US4099408A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for testing sheet metals
Assignee: United States Steel Corp
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Filing: 1977-07-05
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Granted: 1978-07-11
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Expires: 1997-07-05
Abstract
Abstract A method of determining properties of sheet metal uses a specimen having a full width section and a reduced width section about 95% the width of the full width section in a tensile test. The strain hardening exponent is calculated from thickness and width measurements made before and after the specimen is strained to failure. The same and other measurements are used to calculate yield strength, elongation, ultimate strength and plastic strain ratio. Particularly useful for continuously yielding materials, the yield strength may also be determined from calculations using the strain hardening exponent and the ultimate strength.
Inventors
- 👤 David C. Ludwigson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 22:09
CPC Classifications
G; G01; G01N; G01N3/00; G01N3/08
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
93 words
A method for tensile testing a sheet metal specimen comprising the steps of preparing the specimen to have a reduced width portion for a part of the specimen length to be tested, thereby defining a full width section and a reduced width section, measuring the widths of the reduced width section and the full width section and the thickness of the specimen, straining the specimen to failure, measuring the thickness and width of the full width section, and calculating the strain hardening exponent of the sheet metal from the thickness and width measurements.
Claim 2
Independent Claim
93 words
A method for tensile testing a sheet metal specimen comprising the steps of preparing the specimen to have a reduced width portion for a part of the specimen length to be tested, thereby defining a full width section and a reduced width section, measuring the widths of the reduced width section and the full width section and the thickness of the specimen, straining the specimen to failure, measuring the thickness and width of the full width section, and calculating the strain hardening exponent of the sheet metal from the thickness and width measurements.
Claim 3
Dependent Claim
93 words
A method according to claim 1 in which the strain hardening exponent is calculated using the expression ##EQU7## where 1n is the symbol for natural logarithms. n is the strain hardening exponent, rw is the width of the reduced width section, fw o is the width of the full width section before straining to failure, t o is the thickness before straining to failure, fw f is the width of the full width section after straining to failure, and t f is the thickness of the full width section after straining to failure.
Claim 4
Dependent Claim
24 words
A method according to claim 2 in which the specimen is prepared with the reduced width between 92% and 98% of the full width.
Claim 5
Dependent Claim
26 words
A method according to claim 3 in which the specimen is prepared with the reduced width between about 94.5% and about 95.5% of the full width.
Claim 6
Dependent Claim
17 words
A method according to claim 4 in which the specimen is punched out of the sheet metal.
Claim 7
Dependent Claim
51 words
A method according to claim 5 which includes the steps of measuring the yield load while the specimen is being strained to failure, calculating the yield strength from measurements of thickness, width and yield load, and compensating the calculated yield strength for the effect of the sheared edges of the specimen.
Claim 8
Dependent Claim
52 words
A method according to claim 5 which includes the steps of measuring the maximum load while the specimen is strained to failure, calculating the ultimate tensile strength from measurements of thickness, width and maximum load, and compensating the calculated ultimate tensile strength for the effect of the sheared edges of the specimen.
Claim 9
Dependent Claim
46 words
A method according to claim 7 which includes calculating the yield strength according to the expression YS = UTS (C/n).sup.n where YS is the yield strength, UTS is the calculated and compensated ultimate strength, n is the calculated strain hardening exponent, and C is a constant.
Claim 10
Dependent Claim
71 words
A method according to claim 3 which includes the steps of measuring the maximum load while the specimen is strained to failure, calculating the ultimate strength from measurements of thickness, width and maximum load, and calculating the yield strength according to the expression YS = UTS (C/n).sup.n where YS is the yield strength, UTS is the calculated ultimate strength, n is the calculated strain hardening exponent, and C is a constant.
Claim 11
Dependent Claim
24 words
A method according to claim 1 in which the specimen is prepared with the reduced width between 92% and 98% of the full width.
Claim 12
Dependent Claim
26 words
A method according to claim 10 in which the specimen is prepared with the reduced width between about 94.5% and about 95.5% of the full width.
Claim 13
Dependent Claim
17 words
A method according to claim 11 in which the specimen is punched out of the sheet metal.
Claim 14
Dependent Claim
51 words
A method according to claim 12 which includes the steps of measuring the yield load while the specimen is being strained to failure, calculating the yield strength from measurements of thickness, width and yield load, and compensating the calculated yield strength for the effect of the sheared edges of the specimen.
Claim 15
Dependent Claim
52 words
A method according to claim 12 which includes the steps of measuring the maximum load while the specimen is strained to failure, calculating the ultimate tensile strength from measurements of thickness, width and maximum load, and compensating the calculated ultimate tensile strength for the effect of the sheared edges of the specimen.
Claim 16
Dependent Claim
46 words
A method according to claim 14 which includes calculating the yield strength according to the expression YS = UTS (C/n).sup.n where YS is the yield strength, UTS is the calculated and compensated ultimate strength, n is the calculated strain hardening exponent, and C is a constant.
Claim 17
Dependent Claim
71 words
A method according to claim 10 which includes the steps of measuring the maximum load while the specimen is strained to failure, calculating the ultimate strength from measurements of thickness, width and maximum load, and calculating the yield strength according to the expression YS = UTS (C/n).sup.n where YS is the yield strength, UTS is the calculated ultimated strength, n is the calculated strain hardening exponent, and C is a constant.
References Cited (Backward Citations)
US3733049A
Cited
US3927558A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1981-07-10 | 1982-01-09 | 1982-07-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-07-10 | 1986-01-09 | 1986-07-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-07-10 | 1990-01-09 | 1990-07-11 | $7700.00 | Window Closed / Lapsed |