Experimental Mechanics

, Volume 7, Issue 11, pp 476–480 | Cite as

A simple estimate for the effect of cross sensitivity on evaluated strain-gage measurement

A general diagram gives at a glance the probable errors in strain or stress for various test parameters
  • M. L. Meyer
Article

Abstract

The cross-sensitivity factor of a short-wire strain gage can sometimes be estimated by comparison of its gage factor with that of a long gage of similar construction and material.

A plot of the error introduced by the usual neglect of cross sensitivity against the known or estimatedtrue ratio of transverse to longitudinal stress or strain yields a quick estimate for any given cross-sensitivity factorn of the gage, any Poisson's ratio ν of the test piece and any stress or strain ratio. It shows whether in any particular test the influence of cross sensitivity warrants further special attention.

If the longitudinal strain exceeds the transverse strain, the error is seen to be always less than 1.3n, but if the transverse strain is larger, the error may be so high as to vitiate the result. In computations from rosette measurements, the diagram shows that the larger principal stress can be determined with an error below 1.3n, as can Tresca's and von Mises's criteria of yield, while the error in the smaller principal stress tends to be large for principal strain ratios above +10 or below −1.5.

Keywords

Principal Stress Strain Gage Longitudinal Strain Test Piece Principal Strain 

Nomenclature

E

Young's modulus

F

gage factor

n

cross-sensitivity factor

R

resistance of strain gage

ε

strain

ν

Poisson's ratio

σ

stress

Subscripts

a

apparent value (assumingn=0)

o

calibration value

t

true value (for knownn)

x, y

mutually perpendicular directions

1, 2

principal directions

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References

  1. 1.
    Perry, C. C., andLissner, H. R., “The Strain Gage Primer,”2nd ed. McGraw-Hill Book Co., New York, 157–163 (1962).Google Scholar
  2. 2.
    Wu, C. T., “Transverse Sensitivity of Bonded Strain Gages,”Experimental Mechanics,2,11,338–344 (1962).Google Scholar
  3. 3.
    Meyer, M. L., “A Unified Rational Analysis for Gauge Factor and Cross-sensitivity of Electric-Resistance Strain Gauges,” to be published in Jnl. Strain Anal. (Oct. 1967).Google Scholar
  4. 4.
    Bean, W. T., Verbal communication.Google Scholar
  5. 5.
    Campbell, W. R., “Performance Tests of Wire Strain Gages, Part IV—Axial and Transverse Sensitivities,” NACA Tech. Note No. 1042 (1946).Google Scholar
  6. 6.
    Wieringa, H., “Experimental Mechanics at TNO,”Experimental Mechanics,Ed. B. E. Rossi,Pergamon Press,New York,39–41 (1963).Google Scholar
  7. 7.
    Chalmers, C. F., “Loss in Gauge Factor on Miniature Strain Gauges,”Strain,2,2,29 (1966).Google Scholar
  8. 8.
    Baumberger, R., andHines, F., “Practical Reduction Formulae for Use on Bonded Wire Strain Gages in Two-dimensional Stress Field,”Proc. SESA,2,1,113–147 (1944).Google Scholar
  9. 9.
    Male, D. J., “A Tabular Solution for Rectangular Strain Gauge Rosettes,”Strain,2,2,25–28 (1966).Google Scholar
  10. 10.
    Meyer, M. L., “On a General Method of Compensation in Strain Gauge Work,” to be published in Jnl. Strain Anal.Google Scholar

Copyright information

© Society for Experimental Mechanics, Inc. 1967

Authors and Affiliations

  • M. L. Meyer
    • 1
  1. 1.Department of Mechanical EngineeringThe City UniversityLondon

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