Acoustic septum cap honeycomb

• US 20080020176A1
• Filed: 03/22/2007
• Published: 01/24/2008
• Est. Priority Date: 04/04/2005
• Status: Active Grant

• Current Assignee: Hexcel Corporation
• Original Assignee: Hexcel Corporation
• Inventors: Ayle, Earl
• Granted Patent: US 7,510,052 B2
• Time in Patent Office: Days
• US Class Current: 428/118
• CPC Class Codes: E04B 2001/748 Honeycomb materials
• CPC Class Codes: E04B 2001/8245 Machines for manufacturing, shaping, piercing or filling sound insulating elements
• CPC Class Codes: F02C 7/045 having provisions for noise suppression
• CPC Class Codes: F02C 7/24 Heat or noise insulation air intakes having provisions for noise suppression F02C7/045; turbine exhaust heads, chambers, or the like F01D25/30; silencing nozzles of jet-propulsion plants F02K1/00
• CPC Class Codes: F05D 2250/283 honeycomb
• CPC Class Codes: F05D 2260/96 Preventing, counteracting or reducing vibration or noise
• CPC Class Codes: G10K 11/172 using resonance effects
• CPC Class Codes: Y02T 50/60 Efficient propulsion technologies, e.g. for aircraft
• CPC Class Codes: Y10T 428/24165 Hexagonally shaped cavities
• CPC Class Codes: Y10T 428/24785 including layer embodying mechanically interengaged strands, strand portions or strand-like strips [e.g., weave, knit, etc.]

Abstract

An acoustic structure that includes a honeycomb having cells in which septum caps are located. The septum caps are formed from sheets of acoustic material and include a resonator portion and a flange portion. The flange portion has an anchoring surface that provides frictional engagement of the septum caps to the honeycomb cells when the caps are inserted into the honeycomb during fabrication of the acoustic structure. An adhesive is applied to the anchoring surface of the septum caps after the caps have been inserted into the honeycomb cells to provide a permanent bond.

Claims

1. An acoustic structure that is adapted to be located near a source of noise, said structure comprising:

a honeycomb comprising a first edge to be located nearest said source of noise and a second edge, said honeycomb further comprising a plurality of walls that extend between said first and second edges, said walls defining a plurality of cells wherein each of said cells has a cross-sectional area measured perpendicular to said walls and a depth defined by the distance between said first and second edges;

a septum cap located within at least one of said cells, said septum cap comprising a sheet of acoustic material that has a thickness and a perimeter, said sheet of acoustic material being formed into a resonator portion that has an outer edge located at said walls and a flange portion that extends between said outer edge of said resonator portion and the perimeter of said sheet of acoustic material, said septum cap comprising an adhesive flow barrier located along said outer edge of said resonator portion; and

an adhesive that bonds said anchoring surface to said wall, said adhesive covering at least a portion of said anchoring surface.

2. An acoustic structure according to claim 1 wherein said sheet of acoustic material comprises an open mesh fabric comprising woven fibers.

3. An acoustic structure according to claim 2 wherein said woven fibers are monofilament polymer fibers.

4. An acoustic structure according to claim 1 wherein said sheet of acoustic material comprises one or more folding aids located around said perimeter.

5. An acoustic structure according to claim 3 wherein said adhesive flow barrier comprises monofilament fibers that have been flattened.

6. An acoustic structure according to claim 1 wherein at least two septum are located in said cell, said septum caps being located at different depths within said cell.

7. An acoustic structure according to claim 1 which comprises multiple septum caps that are located in multiple cells wherein the septum caps are located at substantially the same depth within said cells.

8. An acoustic structure according to claim 1 wherein said sheet of acoustic material comprises a plurality of openings and wherein the size of said openings is reduced within said adhesive flow barrier.

9. A septum cap precursor comprising:

a sheet of acoustic material that has a thickness and a perimeter, said sheet of acoustic material comprising a resonator portion that has an outer edge located and a flange portion that extends between said outer edge of said resonator portion and the perimeter of said sheet of acoustic material, said sheet of acoustic material comprising an adhesive flow barrier located along said outer edge of said resonator portion.

10. A septum cap precursor according to claim 9 wherein said sheet of acoustic material comprises an open mesh fabric comprising woven fibers.

11. A septum cap precursor according to claim 10 wherein said open mesh fabric comprises monofilament polymer fibers.

12. A septum cap precursor according to claim 9 wherein said sheet of acoustic material comprises one or more folding aids located around said perimeter.

13. A septum cap precursor according to claim 11 wherein said adhesive flow barrier comprises monofilament fibers that have been flattened.

14. A septum cap precursor according to claim 9 wherein the outer edge of said resonator portion is a hexagon.

15. A septum cap precursor according to claim 9 wherein said perimeter is an octagon.

16. A septum cap precursor according to claim 9 wherein said sheet of acoustic material comprises a plurality of openings and wherein the size of said openings is reduced within said adhesive flow barrier.

17. A method for making an acoustic structure that is adapted to be located near a source of noise, said method comprising the steps of:

providing a honeycomb comprising a first edge to be located nearest said source of noise and a second edge, said honeycomb further comprising a plurality of walls that extend between said first and second edges, said walls defining a plurality of cells wherein each of said cells has a cross-sectional area measured perpendicular to said walls and a depth defined by the distance between said first and second edges;

providing at least one sheet of acoustic material that has a thickness and a perimeter, said sheet of acoustic material comprising an adhesive flow barrier;

forming said sheet of acoustic material into a septum cap comprising a resonator portion that has an outer edge and a flange portion that extends between said outer edge of said resonator portion and the perimeter of said sheet of acoustic material wherein said adhesive flow barrier is located along said outer edge of said resonator portion; and

inserting said septum cap into a cell of said honeycomb wherein said flange portion is in contact with said walls; and

adhesively bonding said anchoring flange portion to said walls.

18. A method for making an acoustic structure according to claim 17 said sheet of acoustic material comprises an open mesh fabric that has been flattened within said adhesive flow barrier.

19. A method for making an acoustic structure according to claim 17 wherein said sheet of acoustic material comprises an open mesh fabric comprising woven monofilament fibers that have been flattened within said adhesive flow barrier.

20. A method for making an acoustic structure according to claim 17 wherein said sheet of acoustic material comprises one or more folding aids located around said perimeter