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Precision strain standard by moiré interferometry for strain-gage calibration

Moiré interferometry is proposed as the datum for strain-gage calibration

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Abstract

Moiré interferometry is proposed as an alternative to extensometers to define the strain field used for calibration of electric strain gages. Measurements were conducted with a real reference grating of 1200 lines/mm (30,480 ℓ/in.), a gage length of 41.67 mm (1.640 in.), and a strain excursion of 2000 μm/m. Results showed a standard deviation of 1.1 μm/m at each load level and probable error within 2 μm/m for the 2000 μm/m excursion. Critical factors for accuracy are change of gap between specimen and reference gratings that might occur during loading, and the quality of collimation of incident light. A hollow uniaxially loaded test specimen interrogated by moiré interferometry is recommended for a strain standard of 99.9-percent accuracy.

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References

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Authors and Affiliations

  1. Measurements Group, 27611, Raleigh, NC

    R. B. Watson (Development Engineer)

  2. Virginia Polytechnic Institute and State University, 24061, Blacksburg, VA

    D. Post (Professor)

Authors
  1. R. B. Watson
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  2. D. Post
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Watson, R.B., Post, D. Precision strain standard by moiré interferometry for strain-gage calibration. Experimental Mechanics 22, 256–261 (1982). https://doi.org/10.1007/BF02326390

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  • DOI: https://doi.org/10.1007/BF02326390

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