Development of Rail Impact Test Criteria for Cushioned Draft Gear Rail Cars
Mr. Stanley Poynor, Lockheed Martin Missiles & Fire Control - Dallas
Mr. Wayne Clay, Lockheed Martin Missiles & Fire Control - Dallas
Mr. Jeff Kirk, Lockheed Martin Missiles & Fire Control - Dallas

Abstract:
A study was undertaken to update the shock specification associated with rail impact.  In the absence of measured data, programs previously used a generic criteria supplied by the Association of American Railroads (AAR) as bed-of-the-rail-car inputs for standard draft gear rail cars.  The AAR criteria was not updated following introduction of cushioned draft gear.  The generic value for cushioned rail cars in NATO Standardization Agreement (STANAG) 4370, Method 403 inadequately describes the shock event when compared to values measured during rail impact tests.  The object of the study was to develop rail impact shock test criteria, based on test measurements, applicable to system level test and as bed-of-the-rail-car inputs to dynamic models used to predict component level shocks.  Measurements from a variety of programs were used, resulting in generation of shock criteria varying by system weight class and axis orientation.  Shock criteria were developed in SRS format, matching the maximum expected value of each measurement population.  A method of wavelets and temporal moments was used to improve the similitude of the synthesized waveforms to the measured event time histories.  New shock spectra and the corresponding maximum number of wavelets are recommended as appropriate rail impact shock criteria for future test and modeling tasks.

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