Experimental Mechanics

, Volume 33, Issue 2, pp 110–116

Scanning moiré at high magnification using optical methods

  • D. T. Read
  • J. W. Dally
  • M. Szanto
Article

Abstract

Methods of employing scanning moiré at high magnification are developed and demonstrated. Modern lithographic techniques for producing custom moiré gratings with a frequency up to 250l/mm are described. On a probing station equipped with a video system, pseudo-color moiré fringes are produced using the scannning lines of the color charge-coupled-device (CCD) camera. Fringe multiplication from 1 to 5 is possible with correct combinations of magnification and grating pitch. An analysis is given to show that strain sensitivity depends only on the number of scanning lines used to record the image. The grating pitch and the magnification are important because they reduce the gage length of the strain measurement. The high-magnification scanning moiré was used to study plastic- strain fields in an aluminum tensile specimen. Local disturbances in the strain field were observed at 2 to 2.5 percent applied strain. These discontinuities became more significant at higher levels of applied strain.

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. 1.
    Parks, V.J., Geometric Moiré, Handbook on Experimental Mechanics, ed. A.S. Kobayoshi, Prentice Hall, Englewood Cliffs, NJ, 282–313 (1987).Google Scholar
  2. 2.
    Durelli, A.J. andParks, V.J., Moiré Analysis of Strain, Prentice Hall, Englewood Cliffs, NJ (1970).Google Scholar
  3. 3.
    Theocaris, P.S., Moiré Fringes in Strain Analysis, Pergamon Press, Elmsford, NY (1969).Google Scholar
  4. 4.
    Post, D., “Moiré Interferometry: Advances and Applications,”Experimental Mechanics,31 (3),276–280 (1991).CrossRefGoogle Scholar
  5. 5.
    Ifju, P. andPost, D., “Zero-Thickness Specimen Gratings for Moiré Interferometry,”Experimental Techniques,15 (2),45–47 (1991).Google Scholar
  6. 6.
    Morimoto, Y. andHayashi, T., “Deformation Measurement During Powder Compaction by a Scanning-moiré Method,”Experimental Mechanics,24 (2),112–116 (1984).CrossRefGoogle Scholar
  7. 7.
    Ueda, T., “Electrical Grating Moiré Equipment,”Electrical Comm. Labs Tech. J. (in Japanese),27 (12),2627–2641 (1978).Google Scholar
  8. 8.
    Kishmoto, S., Egashira, M., Shinya, N., andCarolan, R.A., “Local Micro-Deformation Analysis by Means of Micro Grid and Electron Beam Moiré Fringe Method,”Mechanical Behavior of Materials-VI, Proc. 6th Int. Conf., Kyoto, Japan, eds. M. Jono and T. Inoue,4,661–666 (1991).Google Scholar
  9. 9.
    Post, D., “Sharpening and Multiplication of Moiré Fringes,”Experimental Mechanics,7 (4),154–159 (1967).CrossRefGoogle Scholar

Copyright information

© Society for Experimental Mechanics, Inc. 1993

Authors and Affiliations

  • D. T. Read
    • 1
  • J. W. Dally
    • 2
  • M. Szanto
    • 3
  1. 1.Materials Reliability DivisionNational Institute of Standards and TechnologyBoulder
  2. 2.Mechanical Engineering DepartmentUniversity of MarylandCollege Park
  3. 3.Ben Gurion UniversityBeer ShevaIsrael

Personalised recommendations