On the evaluation of the overloads coming from the use of seat-belts on a passenger railway seat

The research activities described in the present paper deal with the causes and the typologies of secondary impact injuries suffered by passengers of a railway vehicle during an assigned crash event; those considerations are to be a starting point to understand the degree in which those injuries can be absorbed and to propose useful ways to reduce or eliminate them. In particular, the seatbelt installation has been investigated as a suitable system to restrain the passengers. An anthropomorphic test device has been made available and experimental tests have been worked out to obtain reliable data about the interaction of passengers, seat and seatbelt of a specific type. By using the experimental data a multibody (MB) numerical model of the sled test has been examined, calibrated and validated and then the performances of restraining configurations, which could not be physically tested, have been simulated. Relevant overloads on the seat frame appear when seatbelts are installed, because of the inertial loads which are transferred from the passenger. Different structural analyses of the seat, by means of finite element simulations, have been undertaken to determine if a stiffening of the seat is required to sustain those overloads. The results showed in this paper refer to the case of a frontal impact and to real geometry, structural characteristics and lay-out of the seat, obtained by considering a specific test case. In the context of the presented study MADYMO(A (R)) code has been adopted to perform the preliminary MB analyses which are required to calibrate and to evaluate the relevant parameters of dummy-seat contact surfaces and of seat-belt stiffness, while LS DYNA(A (R)) code hasbeen used for the structural dynamic FE analyses.