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US5090249A
Expired / Lapsed
US
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Apparatus and method for testing the mechanical properties of a sample
Assignee: Individual
•
Filing: 1990-08-08
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Granted: 1992-02-25
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Expires: 2010-08-08
Abstract
Abstract Creep/recovery tests of a small sample are carried out on a conventional testing machine with vertical compression capabilities using an additional spring which allows the drive system of the testing machine to apply the force to the small sample substantially instantaneously and then to maintain that force substantially constant as required for a creep/recovery test. The addition of the spring allows the drive system to be halted at the predetermined required force with high accuracy. The spring is selected to have a large deformation relative to the deformation of the sample during the creep period so that the force is maintained substantially constant irrespective of the creep deformation of the sample. For the first time this arrangement allows creep/recovery tests of small samples such as seeds to be carried out.
Inventors
- 👤 Jerzy Bielewicz
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 09:04
CPC Classifications
G; G01; G01N; G01N3/00; G01N3/08; G01N33/00; G01N33/0077; G01N2203/00; G01N2203/0001; G01N2203/0005; G01N2203/0014; G01N2203/0016; G01N2203/0019; G01N2203/0058; G01N2203/0069; G01N2203/0071; G01N2203/02; G01N2203/026; G01N2203/0286
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
337 words
A method for testing the mechanical properties of a sample of a solid material comprising providing a first abutment member having first means thereon for engaging the sample, providing a second abutment member having second means thereon for engaging the sample, placing the sample between the abutment members for application thereto of force in a longitudinal testing direction, moving the second abutment member relative to the first abutment member in said longitudinal testing direction to apply stress to the sample to cause strain in the sample, and measuring the stress and strain for analysis of the mechanical properties of the sample, wherein the movement of the second abutment member is applied from a movable element through a spring located between the movable element and the second abutment member so as to communicate force therebetween, the spring being elastically deformed during said movement and wherein the method includes the steps of driving the movable element with a motor in a direction to increase the force and at a rapid rate to simulate instantaneous application of the force, detecting the force with a load cell separate from the spring, automatically controlling the motor in dependence upon the detected force so as to halt the motor upon reaching a predetermined required maximum force, maintaining the motor halted for a predetermined period of time so as to provide a period for creep of the sample during which the sample is maintained under a substantially constant dead load, after said period of time driving the movable element with said motor in a direction to decrease the force and at a rapid rate to simulate instantaneous removal of the force so as to allow recovery of the sample, the spring being selected such that the amount of elastic deformation of the spring at the beginning of the creep period is greater than the amount of deformation of the sample which occurs during the creep period by a factor sufficiently large to maintain the assumption of a constant dead load during the creep period.
Claim 2
Independent Claim
337 words
A method for testing the mechanical properties of a sample of a solid material comprising providing a first abutment member having first means thereon for engaging the sample, providing a second abutment member having second means thereon for engaging the sample, placing the sample between the abutment members for application thereto of force in a longitudinal testing direction, moving the second abutment member relative to the first abutment member in said longitudinal testing direction to apply stress to the sample to cause strain in the sample, and measuring the stress and strain for analysis of the mechanical properties of the sample, wherein the movement of the second abutment member is applied from a movable element through a spring located between the movable element and the second abutment member so as to communicate force therebetween, the spring being elastically deformed during said movement and wherein the method includes the steps of driving the movable element with a motor in a direction to increase the force and at a rapid rate to simulate instantaneous application of the force, detecting the force with a load cell separate from the spring, automatically controlling the motor in dependence upon the detected force so as to halt the motor upon reaching a predetermined required maximum force, maintaining the motor halted for a predetermined period of time so as to provide a period for creep of the sample during which the sample is maintained under a substantially constant dead load, after said period of time driving the movable element with said motor in a direction to decrease the force and at a rapid rate to simulate instantaneous removal of the force so as to allow recovery of the sample, the spring being selected such that the amount of elastic deformation of the spring at the beginning of the creep period is greater than the amount of deformation of the sample which occurs during the creep period by a factor sufficiently large to maintain the assumption of a constant dead load during the creep period.
Claim 3
Dependent Claim
28 words
A testing method according to claim 1 wherein the spring comprises a coil spring having a central axis of the coil spring parallel to said longitudinal testing direction.
Claim 4
Dependent Claim
45 words
A testing method according to claim 1 wherein the movable element is driven by a lead screw and wherein deformation of the sample is measured by a linear detection device connected between the second abutment member and a fixed point on the first abutment member.
Claim 5
Dependent Claim
24 words
A testing method according to claim 1 wherein the deformation of the sample is less than five percent of the deformation of the spring.
Claim 6
Dependent Claim
23 words
A testing method according to claim 1 wherein the dimension of the sample in the longitudinal testing direction is less than five millimeters.
Claim 7
Dependent Claim
92 words
A testing method according to claim 1 wherein each of the first and second abutment members includes a respective sample engaging surface with the surfaces being parallel and at right angles to the longitudinal testing direction for compression of the sample between the surfaces, the spring comprising a compression spring having one end of the spring engaging the second abutment member at a surface parallel to the contact surface thereof and extending therefrom longitudinally of said longitudinal testing direction and engaging the movable element at a surface thereof parallel to said surfaces.
Claim 8
Dependent Claim
27 words
A testing method according to claim 6 including guide means for guiding movement of the second abutment member in a direction parallel to said longitudinal testing direction.
Claim 9
Dependent Claim
25 words
A testing method according to claim 1 including measuring the deflection of the spring to determine the force applied thereby to the second abutment member.
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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) | 1995-02-24 | 1995-08-26 | 1996-02-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-02-24 | 1999-08-26 | 2000-02-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-02-24 | 2003-08-26 | 2004-02-25 | $7700.00 | Window Closed / Lapsed |