simulation of a freight train and the effect of wheel flat defect on the wheel/rail dynamic forces

Wheel/rail interaction is one of the most important research topics in railway engineering and generally includes impact response, vibrations, and track safety. track structure failures caused by wheel/rail impact dynamic forces can lead to significant economic loss through damage to rails, ballast, fastening system, etc. wheel/rail impact forces occur due to defects in wheels and/or rails such as wheel flats, irregular wheel profiles, rail corrugation, etc. a wheel flat can cause a large dynamic impact force as well as high frequency forced vibrations, which will eventually lead to damage to the train and track structure. in the present work, a freight train (3d model) was used to analyze the dynamic impact caused by the wheel flat using um software. the effects of wheel flat depth and length (0, 0.2, 0.5, 1, 1.5, 2, and 3 mm) at two speeds of 50 and 80 km/h on wheel/rail dynamic forces have been investigated. the results showed that the presence of a wheel flat defect significantly increases the wheel/rail dynamic impact. for example, by increasing the wheel flat depth to 3 mm, the values of maximum force at speeds of 50 and 80 km/h have changed by about 235% and 400%, respectively.