Dynamic responses of motor vehicle in low-speed derailment

The low-speed derailment experiment of signal motor vehicle with post-derailment safety device under axle box was carried out.The derailer was installed on the rail to force the vehicle to derail.Acceleration sensors, displacement sensors and strain gauges were used to detect the dynamic responses of derailed vehicle.The motion attitude of derailed vehicle was recorded by using high-speed cameras and surveillance cameras.According to the test data, the ability of overturning resistance for rail and the performance of derailment safety device were verified.The dynamic responses of derailed vehicle and the effects of derailment speed, vehicle mass and track on the responses were studied.Test result indicates that in low-speed derailment, the biggest lateral force between rail and post-derailment safety device is 177.18 kN that is less than the lateral resistance of 510.00 kN, so the post-derailment safety device has the ability to limit the lateral displacement of derailed vehicle by catching the outside of rail after derailment.The derailment process is divided into four stages, including idling, running on the derailer, falling and coasting on the track, at which the dynamic responses of derailed vehicle are increasingwith the increase of derailment speed and vehicle mass.When derailment speed is 22km·h^-1, the derailment distance of CRTSⅡ bi-block sleepers ballastless track is about 15.80 m, while that of CRTSⅠ slab ballastless track is about 20.87 m.Accordingly, the bi-block sleepers of CRTSⅡ bi-block sleepers ballastless track resemble the speed bump and decrease the derailment distance.