基于GTN细观损伤模型的板料成形过程损伤分析

DUCTILE DAMAGE ANALYSIS FOR FRACTURE IN SHEET METAL FORMING BASED ON GTN MESOSCOPIC DAMAGE MODEL

针对金属板料成形过程中的损伤破裂问题,基于Gurson-Tvergaard-Needleman(GTN)细观损伤本构模型建立了相应的损伤力学有限元数值计算方法,将完全隐式应力更新算法与显式有限元计算相结合,并考虑了板料的塑性各向异性行为,通过用户自定义材料子程序VUMAT将损伤模型嵌入到有限元软件ABAQUS中。对AA5052-O铝合金板材圆杯拉深成形损伤破坏过程进行了数值模拟计算。分析了采用不同板坯大小时零件的破裂情况,并与实验进行了对比。结果表明:GTN损伤模型可以有效揭示金属板材的复杂损伤行为并预测破裂缺陷;随着板坯直径的增大,零件的破裂趋势也增大。

Based on the Gurson-Tvergaard-Needleman （GTN） mesoscopic damage constitutive model, a finite element numerical method is developed to describe the damage and fracture problems in the sheet metal forming. It combines the implicit stress integration method and the explicit finite element solving algorithm. The plastic anisotropic behavior is also considered. The GTN damage models are implemented in the commercial finite element software ABAQUS by using the user material subroutine VUMAT to simulate the damage and failure process in AA5052-O aluminum alloy deep cup drawing. Experiments and numerical analysis of damage and fracture are performed with different sheet diameters. Numerical results show that the GTN damage model can effectively reveal the complicated damage behavior and predict the fracture of the sheet metal forming. The theoretical results of the damage model are in good agreement with the experimental observations. The fracture tendency of the cups increases with the increase of the initial sheet diameter.