基于多轴振动环境再现的地铁车辆排障器寿命评估研究

A study on life assessment of metro cowcatcher based on multi-axis vibration environment reconstruction

车辆服役过程中,由于轮轨间的高频激励,极易引发结构共振疲劳问题。文章针对某地铁车辆排障器的疲劳开裂问题,开展了排障器的振动疲劳试验,发现了线路上通过频率为93 Hz的钢轨波磨是引发结构共振疲劳的主要原因。针对试验研究方法存在的传感器布置数量有限、成本较大等问题,文章从仿真分析角度,提出了一种基于多轴振动环境再现的地铁车辆排障器寿命评估方法。首先,建立了基于虚拟激励法的排障器随机振动模型,该模型可以很好地再现排障器的实际振动环境;然后,通过遗传算法对模态阻尼比进行优化,使得仿真和实测响应结果具有较好的一致性,验证了建模方法的正确性;最后,利用多核并行计算的方法实现了排障器任意位置的全程损伤和疲劳寿命计算,显著提高了仿真计算的效率。结果表明:排障器焊缝拐角处为其结构的薄弱位置,其全程工况损伤值为6.25E-03,疲劳寿命为0.60万km,远低于设计使用寿命的360万km,通过上述方法评估出来的排障器最大损伤位置与结构实际破坏位置相同,进一步证明了此方法的正确性。

During the operation,the resonance fatigue of the structure is easily caused by the high-frequency wheel-rail excitation.In this study,the vibration fatigue test with a metro cowcatcher was conducted for the fatigue cracking found in a certain metro cowcatcher.It was found that the resonance fatigue of the structure was mainly caused by the rail corrugation with the frequency of 93 Hz on the line.Given the high cost and limited number of sensors in the experimental research method,a method to assess the life of the metro cowcatcher in the reproduced multi-axis vibration environment was proposed based on the simulation analysis.Firstly,a random vibration model of the cowcatcher was created based on the pseudo-excitation method,which can well reproduce the actual vibration environment of the cowcatcher.Then,the modal damping ratio was optimized by the genetic algorithm,improving the consistency between the simulation and measured response results,and proving the correctness of the modeling method.At last,the whole-course damage and fatigue life of any part of the cowcatcher was calculated by the multi-core parallel computing method,significantly improving the efficiency of simulation calculation.The results show that the weld corner of the cowcatcher is the weakness of the structure,the whole-course damage under operating condition is 6.25E-03, and the fatigue life is 6000 km, which is far lower than the design life of 3 600 000 km. The location of the largest damage on the cowcatcher found by the above method is the same as that of the actual damage to the structure, further proving the correctness of this method.