• Title/Summary/Keyword: Aeroelastic stability

Search Result 71, Processing Time 0.049 seconds

Localization Development of Rotor Blade for Smart Unmanned Aerial Vehicle (스마트무인기 로터 블레이드 국산화 개발)

  • Lee, Myeonk-Kyu
    • Aerospace Engineering and Technology
    • /
    • v.10 no.2
    • /
    • pp.11-19
    • /
    • 2011
  • A localization development of Composite rotor blade for Smart Unmanned Aerial Vehicle(SUAV) has been conducted. Overall localization development encompassed selection of domestic composite material having similar properties to that of original one at its best, coupon tests for data base of new material properties, re-calculation of blade sectional properties, and validation of structural/dynamic design requirements such as isolation of rotor natural frequency from excitation, static and fatigue strength, aeroelastic stability. The results of all these activities are described. This paper briefly discusses the improved manufacturing process for the localization of SUAV blade.

Planform Curvature Effects on the Stability of Coupled Flow/Structure Vibration (면내 곡률이 천음속 및 초음속 유체/구조 연계 진동 안정성에 미치는 영향)

  • Kim, Jong-Yun;Kim, Dong-Hyun;Lee, In
    • Transactions of the Korean Society for Noise and Vibration Engineering
    • /
    • v.12 no.11
    • /
    • pp.864-872
    • /
    • 2002
  • In this study, the effect of planform curvature on the stability of coupled flow/structure vibration is examined in transonic and supersonic flow regions. The aeroelastic analysis for the frequency and time domain is performed to obtain the flutter solution. The doublet lattice method(DLM) in subsonic flow is used to calculate unsteady aerodynamics in the frequency domain. For all speed range, the time domain nonlinear unsteady transonic small disturbance code has been incorporated into the coupled-time integration aeroelastic analysis (CTIA). Two curved wings with experimental data have been considered in this paper MSC/NASTRAN is used for natural free vibration analyses of wing models. Predicted flutter dynamic pressures and frequencies are compared with experimental data in subsonic and transonic flow regions.

Stability augmentation of helicopter rotor blades using passive damping of shape memory alloys

  • Yun, Chul-Yong;Kim, Dae-Sung;Kim, Seung-Jo
    • International Journal of Aeronautical and Space Sciences
    • /
    • v.7 no.1
    • /
    • pp.137-147
    • /
    • 2006
  • In this study, shape memory alloy damper with characteristics of pseudoelastic hysteresis for helicopter rotor blades are investigated. SMAs can be available in damping augmentation of vibrating structures. SMAs show large hysteresis in the process of pseudoelastic austenite-martensite phase transformation which takes place while subjected to loading above the austenite finish temperature. Since SMAs display pseudoelastic hysteresis behavior over large strain ranges, a significant amount of energy dissipation is possible. A damper can be designed with SMA wires prestressed to a baseline level somewhere in the middle of the pseudoelastic stress range. An experimental study of the effects of pre-strain and cyclic strain amplitude as well as frequency on the damping behavior of pseudoelastic shape memory alloy wires are performed. The effects of the shape memory alloy damper on aeroelastic and ground resonance stability of helicopter are studied. In aeroelastic stability, the dynamic characteristics of blades related to pitch angle and the amplitude of lag motion for the rotor equipped with SMA damper were examined. The performance of SMA damper on ground resonance instability are presented through the frequencies and modal damping with respect to rotating speed.

The Vibration Characteristic and Fatigue Life Estimation of a Small-scaled Hingeless Hub System with Composite Rectangular Blades (복합재료 기준형 블레이드를 장착한 축소 힌지없는 허브시스템의 진동특성과 피로수명 예측)

  • Song, Keun-Woong;Kim, Jun-Ho;Kim, Duck-Kwan;Joo, Jin
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
    • /
    • 2003.11a
    • /
    • pp.310-315
    • /
    • 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.

  • PDF

Aeroelastic Compatibility Substantiation of Aircraft External Stores Using the Dynamic Characteristic Data from Ground Vibration Test (지상진동시험 동특성 데이터를 활용한 항공기 외부장착물의 공력탄성학적 적합성 입증)

  • Lim, Hyun Tae;Kwon, Jae Ryong;Byun, Kwan Hwa;Kim, Hee Joong;Kim, Jae hoon
    • Journal of the Korean Society for Aeronautical & Space Sciences
    • /
    • v.45 no.4
    • /
    • pp.269-275
    • /
    • 2017
  • The aeroelastic stability of a fighter type aircraft can be severly affected by the store mass, aerodynamic characteristics, and store combinations. Hence, the stability for the all store configurations must be substantiated before the aircraft in service. For the aeroelastic analysis, the design data and information for the aircraft structure, mass distribution, control surface characteristics, and external shape etc. are required. This is the reason that the store compatibility substantiations by a third party are restricted. However, according to the change of operational environment or the improvement of avionic technology, a new external store is developed and it should be installed on an aircraft without the support from the original supplier. This paper describe the process to substantiate the aeroelastic compatibility between a new external store and an imported aircraft whose design data is not available to a third party operating the aircraft.

