Analysis On Fastening Force Of Ballastless Track

Both the adjustment of the geometric error of ballastless track and providing track elasticity are relying on rail fastening system. Its structure and performance are significant to the application of ballastless track. Preventing the rollover of rail and gauge enlarging are the main functions of fastening. Fracture of clip is the main failure form of fastening. The fatigue damage of elastic clip is related to its vibration characteristics under vehicle dynamic loads. Aim at Vossloh 300 fastening which adopted by China ballastless track, this thesis studies the constraint capability of fastening on rail gauge widening and vibration characteristic of clip.(1) Based on nonlinear contact theory, the finite element models of fastening clip, gauge apron, rail and rail pad are established with finite element anlysis software ANSYS. In order to reflect the change of position and force of elastic clip during the process of instalastion, contact pair between elastic clip, rail and gauge apron are bulit. Rational stress evaluation criterion and stress-strain curve are chosen according to the material of elastic clip, and the accuracy of the calculation results are ensured. The installation position, clamping force and the maximum equivalent stress of the elastic clip are analyzed and calculated. The stress concentration position after the installation of the fastening clip is found at the end of the elastic clip.(2) In order to investigate the anti-rollover performance of rail, eccentric vertical force is applied at the point 15 mm away from rail top and lateral force is applied at the point 10 mm below rail top on the rail. And the anti-rollover capability of elestic clip under different stress state of the rail are calculated. Four cases of rail anti-rollover performance of the fastening are analyzed:with or without applying vertical force after applying lateral force, and with or without applying vertical force after applying lateral force when one side elestic clip is loosened. The rail head lateral displacement under every working condition is analyzed. The lateral displacement and lateral force are basically in linear relationship, and loosening of elastic clip may cause the increase of rail head lateral displacement. The clamping force and equivalent stress of the elastic clip on both side of rail will change as rail head lateral displacement appears.(3) In order to investigate the dynamic performance of fastening when vehicle passing the corrugation rail, corrugation with different amplitude is taken as excitation and the rail vertical displacement is obtained according to vehicle—track coupled dynamic model. The influence of amplitude of corrugation on elastic clip vibration characteristic is analyzed through applying the vertical rail displacement on the top of rail head in the finite element model. The influence of different rail pad stiffness on elastic clip vibration characteristic is analyzed by changing the rail pad stiffness. The increase of corrugation amplitude and the decrease of rail pad stiffness will increase elastic clip vertical vibtation and its fatigue as well as damage.