Inner barrel of an engine inlet with laser-machined acoustic perforations

Patent metadata

Field	Value
Publication number	US-11052490-B2
Application number	US-201815964331-A
Country	US
Kind code	B2
Filing date	Apr 27, 2018
Priority date	Apr 27, 2018
Publication date	Jul 6, 2021
Grant date	Jul 6, 2021

Abstract

A forming system includes a femtosecond laser and a control unit that includes one or more processors operatively connected to the femtosecond laser. The femtosecond laser is configured to emit laser pulses onto an inner surface of a face sheet of an acoustic inner barrel. The acoustic inner barrel includes an acoustic core comprising an array of hexagonal cells attached to an outer surface of the face sheet that is opposite the inner surface. The control unit is configured to control the femtosecond laser to laser drill a plurality of perforations in the face sheet via emitting laser pulses at pulse durations between about 100 femtoseconds and about 10,000 femtoseconds and at frequencies over 100,000 Hz such that the perforations are formed without burning portions of the face sheet or the acoustic core surrounding the perforations.

First claim

What is claimed is:

1. A method comprising:
attaching a face sheet to an acoustic core; and
controlling a femtosecond laser to laser drill a plurality of perforations in the face sheet without burning portions of the face sheet surrounding the perforations, wherein the controlling comprises controlling the femtosecond laser to emit laser pulses at multiple perforation locations along the face sheet one at a time in a sequence such that a first set of one or more laser pulses is emitted at a first perforation location and then a second set of one or more laser pulses is emitted at a second perforation location, the controlling further comprises controlling the femtosecond laser to repeat the sequence multiple times, such that a third set of one or more laser pulses is emitted at the first perforation location subsequent to the second set being emitted at the second perforation location and before a fourth set of one or more laser pulses is emitted at the second perforation location, to gradually form the perforations at the multiple perforation locations in the sequence.

2. The method of claim 1 , wherein the attaching of the face sheet to the acoustic core occurs prior to the laser drilling of the perforations in the face sheet.

3. The method of claim 2 , wherein the acoustic core has an annular barrel shape and an interior side of the acoustic core defines a cavity, wherein attaching the face sheet to the acoustic core comprises bonding an outer surface of the face sheet to the interior side of the acoustic core.

4. The method of claim 1 , wherein attaching the face sheet to the acoustic core comprises forming the face sheet in-situ on the acoustic core.

5. The method of claim 4 , wherein the face sheet is formed in-situ on the acoustic core via auto-fiber placement (AFP) of multiple layers of fiber-reinforced material to define the face sheet.

6. The method of claim 1 , wherein the controlling comprises controlling the femtosecond laser to emit laser pulses on the face sheet at a frequency of at least 100,000 Hz.

7. The method of claim 1 , wherein the controlling comprises controlling the femtosecond laser to emit laser pulses on the face sheet at pulse durations between 100 femtoseconds and 10,000 femtoseconds.

8. The method of claim 1 , wherein the controlling comprises forming the perforations to have diameters between 50 micrometers and 500 micrometers.

9. The method of claim 1 , further comprising mounting the acoustic core and the face sheet to an inner side of an inlet cowl of an engine such that the face sheet provides a boundary for directing air flow through the engine.

10. The method of claim 1 , further comprising curing the face sheet and the acoustic core after attaching the face sheet to the acoustic core and prior to controlling the femtosecond laser to laser drill the perforations in the face sheet.

11. A method comprising: forming a face sheet in-situ on an interior side of an acoustic core that comprises an array of hexagonal cells, the face sheet formed via auto-fiber placement of multiple layers of fiber- reinforced material on the acoustic core; and controlling a femtosecond laser to laser drill a plurality of perforations in the face sheet that is formed via emitting laser pulses at pulse durations between 100 femtoseconds and 10,000 femtoseconds and at frequencies at least 100,000 Hz such that the perforations are formed without burning portions of the face sheet surrounding the perforations, wherein the controlling comprises controlling the femtosecond laser to emit laser pulses at multiple perforation locations along the face sheet one at a time in a sequence such that a first set of one or more laser pulses is emitted at a first perforation location and then a second set of one or more laser pulses is emitted at a second perforation location, the controlling further comprises controlling the femtosecond laser to repeat the sequence multiple times, such that a third set of one or more laser pulses is emitted at the first perforation location subsequent to the second set being emitted at the second perforation location and before a fourth set of one or more laser pulses is emitted at the second perforation location, to gradually form the perforations at the multiple perforation locations in the sequence.

12. The method of claim 11 , wherein the controlling comprises forming the perforations to have diameters between 50 micrometers and 500 micrometers.

13. The method of claim 11 , wherein the acoustic core and the face sheet define an acoustic inner barrel, and the method further comprises shaping the acoustic inner barrel into an annular barrel shape prior to controlling the femtosecond laser to laser drill the perforations in the face sheet.

14. The method of claim 1 , wherein the acoustic core and the face sheet define an acoustic inner barrel that has an annular barrel shape, and the method further comprises gradually rotating the acoustic inner barrel relative to the femtosecond laser as the femtosecond laser drills the plurality of perforations in the face sheet.

15. The method of claim 14 , wherein the acoustic inner barrel is gradually rotated by rollers of a positioning platform, the rollers arranged to engage and hold the acoustic inner barrel in a vertical orientation such that a centerline axis of the acoustic inner barrel is parallel to a horizontal plane of the positioning platform.

Assignees

• Boeing Co

Inventors

• Reeves Jake Adam
• Negley Mark Alan
• Herrera Eric
• Bauman John Scott
• Bertolucci Brandon L
• Horst Perry T

Classifications

• F02C7/045

  having provisions for noise suppression · CPC title

• B23K2101/001

  Turbines · CPC title

• B23K26/384 Primary

  of specially shaped holes · CPC title

• B23K26/0624

  using ultrashort pulses, i.e. pulses of 1 ns or less · CPC title

• F05D2260/96

  Preventing, counteracting or reducing vibration or noise · CPC title