Bifurcation boundary analysis as a nonlinear damage detection feature: does it work?

Eftekhari, S. Ali; Bakhtiari-Nejad, Firooz; Dowell, Earl H.

doi:10.1016/j.jfluidstructs.2010.11.006

Cited by 9 publications

(2 citation statements)

References 28 publications

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“…In the field of aeroelasticity, the nonlinearities may be originated from the unsteady aerodynamic flow, large structural deflections, material behavior, and partial loss of structural integrity (Dowell et al, 2003; Lee et al, 1999). Nonlinear responses can suffer from abrupt changes from damped motions to LCOs, which limits the operational regime of aircraft and may result in structural fatigue, or even to catastrophic failure (Dowell et al, 2003; Eftekhari et al, 2011; Lee et al, 1999).…”

Section: Introductionmentioning

confidence: 99%

Characterization of typical aeroelastic sections under combined structural concentrated nonlinearities

Silva

Marques

2021

Journal of Vibration and Control

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Structural nonlinearities are usually present in aeroelastic systems. The analysis of this system commonly comprises a study involving only one type of nonlinearity, influencing a particular motion of the airfoil. However, practical applications of aeroelastic systems can be affected by different types of structural nonlinearities. It becomes essential to study the stability of the aeroelastic system under these conditions to assess more real operational flight procedures. In this context, this article presents an investigation of a typical aeroelastic section response with trailing edge control surface subjected to combinations of concentrated structural nonlinearities. Different nonlinear scenarios involving cubic hardening stiffness in pitching and free play, free play with preload, and slip dry friction in the trailing edge control surface motion are analyzed. The mathematical model is based on linear unsteady aerodynamics coupled to a three-dof typical aeroelastic section. Hopf bifurcations diagrams are obtained from direct time integration of the equation of motion. The post-flutter limit cycle oscillations are investigated, revealing supercritical and subcritical bifurcations. A complete parametric study of the nonlinear parameters is carried out, thereby allowing a sensitivity analysis of each nonlinear scenario. The results show that aeroelastic tailoring considering the mild post-flutter behavior can be achieved through an appropriate choice of combined nonlinear effects. Moreover, combined nonlinearities can mitigate the undesired subcritical aeroelastic responses caused by free play.

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Section: Introductionmentioning

confidence: 99%

Characterization of typical aeroelastic sections under combined structural concentrated nonlinearities

Silva

Marques

2021

Journal of Vibration and Control

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“…Eftekhari et. al [21] used four methods including Finite Difference, Finite Element, Rayleigh-Ritz and Galerkin approached to investigate the sensitivity of the bifurcation boundary for damage detection. Results of the finite element and RayleighRitz methods agree with each other and also show that the sensitivity of the bifurcation boundary to damage is much less than what previously reported when using a finite difference solution method.…”

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confidence: 99%

Effects of all-over part-through cracks on the aeroelastic characteristics of rectangular panels

AsadiGorgi

Dardel

Pashaei

2015

Applied Mathematical Modelling

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In this study, flutter, limit cycle oscillation, and different nonlinear oscillations analyses of rectangular panels with all-over part-through crack are presented. These analyses are carried out for panels in according to first order shear deformation or Mindlin plate theory. The effects of crack's depth and location on various aeroelastic characteristics of moderately thick rectangular panels are accurately studied. These analyses show that for much of crack's depths and locations, the amplitude of nonlinear vibrations are increased. But there are some crack's locations, for them panel has lower amplitude of vibrations with respect to its intact counterpart. With changing the location and depth of crack, the maximum limit cycle oscillation amplitude will be different from intact counterpart. Also cracked panel may exhibit complex oscillations, other than limit cycle oscillation of intact panel. From these analyses, it can be shown that crack has significant influence on flutter boundary, and amplitude of limit cycle oscillation. Nomenclatureܽ Panel chord-wise length ܷ elastic energy ܾ Panel span-wise length ‫,ݔ‬ ‫,ݕ‬ ‫ݖ‬ Coordinates ‫ܦ‬ Plate bending flexible ߫, ߟ, ‫ݓ‬ ഥ non-dimensional coordinates ‫ܧ‬ Panel module of elasticity ߛ Shear strains ‫ܪ‬ Panel thickness ߝ Tensile strain components ℎ Crack thickness ߢ Shear correction factor ݉, ݊ Number of modes shapes for chord-wise and span-wise direction ߣ ி Dimensionless flutter (critical) aerodynamic pressure ‫ܯ‬ Mass matrix ߩ, ߩ Panel and air densities ‫ܭ‬ Stiffness matrix ߥ Poisson's ratio ‫ܮܰ‬ Nonlinear matrix ߱ Dimensionless frequency ‫ܣ‬ cross-sectional area ߱ Dimensionless i'th transverse frequency ‫ܭ‬ Crack stiffness coefficient ߫ Chord wise dimensionless crack location

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Detection of Structural Damage Through Nonlinear Identification by Using Modal Testing

Aykan

Özgüven

2013

Topics in Modal Analysis, Volume 7

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Bifurcation boundary analysis as a nonlinear damage detection feature: does it work?

Cited by 9 publications

References 28 publications

Characterization of typical aeroelastic sections under combined structural concentrated nonlinearities

Characterization of typical aeroelastic sections under combined structural concentrated nonlinearities

Effects of all-over part-through cracks on the aeroelastic characteristics of rectangular panels

Detection of Structural Damage Through Nonlinear Identification by Using Modal Testing

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