Virtual Strength Testing of Crankshafts Taking into Account Residual Stresses from the Surface Hardening Process

Abstract Crank shafts are subjected to a multi axial stress history during real engine operation, but because of increased efficiency, testing is performed for bending and torsion separately. The sustainable endurance moments are an important characteristic used for designing strength and optimizing the production process. Determining the bending and torsion endurance moments accurately with numerical means is only feasible if the surface hardening is considered. For this both the residual stress field as well as the altered material properties of the hardening layer need to be considered. For strength assessment the “Critical plane - Critical component” hypothesis was used which distinguish normal stress and shear stress type loading in an adequate way related to the material behavior.