焊趾处椭圆表面裂纹的权函数与残余应力强度因子的权函数法

Weight function for weld toe semi-elliptical surface crack and calculating residual stress intensity factors by weight function method

利用三维有限元计算了焊趾处半椭圆表面裂纹的应力强度因子。利用统一的权函数形式,结合得到裂纹半长比a/c=0.2;0.4;0.6;0.8,a/t=0.1~0.8的有限元数据,得到了适用于T型接头焊趾处半椭圆表面裂纹最深点和表面点的权函数。权函数的准确性,用有限元在裂纹面施加高阶载荷进行了验证,对于表面点和最深点,半长比a/c=0.2~0.8,a/t=0.1~0.8,权函数与有限元结果误差在8%以下。基于得到的权函数,计算了T型接头焊趾处半椭圆表面裂纹的残余应力强度因子Kres,并与有限元计算结果进行对比,对比误差在10%以下,表明新的权函数能很好地预测T型接头焊趾处的残余应力强度因子。

The stress intensity factors（SIFs） of semi-elliptical surface cracks at the weld toe were analyzed by using finite element analysis（FEA）. Based on the obtained stress intensity factor data of surface cracks with aspect ratio from a/c=0.2～0.8 and a/t=0.1～0.8 by FEA, new weight functions for the calculation of T-butt weld toe surface cracks SIFs at both surface and deepest point were derived under constant and linear distributed stresses. The new weight functions were extended for higher order stress distribution situation and validated through the results obtained by FEA under parabolic and cubic stress loading. The difference between weight function and FEA is less than 10% for cracks with aspect ratio a/c=0.2～0.8, a/t=0.1～0.8 at both surface point and deepest point. The derived weight function is used to calculate the SIFs of weld toe surface crack due to residual stress, results comparison with FEA method shows new weight function can make good predication for the weld toe surface crack SIFs.