• Smart Structures and Systems
• /
• 제10권1호
• /
• pp.67-87
• /
• 2012

A dragonfly inspired flapping wing is investigated in this paper. The flapping wing is actuated from the root by a PZT-5H and PZN-7%PT single crystal unimorph in the piezofan configuration. The non-linear governing equations of motion of the smart flapping wing are obtained using the Hamilton's principle. These equations are then discretized using the Galerkin method and solved using the method of multiple scales. Dynamic characteristics of smart flapping wings having the same size as the actual wings of three different dragonfly species Aeshna Multicolor, Anax Parthenope Julius and Sympetrum Frequens are analyzed using numerical simulations. An unsteady aerodynamic model is used to obtain the aerodynamic forces. Finally, a comparative study of performances of three piezoelectrically actuated flapping wings is performed. The numerical results in this paper show that use of PZN-7%PT single crystal piezoceramic can lead to considerable amount of wing weight reduction and increase of lift and thrust force compared to PZT-5H material. It is also shown that dragonfly inspired smart flapping wings actuated by single crystal piezoceramic are a viable contender for insect scale flapping wing micro air vehicles.

• 항공우주기술
• /
• 제7권2호
• /
• pp.205-212
• /
• 2008

본 논문에서는 스마트무인기 로터시스템의 공진, 로터 공탄성 안정성 및 휠플러터 안정성 해석을 위한 모델링 데이터와 최종 해석결과를 기술하였다 향후 날개구조 설계변경 가능성을 고려하여 날개 빔, 코드 및 비틀림 강성이 훨플러터 안정성에 미치는 영향이 분석되었다. 파라메트릭 분석 결과 날개의 비틀림 강성 및 빔강성의 변화가 코드방향 강성에 비하여 빔모드 댐핑값에 훨씬 큰 영향을 미치는 것으로 분석되었다. 최종 설계된 로터시스템은 공진가능성이 없고, 스마트무인기 TR-S4 로터/파일론/날개에 대하여 로터 공탄성 안정성 및 훨플러터 안정성이 보장됨을 해석적으로 확인하였다.

• 한국전산유체공학회:학술대회논문집
• /
• 한국전산유체공학회 2004년도 춘계 학술대회논문집
• /
• pp.27-34
• /
• 2004

In the Smart UAV Development Program, one of the 21c Frontier R&D Program, the tiltrotor has been studied as the concept of vehicle. The tiltrortor aircraft take-off and land in rotary wing mode like conventional helicopter, and cruise in fixed wing mode like conventional propeller airplane. For the conversion of the flight mode from helicopter to airplane, the nacelle located at wing tip has to be tilted from about 90 degrees of helicopter mode to about 0 degree of airplane mode. In this study, the aerodynamic characteristics of the wing with tilted nacelle is investigated using computation fluid dynamics technique. In order to feature out aerodynamic interferences between wing and nacelle, the flow calculations are conducted for the wing and the nacelle separately and for the combined geometry of wing and nacelle, respectively. Through this computations, not only the aerodynamic data-base for the wing-nacelle is constructed but also its contribution to the configuration design of the wing-nacelle is anticipated.

• Smart Structures and Systems
• /
• 제6권7호
• /
• pp.867-887
• /
• 2010

An energy-based variational approach is used for structural dynamic modeling of the IPMC (Ionic Polymer Metal Composites) flapping wing. Dynamic characteristics of the wing are analyzed using numerical simulations. Starting with the initial design, critical parameters which have influence on the performance of the wing are identified through parametric studies. An optimization study is performed to obtain improved flapping actuation of the IPMC wing. It is shown that the optimization algorithm leads to a flapping wing with dimensions similar to the dragonfly Aeshna Multicolor wing. An unsteady aerodynamic model based on modified strip theory is used to obtain the aerodynamic forces. It is found that the IPMC wing generates sufficient lift to support its own weight and carry a small payload. It is therefore a potential candidate for flapping wing of micro air vehicles.

• Smart Structures and Systems
• /
• 제3권1호
• /
• pp.89-114
• /
• 2007

Two aspects of the design of a small-scale smart wing are addressed in this work, related to the ability of the wing to modify its cross section assuming the shape of two different airfoils and to the possibility of deflecting the profiles near the trailing edge in order to obtain hingeless control surfaces. The actuation is provided by one-way shape memory alloy wires eventually coupled to springs, Shape Memory Alloys (SMAs) being among the most promising materials for this kind of applications. The points to be actuated along the profiles and the displacements to be imposed are selecetd so that they satisfactorily approximate the change from an airfoil to the other and to result in an adequate deflection of the control surface; the actuators and their performances are designed so that an adequate wing stiffness is guaranteed, in order to prevent excessive deformations and undesired airfoil shape variations due to aerodynamic loads. The effect of the pressure distributions, calculated by way of the XFOIL software, and of the actuators loads, is estimated by FE analyses of the loaded wing. Two prototypes are then realised incorporating the variable airfoil and the hingeless aileron features respectively, and the verification of their shapes in both the actuated and non-actuated states, supported by image analysis techniques, confirms that interesting results are achievable with the proposed lay out and design considerations.

