Technical Reports

Freight Car Fatigue - Coal Car Simulator Demonstration Test

  • 01
  • Dec
  • 1990
AUTHOR: V. Sharma
SUBJECT: Freight Operations, Evaluation
KEYWORDS: Freight Car Simuloader, Load Environment, Road Test, Couplers
ABSTRACT: A full scale fatigue test of a 100-ton coal gondola car on the Transportation Test Center's (TTC) Simuloader facility was successfully completed recently. With a short test encompassing 270 hours of Simuloader testing, the freight car was subjected to fatigue damage equivalent to 600,000 miles of revenue service. The test car developed fatigue cracks at locations where similar cracks had been experienced earlier in revenue service. An over-the-road test was run to collect data required to "drive" the Simuloader and to characterize the structural and dynamic response of the coal car in revenue service. The road test route information was then "condensed" by selecting, from the 120 hours time history, events which were fatigue significant, that is, when the freight car experienced high loads and stresses at critical locations. The uneventful miles were edited out. The 2,200 miles road test route of 120 hours travel time was condensed to the simuloader test load cycle of only one hour. So, during the simuloader test the car was subjected only to the high loads which may cause fatigue damage to the car structure. We observed during our simuloader tests that the car body dynamic response at critical strain gage locations was quite similar to what was observed in our road test. It was also established that, for accurate simulation of coupler loads, it is important to remove as much slack as possible from the draft gear pocket. Also, the gains of the Simuloader actuators can be increased as needed to further accelerate the fatigue test.