Damping Models for Shear-Deformable Beam with Applications to Spacecraft Wiring Harness

: Cabling attached to a spacecraft bus structure can represent a significant fraction of the dry mass. While current models can accurately predict vibration frequencies of the coupled system, typical damping models are inadequate. Instead, a viscous damping model that produces approximately frequency-independent modal damping in Euler-Bernoulli and shear beams is considered. The relevant viscous damping terms are extended and modified for application to Timoshenko beams. The inclusion of rotary inertia does add some frequency-dependence; however, careful selection of damping coefficients can produce a large range of approximately frequency-independent modal damping. This effort will extend recent basic research to explore damping models for use with shear-deformable beams, and will begin to address fundamental physical damping mechanisms and potential non-linear dissipative sources in spacecraft cables. The desired outcome is a time domain beam model that represents with physical consistency the damping behavior of wiring harnesses. The emphasis in this project will be on the extension of the shear-beam damping model to the Timoshenko beam, a beam model that includes the effects of rotatory inertia. Including this sometimes-significant effect is likely to change the damping behavior at higher mode numbers.