Design Of Floating Slab Track Vibration Isolator Based On Chiral Superstructure

With the rapid and heavy development of urban rail transportation,the environmental vibration problem is becoming more and more serious.In order to reduce the impact of urban rail transit vibration,a variety of vibration damping measures are used in the rail structure.At present,the biggest effect of vibration reduction in rail transit is steel spring floating slab track structure,using this structure can effectively reduce the environmental vibration and structural secondary noise caused by the train,but this structure for the specific frequency band vibration control has certain limitations,and the use of steel spring floating slab track system has the problem of large vertical displacement under the action of train load,which in turn has a certain impact on the safety and smoothness of traffic.This in turn has a certain impact on driving safety and smoothness of the train.The chiral metamaterial structure with tensiletorsional characteristics provides a new idea to solve this problem.The application of chiral metamaterial structure as vibration isolator in the floating slab system can not only realize the effective control of vibration in specific frequency band,but also reduce the vertical displacement of floating slab under train load to a certain extent.In this context,this paper focuses on the following aspects.(1)A finite element model of the chiral superstructure vibration isolator was constructed based on the tensile-torsional characteristics,and its equivalent static stiffness was calculated,and the displacement transfer rate of the chiral superstructure vibration isolator was analyzed.The results show that the equivalent static stiffness of the chiral superstructure vibration isolator is mainly influenced by the elastic modulus of the support rod;the use of the chiral superstructure vibration isolator generates a vibration decay domain in a specific frequency band,and the onset frequency of the attenuation domain is mainly controlled by the elastic modulus of the soft material cladding;a resonance peak appears on the left side of the starting frequency of the decay domain,and the resonance peak can be effectively suppressed by applying damping to the structure.(2)The steel springs is replaced with chiral superstructure vibration isolators to form the floating slab track of the chiral superstructure isolator.On that basis,the vibration transmission characteristics of these two track systems were analyzed.The results show that the force transfer rate of the floating slab track system with chiral superstructure isolators in the attenuation domain is much lower than that of the steel spring floating slab track system with the same stiffness,while the vibration transfer effect of the floating slab track system with both isolators in the rest of the frequency band is similar.(3)The steel springs were replaced with chiral superstructure vibration isolators to form a chiral superstructure floating slab track system.Based on this,the vibration transmission characteristics of these two track systems are analyzed.The results show that the force transfer rate of the floating slab track system with chiral superstructure isolators in the attenuation domain is much lower than that of the steel spring floating slab track system with the same stiffness,while the vibration transfer effect of the floating slab track system with both isolators in the rest of the frequency band is similar.(4)Under the condition that the damping effect is similar to that of the steel spring isolator,the chiral superstructure isolator can be used with greater vertical stiffness,when the vertical displacement amplitude of the floating slab under the train load will be reduced,which can effectively solve the problem of larger track vertical displacement of the steel spring floating slab.