Date of Award

12-1996

Document Type

Thesis

Degree Name

Master of Science

Department

Department of Aeronautics and Astronautics

First Advisor

David D. Robertson, PhD

Abstract

Metal matrix composite have potential in a variety of aerospace applications, but they should be better understood before they can be employed. Despite the many studies that have contributed to characterizing the fatigue response of titanium alloy MMCs, few have researched the residual strength. The purpose of this study was to investigate the residual strength and the frequency effects on the residual strength of an unidirectional laminate of SCS-6/Ti-6-4, a titanium alloy matrix based composite under tension-tension, load-controlled conditions at elevated temperatures and different frequencies. Specimens were fatigued at frequencies of 1 and 0.01Hz, and at maximum stress of 900MPa with a stress ratio 0.05 and temperature of 427 °C. Static tests were accomplished to obtain ultimate tensile strength. Macromechanical fatigue responses at different frequencies were compared using stress-strain plots, modulus histories and strain histories, while microscopy and fractography revealed the micromechanical behavior and damage mechanisms.

AFIT Designator

AFIT-GAE-ENY-96D-7

DTIC Accession Number

ADA320769

Comments

The DTIC-sourced PDF of this thesis has some portions illegible.

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