GB690326A - Improvements in or relating to the electrical measurement of mechanical strains - Google Patents
Improvements in or relating to the electrical measurement of mechanical strainsInfo
- Publication number
- GB690326A GB690326A GB2275647A GB2275647A GB690326A GB 690326 A GB690326 A GB 690326A GB 2275647 A GB2275647 A GB 2275647A GB 2275647 A GB2275647 A GB 2275647A GB 690326 A GB690326 A GB 690326A
- Authority
- GB
- United Kingdom
- Prior art keywords
- output
- pulse
- bridge
- circuits
- oscillator
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L1/00—Measuring force or stress, in general
- G01L1/20—Measuring force or stress, in general by measuring variations in ohmic resistance of solid materials or of electrically-conductive fluids; by making use of electrokinetic cells, i.e. liquid-containing cells wherein an electrical potential is produced or varied upon the application of stress
- G01L1/22—Measuring force or stress, in general by measuring variations in ohmic resistance of solid materials or of electrically-conductive fluids; by making use of electrokinetic cells, i.e. liquid-containing cells wherein an electrical potential is produced or varied upon the application of stress using resistance strain gauges
- G01L1/225—Measuring circuits therefor
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R1/00—Details of instruments or arrangements of the types included in groups G01R5/00 - G01R13/00 and G01R31/00
- G01R1/30—Structural combination of electric measuring instruments with basic electronic circuits, e.g. with amplifier
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)
- Measurement Of Length, Angles, Or The Like Using Electric Or Magnetic Means (AREA)
- Arrangements For Transmission Of Measured Signals (AREA)
Abstract
690,326. Electric measuring systems. ELLIOTT BROS. (LONDON), Ltd., and YATES, J. G. Aug. 5, 1948 [Aug. 15, 1947], No. 22756/47. Class 40 (i) [Also in Groups XXXVI and XL(c)] To measure a physical effect, e.g. strain, a number of resistance strain gauges mounted in different positions are connected in pulse-energized bridge circuits having their outputs applied to a cathode ray tube. The pulses may be D.C. or A.C. and in the latter case may be produced by feeding a frequency modulated wave through band pass filters or piezo-electric filters to the gauge circuits. Alternatively the resistance strain gauges may be replaced by temperature, humidity, light-sensitive frequency or magnetic-field sensitive elements or capacitor or inductor transmitters may be used to measure displacement. A number, e.g. ten, bridge-circuits 1 having their outputs connected in parallel are energized sequentially from a pulse-generator 3, comprising eleven flip-flop connected double-triodes arranged to trigger one another in a closed chain Fig. 5 (not shown). The eleventh stage allows for fly back in the C.R.T. time base. The shape of each pulse is regulated by a shaping circuit 5 controlled by a master oscillator 6. A square pulse output from the shaping circuit is used as a brightening pulse for the C.R.T. and is so adjusted that the initial disturbed portion P2 of the bridge-output-pulse due to reactances in the circuits, is left dark. A third output synchronizes a stepped-voltage-generator 7. In one position of the switch 8 the stepped voltage is connected to the X-plate-ampliner 9 and the bridge output is amplified at 2 and connected to the Y-plateamplifier 11. to produce traces as in Fig. 2. In the other position of the switch 8 the stepped voltage is superimposed on amplified bridge output fed to the Y-plates, and a saw tooth wave is applied to the X-plates whereby expanded traces as in Fig. 3 are obtained. For photographic recording the time base is disconnected and the film traversed at a convenient speed. An alternative method of pulsing the bridgecircuits 1 comprises a frequency-modulated oscillator 30 Fig. 9 which increases continuously or in steps from say 500-1000 Kc/s over a 100 microsecond period and returns to 500 Kc/s in 10 microseconds Fig. 10A, said oscillator feeding the bridge circuits through bandpass filters each tuned to accept a band such as OA, AB, &c. When the strains are inaccessible members such as an aeroplane propeller the gauge and band-pass filter units may be mounted on the propeller and connected to common input and output leads terminating on the prop-shaft in slip rings which have instead of a brush, a capacitive coupling to the oscillator and amplifier, Fig. 13 (not shown).. The output pulses may modulate a radio transmitter co-operating with receiver attached to the indicator unit on the ground. When using a high p.v.f. to display high-frequency strains the resistance unit is preferably made equal to characteristic impedance of the balanced co-axial or twin screened cable to which it is connected Figs. 14, 16 (not shown).
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB2275647A GB690326A (en) | 1947-08-15 | 1947-08-15 | Improvements in or relating to the electrical measurement of mechanical strains |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB2275647A GB690326A (en) | 1947-08-15 | 1947-08-15 | Improvements in or relating to the electrical measurement of mechanical strains |
Publications (1)
Publication Number | Publication Date |
---|---|
GB690326A true GB690326A (en) | 1953-04-15 |
Family
ID=10184569
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB2275647A Expired GB690326A (en) | 1947-08-15 | 1947-08-15 | Improvements in or relating to the electrical measurement of mechanical strains |
Country Status (1)
Country | Link |
---|---|
GB (1) | GB690326A (en) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2199954A (en) * | 1986-12-04 | 1988-07-20 | Univ Aberdeen | Thermocouple array |
EP2291630A1 (en) * | 2008-05-27 | 2011-03-09 | BAE Systems PLC | Damage sensors and processing arrangements therefor |
CN102410896A (en) * | 2010-12-08 | 2012-04-11 | 昆山市瑞捷精密模具有限公司 | Tensile stress measurer |
-
1947
- 1947-08-15 GB GB2275647A patent/GB690326A/en not_active Expired
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2199954A (en) * | 1986-12-04 | 1988-07-20 | Univ Aberdeen | Thermocouple array |
GB2199954B (en) * | 1986-12-04 | 1990-08-15 | Univ Aberdeen | Multi point sensor |
EP2291630A1 (en) * | 2008-05-27 | 2011-03-09 | BAE Systems PLC | Damage sensors and processing arrangements therefor |
CN102410896A (en) * | 2010-12-08 | 2012-04-11 | 昆山市瑞捷精密模具有限公司 | Tensile stress measurer |
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