CO ₂ Laser Micro‐Texturing on CFRP Surfaces for Enhanced Adhesive Bonding Joint Strength

ABSTRACT

Adhesive‐based joining of thin carbon fiber‐reinforced polymer (CFRP) sheets finds widespread applications in automotive, aerospace, and other industries. This work seeks to investigate the influence of laser surface texturing parameters on the surface wettability, morphology, and adhesive bonding performance of CFRP. While prior studies have largely focused on the fiber laser systems, investigations employing the more frequently used industrial CO ₂ lasers in the context of adhesive bonding of CFRP surfaces are still scarce. Therefore, in this work, the laser texturing was performed under varying defocus conditions (at three levels) and pitches (at four levels) while keeping the laser power and scanning speed constant, to systematically investigate the evolved surface features and their impact on the interfacial bonding behavior. Texturing aspects such as groove width, groove depth, surface roughness, and fiber exposure were evaluated for processed CFRP samples using a confocal microscope. Lap shear strength was measured for all the joints made with textured surfaces and correlated with the extent of fiber exposure and other geometric aspects of the textured surface. Furthermore, image‐based failure analysis was performed, and different failure modes were quantified and discussed in relation to other responses measured during the study.