Date of Award

12-1993

Document Type

Thesis

Degree Name

Master of Science in Aeronautical Engineering

Department

Department of Aeronautics and Astronautics

First Advisor

Shankar Mall, PhD

Abstract

This study investigated systematically the damage initiation damage progression, and failure modes of a ceramic matrix composite, Nicalon/CAS, when loaded in tension at elevated temperatures in the presence of air. A cross-ply lay-up, [0/90]2s, was studied. The primary means of analysis were stress-strain data taken during monotonic and incremental load tests and crack density assessments. Testing was conducted at room temperature 700°C, and 850°C. The stress-strain response was consistent for monotonic and incremental loading, except for a decrease in failure load at the elevated temperatures. Initial damage progression was also consistent, but the damage leading to failure and the final failure mode at 850°C were different due to the oxidation of the fibers. The oxidation created a brittle interface between the fiber and matrix, which resulted in an increase in fiber pull-out at the failure surface.

AFIT Designator

AFIT-GAE-ENY-93D-1

DTIC Accession Number

ADA275363

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