Simulation study on the surface crack propagation characteristics of 60Si2MnA suspension springs

Abstract As a critical component of the urban rail vehicle suspension system, suspension springs can translate and isolate the interaction of wheel-rail dynamics. However, with the gradual occurrence of fatigue failures in locomotive suspension springs, their reliability needs further attention, as the failure of suspension components can directly threaten the operational safety of heavy-load vehicles. In this study, a 3D model of springs with fatigue cracks was established by using the interactive analysis method of FRANC3D and ABAQUS softwares. The initial stress intensity factor (SIF) of the surface cracks of the spring was calculated by using the M-integral method, and the variation of the initial stress intensity factor of the surface cracks under different parameters was studied. Finally, based on Paris theory, the crack propagation law and the remaining life characteristics of surface cracks under different parameters were discussed. The results show that as the crack inclination angle increases, the initial SIF of the surface cracks first increases and then decreases. The SIF level at the crack tip of the surface cracks also increases with the increase of crack size, crack depth, and loading conditions. In the subsequent crack propagation process, the variation trend of the initial SIF of the surface cracks under all variables tends to be consistent, showing a W-shaped distribution structure, and the peak SIF shifts from the tip to the crack depth direction. The remaining fatigue life analysis of surface cracks shows that within the range of 60° to 120°, as the initial crack inclination angle increases, the crack propagation life first decreases and then increases. Additionally, the fatigue propagation life of surface cracks decreases with the increase of the initial crack size and loading conditions. The crack depth has no significant impact on the propagation of surface cracks, but it also shows a trend of decreasing with the increase of depth, and the crack size extends to about 16 mm, entering the unstable propagation stage.