Damping in Coupled Bending and Torsion - An Experiment

Traditional experimental modal testing methods are used to determine the damping properties of an Euler-Bernoulli beam with offset inertial tip mass. Both viscous and strain rate damping models are considered in bending and in torsion. A partial differential equation model of the coupled system is used. Eigenfunctions are derived for the coupled system by using a Green´s function approach to derive the approximate uncoupled eigenfunctions. These eigenfunctions are used in a decoupled fashion with experimental modal data to estimate the damping parameters of the coupled system. The experimental modal data was obtained from both free and impulse responses using a combined translational and rotational accelerometer.