Energy Transfer From High-to Low-Frequency Modes in a Flexible Structure via Modulation

An experimental study of the response of axially-symmetric (i.e., circular cross section) cantilever beams to planar external excitations is presented. Because of the axial symmetry, one-to-one internal resonances occur at each natural frequency. These resonances cause the planar motions to lose stability and nonplanar (Whirling) motions are observed. Under certain conditions, periodically- and chaotically-modulated motions may occur. In addition, when the beam is excited near one of its high natural frequencies, large first-mode response accompanied by slow modulations of the amplitudes and phases of high-frequency modes are observed