Laser-induced groove optimization for Al/CFRP adhesive joint strength

Akman E., Bora M. Ö., Çoban O., Oztoprak B.

INTERNATIONAL JOURNAL OF ADHESION AND ADHESIVES, vol.107, 2021 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 107
  • Publication Date: 2021
  • Doi Number: 10.1016/j.ijadhadh.2021.102830
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Academic Search Premier, Aerospace Database, Chemical Abstracts Core, Communication Abstracts, INSPEC, Metadex, Civil Engineering Abstracts
  • Keywords: Aluminum, CFRP, Adhesive bonding, Laser surface pre-treatment, Mechanical interlocking
  • Kocaeli University Affiliated: Yes


The ability to achieve sufficient values of adhesive strength depends on many parameters such as type and thickness of the adhesive, and especially appropriate surface preparation. While it is possible to increase the adhesive strength of a surface prepared for bonding by making it chemically suitable, forming of the structures that will provide mechanical interlocking can also increase the adhesive shear strength. Mechanical interlocking groove parameters such as depth, width, and number per unit area formed on the AA2024-T3 aluminum surface by using fiber laser were optimized for adhesive bonding strength with carbon fiber reinforced polymer (CFRP). The top surface and cross-sectional images were used to determine the geometrical change of the grooves produced on the aluminum surface. As the depth of the grooves increased, the adhesion surface area of the samples increased by approximately 308%. According to the single-lap shear strength test results, the increase in the depth of the grooves, hence the adhesion surface area and the entrance width of the grooves have a common effect on the shear strength. While increase in the adhesive surface area and entrance width of the grooves increases the shear strength, decreasing in the entrance width causes the decrease in the shear strength even if the surface area increases. In this study, with the effect of mechanical interlocking caused by laser-induced grooves, approximately 180% increase in adhesive shear strength (26.48 MPa) was achieved compared to the abraded sample. After mechanical tests, failure modes were also observed by using the a photo camera. It was determined that the effect of created grooves with optimized geometrical sizes on the AA2024-T3 aluminum surfaces changed the failure mode that occurred at the CFRP surfaces from adhesive failure to fiber tear failure.