Evaluation of different simplified crash models: application to the under-frame of a railway driver's cab

Due to the high cost and the practical difficulties of full scale rolling s tock vehicle crash tests, numerical simulation proves to be a good alternat ive. Finite element codes provide very satisfying results. Nevertheless, lo ng modelling and Computation times implied by this local approach do not al low this technology to be fully efficient in the early design stages. In th ese cases, a more adequate solution is to use simplified models based on mu ltibody systems. This approach requires the input of specific data for non- linear bars and springs which are determined via experiments, finite elemen t calculations, or in a more efficient way by analytical models. In a class ical way, rigid multibody systems are used. We propose here to evaluate the influence of the flexibility in simplified models, in terms of global resp onses and computation times. The application to an under-frame of a railway driver's cab shows that a multibody model using non-linear springs and ela stic-plastic beam elements dedicated to thin-walled structures carry out th e best compromise.