Archives of Civil and Mechanical Engineering最新文献

This paper focuses on the failure behavior of novel joints between aluminum and copper sheets produced by hole hemming, with potential applications in hybrid busbars for electric vehicle batteries. This technology involves deforming the aluminum sheet to create a mechanical interlock with the copper sheet, eliminating the need for additional elements, heat, or welding. First, the materials are characterized, and the most suitable strain hardening law is determined to model their post-necking behavior. Then, to model their ductile fracture behavior, the Modified Mohr–Coulomb (MMC) fracture criterion is calibrated through uniaxial tension, plane strain, and shear tension tests. Next, hole-hemmed joints are manufactured and subjected to shear tests. A comprehensive numerical model of the hole hemming process and shear test is developed to investigate the joints’ failure mechanisms and study the influence of mechanical interlock and process deformation history on joint performance. The findings show that the created joints achieve a maximum load of 3.56 kN and a displacement of 9.30 mm. The main failure mode predicted is hole bearing, which aligns with the mode observed in experimental tests. Finite element analysis reveals that while no damage occurs in the copper sheet during the joining process, this sheet is damaged during the shear test, leading to joint failure. Additionally, a higher mechanical interlock leads to greater failure displacement and load, although it decreases the initial load level. This research demonstrates that novel hole-hemmed joints can effectively connect aluminum and copper sheets, presenting promising results for battery applications.

This study addresses a critical gap in the literature by developing a unified analytical model for evaluating the stability and dynamic behavior of cylindrical sandwich shells with functionally graded nanocomposite face sheets and variable-porosity cores. The model incorporates graphene nanoplatelets (GNP) and carbon nanotubes (CNT) as reinforcements, with varying distribution patterns across the nanocomposite face sheets. The governing equations are derived using Hamilton’s principle, and an analytical approach based on the state-space method is applied to compute natural frequencies and critical buckling loads under classical boundary conditions. Verification studies confirm the model’s accuracy. The results highlight the significant effects of geometric and material parameters, including reinforcement and porosity distribution profiles, boundary conditions, and shell dimensions, on the buckling and free vibration responses of the structures. Notably, increasing the porosity ratio reduces the critical buckling load and natural frequencies, while a higher nanoparticle weight fraction enhances the fundamental frequencies and critical buckling load.

Extensive reviews have been conducted on the mechanical, structural, and durability properties of cementitious composites incorporating waste materials. However, a significant knowledge gap exists regarding a comprehensive analysis of their thermal insulation and sound absorption properties. This review seeks to bridge that gap by examining the effects of various waste materials, such as rubber, plastic, glass, ceramic, wood, construction waste, and bio-waste, on these properties in concrete. Incorporating these waste materials improves thermal insulation and sound absorption mainly by increasing porosity and creating interconnected micro and macro pores, leveraging the waste materials’ inherent high porosity and low density. Key findings from the review include a 77% reduction in thermal conductivity with 45% volume replacement of dry materials with plastic compared to control concrete. In addition, maximum sound absorption of 60% at 2000 Hz was achieved with a combination of fly ash and rubber at 30% weight replacement of coarse aggregate. Optimizing the thermal insulation and sound absorption properties of concrete is critically dependent on effective particle size, as it directly influences the concrete’s pore structure. Finer rubber particles (0.1–4 mm) significantly enhance thermal insulation by reducing thermal conductivity to 0.28 W/mK, compared to 0.44 W/mK for coarser particles (5–10 mm). In contrast, coarser particles improve sound absorption, achieving a peak absorption of 32% at 1000 Hz, compared to 27% for finer particles. This dual optimization strategy demonstrates the potential for tailored particle sizes to improve the necessary properties of concrete. The review also outlines future research directions and practical applications, highlighting the potential of recyclable waste materials in the building construction and insulation industry.

