基于零点有效缺口应力的薄板焊接接头疲劳评估

Fatigue assessment of thin plate welded joints based on zero-point effective notch stress

文中采用零点有效缺口应力进行了薄板焊接接头的疲劳评估研究.该方法综合考虑整体结构应力以及缺口根部到零点位置的非线性峰值应力的影响,以临界距离法和零点结构应力法为基础,将零点应力位置作为缺口对结构疲劳影响的临界距离对焊接结构进行疲劳强度评估.通过对两种不同类型的焊接接头试样(T形单面焊接头和不同厚度组合搭接接头)的疲劳试验结果进行拟合.结果表明,在对焊根失效的试样进行疲劳评估时,焊根位置不同截面应力线性化之后得到零点有效缺口应力存在较大差异;其中,焊脚截面应力线性化得到的S-N曲线分散带宽度最小;再者,同时考虑焊趾和焊根失效的零点有效缺口应力S-N曲线,与分别考虑焊趾或焊根失效的零点有效缺口应力S-N曲线分散带相差不大,证明该方法可同时用于焊接接头焊趾和焊根疲劳评估.

In this paper,the fatigue assessment of welded joints in thin plates was conducted using zero-point effective notch stress.This method comprehensively considered the influence of overall structural stress and the nonlinear stress peak at the root of the notch to the zero-point position.Based on the critical distance method and zero-point structural stress method,the zero-point stress position was taken as the critical distance for the fatigue assessment of welded structures.Through fitting the fatigue test results of two different types of welded joint specimens(T-type single-sided welded joint and lapped joint with different thickness combinations),the results showed that there were significant differences in the zero-point effective notch stress when evaluating specimens with different cross-sectional stress linearization at the weld root.Among them,the width of the scattered band of the SN curves obtained by linearizing the stress at the weld toe cross-section was the smallest.Furthermore,the difference of scattered bands between the S-N curves of considering for weld toe cross-section and weld root failure simultaneously and separately was not significant,proving that this method could be used simultaneously for fatigue assessment of both weld toe and weld root in welded joints.