带锪窝紧固件孔边三维多裂纹扩展的计算分析

多孔元件是飞机结构中常见的结构细节，起始于多个紧固件孔边的多条三维裂纹的疲劳扩展预测是结构多部位损伤寿命评定的重点问题和技术难点。建立一种高效实用的三维多裂纹扩展数值分析方法，能够对萌生于带锪窝孔边的多条三维裂纹实施疲劳裂纹扩展中的有限元快速建模和自动网格更新，进行三维多裂纹扩展全程自动数值模拟，并利用净截面屈服作为判定最终失效的准则。通过单锪窝孔双边非对称裂纹两种开裂模式情况下的算例计算分析，并与试验实测结果对比，验证了本文扩展分析方法的有效性。

Numerical Simulation of the Multiple 3D Crack Propagationfrom Countersunk Fastener Holes

The multiple 3D cracks initiated from the multiple fastener holes frequently occur in aircraft structural components. The fatigue crack growth life prediction of the situation is one of the major concerns and the technically tough work in the multiple-site damage assessment. Our paper investigates the methodology of fatigue crack growth prediction for multiple 3D cracks starting from multiple countersunk fastener holes. An efficient numerical method was proposed in which the computer code was made using the parametrical language of the finite element analysis package. The fast finite element modeling and automatic mesh regeneration, together with a fast cumulative damage technique of fatigue crack growth, were conducted to achieve the life-span numerical simulation for multiple 3D crack growth. The net-section yielding was considered as the criterion to terminate the fatigue life prediction. Two scenarios of a pair of initial asymmetric corner cracks initiated from both sides of a countersunk fastener hole were taken as example problems and analyzed throughout their fatigue crack growth lives. The simulation results agree well with the experimental results.