• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2002년도 추계학술발표대회 논문집
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• pp.220-223
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• 2002

This paper introduces the development procedure of paddle type small-scaled composite rotor blade for helicopter hingeless rotor system. Paddle type composite blade design was done by using CORDAS program developed by KARI and dynamic analysis for hingeless hub with blade is done by using FLIGHTLAB which is commercial software for helicopter comprehensive analysis. The procedure to manufacture complicated shape of paddle type blade tip was developed and composite blades were manufactured after establishing the effective curing method. Through this research, the development technology of composite rotor blade with complex aerodynamic shape were accumulated and these will be applied to the related research field, for example, full size composite blade development, etc.

• International Journal of Aeronautical and Space Sciences
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• 제7권1호
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• pp.54-64
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• 2006

To augment weakly damped lag mode stability of a hingeless helicopter rotor blade in hover, piezoelectric shunt with a resistor and an inductor circuits for passive damping has been studied. A shunted piezoceramics bonded to a flexure of rotor blade converts mechanical strain energy to electrical charge energy which is dissipated through the resistor in the R-L series shunt circuit. Because the fundamental lag mode frequency of a soft-in-plane hingeless helicopter rotor blade is generally about 0.7/rev, the design frequency of the blade system with flexure sets to be so. Experimentally, the measured lag mode frequency is 0.7227/rev under the short circuit condition. Therefore the suppression mode of this passive damping vibration absorber is adjusted to 0.7227/rev. As a result of damping enhancement using passive control, the passive damper which consists of a piezoelectric material and shunt circuits has a stabilizing effect on inherently weakly damped lag mode of the rotor blades, at the optimum tuning and resistor condition.

• 항공우주시스템공학회지
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• 제6권1호
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• pp.1-6
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• 2012

During helicopter rotor system development process, whirl tower test is conducted basically. For conducting whirl tower test during bearingless hub development process, design new blade or using existing blade with repair or remodeling. Because simple shape and efficient aerodynamic characteristic, BO-105 blade is used for hub system development widely. Originally BO-105 Blade is used for hingeless hub, so flap stiffness and lag stiffness on blade root area is relatively low. So appling BO-105 blade to bearingless hub whirl tower test, root area have to be reinforce. In this paper, suggest reinforcement method of BO-105 blade root area.

• 한국소음진동공학회논문집
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• 제23권2호
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• pp.105-111
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• 2013

Whirl tower test is conducted basically during helicopter rotor system development process. And for whirl tower test of rotor hub system, new design blade or existing blade which is remodeled for new rotor hub system is used. Because of simple shape and efficient aerodynamic characteristic, BO-105 helicopter blade is used for helicopter rotor hub development project widely. Originally BO-105 blade is used for hingeless hub system and blade root is used to flexure. So flap stiffness and lag stiffness at blade root area is relatively low compare with airfoil area. So, in order to apply the BO-105 blade to bearingless hub, blade root area have to be reinforced. And in this process, blade root area's section property is changed. In this paper, we suggest reinforcement method of BO-105 blade root area and study dynamic characteristic of bearingless rotor system with reinforcement BO-105 blade.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2005년도 춘계학술발표대회 논문집
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• pp.213-216
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• 2005

This paper describes the design, analysis and manufacture procedure of the composite blade for hingeless rotor system of unmanned helicopters. Helicopter rotor system is the key structural unit that produces thrust and control forces for intended flight conditions. In this work, a hingeless rotor system is adopted, and base on the design requirements for rotor system, composite blade section design and calculation of material properties were performed. In order to avoid the unstable state such as resonance, vibration characteristics of rotor system were analyzed. Finally, this paper describes simply the forming and manufacture of composite blade.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2012년도 춘계학술대회 논문집
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• pp.622-627
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• 2012

During helicopter rotor system development process, whirl tower test is conducted basically. For conducting whirl tower test during bearingless hub development process, design new blade or using existing blade with repair or remodeling. Because simple shape and efficient aerodynamic characteristic, BO-105 blade is used for hub system development widely. Originally BO-105 blade is used for hingeless hub, ho flap stiffness and lag stiffness on blade root area is relatively low. So applying BO-105 blade to bearingless hub whirl tower test, root area have to be reinforce. In this process, blade root area's section property will be changed. In this paper, suggest reinforcement method of BO-105 blade root area and study dynamic characteristic of bearingless rotor system with reinforcement BO-105 blade.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 추계학술대회논문집
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• pp.310-315
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• 2003

