Flutter of Wings with Localised Masses

1957 ◽  
Vol 61 (562) ◽  
pp. 667-678 ◽  
Author(s):  
W. G. Molyneux
Keyword(s):  
Theoretical Investigation ◽  
General Consideration ◽  
Wing Flutter ◽  
Flutter Speed ◽  
Optimum Choice ◽  
Aircraft Configurations

SummaryFrom a general consideration of the available data on the flutter of wings with localised masses certain deductions are made as to the possible types of flutter that can occur. On the basis of these deductions it is shown that there is an optimum choice of modes for use in flutter calculations for wings with localised masses. These modes are obtained with artificial constraints imposed on the wing at the localised mass section fixing the wing at this section in translation and/or pitch. It is deduced that for certain mass locations types of flutter are obtained that are insensitive to increase of localised mass, beyond a certain value, with flutter speeds considerably greater than that of the fixed root bare wing. It is also deduced that for the majority of aircraft configurations the maximum flutter speeds for these types of flutter will be realised when the localised mass is in the region of two-thirds semi-span from the root. A limited theoretical investigation is made for a rectangular unswept uniform wing with symmetric and antisymmetric body freedoms, to illustrate and confirm the conclusions derived from general considerations. At the same time the investigation shows that an ill placed localised mass can reduce the wing flutter speed to a very low value.

scholarly journals Fuzzy uncertainty analysis and reliability assessment of aeroelastic aircraft wings

2020 ◽  
Vol 124 (1275) ◽  
pp. 786-811
Author(s):  
M. Rezaei ◽  
S.A. Fazelzadeh ◽  
A. Mazidi ◽  
M.I. Friswell ◽  
H.H. Khodaparast
Keyword(s):  
Structural Parameters ◽  
Low Cost ◽  
Fuzzy Variable ◽  
Fuzzy Uncertainty ◽  
Aircraft Wings ◽  
Wing Flutter ◽  
Flutter Speed ◽  
Wing Model ◽  
Safe Region ◽  
Air Speed

ABSTRACTIn the present study, fuzzy uncertainty and reliability analysis of aeroelastic aircraft wings are investigated. The uncertain air speed and structural parameters are represented by fuzzy triangular membership functions. These uncertainties are propagated through the wing model using a fuzzy interval approach, and the uncertain flutter speed is obtained as a fuzzy variable. Further, the reliability of the wing flutter is based on the interference area in the pyramid shape defined by the fuzzy flutter speed and air speed. The ratio between the safe region volume and the total volume of the pyramid gives the reliability value. Two different examples are considered—a typical wing section, and a clean wing—and the results are given for various wind speed conditions. The results show that the approach considered is a low-cost but suitable method to estimate the reliability of the wing flutter speed in the presence of uncertainties.

scholarly journals Analisis Flutter Pada Uji Model Separuh Sayap Pesawat N219 di Terowongan Angin Kecepatan Rendah

WARTA ARDHIA ◽  
2017 ◽  
Vol 42 (4) ◽  
pp. 165
Author(s):  
Sayuti Syamsuar ◽  
Muhamad Kusni ◽  
Adityo Suksmono ◽  
Muhamad Ivan Aji Saputro
Keyword(s):  
Wind Tunnel ◽  
Computational Analysis ◽  
Aerodynamic Force ◽  
Unstable Condition ◽  
Low Speed ◽  
Wing Flutter ◽  
Flutter Speed ◽  
Wing Model ◽  
Speed Range ◽  
Low Speed Wind Tunnel

