Improving the quality of the ultrasonic welded thermoset-based composites using laser surface treatment

In this article, ultrasonic welding of glass fiber-reinforced thermosetting polymers which were surface-treated by laser engraving, is investigated. Composite samples were prepared by hand lay-up method. In the next step, surface treatment of the composite samples was performed by means of a high-power laser confirming two grooved and circular patterns. Polymethylmethacrylate and polypropylene as the amorphous and semicrystalline thermoplastic intermediate layers were incorporated to create a joining between the two thermoset parts. Besides, the welding time was considered in the three different levels. In order to investigate the microstructure of the welding zone, scanning electron microscopy analysis were accomplished. Besides, lap-shear tests were performed so as to evaluate the mechanical performances of the welded parts. Morphological studies indicated that in the surface-treated samples, the penetration of the intermediate material into the welded parts is much higher than neat samples and this leads to the superior interaction between the coupling layer and the surface-treated parts. Confirming the morphological outcomes, the results of the lap-shear tests specified that the application of surface treatment using laser engraving has increased the laps-shear strength almost 5.5 times compared to the samples without preparation.