Deployment sequence of a deployable arch.
Dr Zhong You, Dr Yan Chen, Mr Nicholas Coe, Dr Kaori Kuribayashi, Dr Claire Hillery, Dr Davide De Focatiis and Dr Yaozi Luo.
University of Oxford.
Many natural and man-made structures can change shape whilst retaining function. Insect wings that unfold for flight or umbrellas that fold down for storage are such examples. Similar types of structures that can pack down and then expand automatically at the time of operation are essential for applications such as satellite communications and other space systems. A more everyday example would be a garden trellis. Known as deployable structures, these creations retain the function of a conventional object whilst undergoing large geometric transformations.
Deployable structures used in space systems need to expand automatically in the harsh space environment after several months of pre-flight storage, and during launch they must withstand high accelerations and vibration levels. Failures are expensive and difficult to rectify but they do happen. For example, both the Galileo Space Probe and the Hubble Space Telescope have experienced these types of failure. Zhong You, an expert in deployable structures at the University of Oxford is working on making such structures more reliable.
Zhong is attempting to simplify the construction of deployable structures using basic joints and inexpensive manufacturing. His work is primarily theoretical, and his exhibit focuses on three types of structure: three- dimensional structures based on a linking mechanism known as the Bennett linkage; two-dimensional foldable structures; and tubular structures constructed from polygons (squares or hexagons) that are folded using origami techniques.
'It is almost a century ago that Bennett, a Fellow of the Royal Society and a Cambridge lecturer, published a paper on a new linkage that was later named after him', explains Zhong. 'Until now no application for the linkage has been found'. However, earlier this year Zhong published a paper in a Royal Society journal that presented a method for using Bennett Linkages to build structures that expand to make cylindrical shapes. The structures are scaleable (ie functional at a range of sizes) allowing unlimited extension of the object by repetition of a particular geometric shape and structure. Mobile masts for space systems are a possible application of these constructions.