轨道车辆不锈钢车体焊点强度评估方法研究

摘要

结合国际标准和接头疲劳试验及有限元模型,研究在设计阶段不锈钢车体焊点强度的快速评估.首先,对比分析英国标准EN 15085-3:2007和美国AWS C1.1M/C1.1-2000标准中基本金属的强度、板厚及焊核直径对焊点最小剪切力的影响;然后,对某出口不锈钢超载状态车体承受纵向压缩时,考虑到车体结构复杂与焊点数量庞大,借助梁单元模拟点焊连接,利用美国标准中的焊点最小剪切力对车体焊点的静强度进行评估.指出该车体底架焊点设计存在问题,需要进一步进行改进焊点设计.接着,分析焊点疲劳强度评估各类方法的特点及适用范围,基于焊点接头疲劳试验数据和利用梁单元的合成剪力变化范围,在超载状态车体承受107次垂向加速度为±0.3 g的循环载荷作用下,对该不锈钢车体焊点进行疲劳评估,车体焊点满足设计要求.%Combining with international standards,joint fatigue test and finite element model,rapid evaluation strength method for spot welds is studied during stainless steel car body design phase.First of all,the effect of base metal strength and thickness,and nugget diameter on minimum shear force of spot welds is analyzed by British Standard EN 15085-3:2007 and American Standard AWS C1.1M/C1.1-2000.Then,while expor-ted car body supported overloaded and longitudinal compression,its spot welds strength is evaluated by means of minimum spot welds shear force from the American Standard,and beam element forces representing the spot welds considering complex car-body structure and huge amounts of spot welds.According to the result,the un-der-frame spot welds strength is insufficient,and the spot welds layout need to be improved.Next,the charac-teristics and application scopes of spot welds fatigue assessment methods is discussed, and the spot welds fa-tigue is studied on basis of fatigue test data and resultant shear force range obtained from the beam element when the overloaded car body withstand ±0.3 g vertical load with 107cyclic times.Spot welds in the car-body meet the fatigue requirement.