Noise reduction system for structures

• US 8,127,889 B1
• Filed: 09/15/2009
• Issued: 03/06/2012
• Est. Priority Date: 09/15/2009
• Status: Active Grant

• Current Assignee: The Boeing Co.
• Original Assignee: The Boeing Co.
• Inventors: Mathur, Gopal Prasad
• Primary Examiner(s): San Martin, Edgardo
• Application Number:
  US12/559,710
• Time in Patent Office: 903 Days
• Field of Search: 181/290, 181/292, 181/288, 181/214, 181/285, 181/286, 244/1.N, 244/119, 244/117.R, 244/123.13, 244/121
• US Class Current: 181/290
• CPC Class Codes: B64C 1/40 Sound or heat insulation , e.g. using insulation blankets
• CPC Class Codes: G10K 11/172 using resonance effects
• CPC Class Codes: Y02T 50/40 Weight reduction

Abstract

A method and apparatus are present for reducing noise. The apparatus comprises a core and a face sheet. The core is configured to reduce a speed of shear waves traveling through the core. The face sheet is located over a first surface of the core and is configured to reduce a speed of bending waves traveling through the face sheet. A second surface of the core is configured for attachment to a surface of a structure.

Claims

1. An apparatus for reducing the speed of shear waves and bending waves passing through a structure comprising:

a first core, the first core having a first surface and a second surface a damping layer located on a second surface of the first core;

a first face sheet located over the damping layer and opposite the first core,

a second face sheet located on a second surface of the first core;

a second core located between the second face sheet and a surface of the structure;

wherein the first core, the damping layer, the first face sheet, the second face sheet, and the second core reduce a speed of shear waves traveling through the structure and reduce a speed of bending waves traveling through the structure.

2. The apparatus of claim 1, wherein the first core and the second core reduce the speed of shear waves from a supersonic speed to a subsonic speed.

3. The apparatus of claim 1, wherein the first face sheet and the second face sheet reduce the speed of bending waves from a supersonic speed to a subsonic speed.

4. The apparatus of claim 1, wherein the core is selected from one of a solid core and a honeycomb core.

5. The apparatus of claim 1, wherein a number of channels are present in the core.

6. The apparatus of claim 1, wherein the core is comprised of a material selected from one of foam, paper, melamine foam, polymeric compound foam, aramid fiber paper, and para-aramid fiber paper.

7. The apparatus of claim 1, wherein the face sheet is comprised of a material selected from one of aluminum, metal, glass, carbon fiber, graphite fiber, Kevlar®

fiber, and a composite material.

8. The apparatus of claim 1, wherein the core and the face sheet form a noise reduction device and further comprising:

a number of additional noise reduction devices.

9. The apparatus of claim 1, wherein the core and the face sheet form a noise reduction device and further comprising:

a fiberglass blanket located over the noise reduction device.

10. The apparatus of claim 8, wherein the noise reduction device is in a form of a tile.

11. The apparatus of claim 1, wherein the structure is selected from one of a composite structure and a metallic structure.

12. The apparatus of claim 1 further comprising:

the structure, wherein the structure is for a platform selected from one of a mobile platform, a stationary platform, a land-based structure, an aquatic-based structure, a space-based structure, an aircraft, a surface ship, a tank, a personnel carrier, a train, a spacecraft, a space station, a submarine, an automobile, a power plant, a house, a stadium, a manufacturing facility, and an office building.

13. A method for reducing noise, the method comprising:

identifying a structure for noise reduction;

attaching a first set of noise reduction devices to the structure in which the first noise reduction device comprises a core having a first surface and a second surface, and a first face sheet disposed on the first surface of the core, and wherein the core is attached to the structure;

attaching a second set of noise reduction devices to the first set of noise reduction devices, the second set of noise reduction devices comprising a second core, a second face sheet, and a damping layer positioned between the second core and the second face sheet;

reducing a speed of shear waves traveling through the core; and

reducing a speed of bending waves traveling through the face sheet.

14. The method of claim 13, further comprising reducing the speed of shear waves traveling through the core from a supersonic speed to a subsonic speed, and reducing the speed of bending waves traveling through the face sheet from a supersonic speed to a subsonic speed.

15. The method of claim 13, further comprising the step of absorbing energy from vibrations in the noise reduction device due to the movement of shear waves.

16. The method of claim 13 further comprising:

placing a fiberglass blanket over the number of noise reduction devices.

17. The method of claim 13 wherein the noise reduction devices comprise tiles.

20. The method of claim 13, wherein the first and the second face sheet comprise a material selected from the group consisting of metals, aluminum, glass, carbon fiber, graphite fiber, and, composite materials, and wherein the damping layer comprises a viscoelastic material.

18. A system for reducing the speed of sound waves passing into a structure comprising:

a structure having a first surface;

shear waves traveling through the structure, the shear waves characterized by a speed;

bending waves traveling through the structure, the bending waves characterized by a speed;

a tile having a first surface and a second surface, wherein the first surface of the tile is attached to the first surface of the structure;

the tile comprising a first core having a first surface and a second surface;

a first face sheet disposed on the first surface of the core;

a second core disposed on the first face sheet, a damping layer disposed on the second core, and a second face sheet disposed on the damping layer;

wherein the speed of the shear waves traveling through the core is reduced; and

wherein the speed of the bending waves traveling through the face sheet is reduced.

19. The system of claim 18, wherein the first and the second face sheet comprise a material selected from the group consisting of metals, aluminum, glass, carbon fiber, graphite fiber, and, composite materials, and wherein the damping layer comprises a viscoelastic material.