局部法评定铝合金搅拌摩擦焊接头疲劳性能  

Assessment of Fatigue Performance of Friction Stir Welded Joints with Local Approaches

作　　者：牛亚辉 孙国芹[1] Niu Yahui;Sun Guoqin(College of Mechanical Engineering and Applied Electronics Technology, Beijing University of Technology, Beijing 100124, China)

机构地区：[1]北京工业大学机械工程与应用电子技术学院,北京100124

出　　处：《机械科学与技术》2020年第3期374-378,共5页Mechanical Science and Technology for Aerospace Engineering

基　　金：国家自然科学基金项目(11672010)资助。

摘　　要：三种不同的局部法,临界距离法、应力平均法和等效应力强度因子法,用于评估Al6082-T6铝管搅拌摩擦焊焊接接头的疲劳性能。结果表明,3种疲劳评定方法都能对铝合金搅拌摩擦焊接头做出合理的评定。运用临界距离法时采用Peterson修正公式计算临界距离参数L,结果表明该方法能够精确预测出Al6082-T6铝管搅拌摩擦焊焊接接头的疲劳极限,预测误差仅4%,并能预测出接头疲劳薄弱区域;应力平均法的预测结果偏保守,预测结果较试验值低7.46%,其将焊趾视为尖锐缺口的做法具有工程应用价值。等效应力强度因子法通过将接头模拟成带标准裂纹的构件来计算焊接接头等效应力强度因子范围,并通过与接头裂纹扩展门槛值比较来判断焊接件是否发生疲劳失效,结果表明等效应力强度因子法能够对Al6082-T6搅拌摩擦焊接头做出合理的疲劳评定。Three local methods,critical distance method,stress averaging approach and the approach of equivalent stress intensity factor were used to assess the fatigue performance of Al6082-T6 aluminum tubular friction stir welded joints.The results show that the three kinds of fatigue assessment methods can make a reasonable fatigue assessment of the friction stir welded joints of aluminum alloy.The critical distance parameter L is calculated by Peterson′s revised formula when using the critical distance method.It turns out that the method can predict the fatigue limit(prediction error only 4%)and weak location for Al6082-T6 FS welded tubular joint.The results of the stress averaging approach are conservative.The prediction result is 7.46%lower than the testing result,which indicates the way of regarding the welded toe as the sharp notch has its engineering application value.The approach of equivalent stress intensity factor was used to calculate the equivalent stress intensity factor range of the welded joint by modelling the joint as if it being a crack of standard geometry and determine whether the joint fatigue failure or not by comparing with the crack propagation threshold.The results show that the method can make a reasonable fatigue evaluation of Al6082-T6 friction stir welded joint.

关 键 词：搅拌摩擦焊 临界距离法 应力平均法 等效应力强度因子法 

分 类 号：TG405[金属学及工艺—焊接]