Nonlinear stability evolution of railway wagon system due to wheel profile wear

Railway vehicle hunting instability frequently occurs due to severe operating conditions, significantly affecting trains’ running quality. This paper examines the hunting motion and bifurcation characteristics of a railway wagon fitted with three-piece bogies, emphasizing the effect of wheel profile wear. The Poincaré sections describe the wagon system’s hunting motion characteristics and bifurcation evolutionary trends, which are defined according to the dynamical system’s geometric phase space structure. The influence of the wheel wear on the nonlinear stability of the wagon system is conducted, and the effects of friction performance are investigated subsequently, in which fundamental features of hunting and bifurcations are revealed in detail. The results indicate that the solution branches generate a conspicuous evolution due to the development of wheel wear, which is a process of first simplicity and then complexity. In addition, the frictional characteristics of the system (wheel-rail and wedge friction) are crucial to the system bifurcation. The combination of different friction performance and worn wheel profiles can lead to entirely different system bifurcation. The bifurcation characteristics of the wagon system are demonstrated and analyzed in detail, the different motion regions are divided according to the corresponding characteristics, and the evolution process of the nonlinear dynamic response of the system during the development of wheel wear is further proposed.