A Numerical Model to Simulate Void Dynamics During Processing of Honeycomb Core Sandwich Structures with Prepreg Face-Sheets

Abstract

Composite sandwich structures are fabricated by placing partially-cured thermoset prepreg sheets and an adhesive layer on either side of a honeycomb core enclosed by a vacuum bag in an autoclave and co-cured under a pressure and temperature ramp. It is imperative that the adhesive layer forms a good bond between the core and the prepreg face sheets. One of the complications is the bubbles/voids could form due to outgassing and grow in and around the bond-line during the manufacturing process. In this work, a model of bubble growth is incorporated in a simulation that provides the distribution and size of voids within the adhesive layer as a function of the process, material, and geometric parameters. This understanding should prove useful in reducing or eliminating voids from the bond line during processing of such sandwich structures.