In the present work, micro-residual stresses are measured in fiber prestressed composites. This is carried out by evaluation of residual strains in the fibers subsequent to the curing process. The force-strain curve for the glass fiber before, during and after setting of the epoxy resin shows that some part of the fibers' strain, caused by pretension, is not recovered when the tension is removed at the end of the curing process. The unrecovered strain in the fibers is used to assess the micro-residual stresses in the composite. Experimental results indicate that the micro-residual stresses in the fibers are linear functions of the applied pretension on the fibers during cure.
1. Povirk, G. L., S. R. Nutt and A. Needleman. 1993. "Continuum Modeling of Residual Stresses in Metal-Matrix Composites,"Proceeding of a symposium sponsored by Structural Materials, Division of TMS, Denver, Colorado.
2.
2. Nelson, D. V. and C. M. Lawrence. 1995. "Prediction and Measurement of Residual Stress in Composite Materials;" Unpublished Paper, Private Communication.
3.
3. Treuting, R. G., H. B. Wishart, J. J. Lynch and D. G. Richards. 1952. "Residual Stress Measurements,"American Society for Metals, Cleveland, Ohio.
4.
4. Jayaraman, K. and K. L. Reifsnider. 1993. Composite Science and Technology, 47:119-129.
5.
5. Oakeshott, J. L. and A. J. Fletcher. 1994. Proceeding on the 4th Annual International Conference on Residual Stress, pp. 569-578.
6.
6. Uemura, M., H. lyama and Y. Yamaguchi. 1979. J. of Thermal Stresses, 2:393-412.
7.
7. Motahhari, S. and J. Cameron. 1996. "Proceeding of the Composites '96 and Oriented Polymers Symposium," pp. 591-617. October, Boucheroille, Quebec.
8.
8. Motahhari, S. and J. Cameron. 1996. "Dimensional Changes of Polymeric Resins During the Curing Process," To be published.
9.
9. Jorge, D. A., A. T. Marques and P. M. S. T. De Castro. 1990. "Developments in the Science and Technology of Composite Materials," pp. 897-902.
