考虑裂纹闭合效应的疲劳裂纹扩展有限元分析

Study on the Fatigue Crack Growth Behavior Considering the Crack Closure Effect by Finite Element Method

由材料塑性诱发的裂纹闭合效应对疲劳裂纹扩展的影响显著。针对紧凑拉伸试样,通过构建其有限元模型,同时考虑塑性诱发的裂纹闭合效应,采用恒幅循环加载方式,对试样裂纹扩展区域内节点位移和反力进行计算与处理,获得了裂纹张开载荷,并讨论了网格尺寸、节点释放时刻、监测点位置等对裂纹张开载荷的影响;对于稳定的裂纹张开载荷,探讨了基于节点反力的线性插值计算方法,可获得更加精确的数值,研究成果对疲劳裂纹扩展分析和寿命预测具有参考价值。

The effect of plasticity induced crack closure on fatigue crack growth is significant.For the compact tensile specimen,the finite element model is established considering the effect of plasticity induced crack closure.The crack opening load is obtained by the calculation and treatment of the node displacement and reaction force in the crack growth region under the constant amplitude cyclic loading,and the influence of mesh size,release time of node and position of detection point on crack opening load is discussed.For stable crack opening load,a linear interpolation method of nodal reaction force is proposed to obtain more accurate values.The results are valuable for fatigue crack growth behavior analysis and life prediction.