Piezoelectrics offer high actuation authority and sensing over a wide range of frequencies. A Macro-Fiber Composite is a type of piezoelectric device that offers structural flexibility and high actuation authority. A challenge with piezoelectric actuators is that they require high voltage input; however the low power consumption allows for relatively lightweight electronic components. Another challenge, for piezoelectric actuated aerodynamic surfaces, is found in operating a relatively compliant, thin structure (desirable for piezoceramic actuators) in situations where there are relatively high external (aerodynamic) forces. Establishing an aeroelastic configuration that is stiff enough to prevent flutter and divergence, but compliant enough to allow the range of available motion is the central challenge in developing a piezocomposite airfoil. The research proposed here is to analyze and implement novel electronic circuits and structural concepts that address these two challenges. Here, a detailed theoretical and experimental analysis of the aerodynamic and electromechanical systems that are necessary for a practical implementation of a piezocomposite airfoil is presented. First, the electromechanical response of Macro-Fiber Composite based unimorph and bimorph structures is analyzed. A distributed parameter electromechanical model is presented for interdigitated piezocomposite unimorph actuators. Necessary structural features that result in large electrically induced deformations are identified theoretically and verified experimentally. A novel, lightweight electrical circuitry is proposed and implemented to enable the peak-to-peak actuation of Macro-Fiber Composite bimorph devices with asymmetric voltage range. Next, two novel concepts of supporting the piezoelectric material are proposed to form two types of variable-camber aerodynamic surfaces. The first concept, a simply-supported thin bimorph airfoil, can take advantage of aerodynamic loads to reduce control input moments and increase control effectiveness. The structural boundary conditions of the design are optimized by solving a coupled fluid-structure interaction problem by using a structural finite element method and a panel method based on the potential flow theory for fluids. The second concept is a variable-camber thick airfoil with two cascading bimorphs and a compliant box mechanism. Using the structural and aerodynamic theoretical analysis, both variable-camber airfoil concepts are fabricated and successfully implemented on an experimental ducted-fan vehicle. A custom, fully automated low-speed wind tunnel and a load balance is designed and fabricated for experimental validation. The airfoils are evaluated in the wind tunnel for their two-dimensional lift and drag coefficients at low Reynolds number flow. The effects of piezoelectric hysteresis are identified. In addition to the shape control application, low Reynolds number flow control is examined using the cascading bimorph variable-camber airfoil. Unimorph type actuators are proposed for flow control in two unique concepts. Several electromechanical excitation modes are identified that result in the delay of laminar separation bubble and improvement of lift. Periodic excitation to the flow near the leading edge of the airfoil is used as the flow control method. The effects of amplitude, frequency and spanwise distribution of excitation are determined experimentally using the wind tunnel setup. Finally, the effects of piezoelectric hysteresis nonlinearity are identified for Macro-Fiber Composite bimorphs. The hysteresis is modeled for open-loop response using a phenomenological classical Preisach model. The classical Preisach model is capable of predicting the hysteresis observed in 1) two cantilevered bimorph beams, 2) the simply-supported thin airfoil, and 3) the cascading bimorph thick airfoil. / Ph. D.

Nowadays, the competition among airlines seriously depend upon the saving operating costs, with the premise that not to degrade its services quality. Especially in the face of increasingly scarce oil resources, reducing fleets operational fuel consumption, is an important means to improve profits. Aircraft fuel economy is determined by operational management strategies and application technologies. The application of technologies mainly refers to airplane’s engine performance, Weight efficiency and aerodynamic characteristics. A market competitive aircraft should thoroughly consider to all of these aspects. Transport aircraft aerodynamic performance mainly is determined by wing’s properties. Wings that are optimized for efficient flight in cruise conditions need to be fitted with powerful high-lift devices to meet lift requirements for safe takeoff and landing. These high-lift devices have a significant impact on the total airplane performance. The aerodynamic characteristics of the wing airfoil will have a direct impact on the aerodynamic characteristics of the wing, and the wing’s effective cruise hand high-lift configuration design has a significant impact on the performance of transport aircraft. Therefore, optimizing the design is a necessary airfoil design process. Nowadays engineering analysis relies heavily on computer-based solution algorithms to investigate the performance of an engineering system. Computational fluid dynamics (CFD) is one of the computer-based solution methods which are more widely employed in aerospace engineering. The computational power and time required to carry out the analysis increases as the fidelity of the analysis increases. Aerodynamic shape optimization has become a vital part of aircraft design in the recent years. Since the aerodynamic shape optimization (ASO) process with CFD solution algorithms requires a huge amount of computational power, there is always some reluctance among the aircraft researchers in employing the ASO approach at the initial stages of the aircraft design. In order to alleviate this problem, statistical approximation models are constructed for actual CFD algorithms. The fidelity of these approximation models are merely based on the fidelity of data used to construct these models. Hence it becomes indispensable to spend more computational power in order to convene more data which are further used for constructing the approximation models. The goal of this thesis is to present a design approach for assumed wing airfoils; it includes the design process, multi-objective design optimization based on surrogate modelling. The optimization design stared from a transonic single-element single-objective optimization design, and then high-lift configurations were two low-speed conditions of multi-objective optimization design, on this basis, further completed a variable camber airfoil at low speed to high-lift configuration to improve aerodynamic performance. Through this study, prove a surrogate based model could be used in the wing airfoil optimization design.

