Design and application of discontinuous resin distribution patterns for semi-pregs

Abstract

Vacuum-bag-only (VBO) prepregs fabricated with discontinuous resin (semi-pregs) on a unidirectional fiber bed reportedly exhibit high through-thickness permeability and yield high-quality laminates, even under adverse process conditions, such as poor vacuum or long out-times. In this work, semi-pregs were fabricated using fiber beds of various weaves, fiber types, and areal weights (200–670 GSM). Flat and curved laminates were produced and characterized, confirming that porosity-free parts can be manufactured from a range of constituent materials using VBO semi-pregs. Contoured laminates were produced with negligible porosity, although a slight increase in bulk factor of prepreg plies was observed (Δ∼0.1). In addition, design considerations and limitations for the fabrication of semi-pregs were presented. The findings demonstrate that polymer film dewetting can be used effectively to produce semi-pregs that yield porosity-free laminates via VBO processing, imparting robustness to out-of-autoclave cure of prepreg laminates.

Keywords

• prepreg
• polymer matrix composites
• porosity
• defects
• out of autoclave
• vacuum bag only