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From:
http://www-g.eng.cam.ac.uk/advancedstructures/research.html
The anonymous website composer in 2013 writes:
Surface Texture Through Buckling
"Generating a surface texture in a shell can improve how the shell or structure interacts with the world around it. In the example below, a simple model of an airfoil section has a thin membrane wrapped around a solid core. The membrane is marginally wider than the core, and the wooden endplates can be moved axially in a controlled manner by turning the nuts. In one state, the surface is completely smooth; in the other [next slide], the endplates are compressing the membrane, which has clearly buckled [next slide]. However, the core restricts both local buckling and the out-of-plane movement to such a degree that a regular buckle/wrinkle pattern forms over the entirety of the surface: notice how the size of the buckle facets are proportional to the radius of curvature of the section. Present testing of similar specimens in a wind tunnel indicates that switching on the texture, at the correct windspeed, can reduce the drag signficantly - as the dimples do on a golfball. But unlike a golfball, the surface can be switched to smooth again in order to yield better aerodyanmics at a different speeds. Other potential applications include "haptic" electronic displays, where the user experiences a tactile feedback, and building facades with tuneable reflection and absorption characteristics."
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