The objectives of the research presented in this thesis are the development of a seven degree-of-freedom morphing airplane and the design and integration of a variable camber compliant tail. The morphing airplane was designed and manufactured to study the benefits of large planform changes and flight control morphing. Morphing capabilities of each wing consist of 8 in. wing extension and contraction, 40° of wing sweep and ±20.25° of outboard wing twist in addition to 6 in. of tail extension and contraction. Initial wind-tunnel tests proved that for a large range of lift coefficients, the optimal airplane configuration changes to minimize the drag. Another portion of this research deals with the development of a structural optimization program to design a variable camber compliant tail. The program integrates ANSYS, aerodynamic thin airfoil theory and the Method of Moving Asymptotes to optimize the shape of an airfoil tail for maximum trailing edge deflection. An objective function is formulated to maximize the trailing edge tip deflection subject to stress constraints. The optimal structure needs to be flexible to maximize the tip deflection, but stiff enough to minimize the deflection of the tip due to aerodynamic loading. The results of the structural optimization program created a compliant tail mechanism that can deflect the trailing edge tip with a single actuator ±4.27°. / Master of Science

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Over the last few decades the design of high lift devices has become a very important part of the total aircraft design process. Reviews of the design process are performed on a regular basis, with the intent to improve and optimize the design process. This thesis describes a new and innovative methodology for the design and evaluation of mechanisms for Trailing Edge High-Lift devices. The initial research reviewed existing High-Lift device design methodologies and current flap systems used on existing commercial transport aircraft. This revealed the need for a design methodology that could improve the design process of High-Lift devices, moving away from the conventional "trial and error" design approach, and cover a wider range of design attributes. This new methodology includes the use of the innovative design tool called SYNAMEC. This is a state-of-the-art engineering design tool for the synthesis and optimizations of aeronautical mechanisms. The new multidisciplinary design methodology also looks into issues not usually associated with the initial stages of the design process, such as Maintainability, Reliability, Weight and Cost. The availability of the SYNAMEC design tool and its ability to perform Synthesis and Optimization of mechanisms led to it being used as an important module in the development of the new design methodology. The SYNAMEC tool allows designers to assess more mechanisms in a given time than the traditional design methodologies. A validation of the new methodology was performed and showed that creditable results were achieved. A case study was performed on the ATRA - Advance Transport Regional Aircraft, a Cranfield University design project, to apply the design methodology and select from within a group of viable solutions the most suitable type of mechanism for the Variable Camber Wing concept initially defined for the aircraft. The results show that the most appropriate mechanism type for the ATRA Variable Camber Wing is the Link /Track Mechanism. It also demonstrated how a wide range of design attributes can now be considered at a much earlier stage of the design.

Over the last few decades the design of high lift devices has become a very important part of the total aircraft design process. Reviews of the design process are performed on a regular basis, with the intent to improve and optimize the design process. This thesis describes a new and innovative methodology for the design and evaluation of mechanisms for Trailing Edge High-Lift devices. The initial research reviewed existing High-Lift device design methodologies and current flap systems used on existing commercial transport aircraft. This revealed the need for a design methodology that could improve the design process of High-Lift devices, moving away from the conventional "trial and error" design approach, and cover a wider range of design attributes. This new methodology includes the use of the innovative design tool called SYNAMEC. This is a state-of-the-art engineering design tool for the synthesis and optimizations of aeronautical mechanisms. The new multidisciplinary design methodology also looks into issues not usually associated with the initial stages of the design process, such as Maintainability, Reliability, Weight and Cost. The availability of the SYNAMEC design tool and its ability to perform Synthesis and Optimization of mechanisms led to it being used as an important module in the development of the new design methodology. The SYNAMEC tool allows designers to assess more mechanisms in a given time than the traditional design methodologies. A validation of the new methodology was performed and showed that creditable results were achieved. A case study was performed on the ATRA - Advance Transport Regional Aircraft, a Cranfield University design project, to apply the design methodology and select from within a group of viable solutions the most suitable type of mechanism for the Variable Camber Wing concept initially defined for the aircraft. The results show that the most appropriate mechanism type for the ATRA Variable Camber Wing is the Link /Track Mechanism. It also demonstrated how a wide range of design attributes can now be considered at a much earlier stage of the design.

