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T型焊接接头在钢结构中十分常见 ,它往往因初始微裂纹的疲劳扩展而导致断裂破坏。该文应用边界元( BEM)子域法 ,研究 T型焊接接头中三维混合模式表面裂纹的疲劳扩展问题。按照 T型焊接接头的实验模型建立边界元计算模型。基于端点附近裂纹前沿线位于椭球面上的假设 ,用间接方法求出裂纹前沿线的两个端点。当裂纹扩展时 ,计算网格可以自动进行重新划分。文中对裂纹扩展长度和方向提出了一种扩展准则 ,并与其他准则和实验结果进行了比较。计算结果表明 ,提出的扩展准则是有效的
T-welded joints are very common in steel structures and tend to fracture as a result of fatigue propagation of initial microcracks. In this paper, the boundary-element (BEM) subdomain method is applied to study the fatigue propagation of three-dimensional mixed mode surface cracks in T-shape welded joints. The boundary element calculation model is established according to the experimental model of T-welded joint. Based on the assumption that the crack front line near the end point is located on the ellipsoid, both ends of the crack front line are obtained by the indirect method. When cracks propagate, the calculation grid can be automatically re-divided. In this paper, an extension criterion for crack propagation length and direction is proposed, and compared with other criteria and experimental results. The calculation results show that the proposed extension criterion is effective