Archives of Civil and Mechanical Engineering最新文献

Due to the shape of the prismatic cell container (PCC) and the physical properties of aluminum (Al) alloys, there are limitations in fabrication with common welding methods. Magnetic pulse welding (MPW) is a promising solid-state joining process that provides fast and strong welds without heat-affected zone. Despite the growing interest in this process, there is little understanding of the sealing performance and joining mechanism of PCC structures fabricated by MPW, which is critical for prismatic cell safety. In this study, MPW was used to join the cell case (CCE) and cell cap (CCP) for the fabrication of Al3003 PCC. The sealing performance, mechanical properties and joining mechanism of MPW joints were investigated. The results showed that the overall sealing of the PCC was realized by MPW technology, and the sealing performance reached 0.8 MPa. Peeling tests showed that the strength of the MPW welds was higher than that of the parent material, and one of the main reasons for the excellent strength of the welds was the waveform interface formation. Furthermore, the appropriate collision speed and angle were the key factors for welds generation, which ranged from 315 m/s to 360 m/s and 2–10°, respectively. This study provides potential options for the fabrication of Al PCC for electric vehicles.

Multi-pass multi-directional forging (MDF) was applied to enhance tribological properties of Zn–4Si alloy. According to the results, MDF effectively refined coarse irregular-shaped primary Si particles (PSPs) and encouraged their uniform distribution within the matrix. MDF also modified the microstructure by forging porosities and eliminating entrained bifilm oxides. The average size of PSPs and volume percentage of porosities decreased from 38.7 ± 11.5 μm and 0.82 ± 0.17% in the as-cast sample to 6.8 ± 3.1 μm and 0.19 ± 0.05% in the 8-pass MDFed sample, respectively. The maximum hardness was obtained in a 4-pass MDFed sample where its hardness was increased from 37.8 ± 3.2 in as-cast state to 52.7 ± 1.1 HB. The 4-pass MDFed sample also showed the maximum wear resistance where at applied pressures of 0.25, 0.5, and 0.75 MPa, its wear rate was lower than that of the as-cast sample by 83, 76, and 72%, respectively. MDFed samples also exhibited improved friction properties. At the applied pressures of 0.25, 0.5, and 0.75 MPa, the friction coefficient of the 4-pass MDFed alloy was lower than that of the as-cast alloy by 38%, 29% and 20%, respectively.

In this study, the friction surfaced Al–Si–Cu alloy coating was processed using a low rotational speed, fast multiple rotation rolling (FMRR) process. The effect of traverse speed in the range of 50–200 mm/min at a rotational speed of 600 rpm on the microstructure, mechanical properties, and wear resistance of the Al–Si–Cu alloy coating was investigated. The results showed that compared to the initial friction surfaced coating, the thickness of the coating decreased by 44% and the width of the coating increased by 21% with a decrease in traverse speed from 200 to 50 mm/min. By increasing the traverse speed from 50 to 200 mm/min, the thickness of the processed layer decreased from 102.3 ± 1.1 µm to 54.2 ± 1.3 µm, and the grain size of the processed layer decreased from 2.4 ± 0.1 µm to 1.1 ± 0.2 µm. As the traverse speed increased from 50 to 200 mm/min, the average hardness of the FMRR processed layer increased from 6.7 ± 0.4 GPa to 9.7 ± 0.4 GPa. Additionally, at a traverse speed of 200 mm/min and a rotational speed of 600 rpm, the wear resistance of the FMRR processed layer increased by 65% compared to the AA1050 aluminum substrate.

