Bioinspired engineering of honeycomb structure – Using nature to inspire human innovation

This paper reviews the most significant works in literature about the acoustic behaviour of sandwich panels, starting from the first examples of multi-layered structures, comprising a series of dif...

A review of the vibroacoustics of sandwich panels: Models and experiments

A new composite structure (glass fiber assembly-filled honeycomb sandwich panel) is prepared in order to improve the acoustic properties. Effect of glass fiber assembly with different filling shapes (random and fiber ball), fiber diameter, fiber content and air-layer on acoustic properties are explored. Sound absorption coefficient (SAC) and sound transmission loss (STL) are determined by a B&K impedance tube. The experiment results indicate that the first resonance frequency of SAC disappears along with the improvement of the second resonance frequency by reducing the fiber diameter or increasing the fiber content. STL can be improved by the increase of the fiber content. Random glass fiber assembly with the fine fibers has the best STL in the all testing samples. The advantage of glass fiber assembly for improving the STL of honeycomb sandwich panel is particularly clear at frequencies below 4.5 kHz. Especially, the STL difference reaches the maximum at around 20 dB at frequencies below 3.0 kHz.

Acoustic properties of glass fiber assembly-filled honeycomb sandwich panels

Sound radiation and transmission loss characteristics of a honeycomb sandwich panel with composite facings: Effect of inherent material damping

Optimization of composite sandwich cylinders for underwater vehicle application

Sound transmission loss of foam-filled honeycomb sandwich panels using statistical energy analysis and theoretical and measured dynamic properties

The sound transmission characteristics of an aluminum panel and two composite sandwich panels were investigated by using two boundary element analyses. The effect of air loading on the structural behavior of the panels is included in one boundary element analysis, by using a light-fluid approximation for the eigenmode series to evaluate the structural response. In the other boundary element analysis, the air loading is treated as an added mass. The effect of the modal energy loss factor on the sound transmission loss of the panels was investigated. Both boundary element analyses were used to study the sound transmission loss of symmetric sandwich panels excited by a random incidence acoustic field. A classical wave impedance analysis was also used to make sound transmission loss predictions for the two foam-filled honeycomb sandwich panels. Comparisons between predictions of sound transmission loss for the two foam-filled honeycomb sandwich panels excited by a random incidence acoustic field obtained from the wave impedance analysis, the two boundary element analyses, and experimental measurements are presented.

Boundary element analyses for sound transmission loss of panels.

Sound Transmission Characteristics of Asymmetric Sandwich Panels

Design and analysis of a compact solar concentrator tracking via the refraction of the rotating prism

This paper describes sound quality evaluations of five different automobiles. The primary purpose of the study was to compare sound quality evaluations made of interior vehicle noise during road tests with recordings of the noise of the vehicles played back to a jury of subjects using different playback methods. The experiment consisted of recording the sound fields inside the five cars with dual channel microphones situated in a dummy head. The study involved using a jury comprised of a large number of student subjects who first evaluated the sound quality of the five vehicles during the road tests, as well as later evaluating recordings of the same five vehicles played back through loudspeakers and headphones. It was found that there is a high correlation between the three different methods of evaluation used for the same vehicle. This study demonstrates that it is possible to evaluate the sound quality of a car in the laboratory with some confidence using the playback methods described in this paper. It also shows that laboratory evaluations, which are less expensive to conduct than road test evaluations, are good enough for manufacturers to determine the sound quality of a vehicle and to decide on the important sound quality factors needing improvement.

Ran Zhou

Papers

Sound transmission loss of foam-filled honeycomb sandwich panels using statistical energy analysis and theoretical and measured dynamic properties

Boundary element analyses for sound transmission loss of panels.

Sound Transmission Characteristics of Asymmetric Sandwich Panels

Design and analysis of a compact solar concentrator tracking via the refraction of the rotating prism

Comparison between road test, loudspeaker and headphones evaluations of the sound quality of automobiles