Coupled panel/cavity vibrations.

Ketter, D. J.

doi:10.2514/3.3336

Cited by 3 publications

(1 citation statement)

References 2 publications

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“…(28), and structural damping may readily be included by replacing K p 2 with K P 2 (1 + g p ). Furthermore, the one-term approximation to the effect of an underlying cavity on the fundamental natural frequency 16 where C = M 2 d//3a is the cavity correction factor, and K is a constant dependent on the panel boundary conditions. For all edges simply supported, K = 0.65702; for all edges clamped, K = 0.47656; for two parallel edges simply supported and the other two clamped, K = 0.55956.…”

Section: Alternate Solutionmentioning

confidence: 99%

Flutter of flat, rectangular, orthotropic panels.

Ketter

1967

AIAA Journal

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The principle of minimum potential energy is used in conjunction with the Rayleigh-Ritz method to derive the flutter equation for flat, rectangular, orthotropic panels in terms of orthogonal assumed modes and uncoupled generalized coordinates. Orthotropic stiffness components and midplane stresses are assumed to be independent of the panel coordinates, and airloads are represented by a quasi-steady supersonic aerodynamic expression, valid for M > 2 1/2 . Viscous structural damping is also included. The applicable panel boundary conditions for the flutter equation are 1) simply supported on all four edges, 2) clamped on two parallel edges and simply supported on two parallel edges, and 3) clamped on all four edges. An alternate flutter equation is presented in terms of normal coordinates. Stability boundaries are computed, and curves are presented for example isotropic and orthotropic panels. An assessment of the effect of stiffness coupling for clamped isotropic panels shows that previous theoretical solutions are in considerable error for high panel length-to-width ratios and high midplane tensile stresses. Stability boundaries presented herein for orthotropic panels illustrate the effect of panel boundary conditions and angle of orthotropicity. Convergence studies were conducted for both isotropic and orthotropic panels, and resulting difficulties are identified.

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Section: Alternate Solutionmentioning

confidence: 99%

Flutter of flat, rectangular, orthotropic panels.

Ketter

1967

AIAA Journal

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Finite element analysis of the noise inside a mechanically excited cylinder

Petyt

Lim

1978

Numerical Meth Engineering

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SUMMARYA finite element method is presented for predicting the coupled structural-acoustic response of a flexible cylinder, which contains an acoustic medium and is excited by mechanical forces. The cylinder is represented by an existing axisymmetric, cylindrical shell element. The acoustic space inside the cylinder is modelled using a new axisymmetric, acoustic ring element. The cross-secton of the ring takes the form of an eight node, isoparametric element. The coupled equations of motion for the cylinder and acoustic field are solved using modal analysis techniques. The numerical results obtained are compared with results from an experimental investigation which is also described.

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Natural frequencies of a plate, or a membrane, with an air layer.

Hashimoto¹,

Yasuoka²

1992

J. Acoust. Soc. Jpn. (E), J Acoust Soc Jpn E

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Natural frequencies of a plate, or a membrane, with an air layer which is open-ended along the edge is analyzed, and the effect of the air layer on the plate, or on the mem -brane, is revealed.These results of the analysis are confirmed by the related experi -ment.The air layer acts as a aerodynamic spring when a propagation velocity of the plate vibration is faster than that of the sound pressure in the horizontal direction in the air layer.In the reverse case, the air layer acts as a negative stiffness. Hence, under the former condition, the natural frequencies increase inversely to the decreasing depth of the air layer.Under the latter condition, the natural frequencies decrease. It is, therefore, concluded that the effect of the air layer on the plate vibration, or the mem -brane vibration, reverses at the coincidence frequency.

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Coupled panel/cavity vibrations.

Cited by 3 publications

References 2 publications

Flutter of flat, rectangular, orthotropic panels.

Flutter of flat, rectangular, orthotropic panels.

Finite element analysis of the noise inside a mechanically excited cylinder

Natural frequencies of a plate, or a membrane, with an air layer.

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