Rotary-Wing Aeroelasticity: Current Status and Future Trends

Friedmann, Peretz P.

doi:10.2514/1.9022

Cited by 68 publications

(11 citation statements)

References 89 publications

(76 reference statements)

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“…Substantial amount of work has been done to model the effect of active flaps on helicopter blades and use them for vibration reduction, performance enhancement, and noise reduction as summarized in Friedmann (2004aFriedmann ( , 2004b and Friedmann et al (2001). However, there have been very few studies that have focused on the design of a composite rotor blade with active flaps.…”

Section: Introductionmentioning

confidence: 98%

New strategy for designing composite rotor blades with active flaps

Kumar

Cesnik

2015

Journal of Intelligent Material Systems and Structures

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This article presents the development of a mixed-variable optimization framework for the design of composite rotor blades with active flaps in order to maximize the control authority for vibration reduction. For the studies presented in this article, the amplitude of dynamic twist at the blade tip at 4/rev flap actuation frequency is used as the objective function, and it is shown that there is a direct correlation between the amplitude of dynamic twist and the vibration reduction authority of active flaps. The optimization framework developed includes Intelligent Cross-section Generator as the cross section and mesh generator, University of Michigan/Variational Asymptotic Beam Sectional Analysis for the crosssectional analysis, and Rotorcraft Comprehensive Analysis System for the aeroelastic analysis of active rotor blades. The optimization problem is solved using a surrogate-based approach in combination with the efficient global optimization algorithm. The optimum results with both mixed and continuous design variables are obtained for three different spanwise locations of active flap.

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Section: Introductionmentioning

confidence: 98%

New strategy for designing composite rotor blades with active flaps

Kumar

Cesnik

2015

Journal of Intelligent Material Systems and Structures

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“…In parallel to fixed-wing aircraft, composites are extensively used in the critical structures of rotorcraft. Helicopter rotor blades, which play a dominant role in the overall vehicle performance, are routinely made of composites because of their high strength and stiffness-to-weight ratios and tailorable characteristics [14][15][16][17][18]. Therefore, considerable research has focused on the mathematical modeling of composite rotor blades [19].…”

Section: Introductionmentioning

confidence: 99%

Aeroelastic Response of Composite Helicopter Rotor with Random Material Properties

Murugan

Ganguli

Harursampath

2008

Journal of Aircraft

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This study investigates the effect of uncertainty in composite material properties on the cross-sectional stiffness properties, natural frequencies, and aeroelastic responses of a composite helicopter rotor blade. The elastic moduli and Poisson's ratio of the composite material are considered as random variables with a coefficient of variation of around 4%, which was taken from published experimental work. An analytical box beam model is used for evaluating blade cross-sectional properties. Aeroelastic analysis based on finite elements in space and time is used to evaluate the helicopter rotor blade response in forward flight. The stochastic cross-sectional and aeroelastic analyses are carried out with Monte Carlo simulations. It is found that the blade cross-sectional stiffness matrix elements show a coefficient of variation of about 6%. The nonrotating rotor blade natural frequencies show a coefficient of variation of around 3%. The impact of material uncertainty on rotating natural frequencies varies from that on nonrotating blade frequencies because of centrifugal stiffening. The propagation of material uncertainty into aeroelastic response causes large deviations, particularly in the higher-harmonic components that are critical for the accurate prediction of helicopter blade loads and vibration. The numerical results clearly show the need to consider randomness of composite material properties in the helicopter aeroelastic analysis.

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“…Other analyses on advanced geometry blades were carried out in [28] with the purpose of evaluating the effects of sweep and droop on both rotor aeroelastic stability and rotorcraft aero-mechanical stability. The evolution of the mechanics of helicopter blades, focusing on the aeroelastic and aerodynamic issues, was extensively discussed in [29][30][31][32]. Moreover, even if the aeroelasticity of large wind turbine blades is inherently different, several related aeroelastic problems were solved using rotary wing theories [33][34][35].…”

Section: Introductionmentioning

confidence: 99%

Flutter analysis of fixed and rotary wings through a one-dimensional unified formulation

Filippi¹,

Carrera²

2015

Composite Structures

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a b s t r a c tCarrera Unified Formulation (CUF) is used to perform flutter analyses of fixed and rotary wings. The one-dimensional refined theories are obtained through an axiomatic enrichment of the displacement field components by only setting the input parameters, namely the number of terms and the kind of the cross-sectional functions. Within this work, Taylor-like expansions of N-order (TEN) are used. The aerodynamic loadings are determined through the unsteady strip theories proposed by Theodorsen and Loewy. The finite element method is used to solve the governing equations that are derived, in a weak form, using the generalized Hamilton's Principle. These equations are written in terms of CUF ''fundamental nuclei'', which do not vary with the theory order (N). The flutter instability of fixed and rotary wings with rectangular and realistic cross-sections is investigated. The results are reported in terms of flutter velocities and frequencies and, when possible, they are compared with experimental, numerical and analytical solutions. Despite the intrinsic limitations of the used aerodynamic theories, the proposed methodology appears valid for aeroelastic and vibrational analyses of several structures by ensuring a significant accuracy with a low computational cost.

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Rotary-Wing Aeroelasticity: Current Status and Future Trends

Cited by 68 publications

References 89 publications

New strategy for designing composite rotor blades with active flaps

New strategy for designing composite rotor blades with active flaps

Aeroelastic Response of Composite Helicopter Rotor with Random Material Properties

Flutter analysis of fixed and rotary wings through a one-dimensional unified formulation

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