摘要
研究热点应力梯度对焊接接头疲劳评定的影响。基于Taylor的临界距离理论并结合有限元计算得到十字接头与T形接头的疲劳切口系数,预测主板受拉压和弯曲加载时的疲劳强度差异,与试验结果吻合。将板状焊接接头的热点应力分解为膜应力与弯曲应力,当量化其中的弯曲应力成分以考虑应力梯度的影响,由此定义有效热点应力。十字接头与直角角接接头的分析结果表明,由有效热点应力表述的疲劳切口系数与接头类型以及加载方式基本无关,主板的厚度效应预测可由现有的幂律型关系给出。对多组焊接结构的疲劳数据进行重新分析,结果表明,以有效热点应力作为控制应力时,可望用一条S-N曲线表述不同加载方式下多种焊接结构的疲劳数据,且离散度减小。
The influence of hot spot stress gradient on fatigue assessment of welded joints is investigated.Based on the critical distance theory proposed by Taylor,and which is combined with finite element calculation,the fatigue notch coefficients of both cruciform joints and T-joints are obtained.They are used to predict the variance of fatigue strengths of main plate subjected to tension-compression loading and bending loading respectively,and which agrees with the test result.The effect of hot-spot stress gradient on fatigue behavior is considered by introducing effective hot-spot stress,which is determined with the reduction of the component of bending stress involved.Cruciform joints and right-angle shaped joints of specified geometrical size are examined.It is shown that fatigue notch coefficients of these joints are irrespective to both joint type and loading mode in main plate if the control stress is effective hot-spot stress,also the thickness effect of main plate can be estimated by existing power law type relations.In terms of the concept of effective hot-spot stress,the re-analysis of S-N curves for several types of welded joints is carried out.It is found that an identical S-N curve can be drawn to deal relevant fatigue test data with the scattering band becoming narrow and standard deviation getting smaller.
出处
《机械工程学报》
EI
CAS
CSCD
北大核心
2010年第22期65-69,共5页
Journal of Mechanical Engineering
关键词
焊接接头
疲劳评定
热点应力
应力梯度
疲劳切口系数
Welded joint Fatigue assessment Hot-spot stress Stress gradient Fatigue notch coefficient
