Search Results (1,620)

It is widely recognized that grain variability affects the physical and engineering properties of cowpea and maize varieties. Understanding the effects is vital for designing a dehulling machine that can yield better performance. The physical and engineering properties of nine cowpea varieties and a local maize variety were determined to provide essential data for the design of dehulling and processing equipment. Standard laboratory methods reported in the literature were used to analyze the grains. The study reveals that the physical and engineering properties of nine cowpea and maize varieties varied considerably (p < 0.05). The mean values of moisture content % ranged from 10.06 to 13.81%, length ranged from 7.11 to 11.44 mm, width ranged from 5.65 to 10.28 mm, thickness ranged from 4.60 to 6.73 mm, and thousand-grain weight ranged from 100 to 364 g. Da ranged from 5.79 to 8.89 mm, Dg ranged from 5.66 to 8.59 mm, sphericity ranged from 0.73 to 0.86, surface area ranged from 101.38 to 233.75 mm², and volume ranged from 97.05 to 339.82 mm³. Furthermore, the COF on stainless steel ranged from 0.30 to 0.37, the angle of repose ranged from 20.03 to 30.33°, the bulk density ranged from 688.00 to 814.67 kg/m³, the true density ranged from 1079.91 to 1282.61 kg/m³, and the porosity % ranged from 60.53 to 67.46%. Lastly, grain hardness ranged from 56.27 to 267.91 N, grain compressive energy ranged from 80.91 to 664 mJ, grain stiffness ranged from 6.48 to 26.13 N/mm, seed coat–cotyledon/pericarp–endosperm stickiness force ranged from 0.04 to 0.10 N, Adhesiveness (force to overcome stickiness) ranged from 0.08 to 93.42 N · mm, and fracturability ranged from 56.27 to 267.91 N. These results offer a comprehensive engineering database for the design and optimization of dehulling and post-harvest processing equipment. Full article

To elucidate the evolution of dynamic recrystallization (DRX) mechanisms in cold-worked Cr4Mo4Ni4V martensitic steel, tensile tests were conducted on a 50% cold-deformed material at 600–850 °C at a fixed strain rate of 0.001 s⁻¹, combined with systematic microstructural characterization. Under this specific strain rate, the results reveal a temperature-dependent transition from continuous dynamic recrystallization (CDRX) to discontinuous dynamic recrystallization (DDRX). At 600 °C, CDRX dominates, producing recrystallized grains with orientations close to the parent matrix and relatively strong texture. At 750 °C, CDRX and DDRX coexist, while DDRX is significantly enhanced, characterized by grain boundary nucleation and random orientations, leading to a marked reduction in texture intensity; simultaneously, the fraction of recrystallized grains and high-angle grain boundaries reaches a maximum. At 850 °C, DDRX becomes dominant. This transition in DRX mechanism governs the high-temperature plasticity, with optimal superplasticity achieved at 800 °C, corresponding to an elongation of 748%. Cavities are primarily initiated at carbide/matrix interfaces, and their growth and coalescence dominate the fracture process. These findings clarify the temperature-dependent DRX evolution and its role in regulating superplasticity, providing guidance for microstructure design and superplastic forming of martensitic steels. Full article

This paper proposes a novel Bidirectional Beetle-Informed RRT* (BBI-RRT*) Connect algorithm to enhance the safety and path planning efficiency of 6-DOF robotic manipulators operating in the complex high-altitude environment of angle-steel towers. By digitally reconstructing the tower environment through model registration, the algorithm establishes an accurate foundation for subsequent path planning. A bidirectional beetle antennae search mechanism is employed to guide node sampling, effectively accelerating the convergence rate of the algorithm. To ensure the generation of feasible path, a multi-constraint objective function is designed to balance path length, smoothness, and operability. Additionally, an Informed RRT* process is integrated to refine the path within an adaptive 3D ellipsoid, achieving global path optimization. Both simulation tests on the Unity platform and real-world experiments are conducted to validate the effectiveness and superiority of the proposed algorithm. Full article

