The tensile response of continuous fibre reinforced ceramic matrix composites (CFCCs) is not expected to show the large variation in strength properties commonly observed for monolithic ceramics. Results of recent investigations on a number of two-dimensional reinforced CFCCs have nevertheless revealed a considerable scatter in the initial elastic modulus, in the first matrix cracking stress and in the failure stress. One school of thought considers that the observed variability is caused by experimental factors. Elaborate testing programmes have been set up to clarify the origins of this scatter by investigation of the effects of control mode, loading rate, specimen shape, etc. Another school explains the scatter by the presence of (axial) residual stresses in the fibres and in the matrix. Although plausible, this hypothesis is difficult to verify because experimental determination of the residual stress state in CFCCs is not straightforward. In addition, with the available methods it is impractical to determine the residual stresses in every test specimen. This approach is indeed required for establishing the relationship between the magnitude of the residual stresses and the experimentally observed scatter. At IAM a method has been developed and validated which allows to quantify the axial residual stress state in individual CFCC specimens by subjecting them to intermittent unloading-reloading cycles. The method as well as the derived relationship between residual stress state and scatter in mechanical response will be presented. [S0742-4795(00)01101-7]
Mechanical Property Scatter in CFCCs
Contributed by the International Gas Turbine Institute (IGTI) of THE AMERICAN SOCIETY OF MECHANICAL ENGINEERS for publication in the ASME JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER. Paper presented at the International Gas Turbine and Aeroengine Congress and Exhibition, Stockholm, Sweden, June 2–5, 1998; ASME Paper 98-GT-319. Manuscript received by IGTI March 16, 1998; final revision received by the ASME Headquarters October 20, 1999. Associate Technical Editor: R. Kielb.
Steen , M., and Filiou, C. (October 20, 1999). "Mechanical Property Scatter in CFCCs ." ASME. J. Eng. Gas Turbines Power. January 2000; 122(1): 69–72. https://doi.org/10.1115/1.483177
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