Multibody simulation of railway vehicles with contact lookup tables

Abstract

The use of contact lookup tables is widely used in multibody railway simulations to increase the computational efficiency. However, due to simplifying assumptions the use of contact lookup tables decreases the accuracy of the simulation results. This paper analyses the increase of computational efficiency and loss of accuracy for a particular multibody simulation. To this end the results based on contact lookup tables are compared with the results of the online solution of the wheel-rail contact constraints. The formulation used to compute the equations of motion of railway vehicles has the following features: (1) the equations of motion are obtained using a systematic procedure based on multibody dynamics, (2) generalized forces included in the equations of motion are obtained using symbolic computations when possible, (3) generalized coordinates are referred to a non-inertial track frame, (4) the equations of motion are obtained using a velocity transformation of the Newton–Euler equations of the vehicle bodies, which are assumed to be rigid and (5) wheel-rail tread contact and flange contact are treated with pre-calculated lookup tables which can take into account the track irregularities. The comparative study presented in this paper shows that this formulation can be used to simulate the dynamics of a railway vehicle in real-time.