A 4TH-ORDER PLASTIC POTENTIAL FOR ANISOTROPIC METALS AND ITS ANALYTICAL CALCULATION FROM THE TEXTURE FUNCTION

A fourth-order potential is proposed for anisotropic metals, assuming orthotropic symmetry. It may be used as a yield criterion, but here it is used as a dual potential depending on the strain-rate. The concept of dual potential is recalled and the implementation in simulation co des is discussed, along with the extension to viscoplasticity. The coe fficients depend linearly on the texture coefficients, up to a scale f actor determinable by one mechanical test. The adjustment of the dual potential from texture data is numerically tested for steels, and comp ared with mechanical tests. A significant improvement of the flow rule (strain ratio R) is obtained as compared with both the Taylor model a nd the texture-adjusted Hill criterion. The predicted stress ratios ar e close to those predicted with the latter criterion, which were previ ously found to be in a good experimental agreement.