正交异性钢桥面板三维疲劳裂纹扩展数值模拟方法

Numerical Simulation Method for 3D Fatigue Crack Propagation of Orthotropic Steel Bridge Deck

针对正交异性钢桥面板中典型的疲劳开裂,基于线弹性断裂理论,建立了正交异性钢桥面板关键疲劳易损部位的三维裂纹扩展数值模拟方法。以典型正交异性钢桥面板作为研究对象,对常幅荷载作用下U肋与横肋连接焊缝部位的三维疲劳裂纹扩展进行了数值模拟,通过模型试验验证了所提方法的有效性和可行性,在此基础上,对于该部位三维疲劳裂纹的扩展特性及疲劳寿命预测进行了研究。研究结果表明:所建立的数值模拟方法能够较为准确地预测研究对象的裂纹扩展路径,并为其疲劳寿命评估提供科学依据;Ⅰ型断裂在复合型裂纹扩展中起主导作用;表面裂纹与沿板厚扩展的中裂纹随疲劳裂纹的扩展表现出不同的扩展特性。

According to the typical fatigue cracking of orthotropic steel bridge deck,based on the theory of linear elastic fracture mechanics,a 3Dcrack propagation numerical simulation method for the predominant details vulnerable to fatigue in orthotropic steel bridge deck was established.Taking the typical orthotropic steel bridge deck as the research object,the numerical simulation was carried out on the 3Dfatigue crack propagation of U-rib to transverse joints under constant amplitude loads.The validity and feasibility of the method were proved by model test.Based on this,the 3Dcrack propagation behavior and fatigue life prediction of these vulnerable details were investigated.The results show that by the established method,a relatively accurate crack propagation path of the research object can be predicted,providing a scientific basis for the fatigue life estimation;fracture modelⅠ has a dominant effect on mixed mode crack propagation;the cracks in the surface and along the thickness direction present different propagation behaviors with the propagation of fatigue cracks.