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Research Papers

Design Optimization of Honeycomb Core Sandwich Panels for Maximum Sound Transmission Loss

[+] Author and Article Information
Rohan Galgalikar

Department of Mechanical Engineering,
Clemson University,
Fluor Daniel Building, Room 221,
Clemson, SC 29634-0921
e-mail: rgalgal@g.clemson.edu

Lonny L. Thompson

Department of Mechanical Engineering,
Clemson University,
Fluor Daniel Building, Room 221,
Clemson, SC 29634-0921
e-mail: lonny@clemson.edu

1Corresponding author.

Contributed by the Noise Control and Acoustics Division of ASME for publication in the JOURNAL OF VIBRATION AND ACOUSTICS. Manuscript received August 23, 2015; final manuscript received April 15, 2016; published online May 27, 2016. Assoc. Editor: Ronald N. Miles.

J. Vib. Acoust 138(5), 051005 (May 27, 2016) (13 pages) Paper No: VIB-15-1339; doi: 10.1115/1.4033459 History: Received August 23, 2015; Revised April 15, 2016

This study focuses on sound transmission frequency response through honeycomb core sandwich panels with in-plane orientation. Specifically, an optimization technique has been presented to determine the honeycomb unit cell geometric parameters that maximize the sound transmission loss (STL) through a sandwich panel, while maintaining constraints of constant mass and overall dimensions of panel length and height. The vibration characteristics and STL response of a sandwich panel are parameterized in terms of four honeycomb unit cell independent geometric parameters; two side lengths, cell wall thickness, and interior cell wall angle. With constraints of constant mass and overall dimensions, relationships are determined such that the number of independent variables needed to define the honeycomb cell and panel geometry is reduced to three; the integer number of unit cells in the longitudinal direction of the core, number of unit cells in the height direction, and interior cell wall angle. The optimization procedure is implemented by linking a structural acoustic finite-element (FE) model of the panel, with modefrontier, a general purpose optimization software. Optimum designs are obtained in representative frequency ranges within the resonance region of the STL response. Optimized honeycomb geometric solutions show at least 20% increase in STL response compared to standard hexagonal honeycomb core panels. It is found that the STL response is not only affected by the cell wall angle, but strongly depends also on the number of unit cells in the horizontal and vertical direction.

Copyright © 2016 by ASME
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References

Figures

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Fig. 1

Honeycomb core sandwich panels illustrating (a) In-plane configuration where the load is parallel to the plane of the honeycomb unit cell and (b) out-of-plane configuration where the load is perpendicular to the plane of the honeycomb unit cell

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Fig. 2

Honeycomb unit cell configuration (a) regular and (b) auxetic

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Fig. 3

Examples of sandwich panels with same global dimensions but different core geometries

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Fig. 4

Auxetic honeycomb unit cell configurations with (a) constraint satisfied h > |2 l sin θ| and (b) constraint not satisfied h > |2 l sin θ|

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Fig. 5

Schematic of the structural-acoustic FE model

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Fig. 6

Mesh model of the structural-acoustic domain

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Fig. 7

STL versus Frequency plots for mesh convergence study of the reference honeycomb case in the (a) 200–400 Hz and (b) 600–800 Hz frequency range

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Fig. 8

STL characteristics for the reference design case with 30 deg cell wall angle

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Fig. 9

Work flow describing the different stages of optimization in the current study

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Fig. 10

Four-dimensional bubble chart showing variation in STL response of the sandwich panels as a function of the three independent input variables obtained for DOEs in (a) frequency range 200–400 Hz; and (b) frequency range 600–800 Hz

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Fig. 11

Sandwich panel configurations for the designs with highest STL response (see Table 2) obtained in the DOE for (a) 200–400 Hz; and (b) 600–800 Hz frequency range

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Fig. 12

Four-dimensional Bubble chart showing the results of global optimization study (predicted ASTL) conducted with the Shepherd K-Nearest RSM function for (a) 200–400 Hz frequency range and (b) 600–800 Hz frequency range

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Fig. 13

Four-dimensional Bubble chart showing the results of the local optimization study (predicted ASTL) conducted with the Shepherd K-Nearest RSM function for (a) 200–400 Hz frequency range and (b) 600–800 Hz frequency range

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Fig. 14

Comparison of STL response of the Optimum design and reference design (θ = 30 deg) for (a) 200–400 Hz and (b) 600–800 Hz frequency range

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Fig. 15

Mode shapes of sandwich panel (a) Flexural mode in which the top and bottom face-sheets vibrate in the same direction and (b) Dilatational mode of vibration in which the face sheets vibrate in the opposite direction

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Fig. 16

Comparison of STL characteristics of designs with highest and lowest (three each) values of ASTL for 200–400 Hz frequency range

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Fig. 17

Pareto Chart of Standardized Effects showing the results of sensitivity analysis conducted on the design data of DOE for the 200–400 Hz frequency range

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Fig. 18

Correlation between high STL and low in-plane stiffness (E11) for the honeycomb core sandwich panels for (a) 200–400 Hz and (b) 600–800 Hz frequency range

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