Principles of Aeroelasticity

Abstract

Revised and brought up to date by the inclusion of new gages, cemenbi, instrumentation, etc.-Ed.

Wall effects on pressure fluctuations in turbulent channel flow

“…Pantano & Sarkar (2002) used the inviscid form of (A 1a), considering only acoustic pressure (dp a = a 2 dρ where a is the speed of sound), to study compressibility effects in high-speed shear-layers. Foysi et al (2004) further developed (A 1a) using the Garrick operator (Garrick 1957) [D ct ] 2 of theoretical compressible unsteady aerodynamics and aeroacoustics (Miles 1959;Bisplinghoff & Ashley 1962), which highlights a wavelike influence of the fluctuating density, and Mahle et al (2007) applied it to high-speed compressible mixing-layers All these high-Mach-number studies used Favre decomposition (Favre 1965a,b), and the form ∂ 2 xixj (u i u j − u i u j ) for the slow terms. Since we are interested here in establishing the order-of-magnitude of compressibility effects in comparison with the incompressible flow equation (1.1), we recast the fluctuating part of (A 1a) in a form containing (1.1) plus compressible terms.…”

Modeling and robust Body Freedom Flutter Analysis of flexible aircraft configurations

“…The first feature, familiar to aeroelasticians [7], is that the tendency for instability is more pronounced as the bending ω b and torsional ω t frequencies become closer. This is seen by the curve representing the restrained wing (solid line in Fig.…”

“…The typical section model was introduced in the early stages of aeroelasticity to investigate dynamic phenomena such as flutter [7]. Despite its simplicity, it captures essential effects in a simple model representation, see Fig.…”

“…The position of the relevant points elastic axis (EA), center of gravity (CG) and the aerodynamic center (AC) is also marked. For the aerodynamic loads model, the unsteady formulation proposed by Theodorsen [7] is employed. This approach is The premise of the typical section modeling is that the dynamics of an actual wing can be simulated choosing the aforementioned properties to match those at a span station about 70% distant from the centerline.…”

Explicit solution for the natural frequency of structures with partial viscoelastic treatment

“…In Setion 3 the modal scalar equations for the resonant vibration form of the structure are now determined, where an essential part of the present solution strategy is the introduction of an additional term, representing the modal flexibility from non-resonant residual vibration modes. This type of correction term is commonly applied in numerical analysis for effective truncation of series expansions [17][18][19]. But recently this approach has also been used in [20,21] to derive accurate calibration formulae for resonant vibration damping of flexible structures.…”