Search Results (127)

Widely employed in diverse engineering applications, stiffened steel plates are often subjected to biaxial compressive loads. Under these conditions, buckling may occur, initially within the elastic range but potentially progressing into the elasto-plastic domain, which can lead to permanent deformations or structural collapse. To increase the ultimate buckling stress of plates, the implementation of longitudinal and transverse stiffeners is effective; however, this complexity makes analytical stress calculations challenging. As a result, numerical methods like the Finite Element Method (FEM) are attractive alternatives. In this study, the Constructal Design method and the Exhaustive Search technique were employed and associated with the FEM to optimize the geometric configuration of stiffened plates. A steel plate without stiffeners was considered, and 30% of its volume was redistributed into stiffeners, creating multiple configuration scenarios. The objective was to investigate how different arrangements and geometries of stiffeners affect the ultimate buckling stress under biaxial compressive loading. Among the configurations evaluated, the optimal design featured four longitudinal and two transverse stiffeners, with a height-to-thickness ratio of 4.80. This configuration significantly improved the performance, achieving an ultimate buckling stress 472% higher than the unstiffened reference plate. In contrast, the worst stiffened configuration led to a 57% reduction in performance, showing that not all stiffening strategies are beneficial. These results demonstrate that geometric optimization of stiffeners can significantly enhance the structural performance of steel plates under biaxial compression, even without increasing material usage. The approach also revealed that intermediate slenderness values lead to better stress distribution and delayed local buckling. Therefore, the methodology adopted in this work provides a practical and effective tool for the design of more efficient stiffened plates. Full article

Temperature dependence of the deformation behavior and the residual stress in 304 stainless steel beams with single-sided Al₂O₃ coatings of varying thicknesses are analyzed using the image relative method. The results demonstrate that, due to the mismatch of thermal expansion coefficient between the coating and substrate, residual stresses were produced, which caused the bending deformation of the single-side coated specimens. Moreover, coating thickness significantly influences the deformation behavior of specimens. Within the elastic deformation regime, the single-side coated specimens would exhibit alternating bending and flattening deformations in response to the fluctuations of temperature. The higher ratio of the coating thickness to the substrate thickness is, the smaller bending curvature of specimens becomes, and the lower residual compressive stresses in the coating are. For the specimens undergoing elastic deformation, residual stresses can be effectively calculated through the Stoney’s formula. However, as the thickness of coating is close to that of substrate (the corresponding specimens would be regarded as the laminated composites), plastic deformation occurs. And the residual stresses in those specimens vary along the direction of the thickness and the length. In addition, the residual stress decreased with increasing temperature because of the stress relaxation. Full article

The accumulation of fatigue damage is primarily caused by cyclic plastic deformation. In low-cycle fatigue, cyclic plastic deformation is the dominant deformation mode. In high-cycle fatigue, although most deformation is elastic, plastic deformation may still occur in localized regions of stress concentration and plays a critical role in the initiation of fatigue cracks. Considering that cyclic plastic deformation can be characterized by hysteresis loops, this study modifies the flow stress equation and the cyclic plastic deformation relationship based on stress–strain hysteresis loops at half-life cycles under different strain amplitudes. An improved model for life prediction that incorporates the effects of strain amplitude is proposed. The results of experiments on 310S stainless steel and 1045 carbon steel demonstrate that the model achieved prediction errors within a factor of two and provided reliable predictions for both high-cycle and low-cycle fatigue life across the entire ε-N curve. Full article

