G101014 Identification of Damping Ratios Controlled by an Electromagnetic Damper Installed in a Vibration Apparatus

Abstract

A way of identifying varying damping ratios C, in the liner vibration theory of a single-degree-of-freedom system is studied. Free vibration tests on the damped single-DOF system are conducted using a commercial vibration apparatus. The magnitudes of a damping force are controlled contactlessly by an electromagnetic damper installed in the apparatus, and the corresponding damping ratios are identified using theoretical formulas and a numerical technique. It is shown that the damping ratio can be expressed as a cubic function of a damping current. A relation between the damping ratio and the magnetic flux density is discussed.