To improve steel cleanliness during continuous casting, tundish flow-control devices must effectively regulate molten-steel flow and promote the removal of non-metallic inclusions. In this study, a numerical investigation was conducted to clarify the coupled effects of pore number and pore elevation angle in an inclined porous tundish filter on molten-steel flow behavior and inclusion removal. Twenty-five filter configurations were compared by varying the pore number from 2 to 32 pores and the pore elevation angle from 20° to 40° while maintaining an identical total flow-through area. The results show that inclusion removal is governed by the combined effects of flow guidance, velocity-field uniformity, and post-filter streamline distribution, with the filter containing 8 pores and a 40° pore elevation angle achieving the highest average inclusion removal efficiency of 74.33% for 20–80 μm inclusions. These findings provide a quantitative basis for optimizing tundish filter geometry and improving steel cleanliness during continuous casting. Full article

This study examines the microstructural characteristics and tensile properties of autogenous orbital gas tungsten arc (GTA) circumferential butt welds produced on commercially rolled 304 stainless steel seam pipes (outer diameter 38.1 mm, wall thickness 2.0 mm) for high-purity fluid distribution systems. A three-segment current profile was employed using an AMI 8-4000 orbital system, with peak currents of 70, 67, and 65 A for the penetration, remelting, and downslope (crater-fill) segments, respectively, under high-purity Ar (99.999%) shielding with back purging. Electron backscatter diffraction (EBSD) analysis, including image quality (IQ), inverse pole figure (IPF), and kernel average misorientation (KAM) mapping, showed that the weld metal consists of epitaxially grown columnar austenite grains strongly oriented along the solidification direction, whereas the heat-affected zone (HAZ) exhibits finer equiaxed grains with an increased Σ3 twin boundary fraction and elevated low-angle boundary fraction, indicative of partial recrystallization. Only sparse, discontinuous δ-ferrite stringers were detected in the fusion zone, and no non-metallic inclusions were observed on fracture surfaces, supporting the weld metal’s suitability for semiconductor-grade cleanliness. Vickers microhardness profiles revealed modest hardness differences (typically within 10–20 HV) between the weld metal, HAZ, and base metal, with no pronounced HAZ softening. Cross-weld tensile tests conducted in accordance with ASTM E8/E8M-22 yielded yield strengths above 200 MPa, ultimate tensile strengths of 650–680 MPa, and total elongations approaching 40%, comparable to the as-received pipe. Scanning electron fractography confirmed fully ductile failure via microvoid coalescence without evidence of cleavage, intergranular decohesion, or weld-defect-induced embrittlement. Collectively, these results demonstrate that the three-segment autogenous orbital GTAW procedure produces structurally sound, particle-clean joints suitable for 304 stainless steel seam pipes used in high-purity industrial piping. Full article

Ultra-high-strength steel (UHSS) cross-members with a high height-to-width ratio are prone to forming defects, such as splitting and wrinkling, due to localized stress concentration during the drawing process. In this study, the addendum geometry in first-stage of a two-stage drawing process was optimized to improve the formability of a cross-member made of 1 GPa-grade UHSS. The optimization was performed using the Sigma module of AutoForm, and Latin hypercube sampling was adopted for the design of experiments. The punch opening width, upper bar radius, wall angle, and lower die radius of the addendum were selected as design parameters, and multi-objective optimization was conducted to simultaneously minimize the maximum failure index and maximum wrinkle value, the two AutoForm forming-defect indicators used in this study. In the initial design, the maximum failure index was 1.044, exceeding the splitting criterion of 1.0; however, this value was reduced to 0.961 in the optimized design, thereby mitigating the risk of splitting. In addition, the maximum wrinkle value was reduced by 11.7% compared with that of the initial design. Pareto analysis was performed to quantitatively evaluate the effects of the design parameters on the forming defects, and the results confirmed that the punch opening width and lower die radius were the dominant parameters affecting both splitting and wrinkling. These results demonstrate that die addendum geometry optimization is effective for reducing splitting and wrinkling in 1 GPa-grade UHSS cross-members. Full article

