考虑梁弯扭耦合对钢轨横向振动特性的影响

Effect of Bending-Torsional Coupling of Beams on Lateral Vibration Characteristics of Rails

为准确预测弹性波在钢轨中的传播,且探究考虑Timoshenko梁弯扭耦合的必要性,基于波谱-辛混合法建立了考虑梁弯扭耦合的钢轨-扣件空间无限长模型.在模型验证的基础上,分析考虑Timoshenko梁弯扭耦合对钢轨横向固有频率与速度导纳的影响,进一步从理论和试验方面分析了扣件胶垫垂向预压特性对钢轨横向弯曲振动特性的影响.研究结果表明:考虑梁弯扭耦合使得钢轨横向弯曲共振频率增大了约29.6 Hz,且在钢轨横向弯曲振动中同时出现弯曲和扭转pinned-pinned模态;扣件胶垫垂向预压特性主要影响钢轨横向中低频振动,随着预压的增大,钢轨横向弯曲共振频率增大;当预压从30 kN增加到50 kN时,实测的横向弯曲共振频率增加了13.7 Hz,考虑和不考虑梁弯扭耦合时其分别增加了12.5 Hz和21.7 Hz;不同预压下考虑梁弯扭耦合的钢轨横向弯曲共振频率变化规律与实测的结果更为接近.

To accurately predict the propagation of elastic waves in rails and explore the necessity of considering the bending-torsional coupling(BTC)of Timoshenko beam,a rail-fastener spatial infinite model considering the BTC of the beam was developed based on the spectral element method(SEM)and the symplectic method(SM).Based on model verification,the BTC effect of Timoshenko beam on the lateral natural frequency and velocity admittance of the rail was analyzed,and the effect of vertical preload dependence of fastener pads on the lateral bending vibration characteristics of the rail was analyzed theoretically and experimentally.The research results show that because of the BTC effect of the beam,the lateral bending resonance frequency(BRF)of the rail increases by about 29.6 Hz,and the bending and torsional pinned-pinned modes appear simultaneously in the lateral bending vibration of the rail.The vertical preload dependence of fastener pads mainly affects the lateral low-and mid-frequency vibrations of the rail.As the preload increases,the lateral BRF of the rail increases.When the preload is increased from 30 kN to 50 kN,the measured lateral BRF increases by about 13.7 Hz,while the increase is about 12.5 Hz and 21.7 Hz by considering the BTC effect of the beam or not.The variation law of lateral BRF of the rail considering the BTC of the beam under different preloads is closer to the measured results.