residual layer with a low dip angle. The specific denudation results are as follows: Qian1 Member + Jinghezhen Formation has a denudation area of 6.3 km² with a maximum denudation thickness of 551 m; Qian2 Member has a denudation area of 2.6 km² with a maximum denudation thickness of 164 m; Qian3 Member has a denudation area of 2.3 km² with a maximum denudation thickness of 215 m; Upper Qian4 Submember has a denudation area of 1.54 km² with a maximum denudation thickness of 191 m; and Lower Qian4 Submember has a denudation area of 1.2 km² with a maximum denudation thickness of 286 m. This method overcomes the conventional denudation restoration approaches’ reliance on well logging and geochemical parameters. Using only seismic interpretation results, it achieves relatively accurate denudation restoration in the study area, thereby providing reliable data for timely analyses of the tectonic evolution, sedimentary facies, and hydrocarbon distribution patterns. In particular, the fault displacement characteristics can be employed to promptly examine how reasonable the results on the amount of denudation between faults are during the denudation restoration process. Full article

To overcome the limitation of traditional elastic phase field models that neglect plastic deformation in rock compressive-shear failure, this study developed an elastoplastic phase field fracture model incorporating plastic strain energy and established a coupling framework for plastic deformation and crack evolution. By introducing the non-associated flow rule and plastic damage variable, an energy functional comprising elastic strain energy, plastic work, and crack surface energy was constructed. The phase field governing equation considering plastic-damage coupling was obtained, enabling the simulation of the energy evolution in rock from the elastic stage to plastic damage and unstable failure. Validation was carried out through single-edge notch tension tests and uniaxial compression tests with prefabricated cracks. Results demonstrate that the model accurately captures characteristics such as the linear propagation of tensile cracks, the initiation of wing-like cracks under compressive-shear conditions, and the evolution of mixed-mode failure modes, which are highly consistent with classical experimental observations. Specifically, the model provides a more detailed description of local damage evolution and residual strength caused by stress concentration in compressive-shear scenarios, thereby quantifying the influence of plastic deformation on crack driving force. These findings offer theoretical support for crack propagation analysis in rock engineering applications, including hydraulic fracturing and the construction of underground energy storage caverns. The proposed plastic phase field model can be effectively utilized to simulate rock failure processes under complex stress states. Full article

In this study, the effect of plastic residual strain on the corrosion behavior of ZK60 magnesium alloy was systematically revealed using a research method combining experimental characterization and numerical simulation. Based on the multiphysical field coupling theory, a numerical model containing deformation field, corrosion phase field, and material transfer field was constructed, and the dynamic simulation of plastic residual strain-induced corrosion damage was successfully realized. Tafel polarization curves obtained from electrochemical tests were fitted to the key parameters of the secondary current distribution. The kinetic parameter L controlling the corrosion rate in the phase-field model was innovatively determined by the inverse calibration method, and a quantitative relationship between the kinetics of electrochemical corrosion and the phase-field theory was established. The corrosion depth distribution of the pre-strained specimens is quantitatively characterized and the results are in agreement with the finite element simulation results. The coupled strain-corrosion analysis method proposed in this study provides a theoretical basis for the design and life prediction of corrosion resistance of components under complex stress states. Full article

The process of rock damage and failure is accompanied by the dissipation of energy and an increase in plastic strain. This study attempts to determine the relationship between dissipated energy and plastic strain in sandstone during the damage and failure process. A conventional triaxial cyclic loading and unloading test was conducted on sandstone samples to analyze the energy evolution and plastic strain characteristics of rock during the mechanical performance degradation and deformation failure process. The analysis results indicate that the evolution law of rock energy dissipation and plastic growth during the whole stress–strain process is highly consistent. Before the peak stress, dissipated energy and plastic strain increased linearly with input energy and axial strain, respectively. In the residual stress stage, there is an approximate linear evolution relationship between dissipated energy and plastic strain. Based on the correlation characteristics of energy dissipation and plastic growth, a modified damage model was established by characterizing plastic deformation by damage. In addition, a numerical program was developed using the Finite Volume Method (FVM) based on the damage model. The rock damage model has been validated by experimental results and numerical test. The research findings may provide valuable insights into the correlation mechanism between energy dissipation and plastic growth. Full article

