Dynamic Train-Turnout Interaction – Mathematical Modelling, Numerical Simulation and Field Testing

Doktorsavhandling, 2007

Two models for simulation of dynamic interaction between train and turnout are developed. The first one is derived using a commercial software for dynamics of multi-body systems. The second is based on a detailed model of track dynamics and a multi-body dynamics formulation that accounts for excitation in an extended frequency range (up to several hundred Hz). Using a finite element model of a standard turnout design, a complex-valued modal superposition of track dynamics is applied to account for the structural receptance of the track components. The variations in rail profile, track stiffness and track inertia along the turnout, and contact between the back of the wheel flange and the check rail, are considered. Hertzian theory and FASTSIM are used for the normal and tangential wheel–rail rolling contact. Stochastic analysis methods are integrated with the dynamic simulation model. For one given nominal layout of the turnout, the influence of several parameters on wear and rolling contact fatigue is investigated. Four parameters (axle load, wheel–rail friction coefficient, and wheel and rail profiles) are identified to be the most significant. Random distributions of the transverse wheel profile and of a set of transverse rail profiles along the switch panel are accounted for by use of the Karhunen–Loève expansion technique. To determine input data for the turnout model (rail pad stiffness, ballast stiffness and modal damping), impact load testing for measurement of track receptance was performed in the field. Lateral and vertical wheel–rail contact forces were measured by an instrumented wheelset to validate the mathematical models. Good agreement between measured and calculated contact forces is observed. The influence of train speed, moving direction and route on the measured wheel–rail contact forces is quantified.