Bifurcation and chaos of electromechanical coupling main drive system with strongly nonlinear characteristic in mill

According to the torsional vibration phenomena frequently appeared in the rolling process of rolling mill in recent years, the expressions of electromagnetic torque and electromagnetic stiffness were derived from the energy analysis perspective based on the electric motor principle and the electromagnetic field theory. In addition, a strongly nonlinear torsional vibration model of the main drive system in rolling mill under electromagnetic excitation was established by means of Lagrange-Maxwell equation. The periodic solutions of the strongly nonlinear torsional vibration system were obtained by using the incremental harmonic balance (IHB) method. The stability of the periodic solutions was examined according to the Floquet theory. The dynamic bifurcation behavior of the system with excitation amplitude was studied. It was found that the system displayed different vibration states such as periodic motion, period-doubling motion and chaos, etc. after changing excitation amplitude. The changes of excitation amplitude influenced the motion state of the system, which supplied theoretical bases for optimal control of vibration in rolling mill.