A New Concept for Large Deployable Space Frames

Abstract

This paper proposes a new concept for space frames that can be automatically deployed and regidified. Two functionally separate types of sub-structures are considered: active sub-structures, able to deploy automatically and to retain their stiffness when fully deployed, and passive sub-structures, structural mechanisms that become stiff in the deployed state, and whose deployment kinematics match those of the active sub-structures. A design methodology for space frames based on the new concept is presented and illustrated by an example, a square plate-like space frame that can be deployed by a single motor. In this example both types of sub-structures consist of bars, connected together by simple pin-joints, and cable elements. Most cables go slack when the space frame is folded, but become taut when it is fully deployed. A state of self-stress is set up in the deployed state, thus imposing a state of pretension onto all cables.