The ingenuity of the work lies in joining of 6.18 mm thick IN625 plate with single-pass plasma arc welding without any weld groove preparation and without any filler wire. Two welding speeds (100, 120 mm/min) and welding currents ranging from 115 to 145 A at 5 A intervals were used. The weld joint metallurgy was characterised using field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, etc., to establish a connection with the mechanical performance. The micrograph of the fusion zone exhibited a variety of dendritic structures in terms of size and shape, leading to non-uniform true strains across the weld cross-section. The specimen with the smallest fusion zone area attained a maximum joint strength of 831.8 (pm) 12 MPa, which is 96% of the BM strength. The Laves phase formation and the interdendritic microsegregation were particularly noticeable within the fusion zone and contributed to the joint strength reduction. The fusion zone exhibited the lowest microhardness compared to other zones due to the supersaturation of strengthening elements, namely Nb and Mo in the γ-matrix along with Laves phase developed within the weldment. The partition coefficients in the dendritic core of the Nb and Mo elements were less than the one that leads to microsegregation in the interdendritic region. The fracture surface cross-section view showed that the micro-cracks were initiated during the tensile deformation process in the Laves phase. The fracture surface consisted of shallow dimples, which were attributed to low ductile features.

In this study, we investigated the impact of rhenium doping on the oxidation resistance of the Ni-based Inconel 713C alloy at 1000 °C. A rhenium dopant was introduced into the Inconel 713C alloy powder using an alternative to the mechanical method, a wet chemical method based on the sol–gel process. The doped powder was consolidated by an additive method using the selective laser melting technique, which allowed the Inconel 713C:Re alloy to be obtained. The high-temperature behavior of the Inconel 713C:Re alloy was compared with the alloy without a rhenium dopant, manufactured by SLM, and with the Inconel 713C alloy in cast form. Differences in the microstructure and chemical composition of the oxide scale formed on the tested samples were observed. For the SLM-manufactured Inconel 713C alloy samples undoped and Re-doped, the oxidation process was controlled by the outward diffusion of elements like Ni, Cr, Al, and Ti with simultaneous inward diffusion of oxygen along columnar grain boundaries. Oxygen diffusion was facilitated by the columnar shape of the grains and by the defects in the form of pores and microcracks introduced during the additive manufacturing process. The rhenium dopant significantly reduced the growth of the oxide layer on the Inconel 713C alloy exposed to a temperature of 1000 °C. Based on the determined oxidation rate constants, it can be concluded that the Inconel 713C:Re alloy showed higher oxidation resistance at 1000 °C compared to the other tested samples.

A well-known method of doping powders in the industry is mechanical alloying synthesis. This method synthesizes metal powders by grinding them in high-energy mills, which prevents the achievement of well-dispersed particles throughout the volume and control of particle morphology, size, and agglomeration.

In the present work, rhenium doping of IN 713C was carried out in a polyester network system based on organic acids and diols with specially selected catalysts and experimental parameters leading to the complexation of Rhenium ions. In addition, neutral reagents were used in this research, contributing to the greening of many key industries. The obtained IN 713C powder with rhenium showed high dispersion without agglomeration effect and reasonable flowability. Depending on the polymerization process parameters, the morphology of the rhenium particles on the surface of IN 713C can be modified. The IN 713C powder, with and without rhenium, was used in the SLM process to fabricate IN 713C alloy samples. The study examines the effect of rhenium doped IN 713C on the microstructure and hardness changes of the alloy produced by the 3D-printing methods. This type of chemical modification methods can effectively enhance the hardness and affects the elongation of dendrites in the structure of IN 713C alloys manufactured by the additive methods.

In this study, a general visco-Winkler–Pasternak foundation will be created to analyze the vibrations of functionally graded sandwich plates. The visco-Winkler–Pasternak foundations serve as the base for the suggested viscoelastic foundation, which takes into account a new damping coefficient related to the shear layer’s shear interactions. The new viscoelastic foundation model can be easily reduced to other well-known visco- and elastic foundation models. Establishing the governing equations of motion is achieved using the simple higher-order shear deformation theory and Hamilton's principle. Applying analytical solutions to these equations involves solving them with different boundary conditions. The proposed model is validated through some comparison studies. To demonstrate the effects of certain parameters on the vibration behaviors of functionally graded sandwich plates resting on general visco-Winkler–Pasternak foundations, a parametric study is performed. The numerical results section presents some novel findings and emphasizes the importance of two damping coefficients on plate vibration behaviors.

