Slaving the In-Plane Motions of a Nonlinear Plate to Its Flexural Motions: An Invariant Manifold Approach

Abstract

We show that the in-plane motions of a nonlinear isotropic plate can be decoupled from its transverse motions. We demonstrate this decoupling by showing analytically and numerically the existence of a global nonlinear invariant manifold in the phase space of three nonlinearly coupled fundamental oscillators describing the amplitudes of the coupled fundamental modes. The invariant manifold carries a continuum of slow periodic motions. In particular, for any motion on the slow invariant manifold, the transverse oscillator executes a periodic motion and it slaves the in-plane oscillators into periodic motions of half its period. Furthermore, as the energy level of a motion on the slow manifold increases, the frequency of the largest harmonic of the in-plane motion approaches the in-plane natural frequencies.