焊接缺陷对动车组铝合金车体疲劳寿命影响研究

Research on Influence of Welding Defects on Fatigue Life of EMU Aluminum-alloy Car Body

由铝合金型材焊接而成的高速列车车体,如考虑焊缝处初始焊接缺陷的存在,将造成焊缝质量等级的不同,进而造成其抗疲劳能力产生差异。为寻求在设计阶段能较准确地预测含初始焊接缺陷的动车组车体疲劳寿命的评估方法,通过试验获得3种含初始焊接缺陷试件的疲劳寿命数据,并基于美国ASME(2007)标准中的结构应力法计算出含不同焊接缺陷试件疲劳寿命的"等效初始裂纹";建立包括焊缝在内的动车组车体有限元模型,并依据BS EN12663-1:2010标准的加载方式,基于等效结构应力法和Miner线性累积疲劳损伤理论,预测车体关键焊缝的疲劳寿命;根据反求出来的等效裂纹对模型进行修正,研究初始焊接缺陷的存在对车体疲劳寿命的影响。

The high-speed train car body is made of welded aluminum alloy sections .Consideration of the exist-ence of initial weld defects at weld seams will lead to different levels of weld quality , thus resulting in different resistances to fatigue . In search of the method to accurately predict in the design stage the fatigue life of the EMU car body with initial welding defects , the fatigue life data of test specimens with three types of initial weld defects were collected , from experiments and the initial cracks equivalent to the fatigue life of the test specimens with different types of welding defects were calculated with the structural stress method specified in USA Standard ASME （2007） . The finite element model of the EMU car body with weld lines was set up and loaded according to the loading mode included in Standard BS EN 12663-1 ：2010 , the fatigue life of the critical weld lines of a car body was predicted on the basis of the equivalent structural stress method and the Miner line-ar cumulative fatigue damage theory . The model was modified according to the counter-calculated equivalent cracks and the influence of initial welding defects on the EMU car body fatigue life was studied .