Fenomena flutter akan terjadi apabila ada gaya dan momen aerodinamika yang berinteraksi berlebihan di permukaan sayap di dalam terowongan angin atau pesawat sesungguhnya. Sayap akan bergetar dan berosilasi bertambah besar menuju ke keadaan tidak stabil. Osilasi osilasi membuat osilasi yang lebih besar terjadi sehingga frekuensi dan damping pada daerah kecepatan tertentu dengan mudah terlihat apabila terjadi flutter pada model separuh sayap. Penelitian ini, digunakan model separuh sayap dari pesawat N219 yang di uji pada terowongan angin kecepatan rendah BBTA3, kawasan Puspiptek, Serpong. Kecepatan flutter terjadi pada 40,5 m/s pada hasil analisis komputasional dan hasil pengujian di terowongan angin sebesar 40,83 m/s. [The Analysis of Half Wing Flutter Test N219 Aircraft Model in The Low Speed Wind Tunnel] The flutter phenomenon will occur when the aerodynamic force and moment excessively interacted on the wing surface, whether it takes place in the wind tunnel or on the real aircraft. The wing will vibrate and oscillate towards an unstable condition. Each oscillation will subsequently build a greater one until the damping and frequency on a certain speed range can be seen easily when flutter occur on the half wing model. On this research, the half wing model of N219 aircraft was tested in the low speed wind tunnel of BBTA3, Puspitek Serpong. The flutter speed occurred at 40,5 m/s based on computational analysis while the wind tunnel result is at the speed of 40,83 m/s.

Wind Tunnel Testing of Composite Wing Flutter Speed due to Control Surface Excitation

2013 ◽  
Vol 315 ◽  
pp. 359-363 ◽  
Author(s):  
Mahzan Muhammad Iyas ◽  
Muhamad Sallehuddin ◽  
Mat Ali Mohamed Sukri ◽  
Mansor Mohd Shuhaimi
Keyword(s):  
Wind Tunnel ◽  
Dynamic Instability ◽  
Wind Tunnel Test ◽  
Control Surface ◽  
Wind Tunnel Testing ◽  
Structural Stiffness ◽  
Wing Flutter ◽  
Flutter Speed ◽  
Surface Excitation ◽  
Composite Wing

Flutter is a dynamic instability problem represents the interaction among aerodynamic forces and structural stiffness during flight. The study was conducted to investigate whether deflecting the control surface will affect the flutter speed and the flutter frequency. A wind tunnel test was performed using a flat plate wing made of composite material. It was found that by deflecting the control surface at 45°, the wing entered flutter state at wind speed of 28.1 m/s instead of 33.4 m/s. In addition, the flutter frequency also reduced from 224.52 Hz to 198.96 Hz. It was concluded that by deflecting the control surface, the wing experienced flutter at lower speed and frequency.

Composite Wing Flutter Speed and Frequency due to Variable Control Surface Deflection in Low Speed Wind Tunnel

2013 ◽  
Vol 390 ◽  
pp. 3-7
Author(s):  
Muhammad Iyas Mahzan ◽  
Sallehuddin Muhamad ◽  
Sa’ardin Abdul Aziz ◽  
Mohamed Sukri Mat Ali
Keyword(s):  
Wind Tunnel ◽  
Dynamic Instability ◽  
Wind Tunnel Test ◽  
Control Surface ◽  
Wing Flutter ◽  
Flutter Speed ◽  
Surface Deflection ◽  
Relationship Of ◽  
Low Speed Wind Tunnel ◽  
The Relationship

Flutter is a dynamic instability problem represents the interaction among structural, aerodynamic, elastic and inertial forces and occurred when the energy is continuously transformed by the surrounding fluids to a flying structure in the form of kinetic energy. The study was conducted to investigate the relationship of the control surface deflection angle to the flutter speed and the flutter frequency. A wind tunnel test was performed using a flat plate wing made of composite material. It was found that by deflecting the control surface up to 45°, the flutter speed reduced almost linearly from 35.6 m/s to 22.7 m/s. The flutter frequency greatly reduced from 48 Hz without the control surface deflected to 34 Hz with the control surface deflected at 15°. After 15° deflection up to 45°, the flutter frequency reduced almost linearly.

