Bistable Composite Laminates and Morphing Wing: From Stability Characteristics to Morphing Application

Large out-of-plane deformations are developed in unsymmetric composite laminates at room temperature upon being cured flat in an autoclave. Common applications of composites utilize symmetric stacking sequence to avoid unpredicted warping. Meanwhile, bistable characteristics of unsymmetric composite laminates, if utilized, would allow adding more favorable properties beyond their enhanced mechanical properties and elastic coupling. Focusing on the bistable characteristics of unsymmetric cross- ply laminates two tasks are undertaken. First, key geometric parameters controlling bistable behavior are studied, i.e. spatial dimensions, thickness-to- sidelength ratio and planform shape. Second, actuation to trigger snap-though behavior is optimized utilizing piezoelectric actuators. A finite element methodology is developed using Abaqus commercial code and an experimental program is constructed to validate analytically obtained results. Finally, bistable composite laminates are used to propose a morphing wing design of an Uninhabited Aerial Vehicle (UAV). A preliminary aerodynamic analysis of the proposed UAV wing application is conducted.