Wind tunnel test research on aerodynamic means of the ZG Bridge

  • He, Xiangdong;Xi, Shaozhong
    • Wind and Structures
    • /
    • v.2 no.2
    • /
    • pp.119-125
    • /
    • 1999
  • The ZG Bridge(preliminary design), with unfavorable aerodynamic stability characteristics, is a truss-stiffened suspension bridge, its critical wind speed of flutter instability is much lower than that of code requirement, In the present paper, based on both aerostatic and aeroelastic section model wind tunnel test, not only effects of some aerodynamic means on aerodynamic stability of its main girder are investigated, but also such effective aerodynamic means of it as flap and plate-like center stabilizer are concluded.

Optimum Design of a Composite T-tail Configuration for Maximum Flutter Speed Using Genetic Algorithm (유전자 알고리즘을 이용한 T-형 복합재료 날개의 플러터 속도 최적설계)

  • Alexander, Boby;Oh, Se-Won;Kim, Dong-Hyun
    • Proceedings of the Korean Society For Composite Materials Conference
    • /
    • 2005.11a
    • /
    • pp.173-178
    • /
    • 2005
  • In this paper, an efficient and robust analysis system for the flutter optimization of laminated composite wings has been developed using the coupled computational method based on the genetic algorithm. General three-dimensional doublet-lattice method is efficiently used to compute generalized aerodynamic forces of T-tail configuration in the frequency domain. Structural dynamic analyses of laminated composite T-tail models are conducted using finite clement method. The classical P-k flutter analysis technique is applied to effectively solve the aeroelastic governing equations in the frequency domain. Optimum design studies using genetic algorithm have been conducted in order to obtain maximum flutter stability of a composite T-tail configuration. The results show that flutter stability can be significantly increased using composite materials with proper optimum design concepts even for the same weight and shape condition. In the view point of engineering design, it is also importantly shown that the optimization of the vertical wing part is highly effective comparing to the optimization of horizontal wing part.

  • PDF

Prevention of suspension bridge flutter using multiple tuned mass dampers

  • Ubertini, Filippo
    • Wind and Structures
    • /
    • v.13 no.3
    • /
    • pp.235-256
    • /
    • 2010
  • The aeroelastic stability of bridge decks equipped with multiple tuned mass dampers is studied. The problem is attacked in the time domain, by representing self-excited loads with the aid of aerodynamic indicial functions approximated by truncated series of exponential filters. This approach allows to reduce the aeroelastic stability analysis in the form of a direct eigenvalue problem, by introducing an additional state variable for each exponential term adopted in the approximation of indicial functions. A general probabilistic framework for the optimal robust design of multiple tuned mass dampers is proposed, in which all possible sources of uncertainties can be accounted for. For the purposes of this study, the method is also simplified in a form which requires a lower computational effort and it is then applied to a general case study in order to analyze the control effectiveness of regular and irregular multiple tuned mass dampers. A special care is devoted to mistuning effects caused by random variations of the target frequency. Regular multiple tuned mass dampers are seen to improve both control effectiveness and robustness with respect to single tuned mass dampers. However, those devices exhibit an asymmetric behavior with respect to frequency mistuning, which may weaken their feasibility for technical applications. In order to overcome this drawback, an irregular multiple tuned mass damper is conceived which is based on unequal mass distribution. The optimal design of this device is finally pursued via a full domain search, which evidences a remarkable robustness against frequency mistuning, in the sense of the simplified design approach.

Numerical and analytical study of aeroelastic characteristics of wind turbine composite blades

  • Ghasemi, Ahmad Reza;Jahanshir, Arezu;Tarighat, Mohammad Hassan
    • Wind and Structures
    • /
    • v.18 no.2
    • /
    • pp.103-116
    • /
    • 2014
  • Aeroelasticity is the main source of instability in structures which are subjected to aerodynamic forces. One of the major reasons of instability is the coupling of bending and torsional vibration of the flexible bodies, which is known as flutter. The presented investigation aims to study the aeroelastic stability of composite blades of wind turbine. Geometry, layup, and loading of the turbine blades made of laminated composites were calculated and evaluated. To study the flutter phenomenon of the blades, two numerical and analytical methods were selected. The finite element method (FEM), and JAR-23 standard were used to perform the numerical studies. In the analytical method, two degree freedom flutter and Lagrange's equations were employed to study the flutter phenomena analytically and estimate the flutter speed.

Static Aeroelastic analysis of Morphing flap wign through FSI analysis method (FSI를 이용한 모핑 플랩 날개의 정적 공탄성 해석)

  • Kim, Jonghwan;Ko, Seughee;Bae, Jaesung;Hwang, Jaihyuk
    • Journal of Aerospace System Engineering
    • /
    • v.6 no.4
    • /
    • pp.1-6
    • /
    • 2012
  • The morphing flap wing has different structure unliked general wing structure. The actuated chord length of the morphing flap was more longer than conventional wing flap. In this reason, morphing flap wing structure was important to bending moment by aerodynamic lift force. In this study, through the fluid-structure interaction using computational fluid dynamics and structure finite element analysis to apply that the morphing flap wing's static aeroelastic stability analysis.