In this research project, chaos and bifurcation theory will be used to analyze the nonlinear lateral and yaw stability (commonly called `hunting`) of high-speed rail vehicles. A major challenge in designing rail vehicles in general, and high-speed passenger rail transportation in particular, is the velocity-dependent dynamics of the vehicle. As velocity increases, the vehicle becomes less stable, experiences violent oscillations, and eventually derails. In addition to safety concerns, hunting imposes significant operational costs to the railroads. Increased hunting contributes to more wheel and rail wear, causing millions of dollars of damage to the nation's rail system each year. Through using chaos and bifurcation theory, this research will investigate and provide a better understanding of the effects of dynamic nonlinearities on rail vehicle hunting. The nonlinearities that will be considered include elements such as the primary and secondary suspensions, the vehicle constraints, and the wheel/rail interface. This research will also examine design conditions that yield safer and more cost-effective operation of rail vehicles at high speeds. The techniques developed during this research will be applicable to the design of general nonlinear systems, including high-speed passenger and freight rail vehicles.
