Reduced-Order Modeling and Parameterized Optimization of Bio-Inspired Adaptive Structures

Any aircraft wing design configuration is primarily intended to maximize performance during the predominant flight condition (e.g., cruise in transport aircraft) while control surfaces (e.g., flap and slats) permit necessary wing reconfigurations to transition between phases of flight. Control surfaces lead to higher performance during required maneuvers but are not without drawbacks. Due to their structural and mechanical complexity, they occupy volume inside the wing, which might displace valuable fuel storage and add weight. Due to the use of discontinuous surfaces, extra drag and acoustic noise are also generated for all flight conditions. These disadvantages motivate using alternative adaptive technologies, such as conformal wing morphing, that do not introduce discontinuities to the flow. Adaptive components (e.g., shape memory alloy and piezoelectric actuators) are a key to bioinspired locomotion, but there are unknowns regarding engineering and operational aspects (e.g., how to utilize, control, and design). The operation of a shape memory alloy (SMA) component is first explored for bi-pedal locomotion to demonstrate it operates as an artificial muscle, functioning as an actuator, a brake, or a spring. The following study shows the controllability, robustness, and scalability of an SMA-based morphing wing. Further considerations in how to design involve how to represent the morphed geometry, and new parameterization methods are developed to represent the aircraft topology. Current state-of-the-art methods in this field generally consider only one adaptive technology or do not consider structural restrictions (e.g., the necessary rigid spars and ribs) during the design process. It is proposed herein that a universal tool based on kinematic equations can be used to model morphing structures independent of the actuator technology used. An intuitive parameterization method is proposed that considers kinematic constraints to efficiently generate structurally consistent (i.e., all internal structural constraints are satisfied) morphed configurations with a limited number of design variables. The structurally consistent parameterization method is further implemented to optimize subsonic morphing wings using low-fidelity fluid solvers. Small changes to the wing outer mold line can result in significant noise reduction and drag loss; thus, a method to accurately and efficiently describe the deformed aircraft geometry is developed that allows universal parameterization, including topological representations developed in this work