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The lightweight design of electric heavy quadricycle (L7e) vehicles has contributed to energy savings and sustainable mobility. This study proposes an optimization methodology to design a monocoque sandwich structure under operating conditions for an L7e using a finite element model via HyperWorks. Woven fiberglass fabrics and high-density PVC foam are assigned as the face and core to construct the sandwich structure, respectively. Free-size optimization based on weight minimization is applied to obtain the suitable initial thickness of face and core structures in all components. Multi-objective size optimization is then performed by minimizing both mass and material cost to determine the optimal thickness of each layer. Finally, shuffle optimization is used to modify the stacking sequence for each component to maximize structural stiffness. The results indicate that the core thickness in the passenger compartment is sufficient to maintain stiffness while maintaining the structure's lightweight. However, shuffle optimization is insignificant for the current monocoque model, as the structural stiffness is only marginally improved after the process. Additionally, this study examines the optimized models for structural stiffness and discusses suitable procedures for designing a lightweight and safe electric vehicle. [ABSTRACT FROM AUTHOR]

Abstract Many studies have investigated adhesive tubular joints subjected to axial load. However, previous analytical studies were only limited to the joints with single-layer isotropic or orthotropic materials, and the corresponding mathematical models were highly complicated. Thus, the aim of this article is to develop a simplified but comprehensive model for studying adhesive-bonded tubular coupler joints subjected to tension. The joint adherends can be made of isotropic, orthotropic, or multilayer composite materials. This study presents the formulation of the mathematical model for stress analysis in coupler joints. Assumptions of an axisymmetric joint with linearly elastic adherends and adhesive materials are employed. A thin adhesive layer is considered such that only the out-of-plane adhesive stresses are concerned and are treated to be uniform through the layer thickness. Using elasticity theory and the newly developed finite-segmented method, stress distributions in both adherends and the adhesive can be evaluated. The influence of fiber angle in the cases of composite adherends and joint geometries are studied. The results provide a good guideline in designing adhesive-bonded cylindrical joints with isotropic and composite adherends under axial loads. [ABSTRACT FROM AUTHOR]