Micro-Mechanical Modelling of Fiber Tows Prior to Infiltration

Abstract

One of the main drivers of the limited use of carbon fiber composites is the raw material cost. To bring this cost down, tows with higher fiber counts (~50k fibers) are becoming more popular. These so-called “heavy tows†carry with them several challenges in manufacturing and a decrease in performance. Several aspects that affect the performance and manufacturability of heavy tows are the degree of fiber entanglement and amount of sizing. Highly entangled tows may increase the manufacturability because it binds the tow together, but non-aligned fibers result in decreased stiffness in the tow axial direction in the final part. Additionally, sizing is added to coat the fibers and adhere them together, allowing tow to stay together during processing. The present research introduces a model which will be used to look at the effects of such fiber-scale parameters on the mechanical response of a dry tow under different loading conditions, and results for tows with sizing will be presented. Methods for including these aspects will be highlighted, and conclusions will be drawn about the necessity of including fiber-scale parameters in predictive models to predict the behavior of dry carbon fiber tows during manufacturing.