Large-angle articulated beam truss design methodology considering offset joint modeling

Abstract

Adaptive space structures (deployable trusses, large space antennas) can use actuated members to vary their geometry. In particular, variable geometry trusses can use the same set of actuators for both deployment and subsequent articulation. Such articulating trusses can be applied in space crane orbital construction applications. Previous structural analyses have used idealized truss models; members connect at a point at each node. Further analysis of practical truss models in articulated geometries will show the difference in structural behavior compared to ideal trusses and the need to include realistic geometric modeling, such as including the hinge offsets to give the correct packaged truss geometry. An analytic example truss verifies the finite element modeling technique used. Stiffness sensitivity trends for a range of articulated geometries reveal two causes of stiffness reduction: decreased truss effective bending inertia because of shortened actuators and batten bending caused by asymmetric geometry and hinge offsets. The analyses lead to a structural design methodology, including an initially curved geometry, to alleviate the stiffness reduction for improved structural performance. The initially curved articulating truss allows the location of maximum stiffness to be designed and provides compact packaging, self-deployment, and geometric articulation. c d[ E F