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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 occupant passive safety improvement by optimal designPublication . Carvalho, Marta; Milho, João; Ambrosio, Jorge; Ramos, N.This work presents a systematic approach to the railway occupant passive safety improvement of seating layouts using optimisation methods for the identification of the best design options. The numerical model of this layout is developed using multibody models for the dummies and finite element models for the vehicle interiors, such as seats and any structural part considered as potential target surface during impact being the crash scenario is analysed using the MADYMO code. The objective is the minimisation of the injuries as represented by all relevant injury criteria identified for railway passengers, particularly head and neck, chest and leg. The design variables are seat structural characteristics, easily modified during manufacturing or maintenance without influencing cost. The methodology starts by using a meta-modelling method that supports the definition of a surrogate objective function obtained by fitting a n-dimensional surface to the results of a collection of analysis in which the values of the design variables are varied inside specific domains. A standard deterministic optimisation method is then used to solve the surrogate problem implemented in a Matlab environment. The results show that an optimum design of the interior seating layout is obtained with relevant decreases of the most critical injury criteria.