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A new design for friction stir spot joining of Al alloys and carbon fibre reinforced composites

Bolouri, Amir; Fotouhi, Mohamad; Moseley, William

A new design for friction stir spot joining of Al alloys and carbon fibre reinforced composites Thumbnail


Amir Bolouri
Associate Professor in Manufacturing

Mohamad Fotouhi

William Moseley


Friction stir spot welding (FSSW) has been recently developed to join dissimilar materials. However, the traditional requirement for a rotating tool consists of a pin and shoulder in FSSW leads to a complex joining process and unpredictable defects. In this study, a new static-shoulder design in FSSW was proposed and developed to join Al alloys to carbon fiber-reinforced polymer (CFRP) composites. The main joining parameters, including pin rotational speed, pin feed rate and pin plunge depth, were varied to investigate their effects on the joining temperature, materials interaction and the strength of joints. The pin rotational speed had the largest influence on the joining temperature. Lap shear tensile testing was conducted to evaluate the performance of the joints. The joints exhibited the ultimate lap shear force from 230 to 260 N. A brittle fracture occurred with the displacement-at-fracture load of 0.35-0.41 mm. Cross-sectional images revealed the creation of undulations on the surface of Al alloys in the joining zone. The undulations created a macro-mechanical interlocking bonding between the materials, which determined the performance of the joints. For a flat pin, by increasing the plunge depth from 1.25 to 1.30 mm, the undulation size increased from 0.21 to 0.26 mm, which can enhance the macro-mechanical interlocking bonding between Al alloys and CFRP and accordingly increased the ultimate shear force of the joints from 230 to 241 N. Use of a fluted pin significantly influenced the flow of the plasticized Al alloy which created pronounced undulations and large Al alloy spikes of 0.46 mm. These features seemed to establish an efficient macro-mechanical interlocking bonding, which resulted in a noticeable improvement in the performance of the joint. For a plunge depth of 1.30 mm, the ultimate shear force increased to 261 N using the fluted pin.


Bolouri, A., Fotouhi, M., & Moseley, W. (2020). A new design for friction stir spot joining of Al alloys and carbon fibre reinforced composites. Journal of Materials Engineering and Performance, 29, 4913-4921.

Journal Article Type Article
Acceptance Date Jul 19, 2020
Online Publication Date Aug 3, 2020
Publication Date 2020
Deposit Date Jul 21, 2020
Publicly Available Date Aug 4, 2021
Journal Journal of Materials Engineering and Performance
Print ISSN 1059-9495
Electronic ISSN 1544-1024
Publisher Springer Verlag
Peer Reviewed Peer Reviewed
Volume 29
Pages 4913-4921
Keywords Composites; Polymer Matrix; Aluminum; Joining; Friction stir welding; Dissimilar material joining; Al alloys; Friction stir spot joining
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