Rapidly-deployable lightweight structures have found application in areas spanning e.g. construction, nautics and disaster relief - nowadays you can even get inflatable movie screens. However, these structures are typically either inflatable with poor mechanical properties, or formed of pre-shaped portions of lightweight material meaning they already take up a significant amount of space. This can be a limitation when transporting or storing such items before deployment.
What it does
We have found a way of improving the mechanical properties of inflatable structures, whilst keeping them compact and cheap to produce, by reinforcing them with a stiff foam. We’ve additionally developed a modular design that allows us to link different components together to inflate an entire frame in one go (see Fig. 1).
How it works
Our approach (as depicted in Fig. 2) works by firstly inflating an inner tube, causing the erection of the structure from its initially collapsed state. Following the inflation an outer layer is injected with a fluid that expands and sets into a load-bearing foam. Once the foam is “set”, the structure is capable of bearing much greater loads than a simple inflatable structure. It is possible to further tune the structure’s weight and mechanical properties by varying the density of the foam and the volume it occupies within the wall.
Fig. 1: An example of deployment of a frame that can be constructed by connecting a series of inflatable pieces, showing: the pre-packed state (left), the intermediate inflation states (centre) and fully assembled structure (right).
Fig. 2: Schematic of an inflatable-rigidizable tube. Air can be pumped into the inflatable bladder (48), causing the structure to erect. The structure can then be rigidized by pumping a rigidizing fluid through the inlets (32) into the gap between the inner (64) and outer (22) walls.