基于主S-N曲线法的地铁制动箱焊接疲劳分析

为研究地铁车辆制动箱焊接接头的疲劳寿命，根据实际结构建立4节点壳单元有限元模型，给出搭接焊和T型焊的焊缝建模方法.在3种振动工况下，运用主S N曲线法计算焊缝的等效结构应力和对应损伤比.结果表明：该地铁车辆制动箱焊接结构设计合理可靠；通过与实体单元模型计算结果进行对比证明壳单元模拟焊缝的合理性；在不同尺寸单元下对比2种疲劳评估方法，结果表明名义应力法预测疲劳寿命的准确性较低.

Fatigue analysis of metro brake box based on master S-N curve method

To study the fatigue life of welded joints of metro vehicle brake box, four nodes shell finite element is built according to the actual structure, and the modeling methods are given for lap fillet and T shape welds. Under the three kinds of vibration conditions, the equivalent structural stress and the corresponding damage ratio of the weld seam are calculated by the master S N curve method. The results show that, the design of the metro vehicle brake box is rational and reliable; the comparison of the calculation results with that of the entity unit model proves that the simulation on weld seam using shell elements is rational; the comparison of two different fatigue assessment methods under different size of elements shows that the accuracy of nominal stress method is not high.