Prediction of capillary pressure for resin flow between fibers

Abstract

The flow of resin into fiber tows is driven by an applied pressure gradient and the capillary pressure, which is dependent on the contact angle between the fibers and the resin as well as the fiber diameter and its arrangement with respect to neighboring fibers. Previous work has reported on methods to calculate the average capillary pressure between two fibers which does not take into account the effect of neighboring fibers in a closely packed tow. This paper introduces a novel method to calculate the average capillary pressure of resin moving through a unit cell containing five fibers in a commonly found fiber arrangement within a fiber tow. Both numerical and analytical solutions are presented, validated, and compared. The role of selected parameters on average capillary pressure is investigated. The influence of packing a unit cell with fibers with different surface treatments is also examined. This work should prove useful in predicting the average capillary pressure of resin moving between fibers and the results can be used to address filling of fiber tows during composites manufacturing and addressing void formation within fiber tows. (C) 2016 Elsevier Ltd. All rights reserved.