Abstract
The main purpose of this paper is to analyze and compare the Hopf bifurcation behavior of a two-axle railway bogie and a dual wheelset in the presence of nonlinearities, which are yaw damping forces in the longitudinal suspension system and heuristic creep model of the wheel-rail contact including dead-zone clearance, while running on a curved track. Two-axle railway bogie and dual wheelset were modeled using 12-DOF and 8-DOF system with considering lateral, vertical, roll, and yaw motions. By utilizing Lyapunov’s indirect method, the critical hunting speeds related to these models are evaluated as track radius changes. Hunting defined as the lateral vibration of the wheelset with a large domain was characterized by a limit cycle-type oscillation behavior. Influence of the curved track radius on the lateral displacement of the leading wheelset was also investigated through 2D bifurcation diagram, which is employed in the design of a stable model. Frequency power spectra at critical speeds, which are related to the subcritical and supercritical bifurcations, were represented by comparing the two-axle bogie and dual wheelset model. The evaluated accuracy to predict the critical hunting speed is higher and the hunting frequency in unstable region is lower compared to the dual wheelset model.
Highlights
The prior issue, which should be clarified in railway vehicle design under rail load, is the dynamic response of the vehicle having clearances between wheel tread-rail, wheel flangerail contacting forces, and dry friction in suspension system
To design safe and robust vehicle, it is essential to investigate the influence of the railway vehicle parameters on the hunting motion
Polach [4] has applied the use of nonlinear calculations and bifurcation analysis when dealing with the running stability during vehicle design and development in railway industry and discussed the relationship between the bifurcation diagram and the assessment of safety risk and the dynamic behavior
Summary
The prior issue, which should be clarified in railway vehicle design under rail load, is the dynamic response of the vehicle having clearances between wheel tread-rail, wheel flangerail contacting forces, and dry friction in suspension system. Zboinski and Dusza [8] have investigated the nonlinear lateral stability of railway vehicles with different pairs of wheel/rail profiles in a curved track by using self-exciting vibration and bifurcation theories. Ahmadian and Yang [11] have searched on the analytical representation of Hopf bifurcation and hunting behavior of a rail wheelset with nonlinear primary yaw dampers and wheel-rail contact forces. Reza [12] has investigated the analytical formulation of bifurcation, nonlinear lateral stability, and hunting behavior of rail vehicles in a tangent track by using Bogoliubov method. This model includes a nonlinear primary yaw dampers and flange contact. In the case of high values of spin, the heuristic theory leads to unsatisfactory results [21]
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