Date of Award

12-1993

Document Type

Thesis

Degree Name

Master of Science

Department

Department of Aeronautics and Astronautics

First Advisor

Shankar Mall, PhD

Abstract

A study was conducted which investigated the behavior of a Nicalon/ Calcium-Aluminosilicate (Nicalon/CAS) cross-ply [0/90]2S ceramic matrix composite at elevated temperatures under tension-tension fatigue loading. Tension-tension fatigue tests were performed with a load ratio of R = 0.10 and a frequency of 10 Hertz at 700°C and 850°C. These results were compared to results from a previous study conducted at room temperature. Material behavior and damage was recorded by fatigue life curves, elastic modulus' maximum and minimum strain, acetate replication techniques, and post-mortem fractography. Analysis of these results showed identical matrix dominated damage behavior at RT and 700°C. Ultimate failure was caused by an accumulation of matrix damage, most of which occurred on the first cycle. However, at 8500C, significantly less damage occurred to the matrix and failure was fiber dominated. Fiber debonding was identified as the major damage mechanism responsible for final failure at this elevated temperature.

AFIT Designator

AFIT-GAE-ENY-93D-28

DTIC Accession Number

ADA275466

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