Anisotropic air permeability in out-of-autoclave prepregs: Effect on honeycomb panel evacuation prior to cure

James Kratz, Pascal Hubert*

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

59 Citations (Scopus)

Abstract

Air evacuation is crucial to achieve low porosity for vacuum-bag-only manufacturing of out-of-autoclave prepregs. In this paper, the air permeability of composite skins was evaluated for in-plane and transverse air evacuation. The air permeability and microstructure were evaluated for three common prepreg fabric architectures: unidirectional, plain weave, and 5 harness satin. Since prepreg permeability is anisotropic, a 3-D pressure gradient can arise in honeycomb skins. In-order to calculate the effective air permeability coefficients of honeycomb skins, the computational fluid dynamics software FLUENT was used to determine the 1-D pressure gradient and corresponding area normal to flow. The air permeability coefficients were correlated to the prepreg microstructure using micro-CT imaging. The results showed that the in-plane air permeability was higher for fabrics with larger visible dry tow areas. The transverse air permeability was higher for prepregs that formed connected macro-porosity networks after lay-up, compared to prepregs with isolated macro-pores. (C) 2013 Elsevier Ltd. All rights reserved.

Original languageEnglish
Pages (from-to)179-191
Number of pages13
JournalComposites Part A: Applied Science and Manufacturing
Volume49
DOIs
Publication statusPublished - Jun 2013

Keywords

  • Air permeability
  • A. Prepreg
  • D. Radiography
  • C. Computational modeling
  • GAS-FLOW METHOD
  • POROUS-MEDIA
  • INPLANE PERMEABILITY
  • SANDWICH STRUCTURES
  • PERMEATION
  • PRESSURE
  • REINFORCEMENTS
  • PREFORM

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