基于应力场强法的缺口构件疲劳寿命预测方法研究

Research on Fatigue Life Pridiction of Notched Structrues Based on Stress Field Intensity Method

基于疲劳损伤破坏的机制,研究了应力场强法预测构件疲劳寿命的原理及其具体实现过程,着重讨论了场强法中各场强参数的意义。通过对两种不同材料、不同形状的缺口件应力应变场计算分析,指出了在原有场强法模型中,对于同种材料,尽管缺口形状和大小不变,构件的场强半径也并非某一材料常数,而是关于载荷幅值大小的线性函数,即载荷大小对损伤区域有着重要影响,原有的场强法模型无法较好地预测在较大载荷幅值范围内构件的疲劳寿命。本文提出一种新的损伤场的概念,对原有的场强模型进行改进。计算结果表明:改进后的模型可以降低网格精度的要求,节省计算资源,而且在较大范围内的载荷幅值作用下,均能较好地预测具有不同缺口形式的构件疲劳寿命。

Based on the mechanic of fatigue failure,stress field intensity（SFI） method was used to predict structure fatigue life.The theory and proceeding of SFI were discussed especially the parameters of SFI.By the stress and strain field analysis of two type material specimens with different notches,it was showed that stress field radium was not a constant parameter to a material type,but a parameter has relationship to loading amplitude and notch shapes.So the present SFI can＇t accurately predict fatigue life of different structures.An improved model of SFI was proposed.The caculator results show that this improved model didn＇t relay on a complicated meshing model,and can predict fatigue life accurately to structures with different material types,different notch shapes and various loading amplitudes.