The recycling of waste materials and the promotion of sustainable practices to utilize these waste materials in product development have become imperative in addressing environmental concerns. This study presents a novel approach to utilize waste ashes in the production of sustainable ceramic tiles using an integrated artificial intelligence (AI) model. Experimental investigation was carried out on ceramic tiles using waste ashes produced during the manufacturing process. More than 35 different ceramic tile mixtures incorporating different proportions of waste ashes were prepared at a temperature of 1120 °C using different percentages of waste ashes. The ceramic tiles were evaluated using X-ray diffraction (XRD), flexural strength, water absorption, shrinkage, visual index, and scanning electron microscopy (SEM). The results revealed that up to 5% of waste ashes can be used to manufacture ceramic tile satisfying the minimum specified limits of EN-ISO 10545. Moreover, ceramic tile specimen using waste ashes showed more compact and integrated structure. Further, an AI model was proposed to predict the optimal composition of waste ashes, considering factors such as chemical properties, particle size distribution, and sintering behavior. The results demonstrated that the incorporation of waste ashes in ceramic tile production not only offers environmental benefits, but also proves economically viable. The AI model provides accurate predictions, facilitating the optimization of waste ash composition and ensuring the desired physical and mechanical properties of the tiles. The findings of this study provide valuable insights for policymakers, industry stakeholders, and researchers seeking innovative solutions for sustainable waste management and product development.

A trustworthy prediction of flow stress behaviour is essential to optimise the hot working process parameters. It also helps accurately capture the finite element simulations of many complex processes. In this work, modification in the Johnson–Cook (JC) model has been proposed for better prediction of the flow stress behaviour of the 92W–5Co–3Ni alloy. Initially, uniaxial compression tests were conducted at different strain rates (1 s⁻¹, 25 s⁻¹, 50 s⁻¹, 75 s⁻¹, and 100 s⁻¹) and temperatures (323 K, 473 K, 673 K, 873 K) using Gleeble-3800 thermo-mechanical simulator. It was confirmed that flow stress variation is sensitive to both strain rate and temperature change. Subsequently, various microstructural parameters were evaluated, such as grain size, tungsten–tungsten contiguity (W/W contiguity), tungsten–tungsten connectivity (W/W connectivity), dihedral angle, neck length, solid volume fraction, and matrix volume fraction. Afterwards, the phenomenological-based constitutive models, namely, Johnson–Cook (JC) and modified Johnson–Cook (m-JC), were initially established. The analysis of flow stress prediction based on various statistical parameters revealed that both models demonstrate poor flow stress prediction capabilities with correlation coefficient (R) of 0.7715 and 0.7925, respectively. An improved Johnson–Cook model (i-JC) was proposed, replacing the strain term with the Ludwigson hardening equation and varying the coefficient of strain rate hardening term with plastic strain and strain rate. The i-JC model significantly improved the accuracy of flow stress prediction with a correlation coefficient (R) of 0.9891, average absolute relative error (AARE) of 1.35%, and standard deviation of 1.33%.

This paper introduces the Monte Carlo simulation (MCS) procedure in combination with an effective finite element method (FEM) based on the refined first-order shear deformation theory (r-FSDT) to examine the random vibration of functionally graded sandwich (FGS) plates with different skin layers subjected to double explosive load (DEL). In the stochastic design methodology, the formulation of the state function for design conditions commonly involves integrating random input parameters, assumed distribution functions, and the stochastic responses derived from problem models. The motion equation of the FGS plate is derived by using Hamilton’s principle. Then, the Newmark-beta method is applied to solve linear second-order ordinary differential equations. Finally, the random vibration of the FGS plate is studied by considering the normal distribution parameters. In general, this research tries to shed light on the effects of geometric parameters and material properties and guide the design of FGS plates subjected to double explosive load with uncertain input parameters.

To investigate the torsional performance of reinforced concrete (RC) columns strengthened with carbon fiber reinforced polymer (CFRP) sheets, a mechanical analysis model was established using a three-dimensional numerical method. The model considered the heterogeneity of concrete, and the interactions between steel bars/CFRP sheets and concrete, simultaneously. The validity of the numerical model was first verified. Subsequently, pure torsion was added on 40 CFRP sheet-strengthened RC columns to investigate the influences of the fiber ratio, the structure size, and the cross-section shape on their torsional performance. Results showed that (1) size effect can be observed in the nominal torsional strength of both square and circular CFRP sheet-strengthened RC columns; (2) the size effect of square columns was stronger than circular columns due to weaker confinement effects of CFRP sheets on the square columns; (3) the addition of CFRP sheets can simultaneously improve the torsional strength and weaken the size effect, which is beneficial to the torsional performance of the column. Moreover, a torsional size effect law was proposed to predict the torsional strength of CFRP sheet-strengthened RC columns based on current simulation results.

