Fig. 1. Schematics of laser and optical path. (a) Physical picture of laser; (b) schematic of laser optical path

Fig. 2. Schematics of barb array parameters and fabrication process. (a) Structure of barb array; (b) schematic of barb array parameters; (c) schematics of barb array fabrication process

Fig. 3. Schematics of gluing process. (a) Laser treatment; (b) application of silane coupling agent; (c) application of adhesive; (d) pressurized bonding; (e) addition of gaskets

Fig. 4. 3D morphologies of barb array structure. (a) Macroscopic 3D morphology of barb structure on aluminum alloy surface; (b) macroscopic 3D morphology of barb structure on CFRP surface; (c) 3D microstructure of aluminum alloy barb structure; (d) 3D microstructure of CFRP barb structure

Fig. 5. Cross-sectional views of adhesive joint. (a) Cross section of barb array joint; (b) cross section of joint after sandpaper roughening; (c) cross section of untreated joint

Fig. 6. XPS images of fracture interface of aluminum alloy. (a) Al2p and (b) O1s spectra without silane coupling agent modification; (c) Al2p and (d) O1s spectra after silane coupling agent modification

Fig. 7. Schematic of joint strength

Fig. 8. Fracture diagrams of adhesive joints under different treatment methods. (a) No treatment; (b) sandpaper treatment; (c) only laser treatment; (d) silane coupling agent modification and laser treatment