高匹配焊接接头不均匀体低周疲劳损伤研究

将高匹配的焊接接头抽象为软夹硬力学不均匀体，并运用材料应力幅的变化定义一个新的损伤变量，运用损伤力学的方法对高匹配的焊接接头力学不均匀体在低周疲劳载茶下的损伤行为进行研究。研究结果发现对于高匹配的焊接接头，在低周疲劳的载荷条件下，随着中间高强度的焊缝宽度的增加，焊接接头在断裂时的循环次数将下降，而接头中损伤的发展则在加快。

STUDY OF LOW CYCLE FATIGUE(LCF) DAMAGE ON THE MECHANICAL HETEROGENEITY MODEL OF OVERMATCHED WELDED JOINTS

In the practice of engineering, there are many welding structures that fail to work as expected due to damages resulting from the effect of the low cycle fatigue (LCF). The damages accumulate till the structures are fractured.In this paper, the overmatched joint is abstracted as mechanical heterogeneity model with a newly defined continuum damage variable and then an experimental study is made of the welded joint's fatigue damage based on the material stress range. With this definition no additional equipment is needed for the experiment on the strain controlled LCF and it is made very convenient to determine the degrees of damage in the material by measuring the variations in the material's cycle stress range.The analysis is performed for soft hard soft specimens with three different weld widths, namely 3.1?mm, 4?mm and 7?mm respectively. The two soft zones are made of 16Mn steel whereas the hard zone in between is made of 45 steel.The results of the LCF experiments show that along with the increase of the welded width in the overmatched welded joint model, the number of cycling times tends to decrease and the damage develops faster in the welded joint.