SYMPOSIA PAPER Published: 01 January 1989

Environmental Effects on High Strain Rate Properties of Graphite/Epoxy Composite


A unidirectional graphite/epoxy material was characterized at strain rates ranging from 5× 10-6 to 5 s-1 under various hygrothermal conditions. New techniques were successfully employed for measuring hygrothermal properties and for strain monitoring of “wet” specimens at high strain rates. A time-temperature-moisture equivalence principle was applied to obtain master curves for the longitudinal, transverse, and in-plane shear moduli and corresponding strengths and ultimate strains of the unidirectional graphite/epoxy. It was found that, except for the longitudinal modulus, which shows a slight increase with strain rate, temperature, and moisture, all other longitudinal properties in general remain unchanged. The transverse modulus increases with strain rate but decreases with increasing temperature and moisture content. All transverse and intralaminar shear properties decrease with increasing temperature and moisture content for a fixed strain rate. Transverse ultimate properties as a function of strain rate show a trend reversal with a local maximum. The in-plane shear strength increases noticeably with strain rate, whereas the ultimate shear strain decreases slightly. The time-temperature-moisture shift function is expressed as a function of two variables, allowing interchangeability of the three parameters, time, temperature, and moisture content.

Author Information

Yaniv, G
Northwestern University, Evanston, IL
Peimanidis, G
Northwestern University, Evanston, IL
Daniel, IM
Northwestern University, Evanston, IL
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Developed by Committee: D30
Pages: 16–30
DOI: 10.1520/STP10017S
ISBN-EB: 978-0-8031-5071-3
ISBN-13: 978-0-8031-1196-7