To assess the strength and stiffness of the subgrade, one of the most important parameters in pavement design is the California Bearing Ratio (CBR). Soil compaction and index properties influence CBR; therefore, further research was conducted to explore this relationship. CBR equation so that the thickness design of the flexible pavements can reach a certain probability. CBR estimation in this work is done by using Support Vector Regression (SVR). To enhance the predicted core model accuracy, Rune Kutta Optimization (PKO), Flying Foxes Optimization (FFO), and Henry Gas Solubility Optimization (HGSO) techniques have been employed as optimization methods. These sophisticated hybrid models were developed through an intentional effort to fuze these optimizers intentionally with the base models as a way to improve accuracy. When the SVR model is coupled with HGSO, the formed framework goes under the name of the SVFF framework; when it is combined with FFO, it goes under the name of the SVHG framework; and when connected with RKO, the framework takes the name of SVRK. As selected by the R 2 index, the best performance during the testing phase was given by the model SVRK, with a score of 0.963. The second-best and the best performance was that of the SVFF model, with an R 2 score of 0.957. During testing, the SVRK model outperformed the normal SVR model, which had a better RMSE value of 0.192, while the worst performance was by the latter model itself, with an RMSE value of 0.370.

This study examined the thermal vibration buckling properties of a nanoplate with PZT 5H piezoelectric material in the face layers and graphene platelets (GPLs) reinforced metal (nickel) foam in the core layer. Three different foam models are used to accurately depict the thermomechanical vibration characteristics of the sandwich nanoplate. The constitutive equation of the nanoplate is influenced by various factors, such as thermal expansion, electro-elasticity, strain gradient elasticity, nonlocal elasticity, and sinusoidal higher-order shear deformation theory (SHSDT) that accounts for the stretching effect. The equations of motion for the sandwich smart nanoplate with piezoelectric face plates are derived using Hamilton’s technique and solved with a Navier type solution. We have conducted a comprehensive study on the thermomechanical vibration response, exploring various conditions such as thermal loads, externally provided electricity, foam volume fractions, volumetric GPLs ratios, and foam models. The thermomechanical vibration behavior of sandwich nanoplates with piezoelectric face layers and reinforced metal core is influenced by several factors, including the ratio of open cell foam to solid, external applied electrical and thermal load, nonlocal factors, and various foam models of the core plate.

Driven by the continuous advancements in energy absorber geometries to enhance energy absorption performance, this study utilizes the capabilities of 3D printers to investigate the evolution of energy absorber geometries from simple to multi-cellular, and subsequently to bio-inspired structures. The energy absorption behavior of these structures under axial, three-point bending, and lateral loading conditions is examined. Three distinct bio-inspired designs were introduced to address the challenges of different loading conditions. In addition to experimental evaluations, detailed numerical simulations were conducted to deepen the understanding of deformation mechanisms and to assess the influence of different material types, specifically PLA and TPU, on structural performance. These bio-inspired solutions not only improve the performance of energy absorbers but also highlight the elegance of incorporating biological principles into engineering. The results show that bio-inspired geometries, with their complex designs, enable progressive crushing and offer superior specific energy absorption compared to conventional structures under various loading scenarios. By employing bio-inspired geometries, the specific energy absorption (SEA) was significantly enhanced compared to simple and multi-cell configurations by 43.75% and 29.74% under axial loading, 82.86% and 62.83% under three-point bending, and 98.96% and 81.99% under lateral loading, respectively. The findings demonstrate that nature-inspired design significantly optimizes performance and efficiency, promising a major impact on the development of more innovative and sustainable engineering solutions. The originality of this work lies in its holistic framework that bridges geometry, material selection, and multi-loading functionality, paving the way for next-generation energy-absorbing structures.

Although a compliant gripper is a type of compliant mechanism, existing analytical models rarely account for the real mechanical behavior of the flexible parts within the gripper. In this work, an in-plane motion flexure-based compliant gripper is presented, modeled, and analyzed. An analytical methodology based on the Compliance Matrix Method (CMM) is proposed to compute the relationship between input and output forces and displacements in two different coordinate frames using a single unified expression that represents the real mechanical behavior of the system. The analytical model is validated through Finite Element Analysis (FEA) simulations and experimental tests performed on additively manufactured prototypes. Additionally, the model is used to analyze output displacements resulting from variations in geometric parameters, with results validated through FEA simulations. This demonstrates the method’s utility in optimizing gripper design during early development stages prior to fabrication. The proposed analytical model accurately estimates the compliant gripper’s kinetostatic behavior, achieving less than 5% difference compared to FEA and experimental results. Furthermore, the model is adaptable and can be extended for the kinetostatic analysis of other compliant grippers with similar flexure-based architectures.

In mechanical systems, the effect of friction on the dynamic response of the mechanism is unavoidable. In order to describe the friction behavior at the revolute joint of mechanical systems more accurately, the friction coefficient is modeled as a nonlinear function with respect to pressure and rotational speed based on material-level friction tests. Combined with the Ambrósio friction model, we propose a friction model with nonlinear friction coefficient, and the dynamics of a crank-slider mechanism containing a revolute clearance joint is analyzed based on the proposed model. The results show that the friction model with nonlinear friction coefficient can improve the accuracy of numerical simulation of the system and promote the capability of prediction of dynamic response of complex mechanical systems with joint clearance.

