Full Scale Tank Car Coupler Impact Tests

Abstract

Full scale tests were performed to investigate various aspects of tank car behavior during coupler impacts. A tank car was equipped with 37 accelerometers and an instrumented coupler. Two series of full scale coupler impact tests, comprising 26 impacts, are discussed. In the first series, the tank car was empty. In the second series, the tank car was full. A range of impact speeds was investigated. Accelerometer response and coupler force were measured for each test. Aspects of the tank car response to coupler impacts can be determined by studying the coupler force versus time relationship, Shock Response Spectrum (SRS), and Power Spectral Density (PSD) analyses of accelerations measured on the tank car body. The dominant draft gear load transfer mechanism can be determined from the coupler force vs. time relationship. Accelerations were measured at many locations on the tank car. However, based on preliminary analyses, a single location near the manway was chosen for detailed study. SRS results of accelerations at this location show good correlation with the peak coupler force, although different relationships were observed when the car was empty than when it was full. PSD analyses of empty tank cars have peaks at different frequencies than PSD analyses of full tank cars, so a PSD analysis could be used to determine whether a car is empty or full. Therefore, the combination of SRS and PSD results suggests the possibility of estimating peak coupler forces resulting from yard impacts based on SRS and PSD analyses of accelerations measured at a single location on a tank car.