Acrylate hot-melt adhesives (AHMAs) are widely used in medical dressings, electronic components, and automotive interiors due to their solvent-free nature and high bonding strength. However, their wetting behavior on porous fabric substrates under varying coating temperatures—a critical factor for interfacial adhesion—remains poorly understood. To investigate how coating temperature affects the wetting and adhesion of acrylic hot-melt adhesives on fabric substrates, the apparent surface tension and viscosity of the adhesive (130–160 °C) and the apparent surface energy of the substrate (20–160 °C) were measured. By combining these measurements with contact angle decay curves on steel plates, scanning electron microscopy of cold-brittle cross-sections, and mechanical property tests, the study analysed the effects of temperature on wetting and spreading, penetration depth, and adhesive performance. Results show that with increasing temperature, adhesive surface tension and viscosity decrease, while fluidity improves; substrate surface energy shows no temperature dependence. The penetration depth into the fabric increases from 16 μm to 25 μm, and penetration uniformity gradually improves. However, both peel strength and loop tack continuously decrease with rising temperature, with optimal adhesion at 130 °C. A penetration depth model based on the Washburn equation effectively predicts the penetration behavior. Viscosity accounts for more than 50% of the effect, whilst the wetting factor contributes to a lesser extent. This study provides a theoretical basis for optimizing the coating process of acrylic hot-melt adhesives on fabric substrates. Full article

Accurate discrete element method (DEM) simulations are essential for elucidating the precision seeding mechanisms and collision damage characteristics of cassava seed stem (CSS); however, such simulations are often limited by a lack of precise contact parameters. In this study, “Guire No. 7” CSS was selected as the research object to calibrate discrete element (DE) parameters by integrating physical experiments with DEM simulations. A stem model was constructed in EDEM software (Altair EDEM 2022) using three-dimensional scanning technology combined with SolidWorks 2024 modeling functions to investigate the influence of the model’s mesh face count on simulation accuracy. Physical experiments measured the average repose angle (RA) of the stems (30.28° ± 1.09°), along with parameters including the restitution coefficient for stem-stem and stem-steel plate collisions, and the coefficient of static friction between the stem and steel plate. The Plackett-Burman Design experiment was employed to screen parameters affecting the RA, and the steepest ascent experiment was conducted to determine their optimal value ranges. Using the RA as the response value, a Central Composite Design experiment combined with machine learning regression models was applied to optimize the influencing parameters and compare model performance. The results indicated that the GA-BP algorithm exhibited superior predictive capability compared to Support Vector Regression (SVR) and the BP neural network. Through optimization using a genetic algorithm (GA), the calibrated parameters were obtained: a stem-steel plate static friction coefficient (SFC) of 0.488, a stem-stem SFC of 0.489, and a stem-stem rolling friction coefficient of 0.131. The resulting simulated RA was 30.73°, yielding a relative error of 1.49% compared to the physically measured value. The GA-BP-GA method demonstrated better optimization performance than the central composite design experiment, thereby validating the accuracy of the calibrated contact parameters between stems. Furthermore, parameters for the Tavares model were calibrated through physical experiments on CSS, using collision damage force and collision damage energy (CDE) as validation indicators. The results showed that the relative errors for both collision damage force and CDE were less than 3%, which is within the acceptable error range, thereby confirming the validity of the calibrated DE parameters for the cassava seed stem. Full article

