Passive shape control of space antennas with truss support structures

Abstract

Passive control is achieved by modifying the nodal coordinates of the structure such that the modified structure deforms to the original (unmodified) geometry under the given loading. The modified geometry is obtained by changing the coordinates iteratively, by an amount equal and opposite to the deflections that occurred under the given loading. For this purpose, the structural and material properties and the boundary conditions of the truss, and the load data are assumed given. The technique is illustrated in four cases. In Cases I-III a determinate truss is utilized. In Case I, a modified structural geometry and in Case II, a modified surface geometry under single loading condition is sought and achieved. In Case III, a single modified surface geometry, which would satisfy two loading conditions simultaneously, was sought and an average modified geometry was found. In Case IV, an indeterminate truss was investigated under a single loading condition. In all case studies, the convergence to the modified structure was both rapid and monotonic.