Finite element analysis of railway track under vehicle dynamic impact and longitudinal loads

Impact loads caused by flat spots on railcar wheels impose a major maintenance burden on railroads and can cause severe damage to both railcar and rail track components. In addition, the increasing tractive power of locomotives leads to significant increase in the longitudinal load demand in railway tracks. The capacity of longitudinal restraint of existing rail fastening system and its dependency on track parameters affects the future design of rail fastening system. This thesis focuses on investigating numerically these two problems using finite element (FE) method. An FE model with multiple crossties and their accompanying fastening systems is developed and utilized in this study after being validated using field data. The results of the impact load study indicate that impact loading consists of direct wheel impact loads and track system vibration induced impact loads. Both of these impact mechanisms are sensitive to the parameters considered in this study, including the stiffness of rail pad and the speed of train. It is observed that rail pad with a moderate stiffness provides the most effective impact attenuation. Furthermore, impact load is found to increase with increasing train speed. On the other hand, the study conducted on longitudinal track loads focused on investigating the effects of wheel acceleration, elastic modulus of clips, rail-to-railpad coefficient of friction (COF), and crosstie spacing on the distribution of longitudinal force in the rail fastening system. The FE model results suggest that a coefficient of friction (COF) of 0.65 is most efficient in maximizing the longitudinal restraint per railseat. Additionally, a crosstie spacing of 24 inches can lead to a desired distribution of longitudinal force