弯扭组合载荷下圆管半椭圆表面裂纹应力强度因子的有限元分析

对表面裂纹复合型应力强度因子的研究一直是线弹性断裂力学中的重要课题，例如弯扭组合载荷下圆管半椭圆表面裂纹应力强度因子的计算，到现在也没有一个正确的分析解。考虑到裂尖的应力奇异性，在裂纹前沿手动设置三维奇异单元，用三维有限元法中的1/4点位移法计算弯扭组合载荷下圆管表面椭圆裂纹前沿的Ⅰ型、Ⅱ型和Ⅲ型应力强度因子，并分析其随裂纹深度增加时的变化规律。运用该方法计算了有关模型的应力强度因子，并与该模型的实验值进行了比较，计算结果和实验结果吻合良好。

Finite element analysis for stress intensity factor of semi-elliptical surface crack in circular tube under torsion and bending

Research on compound stress intensity factor (SIF) is a crucial subject in linear elastic fracture mechanism. Taking calculation of SIF of semi-elliptical surface crack (SESC) in circular tube under torsion and bending as an example, there is still no exact analytic solution. Considering stress singularity in the tip of crack, 3D singular elements are set along the front edge of crack manually, and then , Ⅱ, Ⅲ, SIF of SESC in circular tube under torsion and bending is calculated by 1/4 displacement of 3D FEA method. Furthermore, its changing rule with the increase of crack depth is analyzed. By utilizing this model, SIFs of related models are calculated and then the results are compared with those of experiments, which are very close.