扭力轴三维裂纹扩展寿命仿真研究

Simulation to Three-dimensional Fatigue Crack Growth Life of Torsion Bar in Self-propelled Gun

对疲劳载荷谱作用下三维表面裂纹,采用双重边界元理论求解裂纹前沿的应力应变场,运用Forman理论、最小应变能密度法和Elber模型,计算裂纹前沿各点的扩展长度、扩展方向和应力强度因子等特征量。根据增量步下裂纹几何形状的改变,对裂纹面进行网格重划分和迭代计算,模拟三维裂纹的扩展,预测裂纹扩展寿命。扭力轴表面裂纹扩展的仿真结果表明该方法合理可行。

For three-dimensional surface crack propagation under fatigue load spectrum, dual boundary element method is adopted to solve the stress and strain field along the crack fronts. And the propagation size, growth direction and stress intensity factors along the crack fronts are obtained following. Forman law,minimal strain energy density criterion and Elber model. According to the change of crack geometry for each incremental crack extension, the crack surface is newly redivided and the above stress and strain are iteratively evaluated to simulate the three-dimensional surface crack propagation and predict fatigue lives.