scholarly journals Investigation of transmission loss through double wall structures with varying small air gaps using modal analysis.

2014 ◽  
Author(s):  
Richard Phillips
Keyword(s):  
Modal Analysis ◽  
Transmission Loss ◽  
Air Gaps ◽  
Wall Structures ◽  
Double Wall

A FINITE ELEMENT PLATE FORMULATION FOR THE ACOUSTICAL INVESTIGATION OF THIN AIR LAYERS

2013 ◽  
Vol 21 (04) ◽  
pp. 1350014 ◽  
Author(s):  
PING RONG ◽  
OTTO VON ESTORFF ◽  
LORIS NAGLER ◽  
MARTIN SCHANZ
Keyword(s):  
Finite Element ◽  
Power Series ◽  
Transmission Loss ◽  
Fluid Layer ◽  
Single Layer ◽  
Shell Element ◽  
Thin Plates ◽  
Element Analysis ◽  
Shell Elements ◽  
Double Wall

Double wall systems consisting of thin plates separated by an air gap are common light-weighted wall structures with high transmission loss. Generally, these plate-like structures are modeled in a finite element analysis with shell elements and volume elements for the air (fluid) layer. An alternative approach is presented in this paper, using shell elements for the air layer as well. First, the element stiffness matrix is obtained by removing the thickness dependence of the variational form of the Helmholtz equation by use of a power series. Second, the coupling between the acoustical shell element and the elastic structure is described. To verify the new shell element, a simple double wall system is considered. Comparing the predicted sound field with the results from a commercial FE software (with a single layer of volume elements) a very good agreement is observed. At the same time, employing the new elements with a third-order power series (4 DOFs per node), the calculation time is reduced.

scholarly journals 1003 Transmission Loss of Sound Insulator in a reverberation room Using Modal Analysis

2012 ◽  
Vol 2012.87 (0) ◽  
pp. _10-3_
Author(s):  
Yukimasa HORIKAWA ◽  
Hideo UTSUNO ◽  
Hiroshi MATSUHISA ◽  
Keisuke YAMADA ◽  
Katsutoshi SAWADA
Keyword(s):  
Modal Analysis ◽  
Transmission Loss

scholarly journals Explorer 46 Meteoroid Bumper Experiment: Earth Orbital Debris Interpretation

1985 ◽  
Vol 85 ◽  
pp. 97-97 ◽  
Author(s):  
D.J. Kessler
Keyword(s):  
Aluminum Oxide ◽  
Size Range ◽  
Interplanetary Dust ◽  
Orbital Debris ◽  
Earth Orbit ◽  
Solid Rocket Motors ◽  
Rocket Motors ◽  
Wall Structures ◽  
Solid Rocket ◽  
Double Wall

AbstractThe Meteoroid Bumper Experiment on Explorer 46 (launched 1972) was placed in Earth orbit to evaluate the effectiveness of using double-wall structures against meteoroids. This paper re-examines the data from this experiment. Certain sets of sensors were found to be penetrated much more frequently than other sets. The most plausible explanation is that nearly all of the penetrations were from an Earth orbiting population of particulates. In addition, because a large percentage of the penetrations occured soon after solid rocket motors were fired in space, the particulates are most likely 75 μm diameter aluminum oxide. Aluminum oxide particulates are a major exhaust product from solid rocket motors. The size of particulates from most current solid rocket motors is found to range between 0.1 μm to 20 μm. Modeling the orbits of particulates from these rockets predicts that measurements in Earth orbit of interplanetary dust in this size range are also likely to include Earth orbiting particulates from solid rocket motors.

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