Topology optimization of electric vehicle chassis structure with distributed load-bearing batteries

This paper presents a systematic design approach of conceptually forming a lightweight electric vehicle (EV) chassis topology integrated with distributed load-bearing batteries of different shapes and dimensions using a density-based topology optimization approach. A deformable feature description function tailored to commercial Li-ion batteries is proposed to describe cell features with desirable layouts, dimensions, and continuous shapes only from cylinder to cube by applying a handful of design variables. A Kreisselmeier-Steinhauser function Boolean operation and a gradient-norm method are sequentially leveraged to integrate multiple cells enclosed by reinforced shells into a unified battery set. Besides, a new non-overlapping constraint is developed to avoid the geometric overlaps between all cells and further restrict the minimum battery spacing through introducing an auxiliary density filter. By solving the optimization problem, an EV chassis with distributed various specification batteries can be obtained, which exhibits better comprehensive mechanical properties than that with centralized uniform specification batteries under the same battery capacity and structural weight. Numerical examples of different battery capacity requirements, battery shell thicknesses, and minimum battery spacing are given to demonstrate the applicability of the proposed approach.