The Federal Railroad Administration’s (FRA) Office of Research and Development is conducting research into the occupied volume integrity (OVI) of passenger railcars. OVI refers to a passenger railcar’s ability to preserve space for passengers and crew during accident loading conditions. The information developed in this research program will form the basis for establishing alternative OVI evaluation procedures. These alternative procedures, in turn, will allow a wider variety of passenger railcar designs to have their OVI evaluated, will provide guidance for applying modern engineering technologies, such as finite element analysis (FEA), and will continue to ensure a level of safety in evaluated vehicles equivalent to conventional evaluation.

As part of this research program, two tests and corresponding FEA were conducted on a Budd M-1 passenger railcar that had been retrofitted with crash energy management (CEM) components on both ends. This testing and analysis program was sponsored by FRA and carried out by Transportation Technology Center, Inc. (TTCI), Arup, and the Volpe Center. An 800,000 pound load test was conducted on March 13, 2013 and was intended to elastically deform the car. The data generated during this test were, in turn, used to validate FE models of the M-1 car. The second test was performed on July 17, 2013. This test introduced loads into the occupant volume through its CEM attachment points until the ultimate, or crippling, load was reached. By loading the occupant volume through the CEM components, the test load path is similar to the load path that would be traveled by collision loads during activation of the CEM system.

This paper presents the results of the crippling test, discusses the sequence of buckling that was observed to occur in the test, and compares the results of the test with the results from FEA of the test conditions. During the crippling test, the car exhibited a crippling load of 1.1 million pounds. This value is consistent with crippling loads reached by two Budd Pioneer cars that were previously tested in an FRA program. The buckling sequence of the members making up the M-1’s occupant volume were particularly well-captured by strain gages during this most recent test. The load path through the occupant volume and the sequence of progressive buckling of structural members is discussed. Additionally, the presence of existing damage and previously-repaired areas and their likely effects on the crippling behavior of the car are discussed.

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