焊接结构疲劳强度预测的局部法研究

Study on Local Approach of Fatigue Strength Prediction for Welded Structures

以焊缝附近局部半圆区域的平均应力为控制参数,得到焊接结构疲劳切口系数的计算理论,在考虑材料、结构几何形式、残余应力等因素对疲劳强度影响的基础上,建立了对称循环和非对称循环时焊接结构有效应力集中系数预测的局部法模型.通过对几类错位板接头的有限元计算分析,得到这些焊接结构焊缝附近局部区域的应力场,进而预测它们的疲劳强度,并将预测结果与疲劳试验进行了比较,获得了令人满意的结果.用局部法预估焊接结构的疲劳强度,能大量减少疲劳实验,节省经费开支。

Adopting the controlled parameter with average stress around semi-circle region of welded joints, the calculating theory of fatigue notch factor for welded structures is obtained. Taking account of the effect of material properties, the geometric form, residual stress on the fatigue strength,the local approach models of effective stress concentration factor for welded joint are set up under symmetrical cyclic load and unsymmetrical cyclic load respectively.Based on the computation the stress fields of some misaligned welded joints by finite element method, the fatigue strength are predicted.Examples show that good agreement is achieved between the estimations and experiments. It may be greatly decreased for the tests with local approach to estimate the fatigue strength for welded joints. Therefore the model has significance for engineering application.