Development and Optimization of Metal to Polymer Friction Stir Welded Joints

Beatriz Margarida Gaspar Ribeiro

Key information

Authors:

Beatriz Margarida Gaspar Ribeiro (Beatriz Margarida)

Supervisors:

Arménio Neves Correia (Arménio Neves Correia); Virgínia Isabel Monteiro Nabais Infante (Virgínia Isabel Monteiro Nabais Infante)

Published in

07/01/2024

Abstract

Amidst the growing need for lighter, environmentally friendly, and cost-effective solutions in the transportation sector, engineers are adopting innovative dissimilar structures, combining materials like metal alloys and polymers/composites. However, joining dissimilar materials in multi-material structures poses an engineering challenge due to inherent property disparities. Friction stir-based technologies, including Friction Stir Welding (FSW), are showing promising results and offer advantages over traditional joining methods (mechanical fastening and adhesive bonding). In this work, overlap dissimilar joints were produced between a glass fiber-reinforced polymer (NORYL™) and an aluminum alloy (AA6082-T6), using FSW. A Central Composite Design (CCD) methodology was defined, to comprehensively evaluate the joints’ mechanical strength and processing temperature and analyse the main effects, interactions, and influence of the processing parameters, namely, rotational speed, welding speed, and tool tilt angle. Analysis of the processing temperature and tensile strength resulted in a statistical model. The macro and microstructures, and hardness of the joints were also studied. The bending factor of the secondary bending moment was determined using a finite elements model (FEM) and its effect on the joint’s efficiency was studied. The joints’ mechanical strength ranged from 1698.20±17.29 N to 3414.17±317.15 N, with a maximum joint efficiency of 84.55%. The processing temperature was between 203.6±10.7°C and 277.0±25.4°C. The predicted optimal set of parameters encompassed a rotational speed of 1136 rpm, welding speed of 154 mm/min, and tilt angle of 1.7°. The joints fabricated with this set of parameters exhibited an average mechanical strength of 2645.24±232.14 N and a joint efficiency of 69.78%.