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正交异性钢桥面板往往在焊缝及其附近位置出现过早的疲劳损伤问题。考虑到这一结构形式所含的大量焊接接头,对其中的随机初始裂纹及气孔、夹杂等焊接缺陷对疲劳性能的影响展开研究。首先,利用扩展有限元法在求解几何不连续问题方面的高效性,生成了大量含随机缺陷的代表体积元;而后基于等效裂纹扩展长度准则,对随机缺陷进行了均质化处理,并通过数值算例证明了其在早期裂纹扩展中的适用性。作为重要的多尺度方法之一,该均质化方法可用于计算正交异性钢桥面板焊接接头的裂纹扩展。根据某正交异性钢桥面板的典型车辆荷载的现场实测数据,结合欧洲规范建议的年车流量及轮载横向分布,采用均质化的模型对U肋-顶板焊趾的宏观裂纹形成寿命(初始裂纹扩展至可检测尺度的寿命)进行了计算。结果表明:该方法可有效呈现宏观裂纹形成寿命的概率分布,但在现有假设下,初始裂纹尺度的影响明显高于气孔、夹杂等缺陷;若初始裂纹尺度呈均匀分布,将导致宏观裂纹形成寿命的分布较为离散;所得结果的统计特性依赖于所选择的Paris公式形式及其中的材料常数取值。
Orthotropic steel deck often exhibits premature fatigue damage at the weld and its vicinity. Considering the large number of welded joints contained in this structure, the influence of the random initial cracks and the weld defects such as pores and inclusions on the fatigue properties is studied. First, a large number of representative voxels with random defects were generated by using the extended finite element method to solve the geometric discontinuity problem. Then, based on the equivalent crack propagation length criterion, the random defects were homogenized and passed Numerical examples demonstrate its applicability in early crack propagation. As one of the most important multi-scale methods, the homogenization method can be used to calculate the crack propagation of orthotropic steel deck welded joints. According to the field test data of typical vehicle load of an orthotropic steel bridge deck and the proposed model of annual traffic flow and wheelset transverse distribution, Initial crack growth to a detectable scale of life) was calculated. The results show that this method can effectively represent the probability distribution of the macroscopic crack formation life, but under the existing assumptions, the initial crack size is significantly affected by defects such as porosity and inclusions. If the initial crack size is uniformly distributed, the macrocrack will be formed The distribution of life span is relatively discrete; the statistical properties of the results obtained depend on the form of the Paris formula chosen and the value of the material constant in it.