Research On New Type Of Elastic Cushion Plate Under Pillow And Its Dynamic Effect On Vehicle-rail System

The under-pillow elastic pad is an important vibration-damping component of the sleeper-type vibration-damping track structure.Its main function is to improve the vibration-damping effect of the elastic sleeper,reduce the impact effect of the track structure,and protect the track bed,subgrade and other structures.The mechanical properties of the slab will directly affect the vibration-damping effect and service life of the track structure,and even affect the safety and comfort of the train during operation.However,existing studies have paid relatively little attention to the structure and performance of under-pillow elastic pads,and the existing grooved under-pillow elastic pads have limited elasticity,lacking under-pillow elasticity with longer service life and better elasticity.In this thesis,a new mesh-type elastic pad is taken as the research object,based on elastic mechanics,structural dynamics and vehicle-track coupling dynamics theory,using the finite element analysis software(ABAQUS)and multi-body dynamics software(UM).The mechanical characteristics and dynamic behavior of the hole-shaped elastic pads are studied.The main research contents are as follows:(1)The influence of the geometric structure of the under-pillow mesh elastic pads on the static stiffness characteristics of the pads is analyzed,and the mechanical properties of the conventional grooved pads are compared.Studies have shown that reducing the internal aperture angle,decreasing the hole spacing and increasing the thickness of the backing plate can reduce the static stiffness value of the backing plate,while increasing the internal aperture angle,increasing the hole spacing and increasing the thickness of the backing plate can The maximum Mises stress value of the backing plate is reduced.According to the above change law,the static rigidity of the under-pillow mesh elastic pad can be reduced by about 40%under the condition that the stress does not change much,that is,the under-pillow mesh elastic pad can improve the elasticity of the pad.At the same time,it can ensure that the service life of the pad does not change much.(2)The influence of the change of mesh geometry on the dynamic stiffness and dynamic-static stiffness ratio of the under-pillow pad was studied.Under dynamic load,increasing the internal aperture angle,increasing the hole spacing,and reducing the thickness of the pad can increase the dynamic stiffness of the mesh-type elastic pad under the pillow,and the dynamic and static stiffness ratio decreases,so it can Adjust the mesh geometry to reduce the dynamic and static stiffness ratio of the backing plate.Compared with the grooved pad with the same elastic performance,the mesh pad has a lower dynamic and static stiffness,which shows that the under-pillow mesh pad has better rebound characteristics and vibration transmission effect.(3)Two methods of logarithmic decay rate method and hysteresis curve method were used to study the damping characteristics of under-pillow mesh-type elastic pads.In the case of the same elastic properties of grooved and mesh-type pads,the The size of the damping ratio of the two pads.The research shows that the damping ratios calculated by the two calculation methods are consistent,but the logarithmic decay rate method is faster in the calculation process and simpler in the calculation principle.Compared with the grooved pad,the damping ratio of the under-pillow mesh elastic pad is slightly larger.(4)Based on the principle of vehicle-track coupling dynamics,within the static stiffness range of 10kN/mm~20kN/mm,the effect of the static stiffness change of the mesh-type elastic pad under the pillow on the dynamic performance is studied.The corresponding dynamic responses of the vibration-damping rail and the vibration-damping fastener are compared.Studies have shown that as the static stiffness of the mesh cushion under the pillow decreases,the wheel-rail force will decrease,and the vertical displacement of the rail and sleeper will increase,but the displacement of both does not exceed the specified limit.Compared with the traditional sleeper-type vibration-damping track,the sleeper-type vibration-damping track with mesh pads can increase the vertical displacement of the steel rail and sleepers,and reduce the wheel rail vertical and lateral forces of the rail system.Compared with vibration damping fasteners,sleeper-type vibration damping rails with mesh pads can effectively reduce the derailment coefficient of the rail system,the wheel load reduction rate,the wheel rail force and the vertical acceleration of the rail.