焊趾表面裂纹应力强度因子简化计算的比较研究

对接、T型接头与十字接头是船舶与海洋结构的典型结构形式,其大部分疲劳失效是由于焊趾引起的.各种表面裂纹的应力强度因子计算是船舶与海洋结构基于断裂力学安全评定和疲劳寿命预测的基础.Bowness等人提出了T型接头焊趾表面裂纹应力强度因子计算式,作者对其复杂的计算式进行了简化.BS7910针对对接、T型接头与十字接头提出了两套焊趾应力强度因子表达式,一是针对二维表面裂纹提出的,一是针对三维表面裂纹提出的.本文对作者给出的简化表达式以及BS7910的两套表达式进行了比较.结果表明作者给出的简化表达式不仅可以用来计算T型接头的焊趾表面裂纹应力强度因子,而且可以用来计算对接与十字接头焊趾表面裂纹的应力强度因子.同时发现在a/T＜0.05处三者的差别比较大,因此用有限元法进行了验证,结果证明作者给出的简化表达式比其他表达式更加合理.

A Comparative Study of Simplified SIF Calculations of Surface Cracks at Weld Toe

Butt,T-butt and cruciform weldments are typical joints in ship and oce an structures. Most of the fatigue failure can be traced to the weld toe.Fatigue and fracture assessments are based on the calculation methods of stress intensi ty factors (SIF) of various surface cracked joints. Bowness and his co-workers h ave provided the weld magnification factor formulas for semi-elliptical cracks i n T-butt weldment.Their complex formulas were simplified by the authors.BS7910 p rovided two sets of weld toe magnification factors equations for butt, T-butt an d cruciform joints. One is for 2D surface crack and the other is for 3D surface crack.In this paper,a comparative study of the authors'simplified equations with the two sets of equations was carried out.The results show that the simplified equations can be used to calculate the weld magnification factor not only for th e T-butt joint but also for the butt, cruciform joints.Significant difference ap pears at a/T<0.05,validation was made by numerical simulation.The FEA results in dicate the simplified equations are more proper than the set of equations.