Analysis of the deployment of a frame and a foldable membrane: the integrated model of a Contex-T demonstrator

The paper presents a system, made out of a foldable 'kinked' beam structure and a membrane skin, based on a concept referring to origami. The following research question is considered: can the foldable system be stable in intermediate configurations? To investigate this, several numerical models have been made. Finally, a dome-like demonstrator has been designed for which an integrated numerical model has been analysed. The membrane - which is only attached in the nodes of the frame - is represented by a cable net, the frame by 'kinked' beams and bar-elements. One quarter of the system remains fixed, the remaining part can be folded while the nodes at ground level continuously remain at level 0.
For the skin a silicon coated polyester fabric has been chosen. It is modelled as an assembly of flat triangles, tensioned into the frame by belts. The anticlastic curvature is obtained by transforming the flat quadrangular meshes into space. To obtain a well- tensioned membrane in the intermediate positions, the belts connecting the membrane to the frame can be released or increased in tension. This can be simulated by setting the force densities.
Since the membrane has been modelled as a cable net, without shear stiffness, the obtained numerical results are approximate. A real size demonstrator will be built to measure the tensions and evaluate the transformations, thereby assessing the feasibility of the concept.