焊趾裂纹前沿扩展的动态数值仿真分析

摘要

采用半圆形表征焊趾初始表面裂纹,以应力强度因子幅值作为裂纹扩展的驱动力,基于NASGRO裂纹扩展速率模型,考虑应力强度因子幅值门槛值和断裂韧性的影响,研究了整个裂纹前沿的动态演变过程.揭示了复杂焊趾形貌处初始裂纹的位置对裂纹扩展模式的影响规律,得出不同扩展模式下的疲劳寿命分布;分析了裂纹前沿应力强度因子的分布状况以及其在不同方向上的分布特点.开展了十字焊接接头的疲劳对比试验,试验结果与仿真结果具有较好的一致性.%Based on the model for NASGRO crack propagation rate,considering the influence of the stress intensity factor amplitude threshold and the fracture toughness,the stress intensity factor amplitude was used as the driving force of the crack propagation to discuss the whole of the crack front dynamic evolution with the semi-circular shape as the initial surface crack.The influence of the position of the initial crack on the crack propagation mode was revealed,and the fatigue life distribution in different propagation modes was obtained;the distribution of stress intensity factor at the crack front and its distribution in different directions were analyzed.The fatigue comparative test of the cross welded joint was carried out,the results were in a good agreement with the simulated.