Promoting extrinsic bridging of adhesively-bonded CFRP joints through the adhesive layer architecture

Promoting extrinsic bridging of adhesively-bonded CFRP joints through the adhesive layer architecture

Tao, R. (TU Delft Structural Integrity & Composites; King Abdullah University of Science and Technology (KAUST))
Lubineau, Gilles (King Abdullah University of Science and Technology (KAUST))
Teixeira De Freitas, S. (TU Delft Structural Integrity & Composites)

Vassilopoulos, Anastasios P. (editor)
Michaud, Véronique (editor)

2022

Carbon fiber-reinforced polymers (CFRPs) have widely attracted the aerospace and automotive industries due to high stiffness and lightweight. Secondary adhesive bonding of CFRPs is a promising research field to fully explore their potential. However, multiple challenges have limited the further application of adhesively-bonded composite joints since it is difficult to inspect the premature debonding, which leads to catastrophic failure once initiated. Thus, it is crucial to introduce crack arrest features, to slow down (or even stop) the crack growth and achieve progressive failure. Various methods have been reported to introduce crack arrest features, including z-pins and corrugated substrates. Our previous work directly utilized the adhesive layer to bridge the separating CFRP parts, through the extrinsic bridging of adhesive ligaments. The bridging adhesive ligaments are triggered by the patterning of distinct surface treatments. These extrinsic bridging ligaments largely enhance the energy release rate (ERR) and successfully arrest the crack propagation. However, a large portion of the required energy for the further crack propagation is stored elastically in the stretching ligaments, which would cause catastrophic fast joint debonding after the failure of ligaments. In this work, the adhesive layer was architected in order to improve its plasticity. By promoting the plastic energy dissipation, the bridging, stretching, and failure of generated adhesive ligaments could result in tougher and safer joints. CFRP substrates were alternatively patterned by two distinct surface treatments to achieve different interfacial strength and toughness values. Then, double-cantilever beams (DCB) were manufactured by bonding treated substrates with the architected adhesive material, such as integrating 3D-printed nylon wires or newly synthesized adhesive material. Results showed that the proposed joint toughening strategy could improve ERR compared to conventional uniform treatments and increasd adhesive plasticity could also stabilize the crack propagation, leading to a safer joint.

adhesive joint
extrinsic bridging
Toughening
DCB
plastic energy dissipation

http://resolver.tudelft.nl/uuid:b7e82ae7-92b8-4d4e-b3af-4858bbf05008

EPFL Lausanne, Composite Construction Laboratory, Lausanne

978-2-9701614-0-0

Proceedings of the 20th European Conference on Composite Materials: Composites Meet Sustainability: Vol 2 – Manufacturing

20th European Conference on Composite Materials, 2022-06-26 → 2022-06-30, Lausanne, Switzerland

Institutional Repository

conference paper

© 2022 R. Tao, Gilles Lubineau, S. Teixeira De Freitas