自動車外板部品の面ひずみ予測精度に及ぼす
異方性降伏関数の影響

抄録

A “surface deflection” is a surface defect with 30-100 μm surface undulations. The development of simulation technology capable of accurately predicting surface deflections is crucial for the cost-effective production of high-quality automotive outer body panels. In this study, a panel that can be used to model a handle emboss of an automotive door outer panel is experimentally press formed using dies of high rigidity and the distribution of curvature of the panel is precisely measured. The material used is a 0.69-mm-thick bake-hardenable galvannealed steel sheet. Biaxial tensile tests on the material are carried out using a servo-controlled biaxial tensile testing machine to accurately determine the best-fit yield function for the finite element simulation of the panel. It is found that; (1) the Corus-Vegter yield function, which is capable of accurately reproducing the deformation behavior of the material, is superior to Hill’s quadratic yield function in the predictive accuracy of surface deflection, (2) the coefficient of friction and blank-holding pressure more strongly affect the predictive accuracy of surface deflection than element size, element type, forming speed set in the analysis and the number of integration points in the thickness direction.