Design and deformation analysis of an inflatable metallic cylinder based on the Kresling origami pattern

Inflatable space capsules can be compactly folded to a small volume during launch and then deployed in space to create a large enclosed place for astronauts and equipment. Current inflatable space capsules are usually made of soft composite materials and need to be rigidized after deployment, but the rigidization techniques to date cannot meet the requirements of high stiffness and low thermal expansion simultaneously. The study on cylindrical transformable volume structures based on metals is also limited due to the large in-plane deformation during manufacturing and deployment. Here, we propose a novel inflatable metallic cylinder based on the Kresling origami pattern which has a large deployment ratio and high stiffness without rigidization. The folding and deployment process of the cylinder with varying geometric parameters and inflation rates are investigated through numerical simulation that is validated by experiments, from which the deformation process, maximum plastic strain, and the deployment ratio are unveiled. The results show that the maximum plastic strain reduces with the increase in the total number of creases in the cylinder and their transition arc radius, but a large number of creases will lead to a lower deployment ratio. To achieve a deployment ratio of 3.35 which is comparable with those of the state-of-the-art inflatable space capsules, the maximum plastic strain is kept below 0.18. This proposed metallic origami cylinder thus shows great potentials in the application of space capsules.