曲线轨道参数对钢轨振动衰减率的影响研究

Effects of curved track parameters on rail vibration decay rate

建立曲线轨道解析模型,研究扣件刚度、扣件阻尼、扣件间距以及曲线轨道半径对钢轨振动衰减率的影响规律。轨道模型考虑为具有周期性离散支承的曲线Timoshenko梁,在频域内,将曲线钢轨的位移及转角表达为轨道模态的叠加,进而求解固定谐振荷载作用下曲线轨道的平面内和平面外动力响应。由于此轨道模型为无限周期性结构,将周期性结构理论应用于轨道模型的运动方程,可以在一个基本元内高效地求解轨道的动力响应。利用此模型计算固定谐振荷载作用下曲线钢轨的速度频响函数,据此计算钢轨的振动衰减率。经计算分析可知:在2 000 Hz以内,扣件刚度对钢轨振动衰减率有一定的影响,随着扣件刚度的增加,钢轨振动衰减率增大;对于100 Hz以上频段,扣件阻尼对钢轨振动衰减率有非常显著的影响,增加扣件阻尼可以显著提高钢轨振动衰减率;如果考虑全频段的钢轨振动衰减率,0.6 m扣件间距要优于0.4 m和0.8 m扣件间距;对于铁路轨道或城市轨道交通的轨道,曲线轨道半径变化对钢轨振动衰减率没有影响。

Here,an analytical model of a curved track was built to study effect laws of fasteners’stiffness,damping and spacing,and curved track radius on the rail vibration decay rate.The track model was considered as a curved Timoshenko beam with periodically discretized supports.In frequency domain,displacement and slope of the curved track were expressed as superposition of its modes,and then in-plane and out-of-plane dynamic responses of the curved track subjected to harmonic loads with fixed positions were solved.Due to the track model being an infinite periodic structure,the periodic structure theory was applied in the track model’s equations of motion,so the track’s dynamic response could be solved effectively within a basic element.The track model was used to calculate the velocity FRF of the curved track under harmonic loads with fixed positions,and then calculate the rail vibration decay rate.The calculation results showed that within the range of 0-2 000 Hz,fastener stiffness affects the rail vibration decay rate to a certain extent,and the rate increases with increase in fastener stiffness;within the range of larger than 100 Hz,fastener damping affects the rate very significantly,increasing fastener damping can make the rail vibration decay rate lift significantly;if considering the rail vibration decay rate in the whole frequency range,fastener spacing of 0.6 m is better than that of 0.4 m and that of 0.8 m;change in curved track radius does not affect the rail vibration decay rate for railway tracks and urban rail transit system’s ones.