中文摘要：

基于分叉理论和微分方程的特征线理论,建立了在平面应力状态下金属板料成形局部颈缩发生的判据,并根据此判据对成形过程中板料的破裂进行了预测。为了反映塑性变形局部化时塑性应变率对应力率方向的依赖性,在破裂的预测分析中采用了伊藤-吴屋的塑性应变率分量与应力率分量具有一对一关系的本构关系式。通过使用商业非线性有限元软件ABAQUS/EXPLICIT对板料成形过程进行模拟,将得出的模拟结果输入到用MATLAB编写的局部颈缩发生判据程序,实现了板料成形过程中破裂发生的预测。将提出的预测方法应用于A6022铝合金板料的刚性凸模胀形实验,预测的局部颈缩的位置和方向与实验结果大体一致。本板材成形破裂预测方法可用于汽车覆盖件成形及管材液压胀形过程中破裂的预测。

英文摘要：

The criterion of the onset of sheet metal localized necking under plane stress was established based on the general bifurcation theory and the characteristic curve theory of differential equation. According to the criterion,the prediction of rupture of sheet metal during forming process was carried out. In order to be capable to incorporate the directional dependence of the plastic strain rate on stress rate,Ito-Goya＇s constitutive equation,which gave a one to one relationship between stress rate component and plastic strain rate component,was employed. The sheet metal forming process was simulated using the commercial finite element analysis software ABAQUS/EXPLICIT. The onset of rupture during sheet metal forming process was predicted by importing the simulation results into the self-made MATLAB program of local necking criterion. The proposed method was applied to the spherical bulging forming for A6022 aluminum alloy sheet metal,and the predicting results of the position and direction of the localized necking are generally in agreement with the experiments. The method can be used to predict rupture in the forming of automobile body and tube hydro-forming.