基于不同评估方法的高速动车组车体结构气动疲劳性能研究

Research on Aerodynamic Fatigue Performance of High-Speed EMU Carbody Structure based on Different Evaluation Methods

基于IIW-2008和EN1999-1-3标准中名义应力法及ASME-2007标准中结构应力法,研究高速动车组铝合金车体焊接结构的气动疲劳问题.总结接头名义应力与结构应力的选取位置及计算过程,明确各疲劳评估方法的分析步骤,并对两种焊接工艺的铝合金对接接头进行疲劳分析,结果表明:无垫板的疲劳寿命次数高于带垫板的,基于EN1999-1-3标准的无垫板的疲劳寿命次数约为带垫板的1.68倍;在GB/T 32059-2015中的气动疲劳载荷作用下,采用名义应力法和结构应力法对某高速动车组铝合金车体焊接结构进行疲劳分析,累积损伤值较大的部位为司机室侧墙、车顶焊缝等区域.IIW-2008和EN1999-1-3标准中接头FAT等级相同的接头S-N曲线不一致,导致具有相同的名义应力的接头累积损伤不同.通过对司机室大侧窗下的三种结构设计方案的关键焊缝的结构应力分析获得其最终设计方案.基于结构应力法的司机室侧窗角焊缝与司机室立柱与地板角焊缝的累积损伤分别为0.736和0.658,低于名义应力法的计算结果.建议高速动车组车体气动疲劳设计时应重点考察铝合金司机室的焊接结构.

Using the nominal stress method in the IIW-2008 and EN1999-1-3 standards and the structural stress method in the ASME-2007 standard,the aerodynamic fatigue problem of the welded structure of an aluminum alloy car body of the high-speed EMU is studied.The selection location and calculation process of the nominal stress and structural stress of the joint are summarized,the analysis steps of each fatigue assessment method are clarified,and the fatigue analysis of the aluminum alloy butt joint with two welding processes are conducted.The result shows that the number of fatigue life of the non-backed plate is higher than that of the backed plate,and the fatigue life of the non-backed plate based on the EN1999-1-3 standard is about 1.68 times that of the backed plate.Under the aerodynamic fatigue load in GB/T 32059-2015,the nominal stress method and the structural stress method are used to perform fatigue analysis on the welded structure of the aluminum alloy car body of a high-speed EMU.The parts with the larger cumulative damage value are the side wall of the cab,car roof welds and other areas.As the S-N curves of joints with the same FAT grade in the IIW-2008 and EN1999-1-3 standards are inconsistent,the cumulative damage of joints with the same nominal stress is different.Through the structural stress analysis of the key welds of three structural design schemes under the large side window of the cab,the final design scheme is obtained.Based on the structural stress method,the cumulative damages of the fillet welds of the side window of the cab and the fillet welds of the column and the floor of the cab are 0.736 and 0.658 respectively,which are lower than the results calculated by the nominal stress method.The results suggest that the welding structure of the aluminum alloy driver cab should be emphasized in the aerodynamic fatigue design of the high-speed EMU carbody.