In two recent papers (Adhikari and Woodhouse 2001 Journal of Sound and <ibration 243, 43}61; 63}88), methods were proposed to identify viscous and non-viscous damping models for vibrating systems using measured complex frequencies and mode shapes. In many cases, the identi"ed damping matrix becomes asymmetric, a non-physical result. Methods are presented here to identify damping models which pr...

It is shown that among the various damping mechanisms that are generally encountered in a mechanical structure, only the “viscous component” actually accounts for energy loss. The remaining portion of the damping force is due to non-linearities, which do not dissipate energy. Consequently, a linear model of a vibratory mechanical system involves only viscous damping, although the damping factor...

This study makes use of an energy balance to identify damping parameters in mechanical vibration systems. By balancing the energy input as registered in the force-displacement relationship of the real system against the energy lost theoretically in a damping model with unknown parameters, the identification algorithms are developed. We apply the estimation equations to both numerical and experi...

A technique to identifY damping parameters directly from the frequency response functions (FRF) in matrix forms has been developed. Furtl1ermore, the technique identifies the viscous damping and structural damping coefficients separately. The technique provides more accurate damping values because it does not rely on the information of the natural modes as in the conventional method. The dampin...

An equine fetlock joint pendulum test was studied and the influence of post mortem time and intra-articular lipid solvent on the viscous frictional response examined. Fresh equine digits (group 1, n=6 controls; group 2, n=6 lipid solvent) were mounted on a pendulum tribometer. Assuming that pendular joint damping could be modelled by a harmonic oscillator fluid damping (HOFD), damping time (τ),...

Linear dynamics of Euler-Bernoulli beams with non-viscous non-local damping is considered. It is assumed that the damping force at a given point in the beam depends on the past history of velocities at different points via convolution integrals over exponentially decaying kernel functions. Conventional viscous and viscoelastic damping models can be obtained as special cases of this general damp...

Microtubules, which are thought to be the primary organizers of the cytoskeleton, are electrical polar structures with extraordinary elastic deformability at low stress and with energy supply from hydrolysis of guanosine triphosphate (GTP) to guanosine diphosphate (GDP). At least a part of the energy supplied from hydrolysis can excite vibrations. Energy is mainly lost by viscous damping of the...

The purpose of this study was to determine viscous properties of human muscle during plantarflexion efforts. Experiments were performed on 17 subjects with an ankle ergometer allowing sinusoidal oscillations during isometric contractions and isokinetic movements. Sinusoidal oscillations led to the expression of (i) Bode diagrams of the musculo-articular system allowing the determination of a da...

The development and applications of a supplemental viscous damping device with active capacity are described. The system of the dampers de ned as active viscous damping system (AVDS) is presented herein. Structural control principles de ned here as active control theory (ACT) are used to obtain the control forces at each time step during an excitation. Control of the damping forces is possible ...