Flutter analysis of anisotropic panels with patched cracks

Kuo-Jiun, Lin; Lu, Pei‐Jung; Tarn, J. H.

doi:10.2514/3.46115

Cited by 10 publications

(5 citation statements)

References 22 publications

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“…For the elastic axis fixed in the leading half chord, the divergence/flutter speed is more sensitive to the fiber angle than to the crack itself. For fiber angles between 0 and 90 (see Figure 1), the presence of a crack tends to increase the flutter or divergence speed, a similar phenomenon as observed by Lin et al [3]. While a decrease in flutter speed is usually accompanied by an increase in divergence speed in some situations for a wing made of isotropic materials, the cross-type correlation does not hold in all cases, even for an isotropic wing.…”

Section: Discussionsupporting

confidence: 71%

“…An interesting finding here is that cracking can actually increase the flutter speed for certain fiber orientations. While somewhat surprising, Lin et al [3] also report this possibility in patched composites. However, crack growth will eventually prevail and destroy the wing.…”

Section: Discussionmentioning

confidence: 98%

“…The effects of crack length and the flow direction on the aerodynamic stabilities are addressed. Lin et al [3] later studied the flutter characteristics of a cracked composite panel with an isotropic patch by using a finite element method. The flutter performance of the cracked panel is found to degrade due to the crack except in the case that the fibers are orientated at an angle of a certain range.…”

Section: Introductionmentioning

confidence: 99%

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Crack-induced Changes in Divergence and Flutter of Cantilevered Composite Panels

Wang

Inman

Farrar

2005

Structural Health Monitoring

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The aeroelastic characteristics of a cantilevered composite panel of large aspect ratio and with an edge crack are investigated. The panel consists of several fiber-reinforced composite plies, and is modeled with a one-dimensional beam vibrating in coupled bending and torsion. The fundamental mode shapes of the cracked cantilever are used to study the interaction between a crack and aerodynamic characteristics by employing Galerkin’s method. Variation of the divergence/flutter speed with respect to the crack ratio, its location as well as the fiber angle is investigated. The divergence/flutter speed is more sensitive to the bending-torsion coupling parameter than to the presence of the crack. The crack may or may not reduce the divergence/flutter speed, depending on the fiber orientation. The qualitative analysis may help the development of an online prognosis tool for an aircraft with large aspect-ratio unswept composite wings.

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Section: Discussionsupporting

confidence: 71%

Section: Discussionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

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Crack-induced Changes in Divergence and Flutter of Cantilevered Composite Panels

Wang

Inman

Farrar

2005

Structural Health Monitoring

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“…The phenomenon of the increase in instability speeds because of the growth of damage ratio or approaching damage location to the root of wing, in a certain fiber angle, is not an unknown phenomenon because it was also observed by Lin et al (1991) and Wang and Inman (2007). But the reason for this phenomenon is not simply explainable and further research, more rigorous modeling, or even experimental verification is required to justify this issue in certain fiber angles because variation in instability speed is affected by the interaction of several issues such as the damage ratio, location, the elastic bending–torsion coupling of the material, and the inertia bending–torsion coupling of the wing geometric.…”

Section: Resultsmentioning

confidence: 87%

Delamination effects on the unsteady aero-elastic behavior of composite wing by modal analysis

Torabi

Shams

Narab

et al. 2021

Journal of Vibration and Control

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This article deals with the investigation of delamination effects on the flutter behavior of a composite wing subjected to unsteady aerodynamic loads by providing an integrated procedure using exact methods. For this purpose, an undamaged wing structure is modeled as a cantilevered Bernoulli–Euler beam with coupled bending–torsion and delaminated wing structure is modeled as three interconnected intact beams. The modal analysis of the intact and delaminated beams is performed and mode shapes are obtained based on the development of the dynamic stiffness matrix, a computer code and an iterative method. The fundamental modes of the intact and delaminated beam derived from the free vibration analysis are used in Galerkin’s method and the flutter and divergence speeds are obtained with aerodynamic forces applied. In fact, modified shape functions were developed to reflect the delamination effect in the aeroelastic analysis. Also, for the unsteady aeroelastic analysis, an iterative algorithm is developed. It was found that the delamination location and its length can have a positive or a negative influence on the flutter behavior of the wing which depends on the fiber angle.

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“…Another work studied the supersonic flutter behaviour of isotropic thin cracked panels using the hybrid finite element method [43]. Recently, Lin et al [44] studied the panel flutter problems of thin plate-like composite panels with patched cracks using a finite element method (FEM). They showed that flutter performance could be improved by isotropic patching.…”

Section: Flutter Of a Damaged Panelmentioning

confidence: 99%

Flutter prediction, suppression and control in aircraft composite wings as a design prerequisite: a survey

Njuguna

2007

Struct. Control Health Monit.

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Emergence of flutter compromises not only the long‐term durability of the wing structure, but also the operational safety, flight performance and energy efficiency of the aircraft. Effectual means of flutter prevention are, therefore, mandatory in the certification of new flight vehicles. This work intends to address the flutter phenomenon highlighting the above issues, and reviews some of the most recent theoretical and experimental developments in flutter analyses. In the following subsections, theoretical, computational and experimental flutter for composite structures is pursued. In particular, panel flutter, thrust‐induced flutter, wing/store‐type flutter, non‐linear flutter, damaged panel flutter, flutter in compressed flow and flutter control via neural networks are covered. Effects of fibre/ply orientation on flutter are also briefly covered. The review further looks into aerothermoelastic behaviour of composite structures buckling problem and hopf bifurcation point determination. Analysed flutter of actively/passively controlled composite structures is critically reviewed due to the emphasized importance in modern structures. It is appreciable that the knowledge gained from the study of flexible structures and unsteady airflows in aircraft can be transitioned back to more traditional flutter studies. It is hoped that this review work will stimulate research and collaborations that will lead to significant progress in the understanding of this dynamically rich and potentially important area of enhancement of flutter prediction, suppression and control of active and passive composite aircraft structures. Copyright © 2006 John Wiley & Sons, Ltd.

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Flutter analysis of anisotropic panels with patched cracks

Cited by 10 publications

References 22 publications

Crack-induced Changes in Divergence and Flutter of Cantilevered Composite Panels

Crack-induced Changes in Divergence and Flutter of Cantilevered Composite Panels

Delamination effects on the unsteady aero-elastic behavior of composite wing by modal analysis

Flutter prediction, suppression and control in aircraft composite wings as a design prerequisite: a survey

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