用有限单元法计算厚壁圆管疲劳寿命

Computations of the fatigue life for thick-wall cylinder by finite element method

用二维有限元计算应力强度因子的近似值,通过修正系数F的修正得到较精确的应力强度因子KI。利用Paris方程作为厚壁园管内表面裂纹扩展速率模型并给出方程系数,从而计算了厚壁圆管内表面裂纹扩展深度与压力循环次数的关系,计算结果与实验结果相吻合。在此基础上,计算实验模拟管的疲劳寿命,给出了压力-疲劳寿命关系曲线;最后,给出了具有内表面裂纹的高压厚壁圆管的疲劳寿命的保守计算。

The stress intensity factors were computed approximately by two-dimensional finite element method and the more accurate values of the stress intensity factor K1 were obtained through correction by using an effective coefficient F. The Paris equation was used as the model of the growth rate of the crack at the inner surface of the thick-wall cylinder and the coefficients in the equation had been given. Therefore the relationship of the growth depth of the crack and pressure cycles had been calculated and the caleulative results were in agreement with the tests. The fatigue life of each experimental simulated tube and the relation curves of fatigue life vs pressure were given on the basic of that. Finally, the fatigue life of the thick-wall cylinder with the inner surface crack was calculated conservatively.