焊接结构本征疲劳裂纹扩展速率研究

项目名称： 焊接结构本征疲劳裂纹扩展速率研究

项目编号： No.11272029

项目类型： 面上项目

立项/批准年度： 2013

项目学科： 数理科学和化学

项目作者： 鲍蕊

作者单位： 北京航空航天大学

项目金额： 86万元

中文摘要： 先进焊接工艺在飞机中的应用是实现结构减重和低成本的重要途径之一，这对焊接结构完整性评价提出了更高的要求，给损伤容限设计评定提出了新挑战。由于焊接残余应力（RS）和微观结构改变对裂纹扩展的影响相耦合，RS与结构构型和尺寸相关，现有利用母材裂纹扩展速率叠加RS影响的评定方法在精度和适用性上都受到限制。本研究创造性地提出了本征裂纹扩展速率（Intrinsic crack growth rate，ICGR）的概念，分离RS与微观结构改变对裂纹扩展的影响，提取出仅反映微观结构改变的本征参量，建立基于ICGR的焊接结构裂纹扩展分析方法；在此基础上，研究RS分布与结构构型及尺寸的关系，给出焊接整体结构的裂纹扩展评定方法。与现有方法相比，由于ICGR考虑了微观结构改变的影响，将显著提高预测精度；ICGR与结构构型和尺寸无关，将显著提高方法的适用性。本研究成果将为焊接在飞机结构中的应用奠定分析评定技术基础。

中文关键词： 焊接结构；疲劳裂纹扩展；本征参量；残余应力；损伤容限

英文摘要： The application of advanced welding technologies to fabricate aircraft structural components is recognized as one of the most promising methods to achieve further structure weight reduction and manufacture cost saving, which requires a step change in the structural integrity assessment and, consequently, sets new challenges to the damage tolerance evaluation for welded joints. Due to the coupled effects of weld residual stresses and micro-structural changes on fatigue crack growth rates and the interrelation between structural configuration and residual stresses, current crack growth analysis methods, which are based on the superposition of weld residual stresses to the base metal fatigue crack growth rate model, are not widely applicable and the accuracy of these models are not always good enough. The concept of weld intrinsic crack growth rate (ICGR) is innovated to solve this problem. The weld intrinsic property will be evaluated by isolating the effects of residual stresses and microstructure change on fatigue crack growth rate. Based on the ICGR a crack growth analysis approach for welded joints will be proposed. Furthermore, the influence of structural size and configuration on residual stress distribution will be investigated, and then, a method to evaluating the crack growth rates in welded integral comp

英文关键词： welded components；fatigue crack growth；intrinsic properties；residual stress；damage tolerance