三维多裂纹应力强度因子的有限元分析

ANALYSIS OF STRESS INTENSITY FACTORS OF 3-D MULTIPLE CRACKS USING FINITE ELEMENT METHOD

多处损伤和广泛分布疲劳损伤是影响军用老化飞机结构完整性的主要因素之一。三维裂纹前缘应力应变场很复杂 ,除个别理想情况外 ,绝大部分迄今为止无解析解。采用三维 2 0节点等参单元 ,运用ANSYS软件 ,对含半椭圆裂纹的半无限大体进行有限元分析 ,得到裂纹前缘各点的应力强度因子 ,通过对计算结果的分析 ,讨论裂纹长度、裂纹间距比、裂纹前缘位置对应力强度因子的影响以及多裂纹之间的相互影响 ,计算结果和手册的理论值比较表明 ,数值结果准确。

Multi-site damage (MSD) and wide spread fatigue damage (WFD) are the main factors which affect structure integrity of military aging aircraft. Until now, the stress and strain fields around the 3-D crack front are very complex and there is no analytical solution except for individual instance. The 3-D 20-Node isoparametric element is adopted; the body with half elliptic cracks is analyzed by using ANSYS software. The stress intensity factors of crack front are gained, and the influences of different crack length, crack separation ratio, locality of crack front on stress intensity factor and the interaction of multiple cracks are discussed. By comparing numerical results with the theoretical solution, it shows that these results and some conclusions given are correct and the method is feasible.