锻压技术

基于平均等效应力强度因子的焊缝疲劳寿命预测

英文标题：Prediction of weld joints fatigue life based on average equivalent stress intensity factor

作者：宋凯程广鸣

分类号：TH114

出版年,卷(期):页码：2016,41(10):132-137

摘要：

目前普遍应用的焊缝疲劳仿真分析方法主要有名义应力法和结构应力法，针对两种方法的应用局限性及未考虑剪切结构应力导致的预测精度不高等问题，提出了一种新的高精度焊缝疲劳寿命预测方法。该方法是以断裂力学为理论基础，通过有限元软件提取焊缝周围节点的节点力及力矩，并通过一系列计算得到整个裂纹扩展路径上的平均等效应力强度因子ΔKeq，并将其作为本文中焊缝疲劳寿命预测方法的评价参数。通过对DP800GI和HSLA350GI两种高强钢材料的搭接接头进行疲劳试验，并将ΔKeq与试验所得的疲劳寿命数据进行双对数回归分析，得到的一条主ΔKeq-N曲线作为焊缝的疲劳寿命预测曲线，并与目前的名义应力法和结构应力法进行预测精度对比，得出本文中的焊缝疲劳寿命预测方法的预测精度高于目前的名义应力法和结构应力法。

At present, the fatigue simulation analysis method of the weld joints are mainly the nominal stress method and the normal structure stress method. For the limitations in application and low prediction accuracy caused by not considering shear structure stress, a new fatigue life prediction method was proposed. Based on the theory of fracture mechanics, the nodal forces and moments around the weld joints were obtained by finite element software, and an average stress intensity factor ΔKeq in the weld crack propagation path was calculated. Furthermore, it was regarded as the evaluation parameters of fatigue life prediction method. Through conducting shear fatigue test for two high-strength steel-DP800GI and HSLA350GI resistance welding joints, and conducting double logarithmic regression analysis for ΔKeq and the fatigue life data of weld joints, a master ΔKeq -N curve as the fatigue life prediction curve for weld joints was obtained. Furthermore, prediction accuracy with the nominal stress method and the normal structure stress method was compared and analyzed. The results show that the prediction accuracy of fatigue life forecasting method of weld joints in this paper is higher than the current nominal stress method and structural stress method.

基金项目：

广西科技重大专项(1348005-5)；湖南省科技开发计划项目(2013TT1006)；中国博士后科学基金资助项目（2014M552312）

作者简介：宋凯（1981-），男，博士，副教授 E-mail：song_kai@163.com；通讯作者：程广鸣（1991-），男，硕士 E-mai:chengguang_ming@sina.com

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