Ⅰ、Ⅱ型及复合型裂纹动态应力强度因子的有限元分析

对含有预制裂纹的中心穿透裂纹板和三点弯曲试样在动态载荷作用下进行了有限元模拟。前者裂纹面与载荷作用方向的夹角取15°~90°之间的6种情况,后者按纯Ⅰ型和纯Ⅱ型两种方式进行加载。得到了Ⅰ型和Ⅱ型动态应力强度因子的时间历程,并研究不同裂纹角对动态复合比的影响。结果表明:中心穿透裂纹板试样在15°和90°两种情况下KⅡ(t)和KⅠ(t)分别占主导成分;45°时KⅠ(t)和KⅡ(t)基本相同;随着裂纹面与载荷夹角的增加KⅠ(t)呈增加趋势而KⅡ(t)呈先增加后减小趋势。三点弯曲试样按纯Ⅰ型加载时KⅡ(t)基本为零,按纯Ⅱ型加载时KⅠ(t)幅值随时间而增加。

Finite Element Analysis of Mixed Mode Fracture Dynamic Stress Intensity Factors

In this paper,finite element simulation of central-cracked plates with different angles between the load and the crack surface and of three-point bend specimens under impact loading are performed.The central-cracked plates are analyzed with six crack angles ranging from 15° to 90°,while the three-point bend specimens are analyzed under two load modes——Modes Ⅰ and Ⅱ.Dynamic stress intensity factors(DSIF) of Modes Ⅰ and Ⅱ are calculated and the effect of different crack angles on the ratio of K_(Ⅱ)/K_(Ⅰ) is studied.The results show that for the central-cracked plate specimen,K_(Ⅱ)(t) is much lager than K_(Ⅰ)(t) when the crack angle is 15° and that it is just opposite when the crack angle is 90°.K_(Ⅰ)(t) and K_(Ⅱ)(t) are nearly the same when the crack angle is 45°.With the increase of the crack angle,K_(Ⅰ)(t) increases,while K_(Ⅱ)(t) increases first and then decreases.The results of the three-point bend specimens show that under Mode Ⅱ load,K_(Ⅰ)(t) increases as time goes on,but under K_Ⅰ load K_Ⅱ(t) is almost zero.