Manufacture of long spars: Laminate design, experimental trials and non-destructive evaluation

Research output: Contribution to journalArticlepeer-review


Although an enabler of high-rate manufacture, automated forming of components from flat laminates can result in fibre wrinkling. For the first time, fibre length is demonstrated to be a key driver of wrinkling defects when forming a C-spar with a central recess, at industrial length scales. Three such spars, of equal in-plane stiffness, were manufactured using Single Diaphragm Forming. Two contained standard ply angles (0°, 90° or ±45°) including 6 m long 0° fibres but had different stacking sequences, one shown to be formable in short spar trials, the other un-formable. A third spar also had a formable sequence but contained non-standard ply angles (angles other than 0°, 90° or ±45°) so that maximum fibre length was less than 0.6 m. Wrinkles occurred in both standard angle spars but did not occur in the non-standard angle case, demonstrating that use of formable, non-standard angle laminates can reduce scrappage of automatically formed aerospace parts, leading to significant time and cost savings in production.

Original languageEnglish
Article number110646
JournalComposites Part B: Engineering
Early online date23 Feb 2023
Publication statusPublished - 15 Apr 2023


  • Design for manufacture
  • Diaphragm forming
  • Length-effect
  • Non-standard ply angles
  • Wrinkling

ASJC Scopus subject areas

  • Ceramics and Composites
  • Mechanics of Materials
  • Mechanical Engineering
  • Industrial and Manufacturing Engineering


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