THERMALLY-INDUCED VIBRATIONS OF A SPINNING SPACECRAFT BOOM

An analytical study of thermally-induced motions is presented for a beam model of an axial boom of a spin-stabilized spacecraft. The study includes: (1) an uncoupled thermal-structural analysis which assumes that the temperature distribution is independent of the deflections of the boom and (2) a coupled thermal-structural analysis which includes the dependence of the incident heat flux and temperature distribution on the boom's deflected position. In the uncoupled analysis, a steady-state thermal response is determined. The resulting temperature gradient causes stable bending motions which are determined by modal expansion. The coupled analysis assumes a deflected shape and determines governing equations for an approximate response. The stability of the coupled response is studied using Floquet theory. The results show that unstable thermally-induced vibrations are possible for parameters characteristic of a typical spacecraft's axial boom.