SEDL / STP / STP1059-EB / STP24127S

Thermoviscoelastic Characterization and Prediction of Kevlar/Epoxy Composite Laminates

Gramoll, KC
Assistant professor, Memphis State University, Memphis, TN

Dillard, DA
Associate professor, Virginia Polytechnic Institute and State University, Blacksburg, VA

Brinson, HF
Professor and director, University of Texas at San Antonio, San Antonio, TX

Pages: 17    Published: Jan 1990

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Abstract

Unidirectional fiber-reinforced plastic (FRP) composite lamina, made from Kevlar 49 fibers and Fiberite 7714A epoxy, were characterized for nonlinear thermoviscoelastic response using the time-temperature superposition principle (TTSP). Mechanical static creep and creep recovery tests were performed using strain gages on 0°, 10°, and 90° unidirectional specimens at numerous temperature and stress levels. Master curves and shift factor functions for all four orthotropic material properties (fiber direction S¹¹, fiber/transverse coupling direction S¹², transverse direction S²², and shear S⁶⁶ compliances) were obtained. Results were used in a numerical procedure to predict the viscoelastic response of general laminates. Predictions are compared with actual test results on selected two, three, and four fiber direction laminates made from Kevlar/epoxy.