Abstract
A practical new plastic constitutive model is presented on the basis of many experimental facts for initially anisotropic metal after various prestrainings. This model has two surfaces which bound an elastic region. a transitional hardening region and a steady hardening region with respect to elasto-plastic behavior in a five dimensional deviatoric stress space. The surface G which represents the elastic region moves rigidly according to the newly presented rule. The surface G which distinguishes the transitional hardening region from the steady one moves in the direction of the stress vector and transforms its shape. The associated flow rules are adopted with the two surfaces in determining a corresponding plastic strain increment to a stress increment. The modified hardening coefficients are used when the loading point moves in the transitional hardening region. Applications of this constitutive model to some concrete examples will be presented in some following reports.
