US4121008A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Foam sandwich constructions
Assignee: Unitex Ltd Great Britain
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Filing: 1976-10-27
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Granted: 1978-10-17
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Expires: 1996-10-27
Abstract
Abstract A foam sandwich construction and a method for generating same. The construction includes a central foam layer which is formed of materials selected so that central layer can be a stress carrying member of the construction.
Inventors
- 👤 Robert Maxwell Seddon
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 18:41
CPC Classifications
B; B32; B32B; B32B5/00; B32B5/18; B32B27/00; B32B27/06; B32B27/065; B32B3/00; B32B3/26; B32B3/30; B63; B63B; B63B5/00; B63B5/24; E; E04; E04C; E04C2/00; E04C2/02; E04C2/10; E04C2/20; E04C2/205; B32B2250/00; B32B2250/40; B32B2262/00; B32B2262/10; B32B2262/101; B32B2262/106; B32B2266/00; B32B2266/02; B32B2266/0214; B32B2266/0278; B32B2305/00; B32B2305/08; B32B2307/00; B32B2307/50; B32B2307/51; B32B2307/54; B32B2307/542; Y; Y10; Y10S; Y10S428/00; Y10S428/902; Y10T; Y10T428/00; Y10T428/249921; Y10T428/249953; Y10T428/249987; Y10T428/249991; Y10T442/00; Y10T442/30; Y10T442/3325; Y10T442/335; Y10T442/60; Y10T442/647; Y10T442/651
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
130 words
A sandwich structure comprising two external skins each of a material having a relatively high modulus of elasticity and a relatively high tensile strength between which is sandwiched a core of a foam material having a relatively low density, a shear modulus of at least 3,400 kN/m 2 when measured at a strain of 10%, and a shear strength of not less than 620 kN/m 2 , the said external skins being uniformly and firmly fixed to the core, the shear strength of the overall structure being mainly dependent on the properties of the core, and at least 50% of the resistance to deflection of the overall structure when under load being attributable to the core and said core providing the greater part of stress transmission between the external skins.
Claim 2
Dependent Claim
130 words
A sandwich structure comprising two external skins each of a material having a relatively high modulus of elasticity and a relatively high tensile strength between which is sandwiched a core of a foam material having a relatively low density, a shear modulus of at least 3,400 kN/m 2 when measured at a strain of 10%, and a shear strength of not less than 620 kN/m 2 , the said external skins being uniformly and firmly fixed to the core, the shear strength of the overall structure being mainly dependent on the properties of the core, and at least 50% of the resistance to deflection of the overall structure when under load being attributable to the core and said core providing the greater part of stress transmission between the external skins.
Claim 3
Dependent Claim
18 words
A sandwich structure according to claim 1, wherein a said external skin is a fibre reinforced resin material.
Claim 4
Dependent Claim
13 words
A sandwich structure according to claim 2, wherein said fibres include carbon fibres.
Claim 5
Dependent Claim
13 words
A sandwich structure according to claim 2, wherein said fibres comprise glass fibres.
Claim 6
Dependent Claim
20 words
A sandwich structure according to claim 4, wherein said glass fibres are applied in the form of a woven roving.
Claim 7
Dependent Claim
20 words
A sandwich structure according to claim 4, wherein said glass fibres are applied in the form of a woven cloth.
Claim 8
Dependent Claim
21 words
A sandwich structure according to claim 4, wherein said glass fibres are applied in the form of a chopped strand mat.
Claim 9
Dependent Claim
21 words
A sandwich structure according to claim 7, wherein the length of the majority of the individual fibres is at least 3cm.
Claim 10
Dependent Claim
33 words
A sandwich structure according to claim 2, wherein the resin is a resin selected from the group consisting of polyester resin, flexibilized polyester resin, epoxy resin, flexibilized epoxy resin, polyurethane resin, polyether resin.
Claim 11
Dependent Claim
20 words
A sandwich structure according to claim 4, wherein the weight ratio of resin to glass is between 2.5:1 and 3:1.
Claim 12
Dependent Claim
24 words
A sandwich structure according to claim 5, wherein a plurality of said woven rovings are used and adjacent rovings overlap by at least 7.5cm.
Claim 13
Dependent Claim
23 words
A sandwich structure according to claim 7, wherein a plurality of said mats are used and adjacent mats overlap by at least 5cm.
Claim 14
Dependent Claim
19 words
A sandwich structure according to claim 1, wherein each of said external skins is formed of the same material.
Claim 15
Dependent Claim
27 words
A sandwich structure according to claim 1, wherein the modulus of elasticity of a said skin material is at least 3.8 × 10 6 kN/m 2 .
Claim 16
Dependent Claim
26 words
A sandwich structure according to claim 1, wherein the tensile strength of a said skin material is at least 9.3 × 10 4 kN/m 2 .
Claim 17
Dependent Claim
14 words
A sandwich structure according to claim 1, which said core material is polyurethane foam.
Claim 18
Dependent Claim
23 words
A sandwich structure according to claim 16, wherein said foam has a density of between 75 kg/m 3 and 750 kg/m 3 .
Claim 19
Dependent Claim
23 words
A sandwich structure according to claim 17, wherein said foam has a density of between 100 kg/m 3 and 250 kg/m 3 .
Claim 20
Dependent Claim
28 words
A sandwich structure according to claim 16, wherein said foam has a shear modulus measured at 10% elongation of between 4,000 kN/m 2 and 15,000 kN/m 2 .
Claim 21
Dependent Claim
24 words
A sandwich structure according to claim 16, wherein said foam has a shear strength of between 650 kN/m 2 and 2,400 kN/m 2 .
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1981-10-16 | 1982-04-17 | 1982-10-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-10-16 | 1986-04-17 | 1986-10-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-10-16 | 1990-04-17 | 1990-10-17 | $7700.00 | Window Closed / Lapsed |