Abstract
A method for measuring strain on interior planes of some real structural materials is presented. X-ray images are formed of small (10–40 micron) gold markers placed on selected interior planes of optically opaque X-ray transparent materials. The use of well collimated monochromatic synchrotron radiation makes possible high contrast images of the small markers. Images of the particles before and after straining are recorded photographically. Photographs are enlarged 33X and measured using a simple electro-optical setup. In calibration experiments using approximately a 300-micron gage length, the strain measured by this method agreed with extensometer measured strains to within 100 microstrain. Example applications in a graphite-epoxy composite are presented, including measurement of the strain drop off near the free edge, strain concentration around a hole, and the strain field on a particular plane near a hole after local delamination. The technique is currently limited to materials no less X-ray transparent than titanium.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Burger, C.P., “Photoelasticity,”Experimental Mechanics, ed. by A.S. Kobayashi, Prentice-Hall, Englewood Cliffs, NJ (1987).
Chiang, F.P. andKheaton, R.P., “Strain Analysis by One-Beam Laser Speckle Interferometry 2: Multiaperture Method,”Appl. Opt. 18 (13),2175–2186 (1979).
Kupperman, D.S., Majumday, S. andSingh, J.P., “Neutron Diffraction NDE for Advanced Composites,”Trans. of ASME, J. Eng. Mat. and Tech.,112,188–201 (1990).
James, M.R., Morris, W.L. andCox, B.N., “A High Accuracy Automated Strain Field Mapper,”Experimental Mechanics,20 (1),60–67 (March 1990).
Ochi, S.C.U., “Measurements of Internal Strains Using Synchrotron Radiation and Marker Particles,” PhD Thesis, Univ. of Connecticut (May 1992).
Feder, R., “High Resolution Soft X-Ray Microscopy,” Science,197 (1977).
Finkelstein, private communication (Dec. 1992).
McMaster, W.H., Kerr Dell Grande, N. and Mallet, J.H., “Compilation of X-Ray Cross Sections,” Lawrence Radiation Lab. Rep. No. UCRL-50174 (1969).
Chiang, F.P., Adachi, J., Anastasi, R. andBeatty, J., “Objective Laser Speckle Method and its Application to Solid Mechanics,”Opt. Eng.,21 (5),379–390 (1982).
Peters, W.H. andRanson, W.F., “Digital Imaging Techniques in Experimental Stress Analysis,”Opt. Eng.,21 (3),427–431 (1982).
Sharpe, W.N., Payne, T.S. andSmith, M.K., “Biaxial Laser-Based Displacement Transducer,”Rev. of Sci. Instr.,46 (6),741–745 (1978).
Rowlands, R.E., Liber, T., Daniel, I.M. andRose, P.G., “Higher-order Numerical Differentiation of Experimental Information,”Experimental Mechanics,13 (3),105–113 (1973).
Pipes, B. andPagano, N.J., “Interlaminar Stresses in Composite Laminates Under Uniform Axial Extension,”J. Comp. Mat.,4,538–548 (1970).
Kassapagolou, C. andPage, P.A., “Closed Form Solutions for the Interlaminar Stress Field in Angle-Ply and Cross-Ply Laminates,”J. Comp. Mat.,21,292–308 (1987).
Wang, A.S.D. andCrossman, F.W., “Some New Results on Edge in Symmetric Composite Laminate,”J. Comp. Mat.,11,92–106 (1977).
Lekhnitskii, S.G., Theory of Elasticity of Anisotropic Body, Holden-Day, San Francisco (1963).
Konish, H.J. andWhitney, J.M., “Approximate Stresses on Orthotopic Plate Containing a Circular Hole,”J. Comp. Mat.,9,157–166 (1975).
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Jordan, E.H., Ochi, S.C.U., Pease, D. et al. Microradiographic strain measurement using markers. Experimental Mechanics 34, 155–165 (1994). https://doi.org/10.1007/BF02325712
Received:
Revised:
Issue Date:
DOI: https://doi.org/10.1007/BF02325712