The material response of a graphite/polyphenylene sulfide (thermoplastic) composite system to a variety of loadings was experimentally investigated. Quasi-static tension tests were performed on specimens cut from unidirectional panels at angles of 0°, 90°, and 10° in order to the find material properties of the system. The moduli and strengths were compared to those of several other graphite/epoxy systems. The effect of molded-on end tabs on the strength and failure mode of 0° specimens was also assessed. Both quasi-static tension tests and cyclic tension-tension (R=0.1) fatigue tests were performed on (0/±45/90)<sub>s</sub> and (0/90₃)<sub>s</sub> specimens.
A variety of NDT techniques were used to inspect the "as received" panels and to monitor the formation and growth of damage during quasi-static tension and cyclic fatigue testing. The "as received" panels were found to possess initial flaws that included warping of unidirectional panels, dense matrix cracking in all multi-directional laminates, and local matrix rich and matrix poor regions. The predominately observed damage mechanism occurring as a result of applied mechanical load was delamination. Comments on the ability of each NDT technique to locate and monitor damage occurring in each specimen type are also presented.
A preliminary investigation of the creep response of ( ±45₂)<sub>s</sub> specimens was performed. Seventy-two hour creep tests were performed at temperatures of 75°, 160°, 250°, and 350° Fahrenheit and at stress levels of 750 psi and 1000 psi. It was found that when testing specimens repeatedly, a strange stiffening phenomenon was observed to occur during the first creep test performed at 350°. After the initial creep test at 350° was performed, no further stiffening of the specimen occurred and all tests performed thereafter were found to be repeatable. The mechanism causing this stiffening phenomenon has not yet been determined, but such an effect is of obvious importance for design considerations and therefore warrants further study. / M.S.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/101143 |
| Date | January 1986 |
| Creators | Owens, Gregg Russell |
| Contributors | Engineering Mechanics |
| Publisher | Virginia Polytechnic Institute and State University |
| Source Sets | Virginia Tech Theses and Dissertation |
| Language | English |
| Detected Language | English |
| Type | Thesis, Text |
| Format | xiv, 210 leaves, application/pdf, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
| Relation | OCLC# 15255984 |
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