NITINOL-reinforced plates: Part II. Static and buckling characteristics

The static and buckling characteristics of flexible fiberglass NITINOL-reinforced composite plates are controlled by activating optimal sets of NITINOL fibers embedded along the midplane of these plates. The NITINOL fibers are pre-tensioned and activated to generate significant phase recovery forces in order to increase the membrane strain energy which in turn increases the critical buckling load of the NITINOL-reinforced plates. With such control capabilites, the plates can be manufactured from light weight sections without compromising their elastic stability. This feature is invaluable in building light weight structures that have high resistance to failure due to buckling. The NITINOL fibers are trained to memorize the shape of the unbuckled plate and when the plate is deflected under the action of external compressive loads, the controller activates the NITINOL fibers by heating them above their transformation temperature. The generated phase recovery forces bring the plate back to its memorized undeflected position. A finite element model of NITINOL-reinforced plates is developed to describe the interaction between the external loads, operating conditions and the geometrical and physical parameters of the composite plate and the NITINOL fibers. This model predicts the critical buckling loads of NITINOL-reinforced plates. The predicted loads are compared with results available in the literature for symmetrically isotropic, orthotropic and anisotropic laminates. The mathematical model described in this paper provides an invaluable means of predicting realistic performance of NITINOL-reinforced composites.