Experimental studies on the non-linear oscillations of imperfect circular disks spinning near critical speed

Experiments on the non-linear oscillations of a spinning steel plate near c ritical speed are presented. Of particular interest are the effects of impe rfection induced by point masses bolted to the plate. The tests are carried out at very low ambient pressures in a vacuum chamber to minimize the effe cts of aerodynamically induced vibration. Six different cases of asymmetry are tested and the experiments confirm most theoretically predicted results of Raman and Mote (Int. J. Non-Linear Mech. 36 (2001) 261-289). These incl ude the existence of multiple steady solution branches; the onset of pseudo -standing waves and their loss of stability leading to slowly modulated tra velling wave responses; creation of isolas of solution branches; and decoup ling of the internally resonant modes at high asymmetry leading to the redu ction of travelling wave amplitudes at high asymmetry. Additional features observed include resonant mode-jumping at super-critical speed and the pres ence of superposed slow motion on resonant solution branches. (C) 2000 Else vier Science Ltd. All rights reserved.