Curing of Epoxy Matrix Composites

TLDR

The study shows how the model and code can determine an optimal cure cycle that yields uniformly cured composites with low void content and minimal cure time. Models and a computer code were developed to predict temperature, cure degree, resin viscosity, void size, pressure, and residual stress in flat‑plate fiber‑reinforced composites, and to evaluate resin flow and content during curing. Experimental data agreed well with the code’s predictions, validating its accuracy, and the parametric study demonstrated its ability to guide cure‑cycle selection for uniform cure, low voids, and short processing times.

Abstract

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.