韧性断裂准则及损伤模型在冲裁有限元模拟中的应用研究

Research on the application of ductile fracture criteria and damage models in finite element simulation of blanking process

在冲裁有限元模拟中,韧性断裂准则的选择会对冲裁件断面质量与尺寸精度产生很大影响。为了获得符合实际的模拟结果,进而优化冲裁工艺,重点研究了一些常用的韧性断裂判定依据,并从物理学角度阐述了韧性断裂机制。基于试验的韧性断裂准则,考虑了变形历史中的应力应变关系,使用由反求法确定的临界值来判定韧性断裂的发生与否。基于连续损伤力学建立的损伤模型,考虑了变形过程中损伤累积对材料本构关系的影响,能够更准确地描述断裂过程。此外,还分析了冲裁有限元模拟中的关键技术,如采用任意拉格朗日欧拉方法来解决网格畸变问题,使用单元分裂、单元分离与单元删除等技术来处理裂纹的萌发与扩展。探讨了目前韧性断裂模拟中存在问题以及未来发展方向。

In finite element simulation of blanking process, the choice of ductile fracture criterion has a great impact on edge quality and dimensional accuracy of blanking parts. In order to obtain reasonable results and optimize blanking process, some commonly used ductile fracture criteria were mainly studied, and the ductile fracture mechanism was analyzed from the perspective of physics. The stress-strain relationship in deformation history was considered according to the ductile fracture criteria based on experiments and a critical value ob- tained by an inverse method was used to determine whether ductile fracture occurs or not. The influence of damage accumulation on consti- tutive equation was considered according to the damage models based on continuum damage mechanics so that they can accurately describe the ductile fracture process. Furthermore, the key techniques in numerical simulation of blanking process were analyzed, including an Ar- bitrary Lagrangian Eulerian method used to solve mesh distortion as well as methods of element split, element separation and element dele- tion used to deal with crack generation and propagation. In the end, the current issues and future development in the field of ductile frac- ture simulation were discussed.