Friction Stir Joining of CFRP laminates with amorphous polymers: Influence of processing speeds

The influence of the processing speeds during friction stir joining of polycarbonate sheets with carbon fiber reinforced epoxy laminates was investigated. A prototypal CNC machine equipped with load and temperature sensors was used during the experimental tests. Mechanical characterization tests were performed by conducting quasi-static single lap shear tests. In addition, the material flow and the morphology of the welds were investigated. The results indicated that the mechanical behavior of the joints was mainly determined by the temperature of the stirred material and the amount of material reflow. A predictor index given by the ratio of the plunging load by the load along the joining direction was developed to determine processing conditions that facilitate the development of large amount of material reflow. Thus, an empirical model that related the shear strength to the temperature of the stirred material and the predictor index was established. Under optimal processing conditions, the process involved the removal of the superficial layer of epoxy from the CFRP and the substitution with the polycarbonate. This enabled relatively high strength 17 MPa that corresponded to the 89 % of the Interlaminar shear strength of the CFRP.