The study of nonlinear oscillations and chaos of a railway freight car is undertaken. The vehicle is considered as a multiple rigid-body system with nine degrees of freedom. The vehicle forward speed is taken as the control parameter of the system. Hopf bifurcation point, limit cycles, quasiperiodic and chaotic motions of the system are computed by use of numerical methods. The identification of periodic, quasiperiodic and chaotic motions of the system is carried out by using the methods of phase plane portrait and Poincare map. Numerical results show that chaotic motion appears via the route of quasiperiodicity when the vehicle runs over a certain speed. The system vibration has hysteresis effect because of the occurrence of subcritical Hopf bifurcation. The nonlinear critical speed (turning point speed in the bifurcation diagram), where the first stable limit cycle emerges, is lower than the linear critical speed (Hopf bifurcation point speed). Therefore, the nonlinear critical speed should be taken as the limit speed for railway vehicles. Quasiperiodic motion of the feight car, which is an important route towards chaos, occurs via secondary Hopf bifurcation at speed of v = 315 km/h. It is clearly indicated from the calculation that chaotic motion of the car appears at v = 350 km/h through the route of quasiperiodicity. It is important to know from the work of this paper that chaos really happens in a railway freight car even though the speed is not so realistic. It is certain that chaos can probably appear at a lower speed in a different parameter range of the car system.
Nonlinear oscillations and chaos in a railway vehicle system
Nichtlineare Schwingungen und Chaos in einem Eisenbahngüterwagen als Schwingungssystem
Chinese Journal of Mechanical Engineering. English Edition ; 11 , 3 ; 231-238
1998
8 Seiten, 9 Bilder, 9 Quellen
Article (Journal)
English
Schwingungssystem , Schwingungsverhalten , Schwingungstheorie , Eisenbahngüterwagen , Nichtlinearität , Fahrgeschwindigkeit , mathematisches Modell , numerisches Verfahren , dynamisches Verhalten , Eisenbahnrad , Eisenbahnschiene , Wechselwirkung , Kriechen (Werkstoff) , periodische Bewegung , kritischer Zustand , kritische Geschwindigkeit
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