The dynamic response of multi-story steel frames under impact loading exhibits a complex nonlinear behavior. This study develops a three-story, multi-scale spatial steel frame finite element model using ABAQUS 2023 software, and the contact algorithm and material parameters were validated through published drop-weight impact beam tests. A total of 48 impact parameter combinations were defined, covering rational mass–velocity ranges while accounting for column position variations at the first story. Systematic comparisons were conducted on the influence of varying impact parameters on structural dynamic responses. This study investigates deformation damage and progressive collapse mechanisms in spatial steel frames under impact loading. Structural dynamic responses show significant enhancement with increasing impact mass and velocity. As impact kinetic energy increases, the steel frame transitions from localized denting at impact zones to global bending deformation, inducing structural tilting. The steel frame exhibits potential collapse risk under severe impact conditions. Under identical impact energy, corner column impact displacements differ by <1% from edge-middle column displacements, with vertical displacement variations ranging 0–17.6%. The displacement of the first-floor joints of the structure with three spans in the impact direction was reduced by about 50% compared to that with two spans. When designing the structure, it is necessary to increase the number of frame spans in the impact direction to improve the overall stability of the structure. Based on the development of the rotation angle of the beam members during the impact process, the steel frame collapse process was divided into three stages, the elastic stage, the plastic and catenary stage, and the column member failure stage; the steel frame finally collapsed due to an excessive beam rotation angle and column failure. Full article

Lateritic clay is widely distributed in southern China, and its strength is greatly affected by water content. The elevated moisture content in lateritic clay during monsoon periods frequently results in insufficient shear strength for standard engineering applications. Large quantities of solid waste, including steel slag, fly ash, and granulated blast furnace slag, are produced as industrial by-products. This paper is based on the backfilling resource utilization of steel slag, fly ash, and ground-granulated blast-furnace slag as lateritic clay improvement admixtures, along with the stress–strain behavior, strength characteristics, and microstructure of steel-slag-modified lateritic clay, fly-ash-modified lateritic clay, and ground-granulated blast-furnace slag-modified lateritic clay, by combining uniaxial compression tests, straight shear tests, and scanning electron microscopy observation. The experimental results were analyzed to determine the appropriate dosages of three kinds of solid waste and their mechanisms in lateritic clay modification. The results indicate that the unconfined compressive strength of SS-modified lateritic clay exhibited an increase with an increase in SS dosage in the range of 1–7%, the unconfined compressive strength of FA-modified lateritic clay showed an increase with an increase in FA dosage in the range of 1–5%, and the unconfined compressive strength of GGBFS-modified lateritic clay increased with an increase in the use of GGBFS in the range of 1–5%. Under the condition of a 7-day curing age, the unconfined compressive strength of lateritic clay modified with 7% SS increased by approximately 397%, while that modified with 5% FA and 5% GGBFS exhibited increases of about 187% and 185%, respectively. The stress–strain relationship of fly-ash and blast-furnace slag-modified lateritic clays showed elastic–plastic deformation. But the stress–strain behavior of steel-slag-modified lateritic clay at a steel slag dose greater than 5% and a maintenance age greater than 7 days showed elastic deformation. Analyzing the SEM images shows that the more hydration products are generated, the relatively higher the unconfined compressive strength of modified lateritic clay is, and the form of deformation of modified lateritic clay is closer to elastic deformation. Through comparative analysis of modified lateritic clay samples, this study elucidates the property-altering mechanisms of waste powder additives, guiding their engineering utilization. Full article

By integrating a very short shear link–shear slotted bolted connection (VSSL-SSBC) and two self-centering SMA braces (SCBs), a novel self-centering shear link (SC-SL) was developed for installation between a steel brace and steel beam in an eccentrically braced frame (EBF). The SC-SL can enhance the seismic performance and seismic resilience capacity of the EBF by achieving a high bearing capacity and low residual deformation. The mechanical properties of the VSSL-SSBC and SC-SL were designed and analyzed using both experimental and numerical methods. Subsequently, the seismic performances of EBFs equipped with VSSL-SSBC and SC-SL were analyzed under different earthquakes. Validated numerical methods were employed to investigate the deformation modes, stress nephograms, and hysteresis curves of the EBFs. The deformation mode and hysteresis curve of the VSSL-SSBC exhibit an initial frictional slip of the SSBC, followed by the load-bearing response of the VSSL. The skeleton curve of the VSSL-SSBC consists of elastic, slip, elastoplastic, and plastic stages, and the deformation and damage are significantly reduced at the same displacement. In the SC-SL, the SCB undergoes substantial deformation when the SMA is in tension, effectively minimizing residual deformation. Under frequent earthquakes, the stress and displacement of all components in both the EBF-VSSL-SSBC and EBF-SC-SL are essentially equivalent, and the VSSL-SSBC remains elastic, without significant yielding deformation. Under rare earthquakes, incorporating SCB in EBF-SC-SL significantly enhances the ultimate load capacity by 19.66% and reduces the residual deformation by 27.90%. This improvement greatly contributes to the seismic resilience of the EBF. Full article