Control of Structural Flutter Using Piezoelectric Patches

2008 ◽  
Author(s):  
M. Hariri ◽  
S. John ◽  
P. Trivailo
Keyword(s):  
Strain Energy ◽  
Piezoelectric Materials ◽  
Active Material ◽  
Structural Vibrations ◽  
Wing Flutter ◽  
Flutter Speed ◽  
Aerodynamic Loading ◽  
Air Stream ◽  
Air Speed

Aero-elasticity is a major concern in aerospace field. It resultes from the interaction between the air-stream and the structure. Wing flutter is a well known problem of the aero-elasticity. It which occurs when the two lowest system eigenvalues (plunge and pitch motion) coalesce at a certain air speed known as the flutter speed. The increasing use of active material induced-strain actuation such as piezoelectric materials in suppression of structural vibrations has seen its extension to wing flutter control. Higher flutter speed and hence, a wider operating envelope was achieved by delaying the coalescence of these two eigenvalues. This delaying is obtained by adding more strain energy to the system as a result of the activation of the piezoelectric actuators. This paper models a simple beam under nominal aerodynamic loading conditions for the determination of analytically-derived onset of flutter speeds. Also shown in this paper is the effect of orientation of actuated piezoelectric patches on the shift of the flutter speed.

Modelling Piezoelectric Actuation During Structural Flutter

2009 ◽  
Author(s):  
M. Hariri ◽  
S. John ◽  
P. Trivailo
Keyword(s):  
Structural Control ◽  
Strain Energy ◽  
Piezoelectric Materials ◽  
Active Material ◽  
Structural Vibrations ◽  
Wing Flutter ◽  
Flutter Speed ◽  
Air Stream ◽  
Air Speed

Aeroelasticity is a major concern in structural control. It results from the interaction between the air-stream and the structure. Wing flutter is a well known problem of the aero-elasticity. It occurs when the two lowest system eigenvalues (plunge and pitch motion) coalesce at a certain air speed known as the flutter speed. The increasing use of active material induced-strain actuation such as piezoelectric materials in the suppression of structural vibrations has seen its extension to wing flutter control. Higher flutter speed and hence, a wider operating envelope was achieved by delaying the coalescence of these two eigenvalues. This delay is obtained by adding more strain energy to the system as a result of the activation of the piezoelectric actuators. This paper models a simple beam under nominal aerodynamic loading conditions for the determination of analytically-derived onset of flutter speeds. Also shown in this paper, is the effect of orientation of actuated piezoelectric patches, on the shift of the flutter speed.

Control Surface and Wing Stability Problems

1937 ◽  
Vol 41 (323) ◽  
pp. 975-996 ◽  
Author(s):  
A. G. Pugsley
Keyword(s):  
Research Work ◽  
High Density ◽  
Control Surface ◽  
Recent History ◽  
Flexural Stiffness ◽  
General Design ◽  
Stability Problems ◽  
Wing Flutter ◽  
Flutter Speed ◽  
General Similarity

SummaryThis paper seeks to draw from current research work on flutter and related problems results of general design significance; and, avoiding mathematics, endeavours to set these results out in relation to past and present problems.A preliminary section of the paper indicates the main stability and allied troubles concerned and draws attention to the general similarity between wings and tailplanes in relation to these troubles. The remainder of the paper is then devoted to a discussion of the problems involved in terms of wings and ailerons.For this purpose a “ stiffness diagram ” is constructed for a typical wing, indicating the relative stiffnesses, etc., required to prevent wing-aileron flutter, wing flutter, aileron reversal, and wing divergence. By means of this diagram the course of recent history in relation to wing-aileron flutter and aileron reversal is illustrated, and attention is then given to present and future tendencies and problems. The current tendency to employ wings of high density—arisingly largely from high wing loadings—is making wing flutter the problem of immediate importance, and ways of avoiding the provision of increased stiffness as usually adopted to prevent this trouble, as well as to prevent aileron reversal and wing divergence, are discussed.Appendices are given commenting on the variation of wing flutter speed with altitude and on the modern tendency to usa wings of low flexural stiffness.

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