Enhancement of fracture toughness in secondary bonded CFRP using hybrid thermoplastic/thermoset bondline architecture. (20th October 2020)

• Record Type: Journal Article
• Authors: Yudhanto, A.; Almulhim, M.; Kamal, F.; Tao, R.; Fatta, L.; Alfano, M.; Lubineau, G.
• Is Part Of: Composites science and technology. Volume 199(2020)
• Publication Date: 2020-10-20
• Subjects: A. Adhesive joints -- A. Laminate -- B. Fracture toughness -- B. Interface -- B. Delamination; Composite materials -- Periodicals; Composite materials; Fibrous composites; Periodicals; 620.118
• DOI: 10.1016/j.compscitech.2020.108346
• Languages: English
• ISSNs: 0266-3538

Abstract

Abstract: Structures made of carbon fiber-reinforced polymer (CFRP) can be assembled using adhesive bonding. However, such bonding is prone to brittle delamination, and a method to improve delamination resistance is desirable. Here, we propose a technique to introduce crack-arrest features that increase the R-curve response by engineering the adhesive bondline/interface. We specifically designed a wavy net-like thermoplastic insert that was embedded into the thermoset adhesive bondline where the new mechanisms of energy dissipation were generated. We demonstrate that the technique is effective at improving mode I fracture toughness of secondary bonded carbon/epoxy by more than 400%. The hybrid thermoset/thermoplastic bondline architecture was carefully tailored to achieve its best performance. We demonstrate that introducing porosities in the adhesive bondline (by adding a limited amount of thermoset adhesive) further improves the fracture toughness. This toughness improvement originates from the extrinsic toughening of the crack-arrest feature, which is enabled by the insert ductility and microstructures (via strand formation, anchoring and stretching). Graphical abstract: Image 1