Effect of laser cleaning in Laser Assisted Joining of CFRP and PC sheets

The present paper investigates the influence of laser cleaning of Carbon Fibre Reinforced Plastic (CFRP) surface when joining CFRP to Polycarbonate (PC) sheet by means of laser assisted Joining. Experimental tests were conducted to perform polycarbonate-CFRP (with epoxy matrix) joints. The laser cleaning treatment was carried out on CFRP laminate adopting a 30 W Q-switched Yb:YAG fibre laser. Laser assisted joining was performed adopting a continuous wave 200 W diode laser. Untreated samples were adopted as reference. Morphological analysis and single lap shear tests were conducted to characterize the joints. Infrared thermography (IRT) was carried out to determine the temperature distribution and variation during the joining process. ANalysis Of VAriance was applied to investigate the effect of the process parameters, (laser power, energy, and treatment) on the extension of the bonded area and the mechanical properties. The results show that laser pre-treatment enables a significant increase of the joint strength which is, under the optimal conditions, more than double than the reference samples: However, considering the apparent shear strength, the laser pre-treatment does not produce a significant advantage, as it mainly resulted in the enlargement of the bonded area.