Experimental and numerical study of polyethylene hybrid joints: Friction stir spot welded joints reinforced with adhesive

Abstract Nowadays, the friction stir spot welding method is known as a successful method of joining polymers. Therefore, many efforts are developed to improve the mechanical characteristics of the joints subjected to tensile loading. The aim of this article is to introduce a hybrid system of joining polyethylene plates which involves friction stir spot welding and adhesive bonding. This method is adopted to reduce stress gradients around the weld zone which increases the load carrying capacity of the joint. Taguchi design of experiment was employed and the effects of friction stir spot welding (FSSW) parameters e.g. tool rotational speed, dwell time and plunge rate on the joint strength were investigated. Then, the effects of applying an adhesive were studied. Also, a numerical simulation was conducted to interpret the results. The results show that the dwell time has a more significant effect than the other two parameters. Additionally, it was observed that applying the adhesive remarkably increases the joints strength. This is achieved by reducing the stress gradients in the weld zone.