Design Evolution of a Novel LCA for a multi-link Rear Suspension System in a born electric vehicle

The spring link or the lower control arm (LCA) is a critical structural component in a multi-link rear suspension system especially in a sports utility vehicle (SUV). The design of the rear LCA is thus challenging due to higher loads owing to higher suspension articulation typical of a SUV and further complicated in a born electric vehicle (BEV) due to increased vehicle weight contributed by a large battery. In the present work, a novel LCA was designed for the rear suspension system of one such born electric SUV application. The unique link was designed to withstand 20% higher rear axle weight compared to the conventional LCA used in a typical SUV. The LCA housed the spring with increased stiffness and a semi-active damper with varying and higher damping forces which complicated the design. The link design was further complicated with stab link mounting provision and mass damper mounting for improved NVH performance. Furthermore, the link was designed to withstand significantly higher forces due to 25% increased bump travel whilst reducing the panel thickness and weight of the LCA by 10% without compromising on the performance and durability compared to the conventional LCA. The link was also designed for ease of manufacturing with low-cost press worked sheet metal panels despite the higher loads acting on it. The present study details the design evolution of the spring link elaborating the novel design features used and the design optimization study carried out using finite element analysis (FEA) to evaluate the fatigue life and buckling strength. The FEA analysis was performed using commercially available FEMFAT & NASTRAN software to validate the structural performance whilst OptiStruct was used for the bucking analysis. Thus, the present work details the novel design features and the design evolution of the spring link with 10% reduced weight to meet the durability, performance and tighter packaging requirements of a multi-link rear suspension system of a born electric SUV. Keywords: Lower control arm rear, Spring link, multi-link, rear suspension.