Date of Award

12-1990

Document Type

Thesis

Degree Name

Master of Science in Aeronautical Engineering

Department

Department of Aeronautics and Astronautics

First Advisor

Shankar Mall, PhD

Abstract

A laser interferometry technique to measure crack opening displacement was developed and applied to end notched flexure specimens of a Corning Glass Works 1723 glass matrix with silicon carbide fibers. The laser interferometer displacement gauge monitored the crack opening displacement (COD) at the location of a support while specimens were subjected to Mode II (forward shear) cracking at room temperature via three point bend tests on a standard Instron Compression machine. Vertical displacement was measured at the center of the test specimen using a linear variable differential transformer. Load verses displacement curves were generated for both the LVDT displacement and the COD. The COD curve showed a marked improvement in determining the onset of crack growth. From the enhanced critical load determination, the materials fracture toughness in Mode II, GIIc was calculated for varying crack lengths. The calculations provided estimates with a variance of only 10% from the mean thus illustrating the utility of this procedure.

AFIT Designator

AFIT-GAE-ENY-90D-31

DTIC Accession Number

ADA231027

Comments

The author's vita page is omitted.

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