基于解析算法与J积分法的耐候钢接头疲劳裂纹扩展分析

Fatigue crack growth analysis of weathering steel joints based on analytical algorithm and J-integral method

为准确描述焊接接头疲劳裂纹在扩展中的动态过程,借助多阵元超声相控阵设备对12 mm厚耐候钢对接接头的表面裂纹扩展动态进行实时监测,得到半椭圆形裂纹深度、长度与寿命的演化关系.借助Abaqus建立有限元分析模型,将裂纹几何变化历程输入,计算裂纹尖端7个方向的能量释放率,获得裂纹尖端应力强度因子幅值.将裂纹尖端(θ=90°)的K值与BS7910标准中推荐解析公式对比分析,其结果吻合性好.在此基础上,分别采用简化公式与两阶段扩展模型计算试样的疲劳寿命.结果表明,两阶段裂纹扩展模型能准确地预测对接接头裂纹的疲劳寿命,且与试验结果高度吻合.

The surface crack propagation dynamics of 12 mm thick weathering steel butt joints were monitored by using multi-element ultrasonic phased array to accurately describe the dynamic process of fatigue crack propagation in welded joints,and the geometric evolution between semi-elliptical crack depth,length relating with fatigue life was obtained.By using Abaqus,the finite element analysis model was established,with the geometric dimension of the crack as the input,the energy release rate G in seven directions of the crack tip was calculated,and then the range of stress intensity factor of the crack tip was calculated.The K value of the crack tip(θ =90°) is compared with the analytical formula recommended in the BS7910,and the results were in good agreement with each other.Furthermore,the fatigue life of the specimen was calculated by using the simplified formula and the two-stage propagation formula,respectively.The results show that the two-stage crack growth model could accurately predict the fatigue life of butt joints and was in good agreement with the experimental results.