High Temperature Heterogeneous Materials
Final rept. 15 Jan 90-31 Aug 93
NORTHWESTERN UNIV EVANSTON IL CENTER FOR QUALITY ENGINEERING AND FAILURE PREV ENTION
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Experimental and supporting analytical methodologies for the determination and assessment of the integrity of interfaces in composite materials at both room and high temperatures are presented. Experimental test techniques developed in the program are described and supporting analytical methods to assist in the determination of interface fracture toughness from experimental measurements are presented. The test techniques consist of the tensile test on a thin coated fiber and four point bend of a bimaterial bar and were chosen on the basis of their suitability for use at high temperatures. An experimental study of crack tip shieldingantishielding by impurities in alpha-silicon carbide is described. This investigation required the application of stress during high temperature 1873 K anneals. A novel stress fixture, based on thermal expansion mismatch, was designed, constructed and utilized to achieve this in-situ stressing of the crack specimens at high temperatures.
- Laminates and Composite Materials