STRAIN RATE POTENTIAL FOR METALS AND ITS APPLICATION TO MINIMUM PLASTIC WORK PATH CALCULATIONS

In this work, a definition of the strain rate potential for plastically deforming metals is proposed. This potential is defined in six-dimensional deviatoric strain rate space, and its gradient provides deviatoric stresses in the flowing material. For isotropic FCC metals, it is shown that the plastic behavior predicted with this proposed phenomenological description is identical to the behavior predicted with the Taylor/Bishop and Hill polycrystal plasticity model. For orthotropic FCC metals, six material coefficients characterize the anisotropy. This potential provides a definition of the effective strain rate. Together with a work-hardening curve, this equation completely describes the plastic behavior of isotropically hardening metals. This definition is useful for the calculation of work along minimum plastic work paths, as is illustrated for an isotropic FCC metal and a strongly textured aluminum alloy, subjected both to pure shear and simple shear deformation modes.