To reduce the cutting load and increase the cutting efficiency, laboratory and numerical tests involving a constant cross-section (CCS) cutter and an asymmetric cutter acting on precuts were performed. A laboratory study indicated that the asymmetric cutter consumes less energy than the CCS cutter under the same test conditions. In addition, the asymmetric cutter can ensure more effective rock breakages between precuts by generating oriented cracks. The numerical study results, which agree well with the laboratory test results for rock fractures, indicate that the plastic zones shrunken by the asymmetric cutter may be responsible for the decreased energy consumption. In addition, the dynamic stress evolution analysis reveals the fracture differences between the asymmetric cutter and the CCS cutter and further explains why the asymmetric cutter is more efficient.

The high-entropy alloy(HEA) samples FeCoNiCrTi_0.3, FeCoNiCrTi_0.5, FeCoNiCrAl_0.5 were designed and prepared by laser melting deposition (LMD), and their microstructure characterization were observed, physical phase analysis, and tensile properties were investigated. The results show that the microstructure at the top of the same LMD-HEA sample is smaller than that at the bottom. FeCoNiCrTi_0.5, FeCoNiCrTi_0.3, and FeCoNiCrAl_0.5 are all single-phase FCC structures, and the results of XRD and EBSD analysis are consistent. The fracture stroke of FeCoNiCrTi_0.3 is greater than that of FeCoNiCrTi_0.5, the tensile strength of FeCoNiCrTi_0.5 is larger but the section shrinkage is smaller. The maximum breaking load of FeCoNiCrTi_0.5 is slightly larger than that of FeCoNiCrAl_0.5, the tensile strength of FeCoNiCrTi_0.5 is larger than that of FeCoNiCrAl_0.5, the fracture shrinkage is smaller than that of FeCoNiCrAl_0.5, and there is little difference in the elongation. The number of dimples in the tensile fracture of FeCoNiCrTi_0.3 is significantly higher than that of FeCoNiCrTi_0.5, and the fracture of FeCoNiCrTi_0.5 is more flat and smooth. This study guides the study of the mechanical properties of LMD-HEA and is helpful for the high-performance design and integrated manufacturing of LMD-HEA composite components.

The comparative study is made on dissimilar weldments of Inconel 718 and ferritic stainless steel 430 joined by pulsed current tungsten inert gas welding process using ERNiCrMo-4 and ER2209 fillers. The base metals were joined with multiple welds passes by keeping pulse frequency (4 Hz) constant. The samples were examined for internal defects using X-ray radiography along with visual inspection. To understand the weldability of two different fillers, the mechanical properties were assessed by conducting a tension test as well as the hardness measurement. The macro/microstructures were revealed at various zones using an optical microscope with different magnifications. Further, for measuring the corrosion rate at fusion zone, the weld surface area of 0.1257 cm² was submerged in a 3.5% NaCl solution. The weld strength of 542 MPa was observed for ERNiCrMo-4 weldment whereas 469 MPa was observed for ER2209 filler weldment. Higher yield strength to weld strength was observed in ERNiCrMo-4 filler weldment than in the ER2209 filler weldment. ERNiCrMo-4 filler weld exhibited better hardness (198 HV) at the weld zone than the ER2209 filler weld (185 HV). The presence of a fine-grained structure at the interface of ferritic stainless steel 430 provides evidence of efficient blending and solidification in ERNiCrMo-4 filler weld. Whereas the elongated grains and secondary phases could potentially reduce the strength of ferritic stainless steel 430 in ER2209 filler weld. The corrosion resistance of ER2209 weldment (1.117 mm/year) is higher than the ERNiCrMo-4 weldment (1.353 mm/year) because of the presence of fine grain structures along with higher dense filler alloy elements.