Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
6702458 | Composite Structures | 2018 | 7 Pages |
Abstract
Pre-impregnated sheets of advanced carbon fibers with highly viscous thermoset-based resin systems are commonly used in fabricating aerospace composite parts. As prepreg sheets are vacuum bagged and heated during processing, the resin slowly infiltrates in dry spots between fibers. Under vacuum condition, surface tension-induced capillary effects impose deep negative pressures on the liquid resin, leading to tensile stretching. A method is presented to quantify the capillary-induced negative pressure. During processing, samples are quenched to freeze the infiltration process before taking SEM images. Using image analysis and by invoking interfacial stress boundary condition, the pressure distribution is determined. Sub-micron radii of curvature at the resin interface were measured corresponding to local negative pressures up to several atmospheres and an average pressure of â10 to â50â¯kPa. Effects of negative pressures on the state of material and on defects such as resin phase separation are discussed.
Related Topics
Physical Sciences and Engineering
Engineering
Civil and Structural Engineering
Authors
Navid Zobeiry, Caitlin Duffner,