SEDL / STP / STP1309-EB / STP11815S

Subcritical Crack Growth in Ceramic Composites at High Temperature Measured Using Digital Image Correlation

Mumm, DR
Member of Technical Staff, Rockwell Science Center, Thousand Oaks, CA

Morris, WL
Members of Technical Staff and Manager, Rockwell Science Center, Thousand Oaks, CA

Dadkhah, MS
Members of Technical Staff and Manager, Rockwell Science Center, Thousand Oaks, CA

Cox, BN
Members of Technical Staff and Manager, Rockwell Science Center, Thousand Oaks, CA

Pages: 11    Published: Jan 1997

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Abstract

An in situ experimental technique is described that allows high resolution, high sensitivity determination of displacements and full-field strains during high temperature mechanical testing. The technique is used to investigate elevated temperature crack growth in SiC/Nicalon composites. At 1150°C, the reinforcing fibers have a higher creep susceptibility than the matrix. Fiber creep leads to relaxation of crack bridging tractions, resulting in subcritical crack growth. Differential image analysis is used to measure the crack opening displacement profile u(x) of an advancing, bridged crack. With appropriate modeling, such data can be used to determine the traction law, from which the mechanics of cracking and failure may be determined.