Anisotropic yield criterion for polycrystalline metals using texture and crystal symmetries

An anisotropic yield criterion for polycrystalline metals which uses textur e data and takes advantage of crystal symmetries is presented, A linear tra nsformation is developed to map an anisotropic yield surface for a polycrys tal to an appropriate isotropic yield surface. The transformation developed reflects the symmetry of the material being modeled. First, the transforma tion is determined. Then, information regarding the orientation distributio n (texture) of the crystals in a polycrystalline aggregate is used to deter mine, via averaging, the transformation for the polycrystal. The transforma tion, along with appropriate isotropic yield surface, provides a phenomenol ogical approach to modeling yield, yet accounts for microstructural texture . The approach reduces to the Hill (1950) anisotropic plasticity theory und er certain conditions. The yield surfaces and X-values for various face-cen tered-cubic (fcc) polycrystalline textures are computed by this method. Res ults compare favorably with those given by other theories, and with experim ent. The method proves to have the computational efficiency of phenomenolog ical approaches to modeling yield, while effectively incorporating the phys ics of more complex crystallographic approaches. (C) 1999 Elsevier Science Ltd, All rights reserved.