焊趾表面裂纹应力强度因子计算的基本模式法

Elementary Modes Method for Evaluating SIFs Along Fronts of Surface Cracks at Weld Toes

给出一个用来计算对接和角接焊接接头焊趾半椭圆表面裂纹在复杂应力场中，例如在残余应力场中，裂纹前缘应力强度因子（ＳＩＦ）分布的工程实用计算法——基本模式法。本文先通过高自由度的三维有限元分析，给出接头和裂纹几何参数Ｔ１／Ｔ、ａ／Ｔ、ａ／ｃ一系列组合的基本几何模型（文中给出２７种）在选定的基本应力模式（本文给出８种）作用下，沿裂纹前缘的ＳＩＦ分布，并形成一个数据库。利用这些基本模式解的插值和组合，可以非常迅速地求得一般几何参数情况下焊趾半随圆表面裂纹在复杂应力场中沿裂纹前缘的ＳＩＦ分布。在本方法中，可以考虑角接接头板厚比Ｔ１／Ｔ对ＳＩＦ分布的影响。计算过程极简单而迅速，因此特别适用于疲劳裂纹扩展行为及寿命计算问题。

A practical procedure, which is referred to as elementary modes method, was proposed for evaluating stress intensity factors (SIF) along fronts of semi elliptical surface cracks at weld toes in complex stress fields. Distributions of SIFs along crack fronts for 27 elementary geometries of semi elliptical surface cracks at weld toes, which are combinations of parameters T 1/T,a/T and a/c, subjected to 8 kinds of selected elementary stress modes were analyzed by 3 D finite element method, and a database was thus built. SIF distributions for general geometries in complex stress fields can be calculated through interpolations and linear combinations of these elementary solutions. The surface effect of thickness ratio of fillet welded joints on SIF distributions can be taken into account. The procedure is very simple and fast. The method is especially suitable for fatigue analysis.