Bio-Inspired Morphing Aircraft Mechanisms And Applications On Soaring Bat Wing Aerodynamics
Recent advances in smart materials have allowed for the design of low-profile actuators suitable for use in aerospace structures. In conjunction with these innovations, aerodynamic modeling tools have afforded designers new insights into the advantages of changing a platform's geometry while in flight, in order to better adjust aerodynamics to meet instantaneous mission requirements. This type of gross adaptation, known as morphing, forms the basis for the research presented in this dissertation. Sources of inspiration for new airframe designs come from biological examples such as bird and bat wing planforms. The first chapter of this dissertation focuses on the development, modeling, and fabrication of a morphing wing mechanism inspired by shore bird morphology. In this work, wing morphing using shape memory alloy actuators is achieved, and aerodynamic performance is tested experimentally. The actuator used in this work is designed for a finite number of energetically inefficient cycles, and is intended to prove out the concept of employing smart materials to effect gross shape change. The next chapter examines the advantages of bat wing morphology across various species and planforms. A study on bat wing aerodynamics suitable for use in manmade structures takes advantage of heuristic optimization to illustrate that through morphing, significant enhancements in lift and lift-to-drag ratio can be achieved. The final three chapters of this work focus on the development of an actuator system suited to integration onto the aforementioned morphing platforms, incorporating a passive rigidity in order to reduce energy loss during and after wing morphing. The third chapter presents a preliminary model on the active rigidity joint, outlining basic principles of operation, key materials, and correlation with finite element results in predicting deflection behavior. The fourth chapter expands this model, allowing for more accurate prediction of joint behavior under loading and with arbitrary geometry. It also employs heuristic optimization to develop a thorough understanding of expected joint performance over all geometric configurations. The fifth and final chapter describes joint fabrication and experimental results, showing agreement with the analytical model of chapter four under particular conditions.
dissertation or thesis