This paper described that rotating test and fatigue test of a small-scale hingeless hub system with composite rectangular blades. Generally Rotating stability and fatigue test technique is one of Key-technology on test and evaluation for helicopter rotor system Rotating test of hingeless rotor system was achieved by means of rotor vibration characteristic and aeroelastic stability test GSRTS, equipped with hydraulic actuator and 6-component rotating balance was used to test hingeless rotor system especially for an observation of blade motion including flawing, lagging and feathering. Rotating test was done in hover and forward flight condition. Small-scaled blade fatigue test condition was determined by blade load analysis with the reference table of composite materials(S-N curve). Fatigue test bench was developed for the estimation of blade fatigue life, and tested its characteristic.

• 항공우주기술
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• 제2권2호
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• pp.33-44
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• 2003

본 논문은 힌지없는 로터 시스템의 설계 핵심기술인 복합재료 플렉셔 설계 및 패틀형 복합재료 블레이드 설계/해석 기법을 소개하였다. 기존 금속재 혹은 엔지니어링 플라스틱 플렉셔 부품을 복합재료를 사용하여 설계한 후 NASTRAN과 FLIGHTLAB을 이용하여 구조 해석 및 동역학 특성 해석을 수행하였다. 패들형 블레이드를 복합재료 힌지없는 플렉셔 장착 허브에 연결한 힌지없는 로터 시스템에 대한 동적 특성을 살펴보았다. 또한 패들형 블레이드를 기존 실물크기 블레이드 구조 자료를 이용하여 프루드 축소화하였으며 축소값을 이용하여 블레이드를 설계하였다. 이 과정을 통해 형상이 복잡한 패들형 복합재료 블레이드에 대한 형상 설계 및 단면구조 설계 기법을 익혔다. 본 논문은 현재 수행중인 “차세대 헬리콥터 로우터 시스템 개발” 사업 등에 직접 적용될 수 있을 것으로 기대된다.

• 한국항공우주학회지
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• 제42권5호
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• pp.390-397
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• 2014

BO-105 헬리콥터는 무힌지 로터 허브시스템이 적용되었으며, 블레이드의 루트 영역이 무힌지 허브 시스템의 플렉셔에 해당한다. 따라서 본 블레이드를 이용한 훨타워 시험 수행을 대비하여 굽힘 강성이 낮은 플렉셔 부분에 대한 굽힘 강성 보강을 수행하였다. 플렉셔 굽힘 강성 보강 수행을 위해 플렉셔 부분의 단면 형상을 모델링하여 굽힘 강성을 계산하였으며, 이를 바탕으로 강성 보강을 위한 복합재의 두께를 선정하였다. 보강된 플렉셔의 실제 굽힘 강성을 확인하기 위하여 강성보강 전 형상에 대한 강성 측정 시험과 강성보강 이후 형상에 대한 강성 측정 시험을 수행하여 결과를 비교하였다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 춘계학술대회논문집
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• pp.575-580
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• 2004

In this work, the effect of composite couplings and mass distributions on hub loads of a hingeless rotor in forward flight is investigated. 1'he hingeless composite rotor is idealized as a laminated thin-walled box-beam. The nonclassical effects such as transverse shear and torsion warping are considered in the structural formulation. The nonlinear differential equations of motion are obtained by applying Hamilton's principle. The blade responses and hub loads are calculated using a finite element formulation both in space and time. The aerodynamic forces acting on the blade are calculated using the quasi-steady strip theory. The theory includes the effects of reversed flow and compressibility The magnitude of elastic couplings obtained by MSC/NASTRAN is compared with the classical pitch-flap($\delta$$_{3}$) coupling. It is observed that the elastic couplings and mass distributions of the blade have a substantial effect on the behavior of $N_{b/}$rev hub loads. About 40% hub loads is reduced by tailoring or redistributing the structural properties of the blade.f the blade.