A numerical model to analyse the dynamic behaviour of modern tramcars

In this paper, a numerical model specifically developed for tramcar vehicles is presented. The proposed numerical model allows to reproduce the most common tramcar configurations and to analyse the vehicle performance in terms of combined longitudinal, lateral and vertical dynamics. A particularly detailed procedure for the calculation of wheel-rail contact forces is implemented, thus allowing to deeply investigate sharp curve negotiation behaviour and its effect on vehicle safety, comfort and wheel/rail wear and fatigue. The main features of the model are summarised and some numerical results are reported, in comparison with the corresponding experimental data

Crosswind action on rail vehicles: A methodology for the estimation of the characteristic wind curves

The problem of cross wind for rail vehicles gained, in the last years, an increasing interest whithin the European railway operators, due to the continuous expansion of the high-speed railway networks. In order to evaluate the aerodynamic performance of a train in terms of safety towards cross wind, the Characteristic Wind Curves (CWCs), have to be defined. In this paper a stochastic approach for the definition of the CWCs is presented. According to this methodology, the wind speed space-time distribution is reproduced through a stochastic process and the algorithm for the definition of the aerodynamic loads acting on the train is set up, which is based on the admittance function. A numerical model for the admittance function is presented and verified by means of comparison with experimental data. The effects of the admittance function and of the stochastic approach in the definition of aerodynamic forces and of the corresponding CWCs are then analysed in terms for a specific case (assigned reference train, flat ground scenario, tangent track running)

Prediction of running safety for a tramcar equipped with independently rotating wheels by means of numerical simulations and experimental tests

This paper deals with the assessment of flange climb derailment in bogies with independently rotating wheels, through experimental tests and numerical simulations. An extensive experimental campaign has been carried out on a full-scale test rig , allowing to induce the wheelset derailment under controlled conditions, of a tramcar wheelset equipped with independently rotating wheels. In parallel to the experimental tests, a numerical simulator of the test-rig was used, for the definition of the conditions to be tested in order to achieve derailment, and for the validation of the developed wheel/rail contact model, in extreme conditions of flange climb derailment. Finally a vehicle numerical simulator was adopted to extend derailment analysis in transient conditions, also accounting for the dynamics of the whole vehicle

Experimental validation of a numerical model for the simulation of tramcar vehicle dynamics

Tramcar vehicles significantly differ from traditional railway vehicles both for the adopted structural configuration and design solutions and for the operating conditions. For this reason, a new numerical model specific for the analysis of tramcar dynamics has been developed by Politecnico di Milano. Before the numerical model can be adopted as a useful mean to analyse tramcar operational problems, the capability of the model to reproduce the actual tramcar dynamic behaviour has to be verified. The paper deals with the validation of the developed numerical model by means of comparison with experimental data

Software for the numerical simulation of tramcar vehicle dynamics

In this paper, a new simulation software specifically designed for tramcar vehicles is presented. The proposed numerical model allows to reproduce the most common tramcar configurations and to analyse the vehicle performance in terms of combined longitudinal, lateral and vertical dynamics. A particularly detailed procedure for the calculation of wheel-rail contact forces is implemented, thus allowing to deeply investigate sharp curve negotiation behaviour and its effect on vehicle safety, comfort and wheel/rail wear and fatigue. The simulation software also allows to consider the state equations of the traction motors (together with those of the electric converters), in order to analyse the electro-mechanical interaction of the two subsystems in transient conditions, and to compare/optimise different vehicle control strategies. The main software features are summarised, together with their theoretical basis, and some numerical results are reported, in comparison with the corresponding experimental data

Wheel-rail contact phenomena and derailment conditions in light urban vehicles

When dealing with railway systems, wheel-rail contact forces play a key role in vehicle dynamic behaviour and have a strong influence on safety, comfort, noise and wheel/rail wear. Contact mechanisms are particularly important when low radius curves are considered, like those which are typical of urban transportation. This paper is intended to analyse vehicle dynamic behaviour in sharp curves, with particular reference to derailment conditions, by means of a mathematical model that includes a full schematisation of the vehicle and an accurate description of the contact forces

A numerical-experimental approach to evaluate the aerodynamic effects on rail vehicle dynamics

This paper describes the methodology proposed to define the aerodynamic loads acting on a rail carbody, for given turbulent wind conditions and to compute the corresponding vehicle's response. Experimental data of wind tunnel tests, together with numerical simulation results, are shown. Finally, the set up numerical model is adopted to estimate critical wind curves