强度失配焊接接头的裂纹尖端张开位移数值分析

采用有限元方法对平面应变条件下含裂纹不同强度失配的平板拉伸焊接接头进行了弹塑性分析,研究了焊缝与母材强度失配、裂纹长度、母材应力应变曲线类型等因素对焊接接头裂纹尖端张开位移的影响.结果表明,强度失配系数增大,焊接接头裂纹尖端张开位移值降低,裂纹长度越短,强度失配的影响越显著.母材无屈服平台时,裂纹尖端张开位移随外加应变的增大呈单调上升趋势,母材有屈服平台时,在高匹配或者裂纹长度较短时,裂纹尖端张开位移曲线会出现阶段性变化,这主要是由于母材形变硬化滞后焊缝变形所产生的.

Numerical analysis on crack tip opening displacement of strength mismatched welded joint

Elastic-plastic behaviors of strength mismatched welded joints with cracks were investigated with finite element method.Effects of strength mismatching,crack length and stress-strain curve form of base metal on crack tip opening displacement were analyzed.The results show that the crack driving force increases with the increasing of strength mismatch factor,the influence of strength mismatching for welded joints with shallow cracks is more significant than those with deep cracks.When the base metal doesn’t show yield platform,the cracking driving force increases monotonously with the applied strain.For the base metal with yield platform,the cracking driving force and applied strain relationship presents a stage change for over-matched or welded joint with shallow crack,which caused by that the strain hardening of base metal lags behind the deformation of weld metal.