US3948346A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Multi-layered acoustic liner
Assignee: McDonnell Douglas Corp
•
Filing: 1974-04-02
•
Granted: 1976-04-06
•
Expires: 1994-04-02
Abstract
Abstract This invention concerns a multi-layered acoustic liner which breaks up high amplitude sound and shock waves into several waves of the same type but smaller amplitudes, converting some acoustic energy into heat and shifting part of the acoustic energy to a higher frequency level to achieve better absorption by the atmosphere. The sandwich-type perforated plate acoustic liner comprises several layers of honeycomb backing material which are separated by thin perforated sheets.
Inventors
- 👤 Guenter M. Schindler
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 06:18
CPC Classifications
B; B32; B32B; B32B3/00; B32B3/26; B32B3/266; B32B3/10; B32B3/12; E; E04; E04B; E04B1/00; E04B1/62; E04B1/74; E04B1/82; E04B1/84; E04B1/86; G; G10; G10K; G10K11/00; G10K11/16; G10K11/172; B32B2305/00; B32B2305/02; B32B2305/024; B32B2307/00; B32B2307/10; B32B2607/00; E04B2001/742; E04B2001/748; Y; Y10; Y10T; Y10T428/00; Y10T428/24; Y10T428/24149; Y10T428/24165
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
94 words
A multi-layered acoustic liner with perforated sheets between layers of cellular cavity material and a perforated face sheet, each of said sheets having a perforated area of over half its total area for shifting part of the acoustic energy to a higher frequency level to achieve better absorption by the atmosphere, wherein the outgoing wave has a harmonic at some particular frequency f x = (x+1) f o whose amplitude is greater than that of the corresponding harmonic of the incoming wave f o where x = the number of layers in said panel.
Claim 2
Dependent Claim
94 words
A multi-layered acoustic liner with perforated sheets between layers of cellular cavity material and a perforated face sheet, each of said sheets having a perforated area of over half its total area for shifting part of the acoustic energy to a higher frequency level to achieve better absorption by the atmosphere, wherein the outgoing wave has a harmonic at some particular frequency f x = (x+1) f o whose amplitude is greater than that of the corresponding harmonic of the incoming wave f o where x = the number of layers in said panel.
Claim 3
Dependent Claim
31 words
A multi-layered acoustic liner as set forth in claim 1 wherein said layers have the same thickness, said thickness being of less than half a wave length of the incoming wave.
Claim 4
Dependent Claim
36 words
A multi-layered acoustic liner as set forth in claim 1 wherein a sufficient number of layers are in said liner that said harmonic of the outgoing wave is beyond the audible range of the human ear.
References Cited (Backward Citations)
GB822954A
Cited
US3380206A
Cited
US3439774A
Cited
US3542152A
Cited
US3670843A
Cited
US3481427A
Cited
US3769767A
Cited
US3734234A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-04-06 | 1979-10-06 | 1980-04-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-04-06 | 1983-10-06 | 1984-04-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-04-06 | 1987-10-06 | 1988-04-06 | $7700.00 | Window Closed / Lapsed |