Plastic behavior and stretchability of sheet metals. Part I: A yield function for orthotropic sheets under plane stress conditions

A yield function that describes the behavior of orthortropic sheets ,metals exhibiting planar anisotropy and subjected to plane stress conditions is proposed. It is shown to give a reasonable approximation to plastic potentials calculated with the Taylor/Bishop and Hill theory of polycrystalline plasticity for plane stress states. Therefore, this formulation should be particulary useful to study, at a low degree of complexity, the influence of polycrystalline textures on the forming performances of metal sheets. In part II, this yield function will be used to study the influence of the yield surface shape on failure behavior of sheet metals.