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- Validation of a railway inline seating model for occupants injury biomechanicsPublication . Carvalho, Marta; Martins, Ana Alexandra; Milho, JoãoThis paper presents the validation of a finite element model in LS-DYNA of the interior inline seating layout simulating a frontal rail impact event for which the experimental test results provide the reference for the injury biomechanics of the occupants. The representative layout consists in two rows of seats and its supporting structures modelled with nonlinear finite elements and the crash acceleration pulse that represents the impact of the railway vehicle structure is imposed in the floor of the coach. For the appropriate identification of the injury mechanisms to the occupant associated to the frontal crash analysis is used the Hybrid III 50th percentile Anthropomorphic Testing Device, being the interaction between the occupant model and the structure characterised via penalty contact force models. The validity of the numerical model is discussed to ensure the representativeness of the analysis procedure and to identify the most relevant injury indices of the occupants. In particular, the head injury criterion is the most critical injury index for the inline seating layout, with a relative deviation of 6.2% of the simulation result with respect to the experimental test.
- 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.