To explore the damage mitigation mechanism of steel fiber-reinforced cellular concrete (SFR-CC) under underwater explosion loading, this study systematically analyzes two key variables: steel fiber volume fraction (0.5%, 1.0%, 1.5%, and 2.0%) and protective layer thickness (100 mm, 125 mm, 150 mm, 175 mm, and 200 mm). Based on underwater explosion numerical simulation, the influences of different variable combinations on damage evolution process, structural failure characteristics, dynamic mechanical response behavior, and energy dissipation capacity are investigated. The research results reveal that SFR-CC can effectively mitigate the energy of explosion shock waves. Both the steel fiber volume fraction and protective layer thickness exert significant influences on its underwater anti-explosion performance. The SAP20S15 protective layer exhibits excellent underwater protection performance. Under this specific engineering configuration, it achieves a remarkable attenuation of shock wave pressure acting on the protected structure. Increasing the thickness of the protective layer can substantially enhance its energy absorption capacity and markedly reduce the shock wave energy imposed on the protected structure. In addition, the energy dissipation sharing ratio, structural spalling angle, and peak velocity vector sum (PVS) were employed to conduct a systematic evaluation on the protective performance of the structure under various protective schemes. When the volume fraction of steel fibers is 1.5%, the energy dissipation ratio of the protective layer accounts for 80.49%, with the corresponding structural spalling angle and PVS of the protected plate being 59.5° and 21.4 m/s, respectively. When the protective layer thickness increases to 200 mm, the energy dissipation sharing rate rises by 54.8%, while the spalling angle and PVS of the RC slab decrease by 33.1% and 33.6%, respectively. This further verifies the superior underwater protection performance of the SAP20S15 protective layer under the same parametric conditions. Prediction curves for the damage grade of protected structures with different steel fiber volume fractions and protective layer thicknesses were established. The predicted values of the curves are in good agreement with the numerical simulation results, which can provide a theoretical reference for the rapid evaluation of the underwater anti-explosion performance of SFR-CC protective layers. The research findings can offer theoretical support for the engineering application of SFR-CC protective layers under identical parameter conditions in underwater explosion scenarios. Full article

Wire laser cladding (WLC) of bronze on stainless steel offers a promising approach for combining the structural strength of steel with the superior tribological and corrosion properties of copper alloys. In this study, the influence of key process parameters, including wire preheating current, deposition speed, laser power, and wire feed speed on melt pool temperature and clad geometry was investigated using response surface methodology (RSM). Experiments were performed using a robot-assisted coaxial wire feeding laser cladding system, and real-time thermal monitoring was conducted using an infrared camera. The results showed that defect-free bronze clads with good metallurgical bonding and limited dilution were achieved across the investigated parameter range. Statistical analysis revealed that melt pool temperature is primarily governed by laser power and deposition speed, with a significant interaction between these parameters. Clad height was mainly influenced by wire feed speed and deposition speed, whereas clad width was controlled by laser power and deposition speed. The side angle was affected by deposition speed, laser power, and wire feed speed, reflecting the balance between vertical buildup and lateral spreading. Overall, the study demonstrates that stable and high-quality clads can be achieved by properly balancing energy input and material supply. The developed models provide valuable insight for optimizing process parameters in wire laser cladding of bronze on stainless steel. Full article

This study evaluates fatigue crack growth in marine high-manganese steel LNG (Liquefied Natural Gas) storage tanks under cryogenic conditions. A 3D simulation framework using the M-integral for stress intensity extraction and the VCTD (Vertical Crack Tip Displacement) criterion for path prediction was developed. Parametric simulations showed that crack propagation is strongly directional, with the surface growth rate exceeding the depthwise rate. Fatigue life decreased with increasing initial crack surface length and maximum load but increased with crack inclination angle. In addition, the Mode I stress intensity factor along the depthwise path converged during propagation and rose sharply when the crack depth approached 90% of the wall thickness. An XGBoost-based dual-target model further achieved accurate prediction of crack depth and residual life. Full article

Selective laser melting (SLM) offers significant potential for fabricating lightweight 316L stainless steel lattice structures (LSs), while forming defects and microstructural heterogeneity remain challenging, especially in fine struts. In this study, response surface methodology (RSM) and analysis of variance (ANOVA) were employed to quantify the coupled effects of geometric parameters (forming angle, FA; rod diameter, RD) and processing parameters (laser power, LP; scanning speed, SS; hatch spacing, HS) on the mass deviation (MD) of fine struts. The results show that FA and RD are the dominant factors affecting MD within the investigated parameter range, whereas LP and SS exhibit comparatively weaker effects. Representative samples with different FA and RD were further characterized by SEM, XRD, and EBSD to examine the associated microstructural evolution. The observations indicate that changes in FA and RD are accompanied by variations in solidification morphology, defect distribution, crystallographic texture, and GND density. Higher FA is associated with lower MD and stronger texture alignment along the building direction, whereas larger RD tends to promote columnar growth and enhanced texture intensity. These results suggest that geometric parameters can serve as effective design variables for tailoring forming deviation and representative microstructural characteristics of fine struts in SLM-fabricated 316L lattice structures. Full article

