Recent advances in actuation technology and multifunctional materials have presented a unique opportunity to develop structures that have the ability to morph to a variety of shapes while under significant load constraints. One of the many applications of these “high-authority” systems is for morphing air wings for control and drag reduction. The exciting solution to this is the creation of a statically determinate structure that incorporates linear actuators to produce morphing capabilities. Statically determinate structures satisfy Maxwell’s necessary condition that the number of member forces equal the number of joint equilibrium equations. By imposing this condition on the structure it is possible to actively change the shape of the overall structure without resulting in failure. In a morphing foil, the only induced strain within passive members will be due to the hydrodynamic forces present. Deformation of the truss members is stretch-dominated—they do not experience bending—and thus improve the load carrying capacity of the structure. Of primary interest are Shape Memory Alloy (SMAs) actuators. SMAs are useful for shape morphing concepts where large forces are needed. A prototypical foil has been built around a statically determinate structure that incorporates linear actuators to produce morphing capabilities. These “smart” foils have been tested in a wind tunnel to examine their drag reduction capabilities.

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