Simulation of Multiaxial Ratchetting and Nonproportional Cyclic Deformation of IN738LC at High Temperature
Abdel Karim Mohamed; Mizuno Mamoru; Ohno Nobutada
Abstract:In a previous work, the present authors proposed a new extension of the constitutive model of cyclic plasticity developed by Ohno and Wang, and they verified the extension on the basis of uniaxial ratcheting experiments of 316FR steel at room temperature. The extension is featured by the capability of representing steady state ratcheting. In this work, the extension is examined further for the validity under nonproportional cyclic loading by simulating the viscoplastic behavior of IN738LC subjected to multiaxial ratcheting, multiaxial cyclic stress relaxation, butterfly type cyclic straining, and circular cyclic straining with strain hold at 850 degree. The original Ohno and Wang model and the Armstrong and Frederick model are also examined. It is shown that the extension enables us to simulate accurately the multiaxial viscoplastic behavior mentioned above, and that if neither ratcheting nor mean stress relaxation under cyclic loading is significant the three models provide nearly the same predictions as one another. Key Words:constitutive model, cyclic loading, multiaxial ratcheting, nonpropotional behavior, viscoplasticity, IN738LC, high temperature