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기영중,이상원,박선규,Kee, Youngjung,Lee, Sangwon,Park, Seonkyu 항공우주시스템공학회 2010 항공우주시스템공학회지 Vol.4 No.2
Fatigue properties of composite materials are extremely important to design durable and reliable helicopter rotor blades. However, it is very difficult to apply conventional fatigue test loads in short period. Therefore, accelerating test speed and facilitating spectrum load realization are required. In this study, we have developed a fatigue testing method that uses a resonance of simply supported beam type blade specimen. This test consists in exciting the blade specimen with a frequency that corresponds to its natural frequency. In that case, the test specimen similar to a beam fixed between two pivot points starts vibrating and is significantly deformed. Resonant fatigue tests were performed by changing exciting vertical amplitude and frequency, and S-N curves of each composite materials were successfully obtained.
회전 효과를 고려한 Active Gurney Flap 의 동특성 해석
기영중,김태주,김덕관,Kee, YoungJung,Kim, TaeJoo,Kim, DeogKwan 대한기계학회 2015 대한기계학회 논문집. Transactions of the KSME. C, 산업기술과 혁신 Vol.3 No.3
본 논문에서는 헬리콥터 로터 시스템의 진동과 소음을 저감시키기 위해 개발이 진행 중인 능동거니플랩(AGF, Active Gurney Flap)에 대해 유한요소법을 이용하여 수행된 동특성 해석결과를 소개하였다. 거니플랩은 평판의 형태로 블레이드 하부 표면에 수직인 방향으로 전개되며, 블레이드 뒷전(T/E, Trailing Edge) 부위에 장착된다. 거니플랩 조립체는 전기모터와 L-형 링키지 및 플랩 등의 부품들로 구성되어 블레이드 내부에 장착되며, 고정프레임에서의 진동 성분들을 감소시키기 위해 3~5/rev 범위로 능동적인 제어가 필요하다. 따라서 외연적 시간적분법을 통해 로터 회전에 의한 원심력과 제어입력이 적용되고 있는 상황에서 거니플랩의 동적 응답특성을 분석하였으며, 해석 결과를 통해 거니플랩의 하향변위 요구도를 만족시킬 수 있음을 확인하였다. In this study, the finite element analysis was carried out to investigate dynamic characteristics of the AGF(Active Gurney Flap) which is under development for reducing vibration and noise of the helicopter rotor system. The Gurney flap is a kind of small flat plate, mounted normal to the lower surface of the airfoil near to the trailing edge. An electric motor, L-shaped linkages and flap parts were integrated into a rotor bade, and 3~5/rev control was given to the AGF to reduce the vibration in the fixed frame. Thus, an explicit time integration method was adopted to investigate the dynamic response of the AGF with considering both centrifugal force due to the rotor rotation and active control input, and it can be seen that the vertical displacement of the AGF was satisfied to meet the design requirement.
기영중(Youngjung Kee),김승호(Seung-Ho Kim),정재권(Jae-Kwon Jung),허장욱(Jang-Wook Heo) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.11
Helicopter rotor systems are dynamically loaded structures with many composite components such as main and tail rotor blades. Fatigue properties of composite materials are extremely important to design durable and reliable helicopter rotor blades. The safe-life methodology has been generally used in the helicopter industry to substantiate dynamically loaded composite components. However, it is not available to evaluate the strength reducing effects of flaws and defects that may occur in manufacturing and operational usage. Damage tolerance methodology provides a proper means to overcome this shortcoming, but it is difficult to economically apply it to every composite components. Flaw tolerant methodology is an equivalent option to damage tolerance for civil and military rotorcraft. The flaw tolerant safe life evaluation is described and illustrated by means of successful application to substantiate the retirement time of composite blades.