Design optimization of a newly developed aluminum-steel multi-material electric bus body structure

Due to the constraints of power battery energy density, light-weight electric bus body structure is attracting more and more attentions with the capability to extend mileage. In this paper, an aluminum-steel multi-material electric bus body structure is newly developed and corresponding design optimization is performed for lightweight design while satisfying the constraints. The finite element model of the bus body structure is constructed and validated by experimental modal test. The optimization objective is to minimize the total mass, while bending, torsional stiffness, bending and torsional frequency are chosen as the corresponding constraints. The thicknesses of the pre-determined components are screened out using sensitivity analysis to determine the candidate design variables. Continuous and discrete gradient-based optimizers are employed to generate the optimal solutions, which are demonstrated that these new designs could bring benefits in terms of structural performance and structural weight.