铁道车辆焊接结构疲劳强度网格灵敏度与可视化研究

Visualization and mesh sensitivity research of fatigue strength for railway vehicles welded structures

铁道车辆承载结构在服役过程中承受复杂的多轴疲劳载荷,在满足结构功能性要求的前期下,实现承载结构的轻量化设计具有极高的难度。以某铁道车辆转向架构架为研究对象,选取构架疲劳失效的典型部位,分别采用8节点六面体实体单元和10节点四面体实体单元对构架对称区域进行网格划分;基于UIC 615-4、EN 13749、TB/T 2368—2005标准和车辆的实际运行条件,确定构架疲劳强度的计算载荷和载荷工况;根据欧盟关于铁道车辆的标准(ORE B12/RP17)给出的多轴应力转化为单轴应力的方法,分析其疲劳强度;采用C#与Fortran混合编程技术,直接对ANSYS的二进制结果文件进行操作,实现构架疲劳强度分析结果的可视化。分析结果表明:对于薄板焊接结构,在焊缝区域,采用四面体实体单元进行网格划分的节点最大材料利用度是对应节点采用六面体实体单元结果的1.8倍左右。直接对ANSYS的二进制结果文件进行操作,能够显著提高结构疲劳强度分析效率,同时实现疲劳强度分析结果的最大应力、最小应力、平均应力、应力幅、安全系数和材料利用度的可视化,提高了疲劳分析结果的可视性。

Railway vehicle structures endured complex multi-axial fatigue loads in the service process, which has great difficulty for lightweight design of the structure to meet the functional requirements. Taking a vehicle bogie frame as research object, select- ed its typical structure of fatigue failure. The thin sheet structure symmetrical regions were discretized with 8-node hexahedral sol- id elements and 10-node tetrahedral solid elements. Based on the operation condition of the vehicle and the standards of UIC 615- 4 ,EN 13749 and TB/T 2368--2005 ,the load conditions were defined. With the method of multi-axial stress transferring to axial stress in the ORE B12/RP17 reporter,the fatigue of the structure was analyzed. Based on hybrid programming technology of C# and Fortran,operate the ANSYS binary result file directly to achieve the visualization of the fatigue for the frame. The results show as follows：for the thin shell structure, compared with hexahedral elements, using the tetrahedral elements to mesh has a worst re- suit. In the welded area, the maximum material utilization of nodes which uses tetrahedral elements to mesh is approximately 1.8 times than that of hexahedral elements. A direct operation of the ANSYS binary result, can read the result file rapidly. The visual- ization of fatigue result＇ s maximum stress, minimum stress, average stress, stress amplitude, safety factor and material utilization has been achieved, and the visibility of the results of fatigue has been improved.