INFLUENCE of UV-RADIATION on PEEK/CF LAMINATES after to be SUBMITTED to WELDING INDUCTION

One of the functions of the development of advanced polymer composite technologies is the union of different materials, which when combined, have better properties, such as high mechanical strength and hardness, when compared to the separated materials. Since there is a lack of effective integration methods for structural parts, the application of composites in this field is hindered. In general, all welding processes are fast and require little or any surface preparation. Studies prove that induction welding have been shown as promising process for the welding of composite materials.
The aim of this work is to evaluate the most appropriate combination of parameters for the induction welding of polyether ether ketone (PEEK) laminates reinforced with carbon fibers (CF) for aeronautical applications. Additionally, the influence of UV-radiation on the mechanical and viscoelastic properties of the welded CF-PEEK joints is evaluated. A complete factorial design of the welding trials in combination with the lap shear mechanical test was used to find the best combination of parameters. The parameters which were evaluated are time, current and pressure. However, only time and pressure are used for statistical control (current is not variable) (50 s, 150 N). With the optimal combination, samples were welded for the mechanical tests (Iosipescu and End Notched Flexure), thermal analysis (DMA and TMA) and morphological analysis of fractures from mechanical tests using scanning electron (SEM) and optical (OM) microscopies. Beyond that, the welded laminates were conditioned in UV radiation chamber, in order to simulate flight conditions.