Influence of Process Parameters and Material Aging on the Adhesion of Prepreg in AFP Processes

Abstract

In order to increase the quality of CFRP parts, the manufacturing process could be customized to the current condition of the used prepreg material. For that reason, a long term experiment was executed here, where the change of the tack due to material aging at room temperature and variation of material temperature was analyzed. With the existing requirements, among other things, to simulate a real automated fiber placement (AFP) process, a lap shear test was found to be appropriate to measure the tack between two prepreg plies. First results show, that the tack increases dramatically if the temperature of the material also increases. Regarding material aging at room temperature, without heating the material, the tack was constant for a long time and then started to decrease. If the material was heated during the automated layup, the tack did not decrease but surprisingly increased constantly for more than ten days, before it started to decrease. This unexpected behavior could result from the increasing degree of cure which leads to an increase of the viscosity of the resin.