Effect of Anisotropic Yield Functions on The Accuracy of Springback Simulation

摘要

The springback behavior of sheet metals subjected to stretch bending is investigated experimentally and theoretically.We first designed and built an experimental apparatus to implement a plane-strain stretch bending test.The effect on the magnitude of springback of the tensile stress applied to the stretch-bent specimen is examined for a high strength steel sheet.The magnitude of springback decreases with increasing tensile stress,and falls almost to zero when the tensile stresses are larger than the yield stress of the material.We next implemented an elastic-plastic finite element analysis(FEA)for the plane-strain stretch bending.To determine an anisotropic yield function for modeling the work hardening behavior of the material,biaxial tension testing and plane-strain tension testing were performed on cruciform specimens.The observed work hardening behavior of the material agrees well with predictions based on Hosford's or the Yld2000-2d(Barlat et al.,Int.J.Plasticity 19,1297-1319(2003))yield functions;Hill's quadratic yield function overestimates the flow stress of the material under biaxial tension.The magnitude of springback according to FEA agrees well with the experimental results provided that an appropriate anisotropic yield function is used in the computation.