Simulation of ratcheting strain to a high number of cycles under biaxial loading

The Ohno-Wang kinematic hardening rule is modified to incorporate the Burlet-Cailletaud radial evanescence term for an improved simulation of the ratcheting behavior. The Delobelle parameter (theta)’ is implemented in the modified model to compromise shakedown of the BurletCailletaud hardening rule and over-prediction of the Ohno-Wang model. An evolution equation is proposed for (theta)’ to simulate the ratcheting strain over an extended domain of cycles. Ratcheting tests were conducted on S45C steel under four types of nonproportional axial-torsional loading. The new model is found to yield reasonably accurate predictions of ratcheting strain to a much higher number of cycles compared with other studies.