Experimental Mechanics

, Volume 43, Issue 1, pp 61–68 | Cite as

Full-field strain measurement using a luminescent coating

  • James P. Hubner
  • Peter G. Ifju
  • Kirk S. Schanze
  • David A. Jenkins
  • Bruce F. Carroll
  • Yingsheng Wang
  • Phillip He
  • Anthony Brennan
  • Wissam El-Ratal


In this paper we describe an optical-based technique, called strain sensitive skin (S3), for measuring in-plane strain data on structural members under static load. The technique employs a coating consisting of a luminescent dye and polymer binder that is applied to the surface of a test part via conventional aerosol techniques. Proper illumination stimulates the dye, which in turn emits higher wavelength luminescence. The excitation and emission intensities have different wavelengths; therefore, enabling optical filtering to separate the two signals. The optical strain response is intensity based. A network of randomized microcracks within the binder scatters the waveguided luminescence from the excited dye molecules. The amount of scattered luminescence is related to the changes in the microcrack openings and orientations via mechanical strain. Various calibration tests show the optical strain response to be proportional to the sum of in-plane principal strains. With this new experimental testing tool, full-field high-resolution strain measurements can be acquired. The optical strain response of this new sensor is minimally dependent on viewing and lighting directions, rendering the technique viable to imaging and determining strain fields for three-dimensional complex geometries.

Key Words

Full-field strain luminescent coating strain-sensitive coating digital imaging 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. 1.
    Daily, J.W. andRiley, W.F., Experimental Stress Analysis, 3rd ed., McGraw-Hill, New York (1991).Google Scholar
  2. 2.
    Cloud, G.L., Optical Methods of Engineering Analysis, Cambridge University Press, New York (1998).Google Scholar
  3. 3.
    Rastogi, P.K., ed., Topics in Applied Physics: Photomechanics, Vol. 77, Springer, Berlin (1999).Google Scholar
  4. 4.
    Post, D., Han, B., andIfju, P.G., High Sensitivity Moiré: Experimental Analysis for Mechanics and Materials, Springer-Verlag, New York (1994).Google Scholar
  5. 5.
    Post, D., “Moiré Interferometry,”Handbook on Experimental Mechanics, A.S. Kobayashi, ed., Prentice-Hall, Englewood Cliffs, NJ, chap. 7 (1987).Google Scholar
  6. 6.
    McDonald, A., McKelvie, J., andWalker, C.A., “Stress Analysis of Fibrous Composites using Moiré Interferometry,”Opt. Lasers Eng.,1(EM4),85–105 (1980).Google Scholar
  7. 7.
    Morse, S., Durelli, A.J., andSciammarella, C.A., “Geometry of Moiré Fringes in Strain Analysis,”J. Eng. Mech. Div., ASCE,86,105–126 (1960).Google Scholar
  8. 8.
    Wellar, R. andShepard, B.M., “Displacement Measurement by Mechanical Interferometry,”Proc. SESA,VI(1),35–38 (1948).Google Scholar
  9. 9.
    Sciammarella, S.A. andDurelli, A.J., “Moiré Fringes as a Means of Analyzing Strains,”J. Eng. Mech. Div. ASCE,87 (EM1),55–74 (1961).Google Scholar
  10. 10.
    Theocaris, P.S., “Isopachic Patterns by Moiré Method,” EXPERIMENTAL MECHANICS,4(6),153–159 (1964).CrossRefGoogle Scholar
  11. 11.
    Steson, K.A., “Review of Speckle Photography and Interferometry,”Opt. Eng.,14(5),482–489 (1975).Google Scholar
  12. 12.
    Jones, R. andWykes, C., Holographic and Speckle Interferometry, Cambridge University Press, Cambridge (1983).Google Scholar
  13. 13.
    Taylor, C.E., “Holography,”Manual on Experimental Stress Analysis, 5th ed., J. Doyle, ed., Society of Experimental Mechanics, Bethel, CT, 136–149 (1989).Google Scholar
  14. 14.
    Stetson, K.A., andPowell, R.L., “Interferometric Hologram Evaluation and Real-time Vibration Analysis of Diffuse Objects,”J. Opt. Soc. Am.,55,1694–1695 (1965).Google Scholar
  15. 15.
    Zandman, F., Redner, S., andDally, J.W., Photoelastic Coatings, Iowa Press, Ames (1977).Google Scholar
  16. 16.
    D'Agostino, J., Drucker, D.C., Liu, C.K., andMylonas, C., “Epoxy Adhesives and Casting Resins as Photoelastic Plastics,”Proc. SESA,XII(2),123–128 (1955).Google Scholar
  17. 17.
    Kawate, K., “Analysis of Elastoplastic Behavior of Metals by Means of Photoelastic Coating Method,”J. Sci. Res. Instrum.,52,17–40 (1958).Google Scholar
  18. 18.
    Durelli, A.J., Hall, J., andStern, F., “Brittle Coating,”Handbook on Experimental Mechanics, A.S. Kobayashi, ed., Prentice-Hall, Englewood Cliffs, NJ, 516–554 (1987).Google Scholar
  19. 19.
    Ellis, G., “Practical Strain Analysis by Use of Brittle Coatings,”Proc. SESA,VI(2),68–83 (1949).Google Scholar
  20. 20.
    Peters, W.H. andRanson, W.F., “Digital Imaging Techniques in Experimental Stress Analysis,”Opt. Eng.,21(3),427–432 (1982).Google Scholar
  21. 21.
    Sutton, M.A., Cheng, M., Peters, W.H., Chao, Y.J. andMcNeill, S.R., “Applications of an Optimized Digital Correlation Method for Planar Deformation Analysis,”Image Vision Comput.,4,143–150 (1986).CrossRefGoogle Scholar
  22. 22.
    Durelli, A.J. andDeWolf, T.N., “Law of Failure of Stresscoat,”Proc. SESA,6(2),68–83 (1949).Google Scholar
  23. 23.
    Ifju, P.G., Schanze, K.S., Wang, Y., Hubner, J.P., Jenkins, D.A., El-Ratal, W., Brennan, A.B., He, L., Shen, Y., and Carroll, B., System, Method, and Coating for Strain Analysis, Patent No, 6,327,030 (December 2001).Google Scholar
  24. 24.
    Bell, J.H., Schairer, E.T., Hand, L.A. andMehta, R.D., “Surface Pressure Measurements Using Luminescent Coatings,”Ann. Rev. Fluid Mech.,33,155–206 (2001).CrossRefGoogle Scholar
  25. 25.
    Frocht, M.M., “Factors of Stress Concentration Photoelastically Determined,”Trans. ASME,57,A-67 (1935).Google Scholar

Copyright information

© Society for Experimental Mechanics 2003

Authors and Affiliations

  • James P. Hubner
    • 1
  • Peter G. Ifju
    • 1
  • Kirk S. Schanze
    • 2
  • David A. Jenkins
    • 1
  • Bruce F. Carroll
    • 1
  • Yingsheng Wang
    • 2
  • Phillip He
    • 3
  • Anthony Brennan
    • 3
  • Wissam El-Ratal
    • 4
  1. 1.Department of Aerospace Engineering, Mechanics, and Engineering ScienceUniversity of FloridaUSA
  2. 2.Department of ChemistryUniversity of FloridaUSA
  3. 3.Department of Material ScienceUniversity of FloridaUSA
  4. 4.Experimental Engineering Department, Axle/Driveline Systems Engineering, Chassis DivisionVisteon CorporationUSA

Personalised recommendations