A Proposal on Plastic Constitutive Representation Incorporating Stress Rate Dependence

A constitutive equation incorporating stress rate dependence which has been used widely is shown to have a limit for its application, especially, in the case that strain rate changes abruptly its direction. Therefore, the constitutive equation does not have the potential for representing such plastic behaviour that stress vector largely delays relative to strain rate vector. Before proposing our constitutive equation, the basic correlation in a five dimensional stress space is dealt with between local geometries of associated paths of stress and strain under plastic deformations obeying a general constitutive equation incorporating stress rate dependence. Using the basic correlation, we proposed a constitutive equation with flexibility applicable for stress delay angle observed experimentally between stress and strain rate directions in many strain trajectories.