STRUCTURAL RESPONSE AND COUPLER FORCES DURING TANK CAR IMPACTS

This paper describes the results of full scale tank car tests that were preliminary efforts toward developing a system for measuring forces on tank cars resulting from rail yard impacts. The approach was to study the relationship between peak coupler force and the structural response at various locations on the tank car. The behavior for each impact was defined by the load transfer mechanism that develops the peak coupler force. Three types of coupler behavior were observed during these impacts. The different load transfer mechanisms cause different responses of the tank car structure. Therefore, the coupler behavior must be considered when trying to interpret the structural responses. For the impact configuration investigated, the shock response spectrum (SRS) of an accelerometer mounted on the tank car shell was found to predict the coupler behavior during the impact and to provide a good estimate of peak coupler force. Responses from accelerometers mounted on or near the stub sill at the impacted end of the tank car did not provide good estimates of peak coupler forces, especially for the most severe impacts. Further study will be needed to verify and/or extend the observed relationship between the accelerations measured on the tank car shell and peak coupler forces for other impact configurations.