DEVELOPMENT OF ASTM TEST STANDARDS FOR THE MODE I INTERLAMINAR FRACTURE TOUGHNESS (G_(IC)--CRACK GROWTH RESISTANCE) OF CERAMIC MATRIX COMPOSITES

摘要

Ceramic matrix composite (CMC) materials are targeted for high temperature application in aircraft and power turbines, because of their low density and high-temperature thermo-mechanical properties, compared to conventional nickel super alloys. New test methods are needed for the assessment of the effects of delamination cracks on the structural integrity and life of CMC components. The ASTM C28 Fracture Toughness (Crack Growth Resistance --CGR) Working Group has drafted a standard test method for the "Mode I Interlaminar Fracture Tougness (G_(IC) -- Crack Growth Resistance) of Fiber-Reinforced Ceramic Matrix Composites (CMC) by Wedge Loading of a Double Cantilever Beam at Ambient Temperatures" The wedge loading method was developed to avoid the problems of high temperature bonding of loading blocks and hinges. The ASTM test standard details the scope, use, and application of the test method, interferences, test equipment, specimen geometry and preparation, test procedures, data interpretation and calculation, and reporting requirements for the new CMC CGR test method.