ELASTOPLASTIC CONSTITUTIVE ANALYSIS WITH THE YIELD SURFACE IN STRAIN SPACE

A COMMON APPROACH used in formulating elastoplastic constitutive equat ions is to partition the total strain rate into its elastic and plasti c parts, and then develop the constitutive expression for the plastic strain rate using the concept of the yield surface in stress space. An alternative approach is to partition the stress rate into its elastic and plastic parts, and then develop the constitutive expression for t he plastic stress rate using the concept of the yield surface in strai n space. Both of these approaches are used in this paper to derive and compare the final structures of the corresponding constitutive equati ons. It is shown that the preferable choice of the yield surface may b e in either stress or strain space depending on the selected strain an d conjugate stress measures utilized to construct the constitutive for mulation.