Novel epoxy powder for manufacturing thick-section composite parts under vacuum-bag-only conditions. Part II: Experimental validation and process investigations

James Maguire, Kapileswar Nayak, Conchur O Brádaigh

Research output: Contribution to journalArticlepeer-review

Abstract

Validations of a one-dimensional process model are carried out by manufacturing thick-section glass-fibre reinforced composite laminates with a low-exotherm epoxy powder. An experimental apparatus is developed which heats the laminates from one side while insulating the remaining sides (i.e. approximating one-dimensional heat transfer conditions). Temperatures within the laminate are measured using thermocouples and a linear variable differential transformer is used to measure the thickness change of the laminate, with respect to time, due to powder sintering and fabric impregnation. The experimental results are analysed and used to validate process models for the epoxy powder system. Process simulations are performed to analyse the influence of material format, laminate thickness change, and heating methods (i.e. one-sided heating vs two-sided heating, and heated tooling vs oven heating). It is shown that epoxy powder eliminates the risk of ‘thermal runaway’, but thermal and cure gradients persist for a conventional processing cycle. Methods to inhibit the evolution of these gradients are explored using process simulations. These methods include modifying the temperature cycle and using multiple epoxy powders with varied latent curing properties.
Original languageEnglish
Article number105970
JournalComposites Part A: Applied Science and Manufacturing
Volume136
Early online date18 May 2020
DOIs
Publication statusPublished - Sep 2020

Keywords

  • Epoxy powder
  • Process simulation
  • Process monitoring
  • Out of autoclave processing

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