Top-Down Design Approach of Lightweight Composite Battery Pack Enclosure for Electric Vehicles Based on Numerical Modeling and Topology Optimization

To meet the increasing demands for structural lightweighting in electric vehicles (EVs), carbon fiber reinforced plastic (CFRP) has been gradually introduced to reduce weight and enhance passenger safety in automotive engineering. The battery-pack enclosure is a key structural component for EVs, as it significantly influences the driving distance, safety, and road handling of EVs. This study presents a top-down design approach and topology optimization for a lightweight CFRP battery pack enclosure reinforced with cross-shaped stiffeners. The main objective is to develop an efficient composite enclosure that meets performance targets while accommodating the demands of cost-effective mass production. The composite battery pack enclosure was fabricated using the compression molding process. Topology optimization was carried out in the preliminary design stage on the structural shape and geometric parameters following a top-down design approach. Experimental tests recorded maximum deformations of 0.56 mm and 10.33 mm under in-plane and lateral loads, respectively. The final prototype product achieved a total mass of 4.78 kg with a rapid curing cycle of 10-15 min. In conclusion, a lightweight composite battery-pack enclosure with cross-shaped stiffeners was successfully manufactured, integrating a top-down design approach with topology optimization. This study demonstrates an effective design approach to achieving an optimal balance of lightweight, cost-effectiveness, and production efficiency for EV battery-pack enclosures.