SYMPOSIA PAPER Published: 01 January 1996

Modeling the Dynamic Response of the Fiber/Matrix Interphase in Continuous Fiber Composite Materials


A mathematical model was developed for the torsional dynamic response of unidirectional composites with imperfect bonding between the fibers and matrix. The model is basically an assemblage of homogeneous isotropic cylinders with different dynamic properties. The interfacial region where the fibers and matrix are chemically and mechanically bonded was modeled as a nonuniform interphase. The interphase, containing both a stiff region and a soft region, was incorporated into a three-phase model. To study the effects of the interphase on the dynamic response of the composites, the dynamic modulus of the interphase was varied to simulate fiber/matrix bonding conditions. A low storage modulus and high loss modulus of the interphase, corresponding to poor interfacial bonding, were found to result in more damping. The torsional dynamic response for a pitch-based carbon fiber/epoxy composite system with different fiber volume fractions was evaluated with the current models. The dynamic response of the composites predicted by the three-phase model agreed well with values measured by torsional dynamic mechanical test, while the two-phase model with perfect bonding between the fibers and matrix not only underestimated the loss modulus but failed to predict the trend of the loss tangent of the composites. These observations indicated that a viscoelastic interphase was significant and necessary to obtain good correlation with experimental results.

Author Information

Yuan, JJ
Clemson University, Clemson, SC
Kennedy, JM
Clemson University, Clemson, SC
Edie, DD
Clemson University, Clemson, SC
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Developed by Committee: D30
Pages: 67–83
DOI: 10.1520/STP38226S
ISBN-EB: 978-0-8031-5564-0
ISBN-13: 978-0-8031-2046-4