The effect of residual stress on fatigue fracture of automotive leaf springs: Experiment and simulation

The primary fracture mode of leaf springs, which function as a spring in commercial vehicle suspension systems, is fatigue fracture. Shot peening (SP) is a surface finishing and cold working process that suppresses crack propagation and extends service life through the induction of residual stress. This study investigates the effect of residual stress on fatigue fracture. Firstly, different residual stress states were obtained by comparing the influences of SP time, prestress, and shot diameter on the residual stress of leaf springs. Secondly, a SP simulation model was developed in Abaqus to compute residual stresses. These stresses were incorporated into fatigue simulations of leaf springs using SIGINI subroutines. And the fatigue life of leaf springs was simulated using Fe-safe software. Finally, concurrent bench experiments were conducted for the purpose of verifying the results of the fatigue simulation. The simulation and experimental results have demonstrated that the surface residual compressive stress layer’s amplitude and the maximum residual compressive stress layer’s depth and amplitude, are positively correlated with SP time and shot diameter, and the optimal prestress is 1200 MPa. The maximum depth of the residual compressive stress layer most conductive to delay fatigue fracture is 0.15–0.2 mm.