US4099411A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Strain measurement
Assignee: NATIONAL RESEARCH DEVELOPMENT CORP
•
Filing: 1977-03-23
•
Granted: 1978-07-11
•
Expires: 1997-03-23
Abstract
Abstract Apparatus and methods for measuring strain and torque are described. The apparatus, which is used in the methods, usually includes a thin walled cylinder within a thick walled cylinder, the cylinders being fixed together at their ends only, means for vibrating the walls of the thin walled cylinder and means for indicating the frequency of vibration. As torque is applied to the thick walled cylinder and therefore to the thin walled cylinder, longitudinal strain appears in the thin walled cylinder and the frequency of vibration changes. Thus an indication is obtained of the applied torque or of strain in a test member applying the torque.
Inventors
- 👤 George Albert Woolvet
- 👤 Bryan Peter Tolley
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 01:07
CPC Classifications
G; G01; G01L; G01L1/00; G01L1/10; Y; Y10; Y10S; Y10S73/00; Y10S73/01
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
173 words
Apparatus for strain measurement, comprising: a first cylinder having a relatively thin wall at least over a major portion of its length; a second cylinder having a relatively thick wall; one of said first and second cylinders being at least partially disposed within the other, with said first cylinder being fixed against relative rotation and longitudinal movement relative to said second cylinder at two positions which are spaced apart longitudinally with respect to the cylinders, but not so fixed between the said positions; exciting means for vibrating the wall of said first cylinder; loading means for longitudinally straining the wall of said first cylinder by an amount dependent upon a strain to be measured; and means for providing a signal representative of the frequency of vibrations of the wall of said first cylinder, said first cylinder wall being of a thickness such that an appreciable change in said frequency occurs when longitudinal strains, dependent on strains within a range to be measured, are applied to said first cylinder wall by said loading means.
Claim 2
Dependent Claim
173 words
Apparatus for strain measurement, comprising: a first cylinder having a relatively thin wall at least over a major portion of its length; a second cylinder having a relatively thick wall; one of said first and second cylinders being at least partially disposed within the other, with said first cylinder being fixed against relative rotation and longitudinal movement relative to said second cylinder at two positions which are spaced apart longitudinally with respect to the cylinders, but not so fixed between the said positions; exciting means for vibrating the wall of said first cylinder; loading means for longitudinally straining the wall of said first cylinder by an amount dependent upon a strain to be measured; and means for providing a signal representative of the frequency of vibrations of the wall of said first cylinder, said first cylinder wall being of a thickness such that an appreciable change in said frequency occurs when longitudinal strains, dependent on strains within a range to be measured, are applied to said first cylinder wall by said loading means.
Claim 3
Dependent Claim
18 words
Apparatus according to claim 1, wherein said first cylinder is at least partially disposed inside said second cylinder.
Claim 4
Dependent Claim
67 words
Apparatus according to claim 2 wherein said second cylinder has an aperture in its wall between and remote from the said positions, and the apparatus includes an elongated member fixed to said first cylinder and projecting through the aperture, the aperture having a circumferential dimension sufficient to allow the elongated member to rotate about the longitudinal axis of said first cylinder over at least a few degrees.
Claim 5
Dependent Claim
38 words
Apparatus according to claim 3 wherein the elongated member is fixed to a relatively thick portion of the wall of said first cylinder between two relatively thin walled portions, the thick portion extending completely round said first cylinder.
Claim 6
Dependent Claim
25 words
Apparatus according to claim 1 including means for applying an adjustable tension to said first cylinder by tensioning said first cylinder against said second cylinder.
Claim 7
Dependent Claim
54 words
Apparatus according to claim 2 wherein the wall of said first cylinder is of a metal which is attracted by a magnetic field, the exciting means includes a coil magnetically coupled to a member comprising a permanent magnet or magnetic material, and the apparatus includes means for passing an alternating current through the coil.
Claim 8
Dependent Claim
35 words
Apparatus according to claim 6 wherein the means for providing a signal representative of the frequency of vibrations includes a further coil magnetically coupled to a further member comprising a permanent magnet of magnetic material.
Claim 9
Dependent Claim
36 words
Apparatus according to claim 7 wherein the axes of the two coils are mutually at right angles, the two coils are within said first cylinder, and the means for passing alternating current include the further coil.
Claim 10
Dependent Claim
24 words
Apparatus according to claim 8 including a frequency selective amplifier with input connected to the further coil and output connected to the other coil.
Claim 11
Dependent Claim
30 words
Apparatus according to claim 9 wherein the amplifier is within said first cylinder, and said second cylinder is provided with slip rings for connections to the coils and the amplifier.
Claim 12
Dependent Claim
26 words
Apparatus according to claim 9 including shaping means for squaring the waveform of current from the amplifier, and a counter for counting the pulses so formed.
Claim 13
Dependent Claim
33 words
Apparatus according to claim 11 including gating means, means for coupling the gating means between the amplifier and the counter, and means for enabling the gating means for an interval of selectable duration.
Claim 14
Dependent Claim
48 words
Apparatus according to claim 9 including a source of pulses, a counter, gating means, means for coupling the gating means between the counter and the pulse source, and means for enabling the gating means for an interval dependent on the period of the output signal of the amplifier.
Claim 15
Dependent Claim
107 words
Apparatus for strain measurement, comprising: a cylinder; exciting means for vibrating the wall of said cylinder; loading means for longitudinally straining said cylinder wall by applying torsion to the cylinder, the applied torsion being dependent on a strain to be measured; means for so constraining said cylinder that its length cannot change freely; and means for providing a signal representative of the frequency of vibrations of said cylinder wall, the cylinder wall being of a thickness such that an appreciable change in said frequency occurs when longitudinal strains, dependent on strains within a range to be measured, are applied to said cylinder wall by said loading means.
Claim 16
Dependent Claim
107 words
Apparatus for strain measurement, comprising: a cylinder; exciting means for vibrating the wall of said cylinder; loading means for longitudinally straining said cylinder wall by applying torsion to the cylinder, the applied torsion being dependent on a strain to be measured; means for so constraining said cylinder that its length cannot change freely; and means for providing a signal representative of the frequency of vibrations of said cylinder wall, the cylinder wall being of a thickness such that an appreciable change in said frequency occurs when longitudinal strains, dependent on strains within a range to be measured, are applied to said cylinder wall by said loading means.
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) | 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 |