钢桥面板疲劳裂纹耦合扩展机理的数值断裂力学模拟

发布时间：2018-01-20 21:59

  本文关键词： 桥梁工程 钢桥面板 数值断裂力学 疲劳裂纹 耦合扩展机理 扩展有限元法　出处：《中国公路学报》2017年03期 　论文类型：期刊论文

【摘要】：为研究钢桥面板疲劳裂纹耦合扩展机理,建立焊接分析有限元模型,对纵肋-顶板连接细节、纵肋-横隔板连接细节的焊接全过程进行数值模拟,基于扩展有限元方法建立钢桥面板数值断裂力学模型,对疲劳敏感细节裂纹静、动态扩展行为进行分析。焊接过程分析结果表明:纵肋-顶板连接焊缝区域、纵肋-横隔板焊缝端部区域均存在较大的残余拉应力,峰值接近钢材屈服强度;横隔板挖孔边缘存在切向残余拉应力,峰值约为200 MPa。疲劳裂纹扩展行为分析结果表明:纵肋-顶板连接细节在车辆荷载单独作用下以受压为主,考虑残余应力场作用后细节处于拉-拉应力状态,疲劳裂纹为Ⅰ型主导的Ⅰ-Ⅱ-Ⅲ型复合裂纹;车辆偏载作用下纵肋产生扭转变形,计入残余应力后纵肋-横隔板连接焊缝焊趾受拉开裂,萌生于纵肋焊趾、向纵肋腹板扩展的疲劳裂纹为Ⅰ型主导的Ⅰ-Ⅱ-Ⅲ型复合裂纹,萌生于纵肋-横隔板连接焊缝横隔板侧焊趾和横隔板挖孔边缘的疲劳裂纹为Ⅰ-Ⅱ型复合裂纹;纵肋对接细节的疲劳裂纹为Ⅰ型裂纹,车辆荷载作用下以受拉为主,位于纵肋底板弧形过渡区的裂纹相较于纵肋底板中间区域具备更强的扩展能力。
[Abstract]:In order to study the mechanism of fatigue crack coupling propagation of steel bridge panel, the finite element model of welding analysis was established, and the welding process of longitudinal rib-roof connection detail and longitudinal rib-transverse diaphragm connection detail was simulated numerically. Based on the extended finite element method, the numerical fracture mechanics model of steel bridge slab is established, and the static and dynamic propagation behavior of fatigue sensitive crack is analyzed. The welding process analysis results show that: longitudinal rib-roof joint weld zone. The residual tensile stress exists in the end of the weld seam of longitudinal rib-transverse partition plate, and the peak value is close to the yield strength of steel. There is tangential residual tensile stress at the edge of the cut hole of the transverse diaphragm, the peak value is about 200 MPA. The results of fatigue crack growth analysis show that the longitudinal rib-roof connection details are mainly under the action of vehicle load alone. After considering the residual stress field, the detail is in the state of tensile and tensile stress, and the fatigue crack is mode 鈪，

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