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The influence of the representative volume element (RVE) size (in terms of fiber packing and number of fibers for a given fiber-volume fraction) on the residual stresses created during the curing process of a continuous fiber-reinforced polymer matrix tow is investigated with the ultimate goal of finding a minimum unit cell size that can be used later for a homogenization procedure to calculate the response of woven fiber textile composites and in particular, fiber tows. A novel network curing model for the solidification of epoxy is used to model the curing process. The model takes into account heat conduction, cure kinetics and the creation of networks in a continuously shape changing body. The model is applied to the curing of a fiber/matrix RVE. The results for the minimum size of the RVE, obtained on the basis of the curing problem, are compared with a similar RVE, modeled as an elastic-plastic solid subjected to external loads, in order to compare the minimum RVE sizes obtained on the basis of different boundary value problem solutions.

The cure kinetics of epoxy cured with an amine hardener is investigated using a combination of light scattering techniques. Concurrent Raman and Brillouin scattering are used to monitor the formation of epoxy networks over time in terms of both the structural connectivity of the network and the evolution of chemical bonding configurations. The relationship between the elastic properties of the network and the degree of cure was found to depend on the cure temperature and the resin−hardener stoichiometry. A numerical model was created to determine the degree of cure and elastic modulus as a function of time and cure conditions. Accordingly, the modulus of the epoxy comprises two contributions: one directly related to the concentration of covalent bonds that form and another one due to nonbonding interactions that arise as the network relaxes into an optimally packed configuration.

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