Optimisation of Composite Corrugated Skins for Buckling in Morphing Aircraft
AD Shaw, I Dayyani & MI Friswell (Swansea University)
Composite Structures, Vol. 119, January 2015, pp. 227-237
Morphing Aircraft aim to increase the performance of aircraft over multiple flight conditions, by enabling them to change shape in flight in order to optimise their aerodynamic properties for the current conditions. There are many approaches to achieve this, but typically the approach is to modify geometric parameters of the wing. Typically, the skin of the morphing aircraft is critical to its success. It must be compliant in degrees of freedom that are required for actuation to allow the required deformation with minimal force, to enable the actuation systems to remain small and lightweight. However, typically it must also carry structural loads, and therefore be sufficiently strong and stiff in load bearing degrees of freedom. This leads to a requirement for extremely anisotropic materials. A common response to this requirement is to use a corrugated panel. However previous work that addresses the use of corrugations in these situations has not addressed the situation where the panel is subjected to compressive loads, and is therefore liable to buckle. This failure mode is a typical design driver for many aircraft structures. This work analyses the performance of corrugated panels under buckling loads, and optimises corrugation patterns for the objectives of weight, buckling performance, and actuation compliance. Simplified analytical models that derive properties equivalent to conventional plates are used to obtain approximate estimates of the buckling loads. Furthermore a new mode of buckling, that occurs entirely in-plane and is unique to panels with extreme anisotropy is demonstrated and analysed. The simple models allow optimisation to be performed, and both a single-objective and a multi-objective approach are demonstrated. The results are compared to Finite Element Analysis.
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Link to paper using doi: 10.1016/j.compstruct.2014.09.001
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