无干涉铆接搭接结构的多裂纹扩展预测方法

A Prediction Method of Multiple Crack Growth on the Fitted Rivet Lap-joint

建立了含有广布损伤(MSD)裂纹的无干涉铆接搭接结构三维有限元模型,求解裂纹尖端左右两侧的应力强度因子,并提出了等效应力强度因子的概念。以Paris公式为基础,结合改进的载荷循环叠加方法、塑性区连通准则,并考虑MSD裂纹扩展中的相关性,建立了等幅谱下MSD裂纹扩展预测模型。计算结果与试验结果表明,使用该方法预测的3种开裂模式下的寿命值误差均在7%以内;对搭接结构进行分析不能简化为二维模型;MSD裂纹扩展寿命与结构开裂模式有关,结构中共存的裂纹越多其裂纹扩展寿命越短。

Three-dimensional finite element models of neatly fitted rivet lap-joint containing multiple site damage （MSD） cracks are developed and the concept of equivalent stress intensity factor （SIF） is intro- duced based on the calculation of different sides of the crack tip. On the basis of Paris formula, and com bined with the improved load-cycles cumulate method, a prediction method for MSD crack growth under constant amplitude cyclic loading is established, and plastic zone linkup criterion and coherence treatment in MSD evolution are integrated. The results of calculation and experiment show that the prediction results are in good agreement with experimental results, the errors of three damage modes are within 7 percent; the analysis for lap-joint cannot be simplified into plate model, the crack growth life of MSD structure is highly conducted by the mode of damage, the more cracks exist, the faster the cracks grow.