Date of Award

Spring 1978

Document Type


Degree Name

Doctor of Philosophy (PhD)


Mechanical & Aerospace Engineering


Mechanical Engineering

Committee Director

Robert L. Ash

Committee Member

Surendra N. Tiwari

Committee Member

Charlie H. Cooke

Committee Member

Stephen Cupschalk


The diffusion of moisture through fiber reinforced polymeric-matrix composite materials has been studied analytically. The diffusion in the orthotropic, nonhomogeneous material was modeled, in detail, with a two-dimensional transient diffusion analysis. An effective diffusivity for the composite was determined in terms of the fiber volume fraction and the resin diffusivity. This effective diffusivity is in better agreement with recent data than those previously determined using less complex models.

The influence of both material and environmental parameters on the moisture content of the composite was determined analytically. Predicted moisture contents were compared over a wide range of values for emittance, solar absorptance, convective heat-transfer coefficient, ambient temperature, solar radiation, panel orientation with respect to the Sun and geographical location. The calculations showed that absorptance and the heat-transfer coefficient have significant effects on the moisture content. Also, the equilibrium moisture content is relatively insensitive to the geographical location for areas with similar humid environments.


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