ISSN: 0884-6804
CODEN: JCTRER
Page Count: 11

The Interphase in Unidirectional Fiber-Reinforced Epoxies: Effect on Local Stress Fields
Reifsnider, KL
Graduate research assistant and Alexander Giacco Professor, Virginia Polytechnic Institute and State University, VA

Jayaraman, K
Graduate research assistant and Alexander Giacco Professor, Virginia Polytechnic Institute and State University, VA

Gao, Z
Assistant professor, Clarkson University, NY

Abstract

The “interphase” in a composite is usually modeled as a homogeneous region, despite the fact that it may have spatial property variations. However, it is important to the understanding of composite behavior to incorporate a realistic interphasial region into the micromechanical analyses of composite systems. The authors have recently proposed a model for the interphase properties in fiber-reinforced thermosets; the Young's modulus and coefficient of thermal expansion of the interphase are assumed to vary as functions of distance from the fiber in this model. In the current study, the authors' model is used along with Mori-Tanaka analyses for the determination of “nondilute” local stress fields in unidirectional fiber-reinforced epoxies under thermomechanical loading situations. The governing field equations in terms of displacements are solved in “closed form.” It is found that property variations in the interphase have a distinct effect on the local stresses. This is significant, considering the fact that local stresses play an important role in controlling the structural performance of a composite. The ideas behind this study can be extended to characterize and analyze the interphase in metal matrix and ceramic matrix composites.

Keywords:
composite materials, fiber-reinforced epoxies, fiber-matrix adhesion, fiber-matrix interphase, spatial property variation, local stresses, interphase mechanics

Paper ID: CTR10391J
DOI: 10.1520/CTR10391J
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