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- A validated railway vehicle interior layout with multibody dummies and finite element seats models for crash analysisPublication . Ambrosio, Jorge; Carvalho, Marta; Milho, João; Escalante, Susana; Martin, RobertoWe propose a methodology for the validation of a numerical model of a railway interior with an inline seating layout arrangement, based on the use of multibody and finite element approaches for the analysis of the passive safety. We model the railway interior layout using a nonlinear finite element model of the passenger seats and all supporting structures. Multibody models of test dummies, appropriate to the identification of the injury mechanisms, are used as measuring tools of the human exposure to injury. The crash scenario model uses a crash pulse, which is the surrogate for the impact of the railway vehicle structure. Being the multibody dummy validated independently by the software vendor and the nonlinear finite element structural models built with detailed data, the validation of the complete layout involves the identification of the uncertain parameters used in the scenario construction and not of the parameters used in the independent models already validated. The interaction between the multibody and finite element is represented via a penalty contact force model, which, together with the dummy positioning data, provides the uncertain parameter set used in the validation process. An experimental test of the inline seating layout, carried with a physical prototype, provides the reference dynamic response for the validation of the numerical model. The injury levels measured with the dummies provide the reference injury criteria values used in the validation process. Following the model validation, we discuss the results obtained for the nominal crash scenario in the framework of the most relevant injury indices for railway passenger passive safety.
- Railway seat design for injury mitigation in crash scenarioPublication . Carvalho, Marta; Martins, Ana P.; Milho, JoãoA validated framework developed to analyse railway occupant safety is presented here. The inexistence of restraints and the larger distance between contact features for the railway cabin interior decreases the predictability on the kinematics of its occupants. Simulation results are evaluated considering the severity of the injuries, assessed and quantified using the relevant criteria. It was introduced a head padding that conducted to a reduction of the Head Injury Criterion (HIC) but worsening the value of neck-bending moment in extension (NBME). Finally, the multi-objective optimization procedures are applied to achieve a relevant reduction in injuries. With the implementation of a pad with 42 mm thickness and with a reduction of 8.2% of the backseat plate thickness, is obtained a 41% reduction of the HIC but at the cost of an increase of 49% of the NBME index, though this design allows keeping all injury indices below moderate threshold value.