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How To Form Strain-Gage Bridges: Circuit Application Sample Name Output Bridge Box DB-120A/350A Remarks

1) The document discusses different types of strain-gage bridge circuits, listing their key characteristics like number of gages, application, output, temperature compensation, and whether bending strain is cancelled out. 2) It provides examples of common circuit types like 1-gage, 2-gage, and 4-gage setups for measuring uniaxial stress, bending stress, mean strain, and more. 3) The output of strain-gage bridges is expressed as either strain quantity in microstrain or output voltage in mV/V, and the relationship between the two metrics is explained.

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Charles Israel
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253 views2 pages

How To Form Strain-Gage Bridges: Circuit Application Sample Name Output Bridge Box DB-120A/350A Remarks

1) The document discusses different types of strain-gage bridge circuits, listing their key characteristics like number of gages, application, output, temperature compensation, and whether bending strain is cancelled out. 2) It provides examples of common circuit types like 1-gage, 2-gage, and 4-gage setups for measuring uniaxial stress, bending stress, mean strain, and more. 3) The output of strain-gage bridges is expressed as either strain quantity in microstrain or output voltage in mV/V, and the relationship between the two metrics is explained.

Uploaded by

Charles Israel
Copyright
© Attribution Non-Commercial (BY-NC)
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF, TXT or read online on Scribd
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How to Form Strain-gage Bridges

Name Application Sample Circuit Output Bridge Box Remarks DB-120A/350A


Suitable for use under environment of less ambient temerature changes; no temperature compensation. x1 output

1-active-gage 2-wire system


Uniaxial stress (uniform tension/compression) Number of gages: 1

: Gage factor : Strain : Bridge voltage : Output voltage : Gage resistance : Fixed resistance

1-active-gage 3-wire system


Uniaxial stress (uniform tension/compression) Number of gages: 1 Bending

No temperature compensation; thermal effect of leadwires cancelled. x1 output

Dual 1-active-gage 2-wire system in series (to cancel bending strain)


Number of gages: 2 Uniaxial stress (uniform tension/compression) Bending

..... Strain: 1 ..... Strain: 2

: Fixed resistance

No temperature compensation; bending strain cancelled. x1 output

Dual 1-active-gage 3-wire system in series (to cancel bending strain)


Number of gages: 2

..... Strain: 1 ..... Strain: 2

: Fixed resistance Uniaxial stress (uniform tension/compression) Active gage : Gage factor : Strain : Bridge voltage : Output voltage : Strain: o : Fixed resistance ..... Strain: 0

No temperature compensation; bending strain cancelled; thermal effect of leadwires cancelled. x1 output

Active-dummy 2-gage system

Uniaxial stress (uniform tension/compression) Dummy gage

Temperature compensation; thermal effect of leadwires cancelled. x1 output

Number of gages: 2

Orthogonal 2-active-gage system


Uniaxial stress (uniform tension/compression)

Number of gages: 2

: Poisson's ratio : Gage resistance ..... Strain: o ..... Strain: o : Fixed resistance

Temperature compensation; thermal effect of leadwires cancelled. x(1+) output

2-active-gage system (for bending strain measurement)


Bending stress Number of gages: 2

..... Strain: o ..... Strain: o : Fixed resistance

Temperature compensation; thermal effect of leadwires cancelled; compressive/ tensile strain cancelled. x2 output

Opposite side 2-active-gage 2-wire system


Uniaxial stress (uniform tension/compression) Number of gages: 2

..... Strain: o ..... Strain: o : Fixed resistance

No temperature compensation; bending strain cancelled by bonding to the front and rear. x2 output

Name

Application Sample

Circuit

Output

Remarks
No temperature compensation; thermal effect of leadwires cancelled; bending strain cancelled by bonding to the front and rear. x2 output

Bridge Box DB-120A/350A

Opposite side 2-active-gage 3-wire system


Uniaxial stress (uniform tension/compression) Number of gages: 2

..... Strain: o ..... Strain: o : Fixed resistance

4-active-gage system (for bending strain measurement)


Number of gages: 4 Bending stress

..... Bending strain: o ..... Bending strain: o

Temperature compensation; thermal effect of leadwires cancelled; compressive/ tensile strain cancelled. x4 output

Orthogonal 4-active-gage system

: Poisson's ratio ..... Strain: o ..... Strain: o Active gages

Temperature compensation; thermal effect of leadwires cancelled. x2(1+) output

Number of gages: 4 Temperature compensation; thermal effect of leadwires cancelled; bending strain cancelled by bonding to the front and rear. x2 output

Active-dummy 4-gage system

Uniaxial stress (uniform tension/compression) Dummy gages

..... Strain: o ..... Strain: 0

Number of gages: 4

2-active-gage system (for bending strain measurement)


Number of gages: 2

..... Bending strain: o ..... Bending strain: o : Fixed resistance

Temperature compensation; thermal effect of leadwires cancelled. x2 output

4-active-gage system (for bending strain measurement)


Number of gages: 4

..... Bending strain: o ..... Bending strain: o

Temperature compensation; thermal effect of leadwires cancelled. x4 output

4-active-1-gage system (for mean strain measurement)


Number of gages: 4

: Fixed resistance

No temperature compensation; mean strain. x1 output

Relation between strain and voltage


The output of a strain-gage bridge is expressed as a strain quantity () or an output voltage (mV/V or V/V) against the bridge voltage. The strain quantity and the output voltage have the following relation: eo = E Ks . o 4 If the bridge voltage E = 1V and the gage factor Ks = 2.00, 2eo = o. Thus, a strain output is always 2 times larger than a bridge output voltage. e.g. 3000 1500V/V = 1.5mV/V

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