有限大体复合型表面裂纹断裂特性研究

The Fracture Characteristic for Inclined Mixed Mode Surface Crack in Finite Body

应用有限元重合网格法对三维有限大体倾斜表面裂纹复合型应力强度因子进行研究,详细讨论了裂纹倾斜角和裂纹形状变化对复合型应力强度因子的影响。研究发现随着裂纹倾斜角的增大,裂纹前缘Ⅰ型应力强度因子KⅠ减小,而Ⅱ型和Ⅲ型应力强度因子KⅡ和KⅢ先增大后减小;随着裂纹形状的变化,复合型表面裂纹前沿应力强度因子的最大值出现在裂纹最深处或随裂纹形状变化出现在裂纹前缘某处。

The three dimensional mixed-mode surface cracks usually occurrs in engineering complicated structure,and to study on the three dimensional mixed-mode surface cracks is useful to perfect assess technique of three dimensional damage tolerance.In this paper,S-FEM is applied to solve stress intensity factors for inclined mixed mode surface cracks in finite body.The effect of inclination angles and crack shape on the mixed mode fracture solution was discussed in detail.It is shown that mode I stress intensity factors decreased in magnitude along the whole crack front as the inclination angle increases.Mode II and mode III stress intensity factors,on the other hand,increased initially as the inclination angle increases and then decreased for higher inclination angles.It is also shown that maximum stress intensity factors of a surface crack usually appear at the deepest point of the crack,or a certain point along crack front near the free surface depending on the aspect ratio of the crack.The results can be referred for mixed mode damage tolerance analysis of 3-D structure in engineering.