ABSTRACT
This paper presents a novel joint design for use in form-changing structural frames. These structures are comprised of multiple struts, arranged in a geometrically stable array, connected at their end points via the joints. Each strut, acting as part of a truss, can change in length (telescope), and thus their combined variations can change the overall form of the frame. The joints enable multiple struts to be connected together and pivot around each node point. The joints have near-perfect concentricity of rotation around the node point, which enables the tension and compression forces of the struts to be resolved in a structurally-efficient manner. The design evolved from an analysis of simple, pure-tension net structures, combined with aspects of rigid space frame structures, to resist compressive forces. Existing joint configurations are analyzed and compared to the novel joint. Several applications of form-changing structural frames are noted, to demonstrate the advantages of using such joint connectors in these frames; one is a variable-geometry mount for a surgical device, for Imperial College London.
