Curing of Epoxy Matrix Composites

Abstract

ABSTRAGT Models were developed which describe the curing process of composites constructed from continuous fiber-reinforced, thermosetting resin matrix prepreg materials. On the basis of the models, a computer code was developed, which for flat-plate composites cured by a specified cure cycle, provides the temperature distribution, the degree of cure of the resin, the resin viscosity inside the composite, the void sizes, the temperatures and pressures inside voids, and the residual stress distribution after the cure. In addition, the computer code can be used to determine the amount of resin flow out of the composite and the resin content of the composite and the bleeder. Tests were performed measuring the temperature distribution in and the resin flow out of composites constructed from Hercules AS/3501-6 graphite epoxy prepreg tape. The data were compared with results calculated with the computer code for the conditions employed in the tests and good agreement was found between the data and the results of the computer code. A parametric study was also performed to illustrate how the model and the associated computer code can be used to determine the appropriate cure cycle for a given application, which results in a composite that is cured uniformly, has a low void content, and is cured in the shortest amount of time.

Process Induced Defects in Liquid Molding Processes of Composites

“…Traditionally, both linear and non-linear programing techniques were used to obtain optimal cure temperature and pressure cycles. Using these techniques often requires concurrent use of thermomechanical and consolidation models describing the laminate fabrication, which are often solved by numerical methods (Bogetti and Gillespie, 1991;Loos and Springer, 1983;Mawardi and Pitchumani, 2003). The uncertainty associated with the cure parameters, on the other hand, has been incorporated into the optimization process using stochastic, deterministic, and parametric programming (Acquah et al, 2006).…”

Thermo-oxidative degradation of graphite/epoxy composite laminates: Modeling and long-term predictions

“…In addition to thermal aging, Equation (1), in this generic form, has been used to develop phenomenological models for various other applications, including cure modeling of thermoset resins and composite prepregs, and also for describing microstructural changes [18][19][20][21][22].…”

Effect of laminate edge conditions on the formation of microvoids in composite laminates

“…The pressure profile reduces laminate thickness and removes mobile voids by causing resin flow. The compaction of composite components with a laminated microstructure was first modeled by Loos and Springer [13], who described the resin flow through the laminate as a flow through porous media according to Darcy's law. Hence, Ref.…”

“…Hence, Ref. [13] predicted the compaction sequence of a laminate during cure and determined that the processing pressure applied is initially carried by the resin and increasingly transferred to the fiber reinforcement as the resin flows out from the laminate. This is significant given that the stability and growth of voids during cure, as shown by Kardos et al [14], is a function of cure temperature and resin pressure.…”