金属板材渐进成形的数值模拟及破裂预测

针对板材渐进成形破裂预测对应变路径的过分依赖且无法实时预测的问题，首先，运用FORTRAN语言，通过ABAQUS有限元软件的材料子程序接口，将于忠奇破裂准则引入DC56D+Z钢板的VUMAT材料子程序中；其次，分别将于忠奇模型与ABAQUS自带Von Mises模型进行单向拉伸和渐进成形的模拟；最后，结合渐进成形实验与有限元模拟分析，以实验结果为标准，根据有限元模拟的结果，逆向寻找出于忠奇准则下渐进成形模型的临界破裂积分值I.研究结果表明:两种有限元模型的应力应变大小数量级相同，分布一致，从而说明了该子程序的有效性;渐进成形模拟过程中最大破裂积分值I出现的位置在零件的侧壁，与实验结果一致，积分值I=17可以作为预测渐进成形过程中板材是否破裂的有效条件.

Numerical Simulation and Fracture Prediction of Incremental Sheet Forming of Metals

In order to solve the problems in the fracture prediction of incremental sheet forming of metals，in which the prediction strongly depends on the strain path and a real-time prediction cannot be achieved， a numerical model has been built. To perform that， the Yu Zhongqi ductile fracture criterion was firstly added into ABAQUS software through the interface subroutine of the VUMAT for DC56D+Z steel. Then， the uniaxial tensile and incremental forming processes were simulated by the new user-defined model and ABAQUS built-in Von Mises model， respectively. Finally， according to the results of finite element simulation， the critical fracture integral value I of the incremental forming model under the Yu Zhongqi ductile fracture criterion can be reduced reversely based on the actual experimental results. The results show that the calculated stress and strain from the two models have the same order of magnitude and similar distribution， which prove the validity of the subroutine. The maximum fracture integral value I in the simulated sheet forming process appears on the side wall of the workpiece， which is consistent with the experimental ones. The critical fracture integral value I=17 can be used as an effective way to predict the fracture in the incremental sheet metal forming process.