Roll wear significantly affects production efficiency and product quality in hot-rolled strip steel manufacturing by reducing roll lifespan and impeding the control of strip shape. This study addresses these challenges through a comprehensive analysis of the roll wear mechanism and the integration of an elastic deformation model. We propose an optimized wear prediction model for work and backup rolls in a hot continuous rolling finishing mill, dynamically accounting for variations in strip specifications and cumulative wear effects. A three-dimensional elastic–plastic thermo-mechanical coupled finite element model was established using MARC 2020 software, with experimental calibration of wear coefficients under specific production conditions. The developed dynamic simulation software achieved high-precision wear prediction, validated by field measurements. The optimized model reduced prediction deviations for work and backup rolls to 0.012 and 0.004, respectively, improving accuracy by 5.3% and 3.25% for uniform and mixed strip specifications. This research provides a robust theoretical framework and practical tool for precision roll wear management in industrial hot rolling processes. Full article

The article is the result of the question mentioned in its title, namely, whether heat treatments without phase transformation and pressing of parts can improve the physicomechanical properties of metallic materials and alloys. Starting from this hypothesis, the article analyzes the influence of non-phase change thermal treatment TT and plastic deformation (compression) on a steel used for the realization of components in the engineering industry, as presented in the specific standards SR EN-10025 and SR EN-10027. The results of the tensile tests and of the Vickers hardness tests on the specimens made of this material are presented. The results in terms of material ultimate stress σ_u, yield strength S_y, elongation δ, reduction in cross section ψ, as well as those obtained in the Vickers test are summarized in tabular or graphical form. From the research conducted by the authors of this work, it can be seen that the 0.5 × T_m−s (T_m−s—melting-solidifying temperature, K) heat treatment gives the best mix of properties: mechanical strength similar to that of the non-treated material, improved elasticity and ductility, but with a small, negligible reduction in hardness. The results are useful to support the activities of optimal selection of heat treatments and plastic forming for various engineering applications. Heat treatment without phase transformation is essential for improving the mechanical properties of materials used in engineering. This study investigates the impact of heat treatments and plastic deformation on S355J2+N steel, highlighting the increase in yield strength and improvement in ductility. The results show an increase of up to 15% in yield strength and an improvement in relative elongation by 2% for treatments at 0.5 × T_m−s, while hardness remains almost unchanged. Full article

Axial force and deformation during drilling significantly impact the hole quality of thin-walled high-strength steel components. This study analyzed the drilling process of thin-walled AF1410 steel, focusing on axial force, deformation, drill cap formation, and hole exit edge characteristics. The effects of cutting speed (12.6–37.7 m/min) and feed rate (0.01–0.1 mm/r) were also examined. Initially, the steel plate undergoes elastic, outward bulging deformation. Axial force, driven by elastic resistance, rises from 114.9 N to 322.1 N as feed rate increases from 0.025 mm/r to 0.1 mm/r, with minimal influence from cutting speed. As drilling progresses, axial force increases slowly. Near the hole exit, plastic deformation occurs beneath the drill bit, causing material to yield and form a drill cap. This results in a sharp rise in axial force, with maximum values increasing from 314.2 N to 525.3 N at higher cutting speeds and from 314.2 N to 840.1 N at higher feed rates. The formation characteristics of the drill cap directly affect hole edge defects, with larger thickness and width leading to more pronounced burrs. Full article

