Numerical investigation of the structural behaviour of a deployable Tensairity beam

This paper investigates numerically the load bearing behaviour of a deployable Tensairity beam. More precise, it studies the influence of the cables that connect the upper and lower strut of the deployable Tensairity beam on its load bearing behaviour. Finite element analysis shows that these cables are pretensioned when the airbeam is inflated. When both diagonal and vertical cables are present, only the vertical cables become tensioned. These tensioned cables are able to take compressive forces, by the same amount as their initial pretension. This has as result that these cables avoid the hinges to deflect under compression. Or in other words, the pretensioned cables `block' the hinges. Once the external load has reached the value whereby the value of the pretension becomes zero in at least one cable, the hinge is not blocked or supported anymore by this cable. The hinge will experience larger displacements and the stiffness of the deployable Tensairity beam decreases.