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This study involves the comprehensive modeling of material properties and a numerical investigation of the free-damped vibrations exhibited by an innovative composite beam. The beam under consideration is a laminated magnetorheological (MR) elastomer, strategically reinforced with graphene platelets (GPLs). Initially, the mechanical properties of the MR matrix are meticulously calculated using a modified generalized Kelvin–Voigt viscoelastic model. To ensure the accuracy and credibility of the proposed model, nonlinear regression analysis based on the nonlinear least squares technique is employed. This modeling approach enables the tunability of the MR matrix's storage and loss modulus, which depend on factors such as the magnetic field, iron particles, and excitation frequency. The proposed model is verified by comparing the results with experimental data from the literature, using analyses of root mean square error (RMSE) and correlation coefficients. Subsequently, the composite media, comprising the magnetorheological elastomer (MRE) matrix and GPL reinforcements, undergoes homogenization through the application of the Halpin–Tsai micromechanical procedure. Theoretical formulations, encompassing third-order beam theory, strains, linear elasticity, and viscoelasticity, are then utilized to derive the motion equations governing the dynamic behavior of the composite beam. Hamilton's principle guides the derivation of these equations. To obtain the complex frequencies characterizing the system, the generalized differential quadrature (GDQ) method is implemented. In this study, particular emphasis is placed on investigating the performance achieved by adding GPL reinforcements to the MRE with different iron particle volume fractions under various magnetic fields. [ABSTRACT FROM AUTHOR]

The production of non-circular thin optical lenses involves initial processes such as circular cutting, grinding, lapping, and polishing. However, shaping the lenses into non-circular forms requires a final cutting process. This study focuses on addressing the distortion of BK7 thin glass parts during side grinding. Two clamping methods were examined to fix the components. The first method, commonly used in the industry, involves bonding the workpiece to a base using resin and subsequent machining, followed by separating the samples from the base by heating the resin. In contrast, this research explores an alternative approach using vacuum clamping. The components' distortion was measured using an interferometer. The results show that the vacuum clamping method produces more uniform surface parameters for the polished components compared to the typical resin bonding method. Additionally, the analysis reveals that surface parameter variations are more pronounced during square side-grinding compared to circular side-grinding. [ABSTRACT FROM AUTHOR]

Featured Application: The reconfigurable wheel-crawler walking mechanism involved in this study is a type of walking mechanism which can manage a high moving speed and good terrain adaptability given the unstructured terrain existing in the Qinghai–Tibet Plateau's scientific research station. The mechanism can achieve the purpose of switching between circular tire mode and triangular crawler mode without changing the working parts through the integration of wheeled and tracked components. In this study, the grouser effect of the walking mechanism was analyzed, and the parameters with the largest traction force were obtained, which can guide the machining of a prototype of the reconfigurable wheel-shoe integrated walking mechanism. To improve the unstructured terrain traversing performance of the scientific research robot of the Qinghai–Tibet Plateau station, the parameters of the track shoe of the reconfigurable wheel-crawler walking mechanism were studied. Based on a typical track shoe puncture effect model, the experimental design was carried out based on the surface response method, and the dynamic model of the triangular crawler mode of the reconfigurable wheel-crawler walking mechanism was constructed and tested using RecurDyn V9R3 software. Through an analysis of the simulation results, the interaction of the grouser parameters was further clarified, and the regression equation of the traction force of the walking mechanism was obtained. The grouser parameters that enabled the reconfigurable wheel-crawler walking mechanism to have the maximum traction were obtained; these will be used to guide the machining of the prototype walking mechanism. [ABSTRACT FROM AUTHOR]