Technical Reports

Validation of Track Geometry Input to the Vibration Test Unit (VTU) and the Endurance Capability of the VTU

  • 01
  • Jun
  • 1984
AUTHOR: Britto R. Rajkumar, F. D. Irani
SUBJECT: Facilities & Test Equipment
KEYWORDS: Carbody Response, Lading Response, Locomotive Track Hazard Detector, LTHD
ABSTRACT: This report describes a series of tests conducted at the Transportation Test Center, Pueblo, Colorado, to validate two forms of track geometry inputs to the Vibration Test Unit (VTU) in the Rail Dynamics Laboratory, capable of reproducing actual revenue track conditions. The first form consisted of reformatted Plasser geometry input produced by converting the Plasser mid-chord offset data into a Space Curve format with a special software. The second track geometry input was developed based on the Locomotive Track Hazard Detector (LTHD) concept, and was produced by processing the time histories of special axle-mounted accelerometers into a space curve format. The results indicated that the responses of the test vehicle on the VTU, excited with the LTHD input, compared closely with the corresponding responses monitored on the actual track, while the reformatted Plasser input showed considerable variation in the vehicle response on the VTU at speeds of 30 mph and above - in both amplitude levels and frequency content. After the identification of a suitable form of input to the VTU which closely duplicated actual track conditions, a series of endurance cycle test runs was performed to demonstrate the capability of the VTU to operate for sustained periods of time using the track geometry as the input excitation.