Dynamic Effects of a Radar Panel Mounted on a Truss Satellite

Abstract

Presented here is an approach to find an equivalent continuum model of a radar truss structure with a radar panel mounted to the side. Kinetic and potential energy expressions of repeated truss elements are expanded in terms of the displacement components at its center. Two methods are proposed to account for the kinetic energy of the panel. The first considers the panel as a discrete set of point masses and the second method assumes a solid panel of constant density. Hamilton's principle is used to find the equations of motion for six coordinates of vibration for this structure and the original truss. For the truss-panel assembly, this results in two sets of partial differential equations resembling the extended Timoshenko beam equations. Both Euler-Bernoulli and Timoshenko formulations are derived and a finite element analysis is presented for comparison. The results are shown to be in good agreement with those of a finite element. The model demonstrates a significant change in the dynamic properties as a result of the panel. In particular, the longitudinal and torsional motions become coupled with the bending coordinates.