扣件胶垫刚度频变的车-线-隧垂向耦合随机振动虚拟辛分析

Symplectic Random Vibration Analysis of Vertically Coupled Vehicle-Track-Tunnel System Considering Frequency-dependent Stiffness of Rail Pads

为了精确预测车辆转向架、车轮及轮下系统的随机振动频域响应,综合考虑扣件胶垫的低频初始刚度及其刚度频变幅度,运用无穷周期子结构的辛数学方法与虚拟激励法,建立了车-线-隧垂向耦合随机振动虚拟辛分析模型,分析了扣件胶垫频变刚度对耦合系统随机振动的影响.结果表明:扣件胶垫刚度频变对车体垂向随机振动的影响可以忽略,但会提高转向架频率57 Hz以上的随机振动,并显著提高轮对与钢轨随机振动加速度功率谱最大峰值与其对应的第1主频;扣件频变刚度使轨道结构的自振频率及向高频发生偏移,轮轨共振频带的能量也向高频区域转移,轮对加速度功率谱在频域内的分布向高频部分偏移约8.6 Hz.

In order to accurately predict the frequency-domain characteristics of random vibration of vehicle bogies, wheels, and the fundamental structure under wheels, a symplectic mathematics model of random vibration of a coupled vehicle- track-tunnel system is established using the pseudo excitation method （PEM） and the symplectic mathematics of infinite periodic substructures, with consideration of the low-frequency initial stiffness of rail pads and the frequency-dependent extent of stiffness. The model is used to analyze the influence of the frequency-dependent stiffness of rail pads on the random vibration of the coupled vehicle -track -tunnel system. Results show that the frequency-dependent stiffness of rail pads affects little the vertical random vibration of vehicle body, but it will increase vertical random vibration amplitudes of vehicle bogie at frequencies above 57 Hz and meanwhile significantly increase the peak power spectrum density （PSD） of the vertical random vibration of both wheelset and steel rail, as well as their 1st dominant frequencies. As the stiffness of rail pads increaseswith frequency, the natural frequency of the track structure shifts to a higher frequency range, and the energy of the wheel-rail resonance frequency band also transfers to a higher frequency region. As a result, the frequency domain of the wheel acceleration PSD distribution shifts upward by 8.6 Hz.