US3920339A
Expired / Lapsed
US
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Strain arrestor plate for fused silica tile
Assignee: National Aeronautics and Space Administration
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Filing: 1973-11-28
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Granted: 1975-11-18
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Expires: 1993-11-28
Abstract
Abstract The invention is an improvement in the technique of attaching rigid thermal insulator tiles to metallic sub-panels or structural members on the exposed surfaces of space craft or other frameworks. Heretofore this has been done by a flexible bond, but it has been found that at temperatures below the glass transition range such bonds lose their flexibility and transfer more strains to the insulator tiles. Since the tiles are relatively weak and frangible, the effect of transmitted strains, whether mechanical or thermal, is cracking and spalling of the insulation material. The problem is solved by the inventor''s incorporation with the flexible bond a strain arrestor plate, disposed adjacent the insulator tile and secured thereto with an adhesive which may be either a flexible bond or a hard bond. In addition to high strength and high stiffness, the strain arrestor plate must have a coefficient of thermal expansion preferably matching that of the rigid insulator tiles. Since most rigid thermal insulators are made of low expansion materials, Invar may be used for the plate, where weight is not a problem, but the preferred material is the lighter weight combination of fibers cast in a thermosetting resin. The preferred material is graphite fibers in an epoxy resin, built up in layers with various fiber orientations to obtain the desired strength, stiffness and thermal properties. The strain arrestor plate is also amenable to attachment to the structural substrate by mechanical connectors.
Inventors
- 👤 James C Administrator Fletcher
- 👤 Murat H Kural
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 19:06
CPC Classifications
B; B64; B64G; B64G1/00; B64G1/22; B64G1/52; B64G1/58; Y; Y10; Y10T; Y10T403/00; Y10T403/21; Y10T428/00; Y10T428/24; Y10T428/24058; Y10T428/24074; Y10T428/24091; Y10T428/24942; Y10T428/2495; Y10T428/24959; Y10T428/31504; Y10T428/31511; Y10T428/31515; Y10T428/31522; Y10T428/31652; Y10T428/31663
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
192 words
AN IMPROVED JOINT BETWEEN A HIGH STRENGTH METAL STRUCTURAL MEMBER HAVING A RELATIVELY HIGH THERMAL COEFFICIENT OF EXPANSION AND AN INSULATING TILE MEMBER COMPOSED OF CHEMICALLY PURE FUSED SILICA, THE ASSEMBLY BEING SUBJECTED TO TEMPERATURE RANGING FROM -250* TO 2300*F, SAID TILE MEMBER HAVING A THERMAL COEFFICIENT OF EXPANSION IN THE ORDER OF 3 X 10**-7 IN/IN/*F, SAID JOINT COMPRISING ASEPARATE, THIN LAYER OF NONMETALLIC ADHESIVE BOND SECURED TO THE INSULATING MEMBER, A STRAIN ARRESTOR PLATE BEING THE SAME SIZE IN PLAN AS THE TILE SECURED TO THE ADHESIVE BOND, SAID ADHESIVE BOND BEING FLEXIBLE OR RESILIENT AT TEMPERATURES ABOVE ITS GLASS TRANSITION RANGE AND SAID STRAIN ARRESTOR PLATE HAVING A HIGH YIELD STRENGTH, HIGH STIFFNESS, A LOW COEFFICIENT OF THERMAL EXPANSION, APPROXIMATELY EQUAL TO THAT OF THE INSULATING MEMBER, AND BEING OF SUCH A THICKNESS THAT CONTRACTIONS OF THE STRUCTURAL MEMBER RESULTING FROM CHANGES IN TEMPERATURES ARE SUBSTANTIALLY ABSORBED BY THE PLATE, AND A SECOND, SEPARATE, THIN LAYER OF FLEXIBLE NONMETALLIC ADHESIVE BOND SECURING THE STRAIN ARRESTOR PLATE TO THE STRUCTURAL MEMBER, THE THIN LAYERS OF ADHESIVE BOND BEING OF SUFFICIENT THICKNESS TO SECURELY MAINTAIN THE BOND THROUGHOUT THE TEMPERATURE RANGE.
