Summary
Thermoelastic stress analysis was used to document the effect of composite damage on the stress distribution in three ceramic matrix composites. Composite damage was found to significantly alter the thermoelastic response of each material, with the greatest effect noted in SiC/CAS. Thermoelastic imaging of these materials affords a more complete picture of how the various damage mechanisms affect the stress distribution. In particular, a stress concentration factor computed from thermoelastic images, serves as an indicator of stress redistribution. The stress concentration factors were computed by comparing notch root to far field temperatures, and monitored after the introduction of various amounts of damage. In each material, the stress concentration factor diminished as the damaging load approached the ultimate stress. Reduction in the stress concentration is associated with local changes in modulus, mechanistically arising from combinations of fiber, matrix and interface fracture. Stress redistribution occurs as a consequence of modulus changes, leading to lower notch sensitivity in each of the tested composites.
Similar content being viewed by others
References
Heredia, F.E., Spearing, S.M., He, M.Y., Mackin, T.J., Evans, A.G.. Mosher, P. and Bronsled, P., “Notch Effects in Carbon Matrix Composites,” J. Amer Cer Soc, in press.
Suo, Z, Ho, S. and Gong, X., “Notch Ductile-to Brittle Transition Due to Localized Inelastic Band,” J. Mat. Engr. Tech., in press.
Mackin, T.J., Yang, J.Y., Levi, C.G. and Evans, A.G., “Environmentally Compatible Double Coating Concepts for Sapphire Fibers in γ-TiAl,” Materials Science and Eng., A161, 285–293 (1993).
Enke, N.E, “Thermographic Stress Analysis of Isotropic Materials,” Ph.D. Thesis, Department of Engineering Mechanics, The University of Wisconsin-Madison (1989).
Harwood, N. and Cummings, W.M., Thermoelastic Stress Analysis, Adam Hilger IOP Publishing (1991).
Stinchcomb, W.W. and Bakis, C.E., “Fatigue Behavior of Composite Laminates,” Fatigue of Composite Materials, Edited by K.L. Reifsnider. Elsevier Science Publishers B.V., 105–180 (1990).
Wong, A.K., Sparrow, J.G. and Dunn, S.A., “On The Revised Theory of the Thermoelastic Effect,” J. Phys. Chem. Solids 49(4), 395–400 (1988).
Cho, C., Holmes, J.W. and Barber, J.R., “Estimation of Interfacial Shear in Ceramic Composites from Factional Heating Measurements,” J. Am. Ceram. Soc. 74(11), 2802–808 (1991).
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Mackin, T.J., Purcell, T.E. The use of thermoelasticity to evaluate stress redistribution and notch sensitivity in ceramic matrix composites. Exp Tech 20, 15–20 (1996). https://doi.org/10.1111/j.1747-1567.1996.tb01489.x
Published:
Issue Date:
DOI: https://doi.org/10.1111/j.1747-1567.1996.tb01489.x