The Loess Plateau region of China has an anomalous climate and frequent geological disasters. Hipparion laterite in seasonally frozen regions exhibits heightened susceptibility to freeze–thaw (F-T) cycling, which induces progressive structural weakening and significantly elevates the risk of slope instability through mechanisms including pore water phase transitions, aggregate disintegration, and shear strength degradation. This study focuses on the slip zone Hipparion laterite from the Nao panliang landslide in Fugu County, Shaanxi Province. We innovatively integrated F-T cycling tests with ring-shear experiments to establish a hydro-thermal–mechanical coupled multi-scale evaluation framework for assessing F-T damage in the slip zone material. The microstructural evolution of soil architecture and pore characteristics was systematically analyzed through scanning electron microscopy (SEM) tests. Quantitative characterization of mechanical degradation mechanisms was achieved using advanced microstructural parameters including orientation frequency, probabilistic entropy, and fractal dimensions, revealing the intrinsic relationship between pore network anisotropy and macroscopic strength deterioration. The experimental results demonstrate that Hipparion laterite specimens undergo progressive deterioration with increasing F-T cycles and initial moisture content, predominantly exhibiting brittle deformation patterns. The soil exhibited substantial strength degradation, with total reduction rates of 51.54% and 43.67% for peak and residual strengths, respectively. The shear stress–displacement curves transitioned from strain-softening to strain-hardening behavior, indicating plastic deformation-dominated shear damage. Moisture content critically regulates pore microstructure evolution, reducing micropore proportion to 23.57–28.62% while promoting transformation to mesopores and macropores. At 24% moisture content, the areal porosity, probabilistic entropy, and fractal dimension increased by 0.2263, 0.0401, and 0.0589, respectively. Temperature-induced pore water phase transitions significantly amplified mechanical strength variability through cyclic damage accumulation. These findings advance the theoretical understanding of Hipparion laterite’s engineering geological behavior while providing critical insights for slope stability assessment and landslide risk mitigation strategies in loess plateau regions. Full article

Cracks due to stress corrosion cracking in stainless steels are becoming a problem not only in boiling water reactors but also in pressurized water reactor nuclear plants. Stress improvement measures have been implemented mainly for large-bore welded piping, but in the case of small-bore welded piping, post-welding stress improvement measures are often not possible due to dimensional restrictions, etc. Therefore, knowing the actual welding residual stresses of small-bore welded piping regardless of reactor type is essential for the safe and stable operation of nuclear power stations, but there are only a limited number of examples of measuring the residual stresses. In this study, austenitic stainless steel pipes with an outer diameter of 100 mm and a wall thickness of 11.1 mm were butt-welded. The residual stresses were measured by the strain scanning method using neutrons. Furthermore, to obtain detailed residual stresses near the penetration bead where the maximum stress is generated, the residual stresses near the inner surface of the weld were measured using the double-exposure method (DEM) with hard X-rays of synchrotron radiation. A method using a cross-correlation algorithm was proposed to determine the accurate diffraction angle from the complex diffraction patterns from the coarse grains, dendritic structures, and plastic zones. A quantum beam hybrid method (QBHM) was proposed that uses the circumferential residual stresses obtained by neutrons and the residual stresses obtained by the double-exposure method in a complementary use. The residual stress map of welded piping measured using the QBHM showed an area where the axial tensile residual stress exists from the neighborhood of the penetration bead toward the inside of the welded metal. This result could explain the occurrence of stress corrosion cracking in the butt-welded piping. A finite element analysis of the same butt-welded piping was performed and its results were compared. There is also a difference between the simulation results of residual stress using the finite element method and the measurement results using the QBHM. This difference is because the measured residual stress map also includes the effect of the stress of each crystal grain based on elastic anisotropy, that is, residual micro-stress. Full article

To address the issue of cracking in cold-rolled medium manganese steel caused by the formation of a large amount of martensite after hot rolling, intermediate annealing was conducted prior to cold rolling. The research results indicate that after 1 h of intermediate annealing at a temperature of 700 °C, some martensite is replaced by ferrite and residual austenite, leading to a reduction in rolling stress. The dissolution of cementite leads to an increase in the solubility of the alloying elements in austenite. This increases the volume fraction and carbon content of austenite. Following cold rolling and final heat treatment, the Mn content is higher in both martensite and residual austenite, while it is relatively lower in ferrite. Elevated C and Mn content enhances the stability of the austenite. The elongation of the sample with intermediate annealing increased from 17% to 27%, and the yield strength slightly decreased. During the tensile process, ferrite provides plasticity during the early stage of deformation. As strain increases, martensite begins to deform, making a significant contribution to the material’s strength. The TRIP effect of austenite contributes most of the plasticity, especially the stable thin-film residual austenite. When the residual austenite is exhausted, the incompatibility between ferrite and martensite leads to crack propagation and eventual fracture. Full article

