Analysis Of Axle Stress Response And Floating Slab Vibration Characteristics Based On Vehicle-track-floating Slab Coupling Model

With the rapid development of urban rail transit in China,the steel spring floating slab track system with its unique technical advantages to meet the vibration damping requirements in urban rail transit,but because of its typical linear vibration isolation characteristics,so the steel spring floating slab track system to obtain high vibration isolation effect at the same time will certainly cause the wheel track system vibration response increase,its elastic support principle may have an impact on the axle of the main load-bearing components of urban rail vehicles.Therefore,the analysis of the stress response of the axle and the vibration characteristics of the track in the floating slab section,followed by the reasonable range of the steel spring floating slab track structure parameters,can provide more references for future theoretical research and engineering practice.Firstly,based on the modal analysis principle,the finite element model of axle and steel spring floating slab was modally analyzed,and the first eight orders of vibration pattern and its inherent frequency were found out,so that the influence law of structural parameters of steel spring floating slab track system on its inherent frequency was analyzed.Meanwhile,based on the two core theories of vehicle system dynamics and rigid-flexible coupling dynamics,a multi-rigid body vehicle dynamics model and a vehicle dynamics model considering axle flexibility were built,and the two models were compared and verified,and finally a dynamics model of the vehicle-track-floating slab coupling system was built.Next,the fatigue analysis module of the dynamics simulation software was used to calculate the axle Mises stress response of the coupled vehicle-rail-floating slab dynamics model at two different operating speeds of 80 km/h and 160 km/h.The effect of the structural parameters of the steel-spring floating plate track on the axle Mises stress was further analyzed.The results show that the addition of steel spring floating slab track can reduce the axle Mises stress,and the maximum axle Mises stress occurs at the axle body on the inner side of the wheel base at different operating conditions and is less than the allowable stress.The effect of steel spring floating slab track structure parameters on the maximum Mises stress of the axle does not exceed3%.Then,the vibration characteristics of steel spring floating slab at 80 km/h and160 km/h and the vibration response law of floating slab track system with different track structure parameters were analyzed from two perspectives of time domain and frequency domain.The results show that the vibration response of each index increases significantly when the speed increases from 80 km/h to 160 km/h.With the increase of vibration isolator stiffness,can effectively reduce the displacement response of the rail system,but will cause the vibration isolator support reaction force and floating slab acceleration significantly increased;vibration isolator damping increase can make the two speed floating slab acceleration significantly reduced,160km/h vibration isolator support reaction force increased;fastener stiffness increase will reduce the displacement response and rail vibration,but will cause the fastener support reaction force increased by more than 40%.The increase of fastener damping can reduce the rail acceleration as well as the fastener support reaction force and floating slab acceleration at 160 km/h.In the center frequency where the peak vibration response of rail and floating slab is concentrated,the change of fastener stiffness only decreases the acceleration level of rail at 160 km/h and increases the acceleration level of floating slab,and the changes of the rest of structural parameters have the same trend on the vibration response at both speeds.Finally,the following reference range is given for the structural parameters of the steel spring floating slab track system: the recommended range of vibration isolator stiffness is 7-12 MN/m;the recommended range of vibration isolator damping is 40-100 k N.s/m;the recommended range of fastener stiffness is 40-100MN/m;the recommended range of fastener damping is 40-130 k N.s/m.When the technology allows and meets the specifications,the structural parameters of low stiffness and high damping are used.In the technically permissible and to meet the standard,the low stiffness and high damping structural parameters are selected.