Full Scale Accelerated Fatigue Test on a Rail Car

The performance of an accelerated fatigue test to predict the life of a railcar has been discussed in the past. This type of testing requires a previous structural analysis, instrumentation and an Over the Road (OTR) test to collect all the necessary information needed for the generation of the signals which will be used to drive the fatigue test rig (shaker). The railcar to be placed on the shaker is normally the same car that underwent the described process. There are some instances, however, when the railcar to be placed on the shaker is not the same car used to develop the fatigue input data. The two most frequent scenarios when this happens are that the intended car to be tested is of the same design but a different unit or, that the intended car to be tested is of a similar but not the same, design. This presentation deals with the latter scenario, where the intended car to be tested is a different unit with similar design as the one used during the previous phases of analysis and testing. Given these conditions an alternate approach is necessary to convert the real-time, large data inputs from a previous analysis and testing on a different unit into valid equivalent signals which will be used to drive the shaker while creating the equivalent damage on the car structure, typically allowing the simulation of 30-50 years of service in a 3-4 months accelerated test. This presentation describes the alternate procedure.

Challenge

  • Need to develop an accelerated fatigue test on a rail car that is a different design than the rail car that provided all the customer usage data.

Solution

  • An alternate procedure based on fatigue damage analysis in nCode GlyphWorks.
  • Generate a metric called Road Environment Percent Occurrence Spectra (REPOS).
  • These REPOS data allows creation of a test that replicates a long service life in a condensed period of time.

Value

  • Reduce test time and cost by eliminating the need for another rail test (4-6 months time-saving typical).
  • Efficiently test any number of similar railcar designs.

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Test data processing and durability analysis

nCode GlyphWorks is a data processing system that contains a powerful set of pre-defined tools for performing durability analysis and other insightful tasks such as digital signal processing. Designed to handle huge amounts of data, GlyphWorks provides a graphical, process-oriented environment that contains leading analysis capabilities for saving both time and money in environmental qualification and product validation.

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