Design and integration of planar springs in an automotive suspension system

This study presents a novel spring design, successfully applied for the first time in the automotive sector as a replacement for conventional helical springs. Specifically, a pair of predeformed planar springs has been developed to replace a coil spring in the suspension system of a utility trailer. The geometry of the planar springs was carefully designed to replicate the behavior of the original helical spring. A finite element method (FEM) analysis was performed on several alternative geometries, and the results were validated through tensile tests on selected prototypes to quickly identify a configuration that met the application¿s specifications. The modified two-wheeled utility trailer was tested at an official motor vehicle inspection office, which adheres to European Union regulations for vehicle approval. Test results demonstrate that the planar spring prototype not only meets but slightly improves upon the performance of a standard commercial helical spring. A significant contribution of this research is the introduction of planar springs as a promising alternative in the automotive sector, offering advantages, such as a larger ratio between compressed and stroke lengths, higher radial stiffness relative to axial stiffness, and a more versatile, scalable manufacturing process compared to conventional helical springs. These features position planar springs as a valuable solution, particularly in large-scale applications beyond nano- and micro-engineering.