Abstract
A dot map method was used for direct measurement of the microscopic strain field near a crack tip in a rubber-toughened epoxy. Results indicate that very large viscoelastic strains (37 percent) are present at the crack tip, though elongation in a tensile test is only 5.1 percent. Most of the strain is recovered immediately on unloading, and all of the remaining strain is recovered after annealing above the glass transition temperature.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Mao, T.H., Beaumont, P.W.R. andNixon, W.C., “Direct Observation of Crack Propagation in Brittle Materials,”J. Materials Sci. Letter,2,613 (1983).
Brown, N. andWang, X., “Direct Measurements of the Boundary of Crazes in Polyethylene,”Polymer,29,463 (1988).
Hibbs, M. and Bradley, W.L., “Crack Tip Strain Field Measurements Determined In-situ in Scanning Electron Microscope for Mode I Crack Extension in a Polymeric Material,” Proc. Soc. of Exp. Mech. Fall Meeting (October 1987).
Davidson, D.L. andLankford, “The Effect of Water Vapor on Fatigue Crack Tip Stress and Strain Range Distribution and the Energy Required for Crack Propagation in Low-carbon Steel,”Int. J. Fract.,17,257 (1981).
James, M.R., Morris, W.L., Cox, B.N. andDadkhah, M.S., “Description and Application of Displacement Measurements Based on Digital Image Processing,”Exp. Tech. Micromechanics, AMD-Vol 1022,New York, American Society of Mechanical Engineers, 89 (1989).
Chu, T.C., Ransom, W.F. andSutton, M.A., “Application of Digital-image Correlation Techniques to Experimental Mechanics,”Experimental Mechanics,25,232 (1985).
Sutton, M.A., Turner, J.L. andBruck, H.A., “Full-field Representation of Discretely Sampled Surface Deformation for Displacement and Strain Analysis,”Experimental Mechanics,31,168 (1991).
Russell, S.S. andSutton, M.A., “Strain-field Analysis Acquired through Correlation of X-ray Radiographs of Fiber-reinforced Composite Laminates,”Experimental Mechanics,29,237 (1989).
Basxon, W.D., Bitner, J.L., Moulton, R.J. andSiebart, A.R., “The Interlaminar Fracture of Organic-matrix, Woven Reinforcement Composites,”Composites,11,9 (1980).
Tuba, I.A., “A Method of Elastic-plastic Plan Stress and Strain Analysis,”J. Strain Analysis,1,115 (1966).
McClintock, F.A. andIrwin, G.R., “Plasticity Aspects of Fracture Mechanics,”Fracture Toughness Testing and Its Applications, ASTM STP 381, American Society for Testing and Materials, Philadelphia, PA, 84 (1965).
Jordan, W.M., Bradley, W.L. andMoulton, R.J., “Relating Resin Mechanical Properties to Composite Delamination Fracture Toughness,”J. Composite Materials,23,923 (1989).
Anderson, T.L., Fracture Mechanics: Fundamentals and Applications, CRC Press, Boston, 94 (1991).
Dodds, R.H., Jr., Anderson, T.L. andKirk, M.T., “A Framework to Correlate a/W Effects on Elastic-plastic Fracture Toughness (J c ),”Int. J. Fract.,28,1 (1991).
Ritchie, R.O., Server, W.L. andWallaert, “Critical Fracture Stress and Strain Models for the Prediction of Lower and Upper Shelf Toughness in Nuclear Pressure Vessel Steels,”Metallurgical Transactions, 10A,1557 (1979).
Post, D., “Moiré Interfermometry: Advances and Applications,”Experimental Mechanics,31,276 (1991).
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Yongqi, S., Corletto, C., Bradley, W.L. et al. Direct measurement of microscopic strain distribution near a crack tip. Experimental Mechanics 36, 193–198 (1996). https://doi.org/10.1007/BF02318006
Issue Date:
DOI: https://doi.org/10.1007/BF02318006