裂纹扩展的无网格数值模拟方法

疲劳断裂是航空材料的重要失效形式 ,由于裂纹尖端应力存在奇异性 ,传统有限元方法模拟裂纹沿任意路径扩展存在很多不足。作为一种新兴的数值模拟方法 ,无网格计算只需将求解问题离散为独立的节点 ,计算过程中可以实时跟踪裂纹尖端区域进行局布细化。将连续的裂纹扩展过程看作多个线性增量 ,每一个增量内裂纹扩展角根据应力强度因子确定 ,通过在裂纹尖端细化节点和引入外部基函数提高了计算精度。本文给出了应用无网格方法模拟裂纹扩展过程的关键技术和计算流程 ,通过对带有中心斜裂纹的 Ti-6 Al-4 V合金平板进行分析 ,预测得到的裂纹扩展路径与实验值吻合的较好。

Meshless method for numerical simulation of crack propagation

Crack propagation is an important failure mechanism in aeronautical materials that requires accurate numerical model to capture stress singularity at the crack tip As a promising numerical simulation method, meshless computation has some outstanding advantages over the traditional finite element method (FEM) in treatment of arbitrary evolving discontinuity Because of the independence of elements, the adaptive refinement can be easily achieved, which makes the crack propogation analysis dramatically simplified By introducing enriched basis and nodal refinement, the computational accuracy was improved The continuous crack propagation was modelled as a series of linear crack growth increment At each increment the crack growth direction was determined based on the stress intensity factors The key technique and the flowchart of the method were presented The paper concludes with a sample calculation of oblique center crack plate of Ti 6Al 4V alloy under uniaxial tensile load The predicted crack trajectory by meshless method is in good agreement with the experimental data