Date of Award

Fall 2014

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Aeronautics and Astronautics

First Advisor

Byron R. Pipes

Committee Member 1

Wayne Chen

Committee Member 2

Alten F. Grandt

Committee Member 3

Michael D. Sangid

Abstract

A novel trough thickness reinforcement (TTR) technique, proposed by Kravchenko et al., has been tested under mode I fatigue loading conditions in order to investigate characterisation of the onset of delamination growth in unidirectional 8552/IM7. The experimental results, following standard test method ASTM D6115-13, indicate that the mode I fatigue delamination onset behaviour can be altered by the inclusion of TTR both ahead and behind the crack tip. Tests have been conducted at a wide range of maximum displacement values, corresponding to percentages of the critical fracture toughness value determined for the maternal, GIC . The results were found to contain a high degree of scatter, that is thought to be a result of pin installation quality. The results of these experiments show that the cycles to delamination onset for a wide range of the critical value of strain energy release rate, G , can be increased with the inclusion of this novel TTR technique. Further research is required before the TTR technique properties are fully characterised. Research into understanding of the pin failure mechanisms in fatigue is highly recommended.

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