力学不均匀性对焊接接头疲劳裂纹扩展影响的研究

本文将焊接接头简化为夹层材料裂纹体模型，通过实验及弹塑性有限元方法研究了均匀材料和具有力学不均匀性的夹层材料裂纹体中心裂纹试件中疲劳裂纹的扩展规律。发现疲劳裂纹的扩展不但取决于裂纹尖端处材料的性质，而且还受裂纹尖端附近材料力学不均匀性的严重影响；不均匀体裂纹尖端的塑性区、应力应变场与均匀材料裂纹体显著不同；力学不均匀性对疲劳扩展寿命影响的本质在于力学不均匀性对疲劳裂纹闭合的影响

EFFECTS OF MECHANICAL HETEROGENEITY ON FATIGUE CRACK GROWTH IN WELDED JOINTS

Welded joints were simplified as sandwiched crack bodies of CCP type.By means of experiments and elastic-plastic finite element method,the law of fatigue crack propagation in the simplified models both with and without mechanical heterogeneity was researched.It is found that,fatigue crack growth not only depends on material properties of crack tip region,but also on material properties adjacent to the crack tip seriously.The shape of plastic zone and distribution of stress and strain in heterogeneous cracked body magnificently differ from these of homogeneous one.It can be considered that the essential effect of mechanical heterogeneity on the fatigue crack growth life is its effect on crack closure.