Fatigue reliability design of composite helical spring with nonlinear stiffness based on ply scheme design

Abstract

Nonlinear stiffness composite helical spring has gained considerable attention due to its significant lightweight effect and reliable nonlinear stiffness function. Those performance of helical spring is of great significance to the energy saving and comfort improvement of automobiles. In this paper, the design method of nonlinear stiffness composite helical spring using typical materials and ply scheme was put forward. The FEM models of different ply schemes were established. Combined with ABAQUS software and the secondary development subroutine, the strength and fatigue simulation analysis of circular tubes with typical ply schemes was carried out. Then the samples using different ply schemes were prepared. The failure type, stiffness attenuation rate, and height attenuation rate of springs were obtained through the strength test under extreme condition (compression state) and the fatigue test under the full-load condition. Finally, the best ply scheme and typical damage types were obtained. Comparing the test results with the simulation results, a method that can accurately predict the strength and fatigue failure of the nonlinear stiffness composite helical spring was verified. This study can provide a systematic ply scheme design method for the fatigue reliability design of composite structures with circular tube shape.