地铁构架垂向载荷与振动加速度特征关系研究

Research on the Relation between Vertical Load and Vibration Acceleration Characteristics of Metro Bogie Frame

地铁构架承受多源载荷引起构架损伤,台架试验评估损伤需要获得构架真实服役载荷,采用测力构架法识别构架真实服役载荷目前已经取得阶段性进展。但是,测力构架法较为复杂,需要大量前期准备工作,如确定载荷识别点、粘贴应变计、标定桥路系数以及封装测力构架等。实际上,构架承受的载荷与其振动加速度密切相关。以某型地铁构架为研究对象,通过实际线路测试垂向载荷和振动加速度,对比分析两种信号的时频域相关性、特征值分布规律以及谱相似性等,建立构架垂向载荷与振动加速度之间的谱关系,基于等损伤原则验证通过振动加速度建立垂向载荷谱的有效性。研究结果表明,不同服役环境下,两类信号时频域振动趋势基本一致,在构架自振频率和低阶弹性模态频率处振动反馈一致,时域内呈强相关,主频范围内高度相干。两类信号值分布范围大致相同且概率密度分布曲线峰部形态具有高度一致性。在两类信号谱形状高度相似的前提下,引入幅值放大系数和谱长度变异系数建立谱关系,以此获得的等效载荷与实测等效载荷的比值介于1.06~1.25,满足构架疲劳评估要求。研究工作对地铁构架载荷谱建立具有重要的工程意义。

Metro vehicle frames are subjected to multi-source loads which cause frame damage.To assess frame damage through bench tests,frame loads closely related to vehicle operating conditions are required,and the force-measuring frame method has been applied to identify vehicle frame loads on actual routes.However,the force-measuring frame method is more complicated and requires a lot of preparatory work,such as determining the load identification point,pasting the strain gauge,calibrating the bridge coefficient,and packaging the force-measuring frame.In fact,the load on the frame is closely related to its vibration acceleration.As the research object,a metro vehicle frame is used for a line test in which the vertical load and vibration acceleration signals are measured over time.The time-domain correlation,frequency-domain coherence,eigenvalue distribution,and spectral similarity of the two types of signals are compared and analyzed.The spectral relationship between vertical load and vibration acceleration of the frame is established.The effectiveness of the vertical load spectrum established by vibration acceleration is verified based on the principle of equal damage.The results show that the vibration trends in the time and frequency domains of the two types of signals are the same under different service environments,with consistent vibration feedback at the frame self-oscillation frequency and low-order elastic modal frequency,a strong correlation in the time domain,and high coherence in the main frequency range.The distribution ranges of the two signals are approximately the same.The peaks of the probability density distribution curves have high consistency.On the premise that the shapes of the two types of signal spectra are highly similar,the amplification coefficient and the spectral length variation coefficient are introduced to establish the spectral relationship,so that the ratio of the equivalent load to the measured equivalent load is between 1.06 and 1.25,which meets the reliability requirements of the fatigue assessment of the frame.These findings have important engineering significance for the establishment of the metro vehicle frame load spectrum.