弹塑性裂纹扩展的裂尖参数研究

Study of the Crack-tip Parameters of Elastic-plastic Crack Growth

在铝合金材料平面应力 CT型试件裂纹的稳定扩展和动态塑性的低速裂纹扩展实验的基础上 ,利用有限元分析获得了弹塑性裂纹扩展尖端的裂尖参数 ,对高速冲击载荷作用下的裂尖响应作了数值模拟和探讨。通过 3种不同载荷状态下的计算 ,在获得裂尖场分布的同时 ,发现三轴应力约束仅与试件几何和加载方式有关 ,并且三轴应力约束参数在裂尖前方相当长一段距离内保持恒值。通过与增量的积分参数 T* 比较 ,说明对平面应力试件动态 J积分可以在相当长的扩展段内表征断裂韧性。

Based on the experiment of the stable growth and dynamic elastic plastic crack extension using thin plate CT specimen made by LY12CZ, the crack tip parameters of the elastic plastic growing crack were studied by FEM. The crack tip parameters under high level dynamic loading were also calculated. From the three cases mentioned above, two conclusions could be drawn. First, the stress triaxiality constraint was dependent of the geometry and loading form, and it nearly held the constant value for a certain distance ahead of the crack tip. Second, dynamic J integral could be used for plane stress I mode cracked body within certain length of crack growth.