Os recentes desenvolvimentos na tecnologia de sistema aeronáutico de geometria variável têm sido motivados principalmente pela necessidade de melhorar o desempenho de aeronaves. O conceito de Morphing Aircraft, por meio da variação da linha de arqueamento, representa uma alternativa para sistemas aeronáuticos mais eficientes. No entanto, para aeronaves de alto desempenho, projetos com estes novos conceitos podem gerar reações aeroelásticas adversas, o que representa uma questão importante e pode vir a limitar esses novos projetos. A compreensão adequada do comportamento aeroelástico devido à variação da linha de arqueamento, particularmente em regimes transônico, compreende uma questão importante. Este trabalho consiste num estudo preliminar das consequências aeroelásticas de um sistema aeronáutico de geometria variável. O objetivo desse trabalho é explorar as repostas aeroelásticas transônicas de um aerofólio com arqueamento variável no tempo. A metodologia para análise aeroelástica é baseada num modelo de seção típica. A integração no tempo do sistema aeroelástico é obtida pelo método de Runge-Kutta de quarta ordem. A representação do escoamento transônico não estacionário foi computada por um código CFD em um contexto de malhas não estruturadas com uma formulação dada pelas equações de Euler-2D. Esses resultados preliminares podem fornecer aos projetistas informações importantes sobre as respostas aeroelásticas de um sistema aeronáutico com variação da linha de arqueamento, permitindo estabelecer um quadro adequado para futuras investigações de controle aeroelástico de sistema aeronáutico de geometria variável. / Recent developments on aircraft variable geometry technologies have been mainly motivated by the need for improving the flight performance. The morphing wing concept, by means of variable camber, represents an alternative towards more efficient lifting surfaces. However, for higher performance aircraft, this technology may lead to designs that create unsteady loads, which may result in adverse aeroelastic responses, which represents an important and limiting issue. Proper understanding of the aeroelastic behavior, particularly in transonic flight regimes, due to variations in camber comprises an important matter. This work is a primary study of aeroelastic consequences of an real-time adaptive aircraft. The objective of this work is to investigate prescribed variations to airfoil camberline and their influence to the aeroelastic response in transonic flight regime. The methodology is based on computational simulations of typical section with unsteady transonic aerodynamics solved with a Computational Fluid Dynamics (CFD) code. The time integration of the aeroelastic system is obtained by Runge-Kutta fourth order. The unsteady transonic flow was computed by a CFD code based on the 2D-Euler equations with unstructured mesh. Prescribed camber variation of a symmetrical airfoil is transferred to the CFD mesh, and aeroelastic responses and loading is assessed. These preliminary results may provide the designers valuable information on the interaction between changes in camber during airfoil aeroelastic reactions, allowing establishing an adequate framework for further aeroelastic control investigations of morphing wings.

Os recentes desenvolvimentos na tecnologia de sistema aeronáutico de geometria variável têm sido motivados principalmente pela necessidade de melhorar o desempenho de aeronaves. O conceito de Morphing Aircraft, por meio da variação da linha de arqueamento, representa uma alternativa para sistemas aeronáuticos mais eficientes. No entanto, para aeronaves de alto desempenho, projetos com estes novos conceitos podem gerar reações aeroelásticas adversas, o que representa uma questão importante e pode vir a limitar esses novos projetos. A compreensão adequada do comportamento aeroelástico devido à variação da linha de arqueamento, particularmente em regimes transônico, compreende uma questão importante. Este trabalho consiste num estudo preliminar das consequências aeroelásticas de um sistema aeronáutico de geometria variável. O objetivo desse trabalho é explorar as repostas aeroelásticas transônicas de um aerofólio com arqueamento variável no tempo. A metodologia para análise aeroelástica é baseada num modelo de seção típica. A integração no tempo do sistema aeroelástico é obtida pelo método de Runge-Kutta de quarta ordem. A representação do escoamento transônico não estacionário foi computada por um código CFD em um contexto de malhas não estruturadas com uma formulação dada pelas equações de Euler-2D. Esses resultados preliminares podem fornecer aos projetistas informações importantes sobre as respostas aeroelásticas de um sistema aeronáutico com variação da linha de arqueamento, permitindo estabelecer um quadro adequado para futuras investigações de controle aeroelástico de sistema aeronáutico de geometria variável. / Recent developments on aircraft variable geometry technologies have been mainly motivated by the need for improving the flight performance. The morphing wing concept, by means of variable camber, represents an alternative towards more efficient lifting surfaces. However, for higher performance aircraft, this technology may lead to designs that create unsteady loads, which may result in adverse aeroelastic responses, which represents an important and limiting issue. Proper understanding of the aeroelastic behavior, particularly in transonic flight regimes, due to variations in camber comprises an important matter. This work is a primary study of aeroelastic consequences of an real-time adaptive aircraft. The objective of this work is to investigate prescribed variations to airfoil camberline and their influence to the aeroelastic response in transonic flight regime. The methodology is based on computational simulations of typical section with unsteady transonic aerodynamics solved with a Computational Fluid Dynamics (CFD) code. The time integration of the aeroelastic system is obtained by Runge-Kutta fourth order. The unsteady transonic flow was computed by a CFD code based on the 2D-Euler equations with unstructured mesh. Prescribed camber variation of a symmetrical airfoil is transferred to the CFD mesh, and aeroelastic responses and loading is assessed. These preliminary results may provide the designers valuable information on the interaction between changes in camber during airfoil aeroelastic reactions, allowing establishing an adequate framework for further aeroelastic control investigations of morphing wings.