Passive adaptive structures

1. An airfoil structural insert comprising:

an airfoil structural insert frame;

a skin surface disposed about the airfoil structural insert frame;

at least one attachment component configured to facilitate coupling to an aerodynamic structure;

a leading edge disposed on one end of the airfoil structural insert frame;

a trailing edge disposed on an opposite end of the airfoil structural insert frame; and

at least one structural element configured to support the skin surface, wherein the structural element comprises a buckling member within said structural element, the buckling member being selected from the group consisting of a polymer, fiber reinforced polymer composite, engineered plastic, and metal,

wherein said structural element undergoes at least one nonlinear shape change from a first shape to a deflected shape.

2. The airfoil structural insert of claim 1 wherein said nonlinear shape change to said deflected shape occurs at a first predetermined amount of said external stimulus, and said return to said first shape occurs at a second predetermined amount of said external stimulus.

3. The airfoil structural insert of claim 2 wherein said second predetermined amount of said external stimulus is less than said first predetermined amount of said external stimulus.

4. The airfoil structural insert of claim 1 wherein said nonlinear shape change is a stepwise shape change.

5. The airfoil structural insert of claim 1 wherein said external stimulus is a wind gust, sustained high wind speed, sustained high relative air velocity, or turbulence.

6. The airfoil structural insert of claim 1 wherein said nonlinear shape change to said deflected shape mitigates a change in an aerodynamic load created by said external stimulus on said first shape.

7. The airfoil structural insert of claim 1 wherein there is a stopping member capable of limiting said nonlinear shape change.

8. The airfoil structural insert of claim 7 wherein said stopping member limits said nonlinear shape change to said deflected shape.

9. The airfoil structural insert of claim 1 wherein said skin surface remains smooth and continuous.

10. The airfoil structural insert of claim 9 wherein said skin surface is a pre-strained deformable composite.

11. The airfoil structural insert of claim 9 wherein said skin surface is seamless.

12. The method of claim 1 wherein said airfoil structural insert is installable on a wind turbine blade, aircraft wing, or helicopter rotor.