• International Journal of Aeronautical and Space Sciences
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• 제11권4호
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• pp.285-302
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• 2010

Active aeroelastic control is an emerging technology aimed at providing solutions to structural systems that under the action of aerodynamic loads are prone to instability and catastrophic failures, and to oscillations that can yield structural failure by fatigue. The purpose of the aeroelastic control among others is to alleviate and even suppress the vibrations appearing in the flight vehicle subcritical flight regimes, to expand its flight envelope by increasing the flutter speed, and to enhance the post-flutter behavior usually characterized by the presence of limit cycle oscillations. Recently adaptive and robust control strategies have demonstrated their superiority to classical feedback strategies. This review paper discusses the latest development on the topic by the authors. First, the available control techniques with focus on adaptive control schemes are reviewed, then the attention is focused on the advanced single-input and multi-input multi-output adaptive feedback control strategies developed for lifting surfaces operating at subsonic and supersonic flight speeds. A number of concepts involving various adaptive control methodologies, as well as results obtained with such controls are presented. Emphasis is placed on theoretical and numerical results obtained with the various control strategies.

• International Journal of Aeronautical and Space Sciences
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• 제13권1호
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• pp.43-57
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• 2012

In a modern aircraft, there are many variations in its mass, stiffness, and aerodynamic characteristics. Recently, an analytical approach was proposed, and this approach uses the idea of uncertainty to find out the most critical flight flutter boundary due to the variations in such aerodynamic characteristics. An analytical method that has been suggested to predict robust stability is the mu method. We previously analyzed the robust flutter boundary by using the mu method, and in that study, aerodynamic variations in the Mach number, atmospheric density, and flight speed were taken into consideration. The authors' previous attempt and the results are currently quoted as varying Mach number mu analysis. In the author's previous method, when the initial flight conditions were located far from the nominal flutter boundary, conservative predictions were obtained. However, relationships among those aerodynamic parameters were not applied. Thus, the varying Mach number mu analysis results required validation. Using an optimization approach, the varying Mach number mu analysis was found out to be capable of capturing a reasonable robust flutter boundary, i.e., with a low percentage difference from boundaries that were obtained by optimization. Regarding the optimization approach, a discrete nominal flutter boundary is to be obtained in advance, and based on that boundary, an interpolated function was established. Thus, the optimization approach required more computational effort for a larger number of uncertainty variables. And, this produced results similar to those from the mu method which had lower computational complexity. Thus, during the estimation of robust aeroelastic stability, the mu method was regarded as more efficient than the optimization method was. The mu method predicts reasonable results when an initial condition is located near the nominal flutter boundary, but it does not consider the relationships that are among the aerodynamic parameters, and its predictions are not very accurate when the initial condition is located far from the nominal flutter boundary. In order to provide predictions that are more accurate, the relationships among the uncertainties should also be included in the mu method.

• 한국항공우주학회지
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• 제43권9호
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• pp.781-786
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• 2015

공력탄성학적 안정성 해석에 있어서 모델링 오차 및 구조 불확도에 의해 결과의 정확도는 떨어질 수 있다. 따라서, 이러한 모델링 오차 및 구조 불확도를 고려한 공탄성 안정성 경계를 예측할 필요가 있다. 이러한 모델링 오차 및 불확도를 고려한 공탄성 안정성 예측을 위해 강건 공탄성 해석이 제안되었다. 본 연구에서는 ${\mu}$ 해석기법과 모달접근법과 MSA를 사용한 조종날개의 공탄성 모델로 부터 강건 공탄성 모델링과 해석을 수행하였다. 강건 공탄성 해석 프로그램이 개발되었고, 기존의 공탄성 해석 결과와 비교/검증하였다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 춘계학술대회논문집
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• pp.696-702
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• 2006

Flutter characteristics of composite curved wing were investigated in this study. The efficient and robust system for the flutter optimization of general composite curved wing models has been developed using the coupled computational method based on both the standard genetic algorithm and the micro genetic algorithms. Micro genetic algorithm is used as an alternative method to overcome the relatively poor exploitation characteristics of the standard genetic algorithm. The present results show that the micro genetic algorithm is more efficient in order to find optimized lay-ups for a composite curved wing model. It is found that the flutter stability of curved wing model can be significantly increased using composite materials with proper optimum lamination design when compared to the case of isotropic wing model under the same weight condition.

• 한국항공우주학회지
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• 제36권11호
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• pp.1049-1055
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• 2008

최근 다분야 전산유체 역학에서는 설계 최적화, 공탄성, 강제 경계 운동 등에서 요구되어지는 이동경계문제를 다루게 된다. 이동경계의 변위가 클 경우 강건하고 효율적인 격자 변형 알고리즘의 개발이 필요하다. 본 연구에서는 유한 대형요소와 초월유한보간에 근거한 체적격자 변형 코드를 개발하였고, 정렬격자 다중 블록 Navier-Stokes 코드와 연계하였다. 개발된 코드의 검증을 위해 주기적으로 진동 운동을 하는 에어포일 문제에 대해 계산을 수행 하였고 양력, 항력, 모멘트 계수의 이력 계산 결과가 실험 결과와 잘 일치하였다.