出口缅甸3B_0机车焊接构架疲劳寿命预测

Fatigue Life Prediction of Welded Frame of 3B_0 Locomotive Exported to Burma

为了对出口缅甸3B_0机车转向架焊接构架的疲劳寿命进行预测,采用有限元方法对构架在不同疲劳载荷下的应力状态进行分析,确定了箱体梁中主焊缝的多种疲劳应力范围。基于IIW标准和相关文献中焊接接头疲劳寿命数据确定了评估焊接构架的多条S-N曲线方程,在此基础上采用整体名义应力法和局部缺口应力法计算了关键主焊缝的寿命次数。结果表明:所有焊缝的寿命次数均大于2×10~6次,满足轨道车辆焊接接头设计标准要求;其中构架侧梁T型角接头在垂向动载作用下寿命较低,应通过焊缝磨削处理降低其应力集中程度。由于名义应力法分析结果较缺口应力法更为保守,从结构轻量化和局部优化角度出发,采用局部缺口应力进行焊接结构疲劳寿命预测更具有优势。

In order to predict the fatigue life of the welded frame of 3B_0 locomotive exported to Burma, the stress state of welded frame under different fatigue loading cases by FEM was analyzed, and then the fatigue stress ranges of main welds in box girders were determined. Based on IIW standard and fatigue test data in relevant literature, several S-N curve equations of welded joints for assessing the fatigue strength of welded frame was obtained, then the life cycles of some key welds were calculated by using both global nominal stress method and local notch stress method. The result indicated that the fatigue life cycles of all welds were greater than 2 million, which met the requirements of welded joint design standard for rail vehicle; As the T joint in frame＇s side beam under vertical dynamic loads had low life cycles, it should reduce the local stress concentration by weld grinding. Normal stress method generally was partial to be conservative, so it had more advantages by using notch stress method for fatigue life prediction of welded structure from the perspective of structural light weight and local optimization.