TY - GEN
T1 - Quieting a rib-framed honeycomb core sandwich panel for a rotorcraft roof
AU - Hambric, Stephen
AU - Shepherd, Micah
AU - Snider, Royce
AU - May, Carl
N1 - Copyright:
Copyright 2015 Elsevier B.V., All rights reserved.
PY - 2014
Y1 - 2014
N2 - 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.
AB - 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.
UR - https://www.scopus.com/pages/publications/84923631632
UR - https://www.scopus.com/pages/publications/84923631632#tab=citedBy
M3 - Conference contribution
AN - SCOPUS:84923631632
T3 - INTERNOISE 2014 - 43rd International Congress on Noise Control Engineering: Improving the World Through Noise Control
BT - INTERNOISE 2014 - 43rd International Congress on Noise Control Engineering
A2 - Davy, John
A2 - Burgess, Marion
A2 - Don, Charles
A2 - Dowsett, Liz
A2 - McMinn, Terry
A2 - Broner, Norm
PB - Australian Acoustical Society
T2 - 43rd International Congress on Noise Control Engineering: Improving the World Through Noise Control, INTERNOISE 2014
Y2 - 16 November 2014 through 19 November 2014
ER -