US3718065A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Tension indicating fastener
Assignee: IIT Research Institute
•
Filing: 1970-12-24
•
Granted: 1973-02-27
•
Expires: 1990-12-24
Abstract
Abstract A bolt having a shank and integral head has a strip of photoelastic material mounted in the head for manifesting in the form of photoelastic fringes linearly related to bolt tension the bending stresses created in the head during loading of the bolt. To determine the tension in the bolt during or after loading, polarized light is directed toward the photoelastic strip and reflected light from the strip is analyzed to measure fringe order. The fringe order is related to the amount of bending stresses in the head of the bolt by a predetermined calibration curve, the bending stresses being linearly related to bolt tension.
Inventors
- 👤 T Liber
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 23:59
CPC Classifications
G; G01; G01B; G01B11/00; G01B11/16; G01B11/18; F; F16; F16B; F16B31/00; F16B31/02; G01L; G01L5/00; G01L5/24
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
140 words
A bolt comprising an externally threaded shank, a head integrally mounted to the end of said shank, a ridge formed on said head, said ridge being adapted to transmit bending stresses created in said head during tensioning of said bolt while minimizing the influence of stresses transverse to said bending stresses on said ridge, a strip of photoelastic material having a side mounted upon said ridge, said strip being adapted to manifest said bending stresses in the form of photoelastic fringes linearly related to the bolt tension, other sides of said strip being free of said head to reduce the effect of said transverse stresses on said strip, and a layer of reflecting adhesive for mounting said strip to said ridge, said layer of reflecting adhesive being adapted to permit the observation of said fringes on said strip by reflection.
Claim 2
Dependent Claim
140 words
A bolt comprising an externally threaded shank, a head integrally mounted to the end of said shank, a ridge formed on said head, said ridge being adapted to transmit bending stresses created in said head during tensioning of said bolt while minimizing the influence of stresses transverse to said bending stresses on said ridge, a strip of photoelastic material having a side mounted upon said ridge, said strip being adapted to manifest said bending stresses in the form of photoelastic fringes linearly related to the bolt tension, other sides of said strip being free of said head to reduce the effect of said transverse stresses on said strip, and a layer of reflecting adhesive for mounting said strip to said ridge, said layer of reflecting adhesive being adapted to permit the observation of said fringes on said strip by reflection.
Claim 3
Dependent Claim
15 words
A bolt according to claim 1, wherein said strip is formed of a birefringent material.
Claim 4
Dependent Claim
12 words
A bolt according to claim 2, wherein said material is an epoxy.
Claim 5
Dependent Claim
32 words
A bolt according to claim 1, wherein said head has a slot formed therein substantially parallel to and adjacent said ridge to isolate said strip mounted upon said ridge from said head.
Claim 6
Dependent Claim
134 words
A fastener for providing indication of the tension therein, comprising a shank, a head integrally mounted to the end of said shank, a portion of said head being substantially isolated from transverse stresses, and a photoelastic member having a side thereof mounted to said head portion and extending substantially across the entire width thereof, for manifesting in the form of photoelastic fringes bending stresses created in the head during tensioning of said fastener, said bending stresses being linearly related to fastener tension, said head portion being formed between a pair of parallel slots extending substantially across the entire width thereof, the portion of said head therebetween comprising a ridge, said slots serving to minimize the influence of stresses transverse to said bending stresses on said ridge, said photoelastic member being mounted upon said ridge.
Claim 7
Dependent Claim
134 words
A fastener for providing indication of the tension therein, comprising a shank, a head integrally mounted to the end of said shank, a portion of said head being substantially isolated from transverse stresses, and a photoelastic member having a side thereof mounted to said head portion and extending substantially across the entire width thereof, for manifesting in the form of photoelastic fringes bending stresses created in the head during tensioning of said fastener, said bending stresses being linearly related to fastener tension, said head portion being formed between a pair of parallel slots extending substantially across the entire width thereof, the portion of said head therebetween comprising a ridge, said slots serving to minimize the influence of stresses transverse to said bending stresses on said ridge, said photoelastic member being mounted upon said ridge.
References Cited (Backward Citations)
CA687405A
Cited
US1473033A
Cited
US2272030A
Cited
US2543705A
Cited
US2824481A
Cited
GB959785A
Cited
US3106862A
Cited
US3224316A
Cited
GB1119530A
Cited
US3354702A
Cited
US3462223A
Cited
US3495907A
Cited
US3383974A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-02-27 | 1976-08-28 | 1977-02-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-02-27 | 1980-08-28 | 1981-02-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-02-27 | 1984-08-28 | 1985-02-27 | $7700.00 | Window Closed / Lapsed |