This study investigates the shear behavior of steel truss ceramsite concrete composite interfaces through double-sided direct shear tests and finite element simulations. The results reveal three distinct shear response phases: elastic deformation, plastic softening, and full yielding. The interfacial shear capacity arises from synergistic contributions of bond strength, friction, and truss reinforcement action. Comparative analysis of design codes identifies Eurocode 2 as providing an optimal alignment with the experimental data. An ABAQUS-based finite element model incorporating a cohesive spring composite interface mechanism confirms the model’s reliability. The findings validate Eurocode 2 for ceramsite concrete interface design and propose single-row truss configurations as economically efficient solutions for lightweight high-strength composite structures. The research results are aimed at providing a theoretical basis for the design optimization and code revision of ceramsite concrete composite structures, and promoting the wide application of lightweight high-strength concrete in sustainable buildings. Full article

This study investigates the longitudinal deformation behavior of ultra-high-strength steel (UHSS) during the cold rolling process. First, rolling experiments were conducted on UHSS, and longitudinal surface coordinates of the deformation zone were collected using a probe-type profiler to obtain the actual profile. The forward slip value was derived from production data. An elastic–plastic finite element model of the UHSS rolling process was then established using the nonlinear finite element method. The model calculated the contact arc shape and forward slip within the deformation zone, with errors of less than 15% for the contour and 10% for forward slip. The model was further used to analyze the impact of rolling parameters on contact profile, stress, and forward slip. The results indicate that reducing plate thickness and tension, along with increasing depression and yield strength, promotes the formation of a neutral zone in the deformation zone. The peak contact stress is linked to increased elastic compression of the rolls and the expansion of the roll exit. Additionally, increases in roll diameter, friction coefficient, and yield strength lead to a gradual increase in forward slip in the deformation zone. Full article

Ultra-high-performance fiber-reinforced concrete (UHPFRC) has the characteristics of high strength, toughness, and excellent crack resistance. In order to fully utilize the high-strength properties of UHPFRC and reduce the structural weight and construction cost, solid slabs can be fabricated into hollow-core slabs or composite sandwich slabs. In order to further analyze the mechanical properties and mechanism of action of UHPFRC hollow-core slabs, one solid slab and two hollow-core slabs with the same geometric dimensions, reinforcement, and steel fiber volume content are designed in this paper, and their stress performance under a static load was investigated using a four-point bending test. The research results show that the UHPFRC hollow-core slab is anisotropic, and the bending stiffness of the section with parallel, distributed tubes is slightly smaller than that of the solid slab. The addition of steel fibers can greatly limit the development of cracks on a slab surface, so the elastic limit of a UHPFRC hollow slab is higher than that of a conventional concrete hollow slab. The whole bending process is roughly divided into the elastic stage, the elastic–plastic stage, and the plastic stage; the crack development process on the bottom of the slab can be classified into the cracking stage, the stable crack development stage, and the rapid propagation stage. In the elastic stage, the cross-sectional deformation of the UHPFRC hollow-core slab in the bending process still satisfies the assumption of a flat section. A row of parallel, round tubes on the neutral axis has a little effect on the cracking load, bearing capacity, and deformation capacity of the UHPFRC slab. By conducting the comparative analysis of the hollow rate and bearing capacity, when the hollow rate reaches 13.57%, the comprehensive weight of the solid slab is reduced by 13.16%, the cracking moment is slightly reduced, and the ultimate load is only reduced by 8.78%. Under the premise of meeting the bearing capacity, the hollow rate of the UHPFRC hollow-core slab can be appropriately increased to save money and energy. Full article

