1 Introduction
2 Analytical Model
2.1 The Sound Transmission Loss
2.2 The Governing Equation of Sound Wave
2.2.1 Inner Cavity
2.2.2 Outer Cavity
2.3 Equations of Motion
2.4 Boundary Conditions at the Fluid–Structure Interfaces
2.5 Solutions
2.6 Results
3 Introduction of the SEA and the FE&SEA Method
3.1 The SEA Method
3.2 The Hybrid Method
4 Comparison of the Results Computed by the Three Methods
5 Study on Composite Cylinders by the SEA Model
5.1 Effect of the Laminate Layup
Layup |
E
z[Pa] |
\( {E_\varphi } \)[Pa] |
G
12[Pa] |
B
|
D
11
|
---|---|---|---|---|---|
[45/−45/45/−45/45]s
| 1.77E10a
| 1.77E10 | 5.62E10 |
\( \left( {\begin{array}{*{20}{c}} 0 & 0 & 0 \\ 0 & 0 & 0 \\ 0 & 0 & 0 \\ \end{array} } \right) \)
| 11.5 |
[0/90/45/−45/0]s
| 1.08E11 | 6.78E10 | 2.54E10 |
\( \left( {\begin{array}{*{20}{c}} 0 & 0 & 0 \\ 0 & 0 & 0 \\ 0 & 0 & 0 \\ \end{array} } \right) \)
| 22.9 |
[0/90]5
| 1.14E11 | 1.14E11 | 4.80E9 |
\( \left( {\begin{array}{*{20}{c}} { - 9E3} & 0 & 0 \\ 0 & {9E3} & 0 \\ 0 & 0 & 0 \\ \end{array} } \right) \)
| 20.9 |
[0/10/20/30/40/50/60/70/80/90] | 8.42E10 | 8.42E10 | 2.49E10 |
\( \left( {\begin{array}{*{20}{c}} { - 3.8E4} & 0 & { - 5.3E3} \\ 0 & {3.8E4} & {5.37E3} \\ { - 5.3E3} & {5.37E3} & 0 \\ \end{array} } \right) \)
| 19.5 |
5.2 The Effect of Material
Graphite/Epoxy | Fiberglass/Epoxy | Aramid/Epoxy | |
---|---|---|---|
Density[kg/m3] | 1,600 | 1,900 | 1,500 |
E
1[Pa] | 2.21E11 | 5.6E10 | 7.6E10 |
E
2[Pa] | 6.9E9 | 1.3E10 | 5.5E9 |
v
12
| 0.25 | 0.26 | 0.34 |
G
12[Pa] | 4.8E9 | 4.2E9 | 2.3E9 |
5.3 The Effect of Radius and Length
5.4 Effect of the Structure Morphology
5.4.1 Comparison Between the Sandwich Panels and the Laminates
10-layered laminates | Sandwich t
c = 10 mm | Sandwich t
c = 20 mm | Sandwich t
c = 30 mm | |
---|---|---|---|---|
S
b [Nm] | 23 | 7,240 | 25,125 | 53,789 |
f
c [Hz] | 4,626 | 552 | 323 | 238 |
5.4.2 Comparison Between Sandwich and Stiffened Structure
Non-stiffened cylinder | Sandwich cylinder | Stiffened cylinder | |
---|---|---|---|
TL at 20 ~ 2,000 Hz | Highest | Middle | Lowest |
TL at 2,000 ~ 2,000 Hz | Middle | Highest | Lowest |
Dips of the TL curve | 2 or 3 | Very few | More than 4 |
6 Conclusion
-
Laminate layup
-
Fiber material
-
Cylinder dimensions
-
Structure morphology