Simulating hydrogen embrittlement fracture based on phase field method

基于相场法的氢脆断裂模拟

School of Aeronautics, Northwestern Polytechnical University, Xi’an 710072, China

Received: 12 August 2021

Abstract

The phase field hydrogen embrittlement fracture model is improved by introducing tension-compression split of strain energy. The numerical formulas of the model are provided, besides, the coupling term of concentration field and displacement field is deduced. The matlab software is used to compile the numerical program of phase field hydrogen embrittlement fracture. The modes I and II cracks of hydrogen embrittlement are simulated respectively. The simulation results show that hydrogen ions concentrate at the crack tip where stress concentration happens, and that the hydrogen concentration reduces the critical failure load of the square plate. Compared with the numerical results of the existing models, the improved model can accurately calculate the critical failure load in the mode I crack and capture the embrittlement fracture phenomenon when the phase field and the concentration field are accumulated near the crack tip. Moreover, the improved model can effectively simulate the mode II crack with hydrogen embrittlement.

摘要

通过引入应变能拉压分解, 对相场氢脆断裂模型进行了改进, 并给出了改进模型的数值求解公式, 推导了浓度场和位移场耦合项刚度矩阵。编写Matlab相场氢脆断裂计算程序, 分别模拟了Ⅰ型和Ⅱ型2种不同模式的氢脆断裂过程。数值计算表明: 在断裂过程中氢离子会向裂尖处扩散集中, 且氢浓度越高, 临界破坏载荷越小; 对比已有模型计算结果, 改进模型能精确计算Ⅰ型断裂问题的临界破坏载荷, 准确捕捉脆弹性材料的瞬断过程, 且能更有效地模拟Ⅱ型的氢脆断裂过程。