Claim 2
Dependent Claim
192 words
AN IMPROVED JOINT BETWEEN A HIGH STRENGTH METAL STRUCTURAL MEMBER HAVING A RELATIVELY HIGH THERMAL COEFFICIENT OF EXPANSION AND AN INSULATING TILE MEMBER COMPOSED OF CHEMICALLY PURE FUSED SILICA, THE ASSEMBLY BEING SUBJECTED TO TEMPERATURE RANGING FROM -250* TO 2300*F, SAID TILE MEMBER HAVING A THERMAL COEFFICIENT OF EXPANSION IN THE ORDER OF 3 X 10**-7 IN/IN/*F, SAID JOINT COMPRISING ASEPARATE, THIN LAYER OF NONMETALLIC ADHESIVE BOND SECURED TO THE INSULATING MEMBER, A STRAIN ARRESTOR PLATE BEING THE SAME SIZE IN PLAN AS THE TILE SECURED TO THE ADHESIVE BOND, SAID ADHESIVE BOND BEING FLEXIBLE OR RESILIENT AT TEMPERATURES ABOVE ITS GLASS TRANSITION RANGE AND SAID STRAIN ARRESTOR PLATE HAVING A HIGH YIELD STRENGTH, HIGH STIFFNESS, A LOW COEFFICIENT OF THERMAL EXPANSION, APPROXIMATELY EQUAL TO THAT OF THE INSULATING MEMBER, AND BEING OF SUCH A THICKNESS THAT CONTRACTIONS OF THE STRUCTURAL MEMBER RESULTING FROM CHANGES IN TEMPERATURES ARE SUBSTANTIALLY ABSORBED BY THE PLATE, AND A SECOND, SEPARATE, THIN LAYER OF FLEXIBLE NONMETALLIC ADHESIVE BOND SECURING THE STRAIN ARRESTOR PLATE TO THE STRUCTURAL MEMBER, THE THIN LAYERS OF ADHESIVE BOND BEING OF SUFFICIENT THICKNESS TO SECURELY MAINTAIN THE BOND THROUGHOUT THE TEMPERATURE RANGE.
Claim 3
Dependent Claim
22 words
The strain arrestor plate of claim 1 in which said plate is made of graphite fibers in a matrix of epoxy resin.
Claim 4
Dependent Claim
34 words
The strain arrestor plate of claim 1 in which the thickness of said plate is of the order of 0.01-0.03 inch when said refractory members have a thickness of the order of 1-10 inches.
Claim 5
Dependent Claim
28 words
The strain arrestor plate of claim 3 which is formed of laminae in which the graphite fibers are oriented at various angles between one lamina and its neighbor.
Claim 6
Dependent Claim
32 words
The improved joint specified in claim 1 in which the strain arrestor plate has a thickness of approximately 0.03 inches and the flexible adhesive bond has a thickness of approximately 0.09 inches.
Claim 7
Dependent Claim
174 words
In an insulating system for a space vehicle formed of a plurality of tile of substantially chemically pure fused silica attached to a metal substrate of the space vehicle, the tiles having a coefficient of thermal expansion markedly lower than the coefficient of expansion of the metal substrate, the improvement comprising: an intermediate member between each tile and the metal substrate forming a strain arrestor plate, said plate attached to each tile by a separate, thin layer of flexible adhesive bond, said plates attached to the metal substrate by a separate layer of adhesive bond, said plate being approximately the same size in plan as the tile, to which it is attached, said plate having a thermal coefficient of expansion approximating that of the tile and a said plate having a high modulus of elasticity and high yield strength and being of such thickness that strains resulting from contraction by the metal substrate are substantially absorbed by the strain arrestor plate, and the layer of flexible bond between the strain arrestor plate and tile.
Claim 8
Dependent Claim
174 words
In an insulating system for a space vehicle formed of a plurality of tile of substantially chemically pure fused silica attached to a metal substrate of the space vehicle, the tiles having a coefficient of thermal expansion markedly lower than the coefficient of expansion of the metal substrate, the improvement comprising: an intermediate member between each tile and the metal substrate forming a strain arrestor plate, said plate attached to each tile by a separate, thin layer of flexible adhesive bond, said plates attached to the metal substrate by a separate layer of adhesive bond, said plate being approximately the same size in plan as the tile, to which it is attached, said plate having a thermal coefficient of expansion approximating that of the tile and a said plate having a high modulus of elasticity and high yield strength and being of such thickness that strains resulting from contraction by the metal substrate are substantially absorbed by the strain arrestor plate, and the layer of flexible bond between the strain arrestor plate and tile.
Claim 9
Dependent Claim
20 words
The improved joint of claim 6 in which said plate is composed of graphite fibers in an epoxy resin matrix.
Claim 10
Dependent Claim
30 words
The improved joint of claim 7 in which said graphite fibers-epoxy resin plate is of the order of 0.01-0.03 inch for an insulator thickness of the order of 1-10 inches.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-11-17 | 1979-05-19 | 1979-11-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-11-17 | 1983-05-19 | 1983-11-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-11-17 | 1987-05-19 | 1987-11-18 | $7700.00 | Window Closed / Lapsed |