Overview of a Crash Energy Management Specification for Passenger Rail Equipment

PDFProceedingsJRC2006-94044CrashworthinessImpact testsCollisionsFinite element methodStructural analysisSpecificationsPassenger carsCommuter carsCouplersAmerican Society of Mechanical EngineersInstitute of Electrical and Electronics EngineersTyrell, DavidMartinez, EloySeverson, KristineJacobsen, KarinaParent, DanielPriante, MichellePerlman, A. BenjaminJohn A. Volpe National Transportation Systems Center (U.S.)Tufts UniversityNTL-RAIL TRANSPORTATION-RAIL TRANSPORTATIONNTL-SAFETY AND SECURITY-AccidentsNTL-SAFETY AND SECURITY-SAFETY AND SECURITYVolpe National Transportation Systems Center, Technical Reference CenterAt the request of METROLINK, the Federal RailroadAdministration (FRA), with the Federal Transit Administration and theAmerican Public Transportation Association, formed the ad hoc CrashEnergy Management Working Group in May 2005. This groupdeveloped recommendations for crush zones in passenger rail cars forMETROLINK to include in its procurement specification. The VolpeCenter provided the Working Group with technical information fromthe research on passenger rail equipment crashworthiness it isconducting for FRA. METROLINK released its specification,including the recommendations from the Working Group, onSeptember 16, 2005, as part of an invitation for bid.The specification includes three levels of requirements: train,car, and mechanism. The train level requirements specify a collisionscenario for which there must be no intrusion into the occupied areasand limits on the relative velocities at which the operator andpassenger may impact interior surfaces. The car and mechanism levelrequirements follow from the train level requirements. The car levelrequirements include specifications for a cab end crush zone capableof absorbing 3.0 million ft-lbs of energy and a non-cab end crush zonecapable of absorbing 2.0 million ft-lbs. There are also specificationson the crush zone kinematics and on the target force/crushcharacteristics. Mechanism level requirements include specificationsfor the coupling mechanism, the load transfer mechanism, and theprincipal energy absorption mechanism. The coupling mechanismpermits the coupler to push back, allowing the ends of adjacent cars toremain aligned and come together during an impact. The load transfermechanism transmits the load from the adjacent equipment into thecrush zone in a manner that allows the principal energy absorptionmechanism to function as intended. The cab end load transfermechanism can include a deformable LD that acts similarly to anautomobile bumper, and resolves eccentric impact loads into loads thatcan be appropriately reacted by the supporting structure. Theprincipal energy absorption mechanism is the section of the carbodystructure intended to deform gracefully and to provide most of therequired energy absorption.The specification prescribes performance for the train, the caband trailer cars, and the mechanisms. Each requirement includesquantitative criteria for evaluation of compliance. The Working Groupextensively discussed various evaluation methodologies, includingnon-linear large deformation finite element analysis and dynamiccomponent tests, and worked to assure that practical evaluationmethodologies are available for each requirement. For componentscritical to the functioning of the crush zone, tests are required. Thispaper describes the requirements, the associated criteria, and theavailable evaluation techniques. The technical bases driving the needfor each of the requirements are discussed