Research On Cellular Flexible Skin For Morphing Wing

Flexible skin is one of the most important components of the morphing aircraft, which plays a great role in the change of the aerodynamic performance of the aircraft. Recently, a lot of new materials and technologies have been utilized to develop and fabricate new flexible skins, such as SMP skin, corrugated composite skin, flexible matrix composite skin and cellular structure integrated skin, etc. Cellular structure integrated skin as the most promising solution attracts the attention of many researchers and engineers, and a large amount of research results have also been achieved. However, there are still lots of problems that need to be solved. Three aspects are mainly studied from the in-plane mechanical properties of integrated skins, the relation between the mechanical properties of the integrated skin and its components, and the design of the actuator for the skin.The main research works and results of this thesis are as follows:(1) The expressions of the in-plane mechanical properties of different cellular structures were derived, which were verified numerically to determine the most suitable cell structure for two-dimensional morphing. Moreover, the geometric and material nonlinearity effects on the in-plane mechanical properties of the cell structures were also discussed. Finally, the in-plane mechanical properites of different cellular structures were experimentally determined to further testify the theoretical expressions in this thesis.(2) The material constants of a silicone rubber face sheet in its constitutive relation were experimentally tested and its in-plane extension behaviour was simulated under different boundary conditions. Then the two-dimensional morphing performance of integrated skin was numerically validated as well as the influence of one-side or two-side face sheet on the mechanical properties of integrated skin. Additionally, a composite cellular structure from glass and carbon fibres was fabricated, and its merits and demerits over aluminium cellular structure were discussed.(3) A SMA based antagonistic flexible actuator was designed and experimentally testified. Repeated span morphing of the flexible skin was finally realized with this actuation system.