The anti-corrosion performance of epoxy coatings in saline solution environments is restricted by their surface hydrophilicity and microporous defects. Herein, we developed a modified epoxy (MEP)-based superhydrophobic anticorrosive coating by fluorinated resin matrix and incorporation of polyaniline@expanded graphite (FPANI@MEG) anticorrosive fillers. The FPANI@MEG fillers were fabricated via in situ polymerization of aniline on the surface of dopamine-modified expanded graphite to construct the micro-nano hierarchical structure required for superhydrophobicity, while providing barrier shielding and active passivation functions. The results showed that the final coating exhibited excellent superhydrophobicity with a water contact angle of 156.5 ± 1.8° and sliding angle of 3.0 ± 0.6°, along with excellent adhesion and adaptability to various complex environments. Meanwhile, the coating maintained superhydrophobicity after 400 cycles of Taber abrasion and 450 g of falling-sand impact, demonstrating hydrophobic robustness. Furthermore, the coating exhibited a low-frequency impedance modulus of 2.30 × 10⁷ Ω·cm² after immersion in NaCl solution for 15 days. The synergistic combination of air film shielding, physical barrier, and active passivation endowed the coating with good anticorrosion performance. This work may provide a theoretical reference for improving the corrosion protection of epoxy-based superhydrophobic coatings on carbon steel in aggressive saline solution environments. Full article

The effect of nanosecond laser modification on X165CrMoV12 tool steel before and after heat treatment was investigated. Three laser texturing modes were applied to the studied material, with the variables being the frequency used and the pulse energy: 50 kHz/pulse energy 0.9 mJ, 100 kHz/pulse energy 0.45 mJ, and 150 kHz/pulse energy 0.3 mJ. The other parameters of laser texturing were power—90%; speed—500 mm/s; hatching angle—0° (horizontal), +60°/−60° (or equivalent 120°), and +30°/−30° (or equivalent 150°); and Hatching Distance—0.02 mm. The surface laser modification process aims to obtain a homogeneous and adaptive surface relief optimizing the operational properties of the working surfaces of the parts under dry contact friction conditions. The influence of the used laser modification modes on the roughness class of the obtained surfaces, the structure of the formed modified surface and the friction coefficient was studied. The comparative analysis showed that the lowest roughness class (Ra—4.123 µm) was obtained when using an operating frequency of 50 kHz. The obtained friction coefficient values were lowest in the following sequence of processes: laser texturing and subsequent thermal treatment. The lowest friction coefficient (µ = 0.0041) was registered in the test bodies processed with a mode in which the operating frequency was 50 kHz and the pulse energy was 0.9 mJ, after which they were subjected to thermal treatment according to the used cycle. In this processing sequence, no diffusion-related defects (decarburization) were observed on the surface layer of the tested steel. Full article

In punch-bending of thin stainless steel components, the final product angle is significantly influenced by springback after process completion. In the present study, an attempt has been made to investigate the effect of wire straightening strategies and bending tool parameters on the springback behavior of cold-rolled EN 1.4310 flat wire (3.9 mm × 0.4 mm). The wire, supplied in coiled form with inherent residual stresses, was subjected to single-pass, two-pass, and four-pass three-roller straightening prior to bending. Tensile characterization was performed to examine changes in elastic-plastic flow stress behavior, and the experimentally obtained true stress–true plastic strain data were directly implemented in finite element simulations. A full factorial parametric study was conducted by varying the bending angle (66–90°), bending radius (1.33 mm–2.93 mm), and die-punch clearance conditions. Experimental investigations on a subset process parameters were performed to assess the simulation outcomes. It was observed that the straightening history modifies the springback magnitude. Among the parameters considered, the bending radius was found to be the dominant factor governing springback sensitivity. An increase in the clearance gap between the die and punch produces systematic and monotonic shifts in the final product angle due to an increase in the effective bending radius. Full article