Radiated Sound Power from a Curved Honeycomb Panel

Abstract

The validation of finite element and boundary element model for the vibro-acoustic response of a curved honeycomb core composite aircraft panel is completed. The finite element and boundary element models were previously validated separately. This validation process was hampered significantly by the method in which the panel was installed in the test facility. The fixture used was made primarily of fiberboard and the panel was held in a groove in the fiberboard by a compression fitting made of plastic tubing. The validated model is intended to be used to evaluate noise reduction concepts from both an experimental and analytic basis simultaneously. An initial parametric study of the influence of core thickness on the radiated sound power from this panel, using this numerical model was subsequently conducted. This study was significantly influenced by the presence of strong boundary condition effects but indicated that the radiated sound power from this panel was insensitive to core thickness primarily due to the offsetting effects of added mass and added stiffness in the frequency range investigated.

Reduction of the sound transmission of a periodic sandwich plate using the stop band concept

“…In range IV, the trend of STL is similar to that of the infinite plate, and the envelope curve of STL gradually approaches that of the infinite plate. 14 From Fig. 5(b), compared to the bare sandwich plate, the STL for the periodic sandwich plate with resonators is observed to greatly increase within the complete stop band indicated by the shaded area (i.e., range III').…”

“…When a particular phase constant is specified, the eigenvalues indicate the frequencies at which a wave can propagate in the structure, while the eigenvectors describe the corresponding motion of the unit cell. According to the Bloch theory, to determine the complete stop band, it 7 is sufficient to just assign the values of the phase constants to the boundary MГXM of the irreducible first Brillouin zone [1,14,22,30], as shown in Fig. 1(c).…”

“…Moore and Lyon [10] investigated the sound transmission loss in the unidirectional sandwich panels with isotropic and orthotropic cores. Recently, some researchers used the finite element method in the study of the dynamic characteristics of sandwich structures [7,8,[11][12][13][14][15]. Buehrle et al [11] and Robinson et al [14] developed a finite element and boundary element model to investigate the vibro-acoustic response of a curved honeycomb composite panel.…”