周期性轨道结构的弯曲振动波控制

Flexural wave propagation control in periodic track structure

为探究周期性轨道结构中弯曲振动波调控的可行性,本文以CRTSⅢ型无砟轨道为研究对象,带隙特性为评价指标,采用能量泛函变分法建立了无砟轨道结构带隙特性分析模型.结合无砟轨道结构的带隙特性,获取了无砟轨道结构中弯曲波传播路径特征.在此基础上,针对钢轨的弯曲波调控,对比评估了周期性附加调谐质量阻尼器(TMD)和调谐质量阻尼惯容器(TMDI)对钢轨弯曲波的调控效果.针对轨道板的弯曲波调控,分析了轨道板参数对轨道结构带隙特性的影响,并进一步探讨了附加惯性增强装置对轨道板中传播的低频弯曲波的影响.结果表明,对于CRTSⅢ型无砟轨道结构,在0~1500 Hz范围内, 0~90.2 Hz范围内的弯曲波直接传递至下部基础,122.3~228.5 Hz范围内的弯曲波经由钢轨传递至轨道板且继续在轨道板中传播,其余频段的弯曲波则在钢轨中传播.对于钢轨的弯曲波调控,无论是周期性附加TMD还是TMDI均能打开新的弯曲波带隙,抑制钢轨中弯曲波的传播,且带隙的宽度与附加机构的有效质量呈正相关趋势,从宽频调控角度考虑, TMDI比TMD更具优势.对于轨道板的弯曲波调控,增大轨道板的有效质量或软化轨道板下部支承刚度均可缩减传递至下部基础的弯曲波频段,前者可以通过在轨道板上附加惯性增强装置来实现,后者可以通过改变轨道板下部支承条件来实现.

To explore the feasibility of flexural vibration wave regulation in periodic track structure,taking the CRTSⅢballastless track structure as the research object and the bandgap characteristics as the evaluation index,an analysis model of the bandgap characteristics of the ballastless track structure was established using the energy functional variational method.Combined with the bandgap characteristics of the ballastless track structure,the characteristics of the flexural wave propagation path in the ballastless track structure are obtained.On this basis,for the regulation of the flexural waves of rails,the effects of periodically added tuned mass damper(TMD)and tuned mass damper inerter(TMDI)on the flexural waves of rails were compared and evaluated.To enable the regulation of the flexural waves of the track slab,the influence of the track slab parameters on the bandgap characteristics of the track structure is analyzed.Furthermore,the influence of the additional inertial enhancement device on the low-frequency flexural wave propagating in the track slab is discussed.Results showed that for the CRTSⅢballastless track structure,in the range of 0–1500 Hz,the flexural waves in the range of 0–90.2 Hz are directly transmitted to the lower foundation,and the flexural waves in the range of122.3–228.5 Hz are transmitted via the rail to the slab and continue to propagate in the slab,and the flexural waves in the remaining frequency bands propagate in the rail.For the regulation of the flexural waves of the rail,whether it is periodically added TMD or TMDI,a new flexural wave bandgap can be opened to suppress the propagation of flexural waves in the rail.Moreover,the width of the bandgap is positively correlated with the effective mass of the additional mechanism.From the perspective of broadband regulation,TMDI has more advantages than TMD.For the regulation of the flexural waves of the track slab,increasing the effective mass of the slab or softening the support stiffness of the lower part of the slab can reduce the frequency band of flexural waves transmitted to the lower foundation.The increase in the effective mass of the slab can be achieved by attaching an inertia-reinforcing device to the slab.Meanwhile,the softening of the support stiffness of the lower part of the slab can be achieved by changing the supporting conditions of the lower part of the slab.