Modeling material failure during cab car end frame impact

PDFProceedingsJCR2009-63054CollisionsCrashworthinessDeformation curveDynamic testsImpact testsCrash injury researchFinite element methodDynamic structural analysisUnited StatesAmerican Society of Mechanical EngineersInstitute of Electrical and Electronics EngineersStringfellow, Richard G.Paetsch, ChristopherTIAX LLCJohn A. Volpe National Transportation Systems Center (U.S.)United States. Federal Railroad Administration. Office of Research and DevelopmentNTL-RAIL TRANSPORTATION-Rail SafetyNTL-SAFETY AND SECURITY-Rail SafetyNTL-SAFETY AND SECURITY-Vehicle DesignVolpe National Transportation Systems Center, Technical Reference CenterNew standards have been proposed to increase the strength requirements for cab car end structures and impose further requirements on their ability to absorb energy during a grade-crossing collision. This conference paper reports on a set of full-scales tests completed by Federal Railroad Administration (FRA) and the Volpe Center to assess the quasi-static and dynamic crush behavior of these end structures. In support of this testing program, end frames designed to meet the new standards were fabricated and retrofitted onto the forward end of an existing cab car. A series of large-deformation quasi-static and explicit dynamic finite element analyses (FEAs) were performed to evaluate the performance of the design. A material failure model, based on the Bao-Wierzbicki fracture criterion [3], was implemented in the FEA model of the cab car end frame using ABAQUS/Explicit. The FEA model with material failure was used to assess the effect of fracture on the deformation behavior of cab car end structures during quasi-static loading and dynamic impact and, in particular, the ability of such structures to absorb energy. Model parameters were validated and material strength and failure parameters were derived for A710 steel. The model was then used to simulate the three full-scale tests that were conducted during 2008 as part of the FRA program: a collision post impact, and quasi-static loading of both a collision post and a corner post. The researchers found need for revisions to both the design of some key end frame components and to key material failure parameters. Using the revised model, pre-test predictions for the outcome of the corner post test were found to be in very good agreement with test results