Oil sands tailings consist of a combination of sand, fine particles, water, and residual unextracted bitumen in varying ratios. The management of these mine waste tailings is largely influenced by their consolidation behavior. Large strain consolidation testing, such as the multi-step large strain consolidation (MLSC) test, is commonly used to determine consolidation properties but requires considerable time. A benchtop centrifuge (BTC) apparatus was proposed to derive the consolidation parameters of the following three clay-rich oil sands tailings slurries: two samples of high-plasticity fluid fine tailings (FFT) and one of low-plasticity FFT. Comparison with the MLSC tests illustrates that the BTC-derived compressibility data closely matched the MLSC test’s compressibility curve within the BTC stress range. However, the hydraulic conductivity from the BTC test was an order of magnitude higher than that from the MLSC test. The consistency of the BTC method and the validation of scaling laws were confirmed through modeling-of-models tests, showing a consistent average void ratio regardless of the specimen height or gravity scale. The influence of the small radius of the BTC was found to be minimal. The limitations of the BTC in the physical modeling of the consolidation behavior are discussed and their impact on the interpretation of the observed consolidation behavior is addressed. Overall, the BTC test provides a rapid method to gain insight on high-water-content slurries’ large strain consolidation behavior. Full article

This study investigates enhancing polylactic acid (PLA) by incorporating recycled polycarbonate (r-PC) to address PLA’s inherent brittleness and limited thermal stability. Blends with varying PLA/r-PC ratios (100:0 to 0:100) were prepared using an internal mixer, with r-PC sourced from discarded compact discs. The thermogravimetric analysis (-A) demonstrated significant improvements in the thermal stability. The degradation onset temperature (T₅ wt%) increased from approximately 315 °C for pure PLA to about 400 °C in the blends, with a maximum decomposition temperature (T_max) of 520 °C observed for pure r-PC. The char residue also increased markedly, from 1.35% in pure PLA to 24.42% in r-PC, indicating enhanced thermal resistance. Differential scanning calorimetry (DSC) revealed a considerable reduction in PLA crystallinity, declining from 68.17% in pure PLA to 10.32% in the 10PLA90r-PC blend, indicative of the disruption of PLA’s crystalline structure. The X-ray diffraction (XRD) analysis supported these findings, showing a transition to a predominantly amorphous structure at higher r-PC contents. Tensile testing highlighted the mechanical improvements achieved through blending. While pure PLA exhibited brittle failure, the 30PLA70r-PC blend displayed plastic deformation, signifying improved toughness. The stress–strain analysis revealed that the 30PLA70r-PC blend achieved a peak toughness of 8725 kJ/m³, nearly ten times higher than the 924 kJ/m³ recorded for pure PLA. However, excessive r-PC content introduced brittleness, diminishing toughness. The dynamic mechanical thermal analysis (DMTA) demonstrated a broadening of the glass transition range, with the T_g shifting from 61 °C for pure PLA to 141 °C in r-PC-dominant blends, reflecting improved phase interactions between the two polymers. Scanning electron microscopy (SEM) revealed significant morphological changes; at high r-PC contents, phase separation and voids were observed, leading to reduced mechanical performance. These results highlight the synergistic potential of blending PLA’s biodegradability with r-PC’s superior thermal and mechanical properties. Full article

In this paper, the effect of the combination of steel fiber and rubber particles on the compressive behavior of steel fiber-reinforced rubberized concrete (FR-RC) under uniaxial cyclic compression was investigated. A total of 60 specimens with steel fiber volume fractions ranging from 0% to 1.5% and rubber particle volume substitutions ranging from 0% to 20% were fabricated and tested. The compressive stress–strain relationship and the failure mode of FR-RC were examined. The results indicate that the introduction of steel fiber and rubber particles has a synergistic effect on improving the cyclic mechanical behavior of concrete, including ductility, hysteretic energy dissipation, and stiffness degradation. Additionally, increasing the steel fiber and rubber particle content leads to a significant decrease in plastic strain accumulation. Based on the test results, formulas are proposed for the characteristic points of the hysteresis loop, such as the peak strength and strain, residual point, turning point, and end point. Furthermore, a cyclic constitutive model and its simplified form are developed to generalize the cyclic stress–strain behavior of FR-RC. Full article

CSAM is a solid-state process for depositing metal or metal-based composite materials in which the fine particles of metal or composite material are accelerated to supersonic velocity, making successful bonding feasible due to the high-impact velocity and heavy plastic deformation, all without the melting of the feedstock material. This review examines the basic CSAM mechanism, including deposition dynamics, bonding mechanism, dynamic recrystallization, residual stress evolution, and post-spray heat treatments which affect microstructural and mechanical properties. Although controlled by a few key factors like particle velocity, strain rate, and temperature rise, the bonding efficiency itself refines the grains through dynamic recrystallization, hence improving coating strength and performance. The predominating compressive residual stresses that enhance fatigue resistance and mitigation strategies to improve coating durability by post-spray annealing and laser peening are discussed. This review, by providing an overview of material behavior, optimization techniques, and advanced modeling approaches, underlines the CSAM potential for high-performance applications in aerospace, biomedical industries, and machinery. It further underlines its importance for the advancement of manufacturing innovation and materials science. Full article