A multibody methodology for the design of anti-climber devices for train crashworthiness simulation

Abstract

The impact of train sets is characterized by a very high potential for the longitudinal instability of the train resulting in overriding of the individual car-bodies. Consequently, the end-underframe structural mechanisms for crash energy management are not loaded and the train kinetic energy has to be dissipated by structural components not designed for that purpose. In this work, a multibody-based methodology is presented for the study of train crashworthiness including the anti-climber devices. The simulation of train impact requires models for the structures of the individual train car-bodies, contact forces between train components, systems and mechanisms responsible for the connections between vehicles. The most important motions of the train set are developed in the vertical plane, therefore, the methodology now developed uses a planar dynamics formulation. The vehicles are described by a set of rigid bodies with their relative motions constrained by kinematic joints. The forces that develop during contact, except for the joint reactions are modelled by nonlinear deformable elements. The mechanical characteristics of such elements represent the force-deformation structural response of each train car-body end, obtained by experimental testing or through detailed finite element models. The nonlinear characteristics of the suspension systems, the structural behaviour of the couplers and the friction forces between wheel-sets and rail arc also represented in these models. The anti-climber mechanical devices are modelled using the description of the contact between the train car-bodies ends. This is represented by a continuous contact force model, which accounts for the relative geometry between the car-body ends and material characteristics of the structural devices. The formulation is finally applied to train impacts in various crash scenarios, which are characterized by the collision of complete train sets with different velocities against stopped trains. The modelling assumptions and the suitability of the numerical tools developed are discussed in the framework of their application to the design of train crashworthy components.