基于有限元法的表面疲劳裂纹扩展模拟

Simulation of Fatigue Crack Growth of Surface Cracked Plates by Finite Element Method

基于有限元法模拟了受远场拉伸和弯曲载荷有限厚度平板的表面疲劳裂纹扩展。裂纹体网格由等参奇异单元构成,裂纹体和非裂纹体之间采用多点约束连接不匹配的节点;采用1/4节点位移法计算应力强度因子,根据Paris公式计算裂纹扩展增量,三次样条插值函数描述裂纹前沿;自编软件实时跟踪裂纹扩展。计算得到的应力强度因子与Newman和Raju的经验公式结果比较,符合良好。

Fatigue crack growth of surface crack in plates under remote tension and bending load is simulated by finite element method. The, cracked part is meshed by isoparametric 20-node singular element. Multi-point constrain（MPC） is used to connect unmatched nodes between the cracked part and uncracked part. Stress intesity factor（SlF） is caculated by 1/4-point displacement method in this paper and the crack growth increment is caculated by Paris law. A new crack front is described using a cubic spline. The crack growth is followed by procedure step by step. A good agreement is obtained between Newman and Raiu＇s empirical SIF and present numerical SIF.