Document Type : Research Article
School of Railway Engineering, Iran University of Science and Technology, Tehran, Iran
One of the main problems of the damages of rail tracks which is caused by track settlement is unsupported sleeper. Due to this defect the underlying area of sleeper is not supported on the ballast and causes the sleeper displacement to increase. The increase creates vibration in the track and vehicle components and causes problems on their performance. Hence, in this study the investigation of rail displacement in tracks with unsupported sleeper has been dealt with. 3D modeling of the vehicle and ballasted track has been carried out using ANSYS and SIMPACK programs. To use this software, the modeling of a flexible track in the vehicle multibody model is possible. Ballasted track which is formed from components as rail, sleeper and ballast, has been considered to be flexible. In simulating the vehicle all of its main components have been considered and damping and stiffness values of bogie suspension systems have been considered to be nonlinear. The results obtained from numerical simulation have good agreement with field test results. The results show that the speed of the vehicle on the track displacement with less than four unsupported sleepers has no effect, but by increasing the number of unsupported sleepers, the effect of increasing velocity would be considerable.