Quieting a rib-framed honeycomb core sandwich panel for a rotorcraft roof

Stephen Hambric, Micah Shepherd, Royce Snider, Carl May

Research output: Chapter in Book/Report/Conference proceedingConference contribution

2 Scopus citations

Abstract

A rotorcraft roof sandwich panel has been redesigned to optimize sound power transmission loss (TL) for frequencies between 1 and 4 kHz. The roof section, framed by a grid of ribs, was originally constructed of a single honeycomb core/composite facesheet panel. The original panel, characterized in [1], has coincidence frequencies near 700 Hz, leading to poor TL across the frequency range of 1 to 4 kHz. To quiet the panel, the section was split into two thinner sandwich subpanels separated by an air gap. The air gap was sized to target the fundamental mass-spring-mass resonance of the panel system to less than 500 Hz. The panels were designed to withstand structural loading from normal rotorcraft operation, as well as 'man-on-the-roof' static loads experienced during maintenance operations. Thin layers of VHB 9469 viscoelastomer from 3M were included in the facesheet ply layups, increasing panel damping loss factors from about 0.01 to 0.05. The optimized panel is expected to provide more than 10 dB transmission loss improvement at critical rotorcraft transmission tonal frequencies.

Original languageEnglish (US)
Title of host publicationINTERNOISE 2014 - 43rd International Congress on Noise Control Engineering
Subtitle of host publicationImproving the World Through Noise Control
EditorsJohn Davy, Marion Burgess, Charles Don, Liz Dowsett, Terry McMinn, Norm Broner
PublisherAustralian Acoustical Society
ISBN (Electronic)9780909882037
StatePublished - 2014
Event43rd International Congress on Noise Control Engineering: Improving the World Through Noise Control, INTERNOISE 2014 - Melbourne, Australia
Duration: Nov 16 2014Nov 19 2014

Publication series

NameINTERNOISE 2014 - 43rd International Congress on Noise Control Engineering: Improving the World Through Noise Control

Other

Other43rd International Congress on Noise Control Engineering: Improving the World Through Noise Control, INTERNOISE 2014
CountryAustralia
CityMelbourne
Period11/16/1411/19/14

All Science Journal Classification (ASJC) codes

  • Acoustics and Ultrasonics

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