RESONANT VIBRATIONS OF NONLINEAR ROTORS

In this paper the primary resonance of a non-linear rotor system under the influence of monofrequency excitation is studied. The nonlinearit y is caused by non-linear elastic material properties. The rotor syste m is a two-degree-freedom system described by a differential equation with complex deflection function. An averaging method for obtaining th e amplitude and phase variation in time is developed. It is based on t he method of slow varying amplitude and phase developed for one-degree -of-freedom system. The steady state solution is also considered. The method is applied for a rotor with small damping, nonlinearity and exc itation function. The transient and steady state motion of the system are analyzed for various values of parameters. An experiment is carrie d out with shafts made of different materials. The analytical solution s are proved experimentally.