Effect of thermoplastic fiber veils interleaving on the fracture toughness and flexural behavior of carbon-reinforced aluminum laminates (CARALLs)

Üstün T., Yar A., ESKİZEYBEK V.

Composites Communications, cilt.63, 2026 (SCI-Expanded, Scopus) identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 63
  • Basım Tarihi: 2026
  • Doi Numarası: 10.1016/j.coco.2026.102756
  • Dergi Adı: Composites Communications
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Anahtar Kelimeler: Delamination, Fiber metal laminate (FML), Interleaving, Thermoplastic veil
  • Çanakkale Onsekiz Mart Üniversitesi Adresli: Evet

Özet

This study evaluates nonwoven thermoplastic fiber veils placed at the carbon fiber–aluminum interface to enhance the interlaminar fracture toughness (IFT) of carbon-reinforced aluminum laminates (CARALL). Five veils—fine glass (FG), poly(phenylene sulfide) (PPS), polyetherimide (PEI), poly(ether-ether-ketone) (PEEK), and polyimide (PI)—were interleaved in CARALL fabricated via vacuum bagging using 2024-T3 aluminum sheets and carbon/epoxy prepreg. Flexural behavior and interlaminar fracture toughness were characterized through three-point bending, Mode-I double cantilever beam (DCB), and Mode-II end-notched flexure (ENF) tests. Thermoplastic interleaving increased flexural strength relative to the unreinforced laminate, with PEEK achieving the highest improvement (9%). In Mode-I, PPS delivered the greatest gains in crack-initiation and crack-propagation energies (157% and 69%, respectively), while FG and PI underperformed the control. Mode-II interlaminar fracture toughness (GΙΙc) was also maximized by PPS (128% increase). Microscopy of fracture surfaces showed that fiber bridging and fiber pull-out were common in PEEK, PEI, and PPS-interleaved laminates. This was in line with rising R-curves and longer fracture damage zones. Overall, the PPS-reinforced CARALL composite shows enhanced Mode-I/II interlaminar fracture toughness; in addition, other thermoplastic veil reinforcements demonstrate effective performance depending upon the material type.