Finite element-based fatigue life prediction of a lower suspension arm under various Road-Induced loading histories

Fatigue failure is a critical cause of mechanical degradation in vehicle components, especially in suspension systems that are continuously subjected to fluctuating road loads. Among these components, the lower suspension arm plays a vital role as a connector between the wheel assembly and the chassis, and it is highly prone to fatigue damage due to repetitive tensile, compressive, and torsional stresses. This study focuses on predicting the fatigue life of a lower suspension arm using a strain-based finite element analysis (FEA) approach. A three-dimensional model was developed in SolidWorks and analysed in ANSYS Workbench under four different strain histories, namely fully reversed constant amplitude, bracket, suspension, and transmission strain conditions. Structural steel was selected as the material, and fatigue life was estimated using the Coffin-Manson strain-life model with the Goodman mean stress correction. The results revealed that the bracket strain condition exhibited the shortest fatigue life of 0.314 × 10⁴ cycles, while the suspension strain condition provided the longest life of 69.056 × 10⁴ cycles, followed by the transmission strain with 8.380 × 10⁴ cycles. The findings demonstrate that the strain-based FEA method effectively captures localized deformation and provides reliable fatigue life predictions for automotive suspension components under realistic road-induced load conditions.