Forming of Materials with Cubic Crystal Structure

Abstract

Generally, the plastic behavior of orthotropic metallic materials with cubic crystal structure is modelled with yield criteria that predict the same response in tension and compression. One drawback associated to using orthotropic yield criteria for simulation of forming processes is related to the uncertainties introduced by the methods used for parameter identification. Very recently, it was shown that advanced non-quadratic criteria such as Yld91 can be represented as polynomials in terms of stress components. Using this equivalent expression, the anisotropy coefficients involved in Yld91 can be obtained using analytical formulas in terms of only experimental flow stresses, or alternatively in terms of only Lankford coefficients for three orientations. In this paper, the predictive capabilities of Hill, Yld 91 and Cazacu calibrated using different identification procedures, either analytical or by numerical minimization are discussed. Moreover, simulation results of deep drawing are presented.