Experimental Mechanics

, Volume 36, Issue 3, pp 269–276

2D and 3D separation of stresses using automated photoelasticity

  • S. J. Haake
  • E. A. Patterson
  • Z. F. Wang


A procedure for the separation of full-field photoelastic images for use with an automated polariscope is described. Regions of background in the image are identified thus producing the boundary of the model. The shear difference method is used to calculate the components of stress along all raster lines in the image using photoelastic parameters at the boundary points to calculate the initial values of stress. Algorithms were also used to evaluate the stress components along raster lines which did not contain boundary points. A plastic template was used to evaluate the efficiency of the boundary routine. It was found that it was able to identify edges to within approximately one pixel on screen. The complete procedure for stress separation was evaluated using a stress frozen disc in compression and a turbine slot. The values of stress found using the automated polariscope with the stress-separation procedure were found to agree well with theory and with results determined using the method of Tardy compensation and manual analysis. The automated polariscope was also used to analyze three-dimensional stress components along arbitrary lines of a 3D model. A two-model slicing regime was used to analyze a strut subjected to a vertical load. This work was compared to results obtained by Frocht and Guernsey on an identical model machined from Fosterite and subjected to a higher load. Good agreement was found between the results for points away from the region of loading. Significant differences were found near to the load point, however. A finite element analysis of the same problem suggested that this was due to the effects of plasticity.

Key Words

photoelasticity three-dimensional automation 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. 1.
    Patterson, E.A., “Automated Photoelastic Analysis,”Strain,24,15–20 (1988).Google Scholar
  2. 2.
    Haake, S.J. andPatterson, E.A., “The Determination of Principal Stresses from Photoelastic Data,”Strain,28 (4),153–158 (1992).Google Scholar
  3. 3.
    Frocht, M.M., Photoelasticity, vol. 1, John Wiley and Sons, Inc., New York (1941).Google Scholar
  4. 4.
    Tésar, V., “La Photoélasticimétrie et ses applications dans la construction aeronautique,”La Science Aerienne,II,372–394 (1935).Google Scholar
  5. 5.
    Patterson, E.A. andWang, Z.F., “Towards Full-field Automated Photoelastic Analysis of Complex Components,”Strain,27 (2),49–56 (1991).Google Scholar
  6. 6.
    Wang, Z.F. andPatterson, E.A., “Use of Phase-Stepping with Fuzzy Sets for Birefringence Measurement,”Optics and Lasers in Engineering,22,91–104 (1995).Google Scholar
  7. 7.
    Haake, S.J., Wang, Z.F. andPatterson, E.A., “Evaluation of Automated Full Field Analysis Using Phase Stepping,”Exp. Tech.,17,19–25 (1993).Google Scholar
  8. 8.
    Frocht, M.M. andGuernsey, R. Jr., “Further Work on the General Three Dimensional Problem,”J. Appl. Mech.,22 (2),183–189 (1955).Google Scholar
  9. 9.
    Dally, J.W. and Riley, W.F., Experimental Stress Analysis, 3d ed., McGraw Hill, 1991.Google Scholar
  10. 10.
    Allison, I.M. andBlakemore, R.H., “The Analysis of Photoelastic Data for Stress Separations,”Recent Advances in Stress Analysis, Royal Aeronautical Society, London, 4–17 to 4–12 (1968).Google Scholar
  11. 11.
    Fessler, H., Marston, R.E. andOllerton, E., “A Micropolariscope for Automatic Stress Analysis,”J. Strain Anal.,22 (1),25–35 (1987).Google Scholar
  12. 12.
    Allison, I.M. and Nurse, P. “Automatic Acquisition of Photoelastic Data,” Proc. JBCSA Conf. Recording and Interpret. of Engin. Measure., Inst. Mar. Engrs., London, 203–207 (1972).Google Scholar
  13. 13.
    Takashi, M., Mawatara, S., Toyoda, Y. andKunio, T., “A New Computer Aided System for Photoelastic Stress Analysis with Structure Driven Type Image Processing,”Applied Stress Analysis, eds. T. H. Hyde andE. Ollerton, Elsevier Applied Science, London, 516–525 (1990).Google Scholar
  14. 14.
    Frocht, M.M., Photoelasticity, vol. 2, John Wiley and Sons, Inc., New York (1941).Google Scholar
  15. 15.
    Taroni, M., “Photoelastic Analysis of Jet Turboengine Parts,”10th Int. Conf. on Exp. Mech., eds. Silva Gomes et al., vol. 1, Balkema, Rotterdam, 161–166 (1994).Google Scholar

Copyright information

© Society for Experimental Mechanics, Inc. 1996

Authors and Affiliations

  • S. J. Haake
    • 1
  • E. A. Patterson
    • 1
  • Z. F. Wang
    • 1
  1. 1.Department of Mechanical and Process EngineeringUniversity of SheffieldSheffield

Personalised recommendations