This study aims to systematically investigate the wave propagation behavior in curved sandwich nanoplates incorporating zirconia–Ti6Al4V cores and graphene-enhanced foam layers, subjected to combined thermal and magnetic fields. To achieve this, a high-order shear deformation plate theory coupled with nonlocal strain gradient elasticity theory is employed. Three distinct foam distribution patterns—U-foam, S1-foam, and S2-foam—are considered to assess their influence on wave characteristics. The results reveal that phase and group velocities decrease with increasing foam content, thermal softening effects, and reduced curvature radius, whereas the presence of a magnetic field contributes to increased wave velocities. Interestingly, the impact of foam distribution varies significantly among configurations, with U-foam showing the most pronounced effect (40%), followed by S1-foam (10%) and S2-foam (3%). These findings underscore the potential applicability of such nanostructures in advanced engineering systems, particularly in radar-absorbing materials; high-temperature nanoelectromechanical systems; and lightweight, thermally responsive sensors for wearable healthcare technologies.

This study aims to examine the behavior of thermoelastic vibrations in a solid cylinder containing voids using a novel approach that involves the Moore–Gibson–Thompson equation for heat conduction within the context of Klein–Gordon nonlocality. This unique method offers a fresh perspective on heat transfer in elastic materials with voids. The results of this study, which can provide valuable insights for designing structures with better thermal stability and vibration resistance, were obtained by focusing on vibrations caused by thermal shock at the cylinder surface. The research findings can potentially contribute to designing structures with enhanced thermal stability and resistance to vibrations. In our numerical programming, we used the Laplace transform technique, which was implemented in Mathematica software, to analyze the system’s response to thermal shock. Specifically, we applied Durbin’s Fourier series-based method for the numerical inversion of the Laplace transform, which has proven efficient and accurate for this type of problem. Graphical representations were created from numerical data. Different theoretical approaches were compared to illustrate how phase lags and nonlocally influence physical phenomena. These findings indicate that the size of the voids plays a crucial role, with practical implications for the design and performance of materials. Additionally, the anisotropy of waves is relatively minor for a cylinder with voids under the effect of the examined model.

The present work aims to estimate the thermal mechanical behavior of composite slabs made with both normal weight concrete (NWC) and lightweight concrete (LWC) using a hybrid calculation method. This method combines the simple analytical approach outlined in Eurocode 4 (Eurocode 4 2005) with the thermal results of the finite element method (ANSYS). In this study, the key factors considered include the concrete type, the geometry of the steel profile and the airgap between the steel profile and the concrete. The results found show that the presence of the LWC decreases the temperature evolution by 22% and 41% for the trapezoidal and reentrant slab sections, respectively. It was also found that slabs with trapezoidal sections heat up more and lose more of their load-bearing capacity compared to slabs with reentrant sections. Concretes with higher mechanical performances result in a significant residual moment after heating, while the stability is still monitored. The development of the deflection is more important in LWC than in NWC. The suggested method, a novel contribution of this work, combines the simple analytical approach from Eurocode 4 with the finite element method, yields similar and promising results, aiding in more accurate the fire resistance time estimation.

The efficiency of frictional anti-loosening fasteners depends on the sufficiency of their anti-loosening torque. The currently recommended values of the frictional anti-loosening torque (Tf ) were determined under well-controlled conditions using DIN25201 or NAS3354 tests. However, the operational environment of bolted assembly can differ significantly from the laboratory settings, including the possibility of excessive clamping force, significant transverse displacement of the clamped bodies, and deviations from the fasteners’ nominal size. In the case of ordinary fasteners, these factors were proven to compromise loosening resistance. However, their effects on frictional fasteners’ performance have yet to be thoroughly explored. This study aimed to fill the gap. Our analytical and experimental results failed to demonstrate any significant impact of the transverse displacement and geometric deviations on loosening resistance, providing the frictional fasteners’ Tf was set to the recommended value. Thus, this study emphasizes the necessity to strictly follow the tightening standards, irrespective of the presumed unfavorable conditions.

The critical moment of unstrengthened and strengthened mono-symmetric and doubly symmetric steel beams was investigated using two approaches: analytical and finite element models (FEMs). The newly developed analytical model was formulated based on solving six homogeneous differential equations of a steel beam controlled by elastic lateral-torsional-buckling (LTB). The carbon-fiber-reinforced plastic (CFRP) plate was included in the analysis based on the virtual-section method. The solution consisted of a 6 × 6 eigenvalue problem. The proposed solution can predict reasonably the critical moment in the elastic range of a steel beam strengthened fully or partially at top or bottom flanges with CFRP plates. Twenty-six FEMs were built using ABAQUS software to examine the accuracy of the proposed analytical model. The FEM models included: unstrengthened and strengthened steel beams with 1-m and 2-m lengths of composite strips. Due to lack of experimental data in the elastic LTB stage and in order to further validate the analytical model, an extension of the model was proposed to compare results with other available experimental data in the inelastic-buckling zone for steel beams strengthened with steel or CFRP plates. The comparison showed that the finite element and analytical models, utilizing the virtual-section concept of CFRP plate, can reasonably predict the improvement in moment-capacity of beams in the elastic- and inelastic-buckling zones.