To investigate the interfacial bonding performance between high-early-strength high-ductility concrete (HES-HDC) and existing concrete, 108 bonding specimens were used to study the effects of concrete substrate roughness, the content of silica fume, hydroxypropyl methylcellulose (HPMC), and polyethylene (PE) fiber in HES-HDC, as well as curing age and testing methods on the interface failure mode, load-slip curve, and interfacial bonding strength between HES-HDC and concrete. The results show that the interfacial bonding strength at 2 h of all bonding specimens exceeded 1.2 MPa, with the interfacial bonding strength at 1 day reaching 60% of that at 28 days, demonstrating significant high-early-strength properties, meeting the requirements for rapid repairs. The concrete substrate roughness significantly influenced the interface failure mode and the characteristics of the shear load-slip curve. The interfacial shear strength increases with increasing concrete substrate roughness, HPMC content, fiber content, and curing age. HES-HDC with 6% silica fume exhibits higher interfacial shear strength with existing concrete. Based on the experimental results, a formula for the interfacial bonding strength between HES-HDC and concrete was proposed, considering interface properties and material strength, which could be applicable for predicting bonding strength using different interface testing methods.

This article primarily focuses on optimizing the composition of cementitious materials, such as fly ash, ground granulated blast furnace slag, nano-silica, silica fume, and superabsorbent polymers, to investigate their effectiveness in mitigating early residual expansion deformation in steam-cured concrete. Additionally, it evaluates the long-term performance of steam-cured concrete samples incorporating these cementitious materials. The article concluded that replacing 30% of the cement in the concrete mix with 20% fly ash and 10% slag, along with the additional inclusion of 0.2% super absorbent polymers, yields the best results in mitigating the above deformation and enhancing the performance of steam-cured concrete. The recommended mix proportion suggested in the article for 1 cubic meter of concrete includes 315 kg of cement, 90 kg of fly ash, 45 kg of slag, 0.9 kg of super absorbent polymer, 660 kg of sand, 1210 kg of limestone aggregate, 135 kg of water, and 4 kg of superplasticizer. This approach also prevents the reduction or insufficient development of the later-stage mechanical properties of steam-cured concrete and improves its pore structure. By focusing on optimizing the cementitious system of steam-cured concrete, this article provides theoretical and technical support for the preparation of high-performance prefabricated steam-cured concrete components.

Aggressive environments can lead to deficiencies or failure in reinforced concrete (RC) members because of the corrosion of reinforcing steel bars. Therefore, bars manufactured from fiber-reinforced polymer (FRP) composites have been employed as a possible substitute for steel bars in RC members. FRP bars have corrosion resistance greater than the conventional steel rebars and a higher ultimate tensile strength. The aim of current investigation was to examine the flexural and compression behavior of slender RC columns having Basalt FRP (BFRP) rebars. Six square slender columns of 240 mm size and 2.8 m long were fabricated in three sets with each set of 2 columns. The columns of the first set were reinforced with 6ϕ12 mm steel rebars (1.1%), whereas the columns of the second and third sets had internal BFRP rebars. The second and third sets differed in the diameter of BFRP rebars, and the percentage of reinforcement was nearly same. The second and third sets had longitudinal BFRP rebars of 6ϕ12 mm (1.1%) and 12ϕ8 mm (1.0%), respectively. Test specimens were subjected to concentric and eccentric (eccentricity = 50 mm) compression. The average compressive strain in BFRP rebars at maximum load was slightly greater than the crushing strain of concrete for both BFRP bar diameters (ϕ8 mm and ϕ12 mm) indicating that the compressive stress in BFRP bars can be calculated from strain compatibility. Analytical model was also carried out for developing the P–M interaction graphs for columns having BFRP rebars. The developed model included the compression resistance of BFRP rebars. The analytically predicted interaction diagrams were conservative and near the experimental ones. The test results of this study were compared with other similar studies from the literature, and the effects of eccentricity-to-depth and slenderness ratios on the second-to-first-order moment ratios were examined for eccentrically loaded FRP-reinforced concrete columns.