正交异性钢桥面板裂纹扩展的均质化方法

发布时间：2019-07-02 10:23

【摘要】：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。
[Abstract]:Orthotropic steel bridge panels tend to have premature fatigue damage at the weld and its adjacent locations. The effects of welding defects such as random initial cracks and air holes and inclusions on the fatigue performance of the welding joints in this structural form are studied. First, using the extended finite element method to solve the geometric discontinuity problem, a large number of representative volume elements with random defects are generated, and then the random defects are subjected to homogenization treatment based on the equivalent crack propagation length criterion. The applicability of the numerical examples to the early crack propagation is proved. As one of the important multi-scale methods, the homogenization method can be used to calculate the crack propagation of the welded joint of the orthotropic steel bridge panel. according to the field measured data of a typical vehicle load of an orthotropic steel bridge panel, the annual vehicle flow and the wheel load lateral distribution recommended by the European specification are combined, A homogenization model is used to calculate the macro-crack formation life of the U-rib-top weld toe (the initial crack is extended to the life of the detectable scale). The results show that the method can effectively present the probability distribution of the macro-crack forming life, but under the existing assumption, the initial crack-scale influence is obviously higher than that of the air hole, the inclusion and the like; if the initial crack scale is uniformly distributed, the distribution of the macro-crack forming life is more discrete; The statistical properties of the results obtained depend on the selected Paris formula and its material constant.
【作者单位】：同济大学桥梁工程系;根特大学土木工程系;
【基金】：国家自然科学基金项目(51678437)
【分类号】：U441.4

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