• 한국복합재료학회:학술대회논문집
• /
• 한국복합재료학회 2005년도 춘계학술발표대회 논문집
• /
• pp.9-12
• /
• 2005

Recently, research on the morphing wing is an interesting issue to develop the capability of the wing such as improving the lift and reduction of drag during the operation of an aircraft by changing the wing shape from one configuration to another. A more efficient weight reduction of the wing using smart or morphing wing concept can be achieved in comparison with the conventional flaps. In this study, it is investigated the behaviors of the morphing wing using Macro Fiber Composite (MFC) actuators. Generally, MFC is the piezocomposite actuator with the rectangular PZT fiber and epoxy matrix, and uses the interdigitated electrode to produce more powerful actuation in the in-plane direction. Furthermore, it can produce the twisting actuation as compared with the traditional PZT actuators. In the formulation, the first-order shear deformation plate theory is used, and finite element method is adopted in the numerical analysis of the model. Results show the characteristics of the static behavior of the morphing wing according to the change of the actuation voltage.

• 한국추진공학회지
• /
• 제7권3호
• /
• pp.38-44
• /
• 2003

본 연구에서는 회전익 상태에서 이/착륙, 저속 전진비행을 하고, 고정익 상태에서 고속 전진비행을 하는 스마트 무인기 추진시스템을 모델링하고 회전익 모드, 고정익 상태의 고속 비행모드, 팁 제트 노즐과 주 엔진 노즐을 모두 이용하는 혼합모드에 대해 정상상태 성능해석을 수행하였다. 성능해석 결과는 각 비행모드에서 덕트의 손실로 인한 추진 시스템의 운용영역이 제한되는 결과를 보였으며, 비행 마하수 변화에 대한 결과와 비교해 고도의 변화에 대한 해석결과가 더 넓은 영역에서 비행영역을 제한함을 알 수 있었다.

• 한국추진공학회:학술대회논문집
• /
• 한국추진공학회 2003년도 제20회 춘계학술대회 논문집
• /
• pp.177-182
• /
• 2003

본 연구에서는 회전익 상태에서 이/착륙, 저속 전진비행을 하고, 고정익 상태에서 고속 전진비행을 하는 스마트 무인기 추진시스템을 모델링하고 회전익 모드, 고정익 상태의 고속 비행모드, 팁 제트 노즐과 주 엔진 노즐을 모두 이용하는 혼합모드에 대해 정상상태 성능해석을 수행하였다. 성능해석 결과는 각 비행모드에서 덕트의 손실로 인한 추진 시스템의 운용영역이 제한되는 결과를 보였으며, 비행 마하수 변화에 대한 결과와 비교해 고도의 변화에 대한 해석결과가 더 넓은 영역에서 비행영역을 제한함을 알 수 있었다.

• Smart Structures and Systems
• /
• 제14권4호
• /
• pp.659-678
• /
• 2014

The study is aimed at investigating the feasibility of a high TRL solution for a wing flap segment characterized by morphable camber airfoil and properly tailored to be implemented on a real-scale regional transportation aircraft. On the base of specific aerodynamic requirements in terms of target airfoil shapes and related external loads, the structural layout of the device was preliminarily defined. Advanced FE analyses were then carried out in order to properly size the load-carrying structure and the embedded actuation system. A full scale limited span prototype was finally manufactured and tested to: ${\bullet}$ demonstrate the morphing capability of the conceived structural layout; ${\bullet}$ demonstrate the capability of the morphing structure to withstand static loads representative of the limit aerodynamic pressures expected in service; ${\bullet}$ characterize the dynamic behavior of the morphing structure through the identification of the most significant normal modes. Obtained results showed high correlation levels with respect to numerical expectations thus proving the compliance of the device with the design requirements as well as the goodness of modeling approaches implemented during the design phase.

• 한국항공우주학회지
• /
• 제35권5호
• /
• pp.390-396
• /
• 2007

본 연구에서는 새의 날개운동을 모사하기 위하여 스마트 재료를 이용한 플래핑 날개를 설계 및 제작하였다. 날개는 복합재료 프레임과 유연한 PVC 표피 그리고 표면 작동기로 구성되어 있으며, 주요 날개운동으로서 날갯짓, 비틀림 그리고 캠버 운동을 선정하였다. 날개의 캠버를 변화시키기 위하여 Macro-Fiber Composite를 표면작동기로서 적용하였으며, 압전-열 관계식을 이용하여 MFC의 구조 응답을 해석하였다. 양력과 추력을 동시에 측정하기 위하여 두개의 로드셀로 구성된 시험대를 제작하였으며, 공기역학적 특성을 평가하기 위하여 풍동실험을 수행하였다. 실험결과로부터 주요 양력은 기체의 전진속도와 피치각에 의존되며, 추력은 날갯짓 주파수에 의존됨을 확인하였다. 또한 MFC 작동기를 이용한 캠버효과를 통하여 정적조건에서 24.4%와 동적조건에서 20.8%의 충분한 양력증가를 확인할 수 있었다.