Study on Yield Function and Plastic Potential Under Non‐Associated Flow for Accurate Earing Prediction in Cup Drawing

Abstract

Prediction of more than four ears in a cup drawing process can be successfully achieved by considering r‐value and stress directionalities. Yld2004‐18p based on associated flow rule and Yld2000‐2D based on non‐associated flow rule are the examples. The former, however, is more costly in terms of computational efficiency than the latter. In this work, an anisotropic constitutive model based on non‐associated flow rule which combines two different functions, Hill (1948) and Yld2000‐2d, is implemented to a user defined material model. The accuracy of the anisotropic directionalities (yield stresses and plastic strain ratios) is evaluated. Simulation of a mini‐die cup drawing with a body stock alloy predicted eight ears, in good agreement with the experimental results. The use of Hill (1948) model for the yield function and Yld2000‐2d for plastic potential under the framework of non‐associated flow rule led to accurate prediction of up to eight ears at the lower computational cost.