This paper employs in situ Electron Backscatter Diffraction (EBSD) tensile technology to thoroughly consider the evolution of microstructure, grain size, grain boundary characteristics, orientation differences, and dislocation density of H13 steel during the elastic and plastic stages of room temperature tensile testing. The study unveils the deformation mechanisms of inclusions, carbides, and the matrix in H13 steel during the various stages, providing a comprehensive explanation for the slightly superior tensile properties of H13 steel when refined by Vacuum Induction Melting combined with Vacuum Arc Remelting (VIM + VAR) over those when refined by Electroslag Remelting (ESR). This discrepancy is primarily attributed to the differences in inclusions and carbides present in the two refining processes. The quantity and size of inclusions and carbides are closely related to material fracture. Large-sized carbides and inclusions were shown to be more likely to cause dislocation pile-ups and stress concentration. This, in turn, leads to faster crack initiation and propagation during plastic deformation. Conversely, the formation of micro-pores within these fine inclusions and the matrix is contingent on greater plastic deformation, resulting in a gradual and incremental linkage of these micro-pores to form dimples beneath the influence of slip. Full article

Stainless steels have many practical applications requiring various mechanical or chemical demands in the working environment. By optimizing a device used in mechanical experiments for torsional loading, several cylindrical samples were tested (both ends twisted with the same torque value in opposite directions) of 316L stainless steel (SS) to evaluate changes in the structural, chemical, and mechanical characteristics. Initially, the experimental samples were pre-loaded by tension in the elastic range (6%) and then subjected to torsion (772°) at different rates: 5, 10, and 20 mm/min. The experimental sequence consisted of a combined loading protocol with an initial tensile test followed by a subsequent torsional test. Two reference tests were performed by fracturing the samples in both torsion and tension to determine the mechanical strength parameters. The macro- and microstructural evolution of the samples as a function of the torsional degree was followed by scanning electron microscopy. The microhardness modification of the material was observed because of the strain (the microhardness variation from the center of the disk sample to the edge was also monitored). Structurally, all samples showed grain size changes because of torsional/compressive deformation zones and an increase in the degree of grain boundary misorientation. From the tensile and torsional behaviors of 316L SS and the structural results obtained, it was concluded that these materials are suitable for complex stress states in the elasto-plastic range through tensile and torsion. A reduction in Young’s modulus of up to four times the initial value at medium and high stress rates was observed when complex stresses were applied. Full article

To reveal the mechanical behavior and deformation patterns of geotechnical reinforcement materials under tensile loading, a series of tensile tests were conducted on plastic geogrid rib, fiberglass geogrid rib, gabion steel wire, plastic geogrid mesh, fiberglass geogrid mesh, and gabion mesh. The full tensile force–strain relationships of the reinforcement materials were obtained. The failure modes of different geotechnical reinforcement materials were discussed. The standard linear three-element model, the nonlinear three-element model, and the improved Kawabata model were employed to simulate the tensile curves of the various geotechnical reinforcement materials. The main parameters of the tensile models of the geotechnical reinforcement materials were determined. The results showed that a brittle failure occurred in both the plastic geogrid rib and the fiberglass geogrid rib subjected to tensile loading. The gabion steel wire presented obvious elastic–plastic deformation behavior. The tensile resistance of fiberglass geogrid mesh was higher compared to that of plastic geogrid, which was mainly caused by the difference in the cross-sectional areas of these two types of geogrid. Due to a hexagonal mesh structure of gabion mesh, there was a distinct stress adjustment during the tensile process, resulting in a sawtooth fluctuation pattern in tensile curve. Compared to the strip geogrid material, hexagonal-type gabion mesh could withstand higher tensile strain and had greater tensile strength. Brittle failure occurred in both the plastic geogrid rib and the fiberglass geogrid rib when subjected to tensile loading. The gabion steel wire presented obvious elastic–plastic deformation behavior. The standard linear and nonlinear three-element models as well as improved Kawabata model could all well reflect the tensile behavior of geotechnical reinforcement materials before the failure of the material. Full article