TY - JOUR

T1 - Refill friction stir spot welding of thermoplastic composites: Case study on Carbon-fiber-reinforced polyphenylene sulfide

AU - Schäfer, Holger

AU - Blaga, Lucian Attila

AU - Stöver, Enno

AU - Klusemann, Benjamin

N1 - Funding Information: The authors would like to thank Dr. Ing. Henry Ovri (Helmholtz-Zentrum Hereon) for his support with the nanoindentation measurements and supply of technical equipment. Publisher Copyright: © 2023 Elsevier Ltd

PY - 2023/10/1

Y1 - 2023/10/1

N2 - Refill Friction Stir Spot Welding (refill FSSW) is an innovative solid-state welding technique that has been successfully applied to various combinations of metallic materials. The objective of the present study is to investigate the feasibility of refill FSSW for polymer–polymer structures, with a specific emphasis on carbon-fiber-reinforced polyphenylene sulfide (CF-PPS). The influence of the key joining parameters, i.e. force, plunge depth, rotational speed, and tool diameter, has been analyzed in terms of the resulting joint microstructure, mechanical strength, and failure mechanisms. The lap shear tests revealed two primary failure modes: interfacial shear failure and nugget pull-out. Fracture surfaces exhibited broken fibers. The depth of the joint was found to play a crucial role in determining the failure mode, with interfacial shear failure resulting in higher lap shear strength. Thermal analyses conducted on the produced joints showed no evidence of thermal degradation, which aligns with the temperature measurements during the process, as they remained below the melting temperature of CF-PPS.

AB - Refill Friction Stir Spot Welding (refill FSSW) is an innovative solid-state welding technique that has been successfully applied to various combinations of metallic materials. The objective of the present study is to investigate the feasibility of refill FSSW for polymer–polymer structures, with a specific emphasis on carbon-fiber-reinforced polyphenylene sulfide (CF-PPS). The influence of the key joining parameters, i.e. force, plunge depth, rotational speed, and tool diameter, has been analyzed in terms of the resulting joint microstructure, mechanical strength, and failure mechanisms. The lap shear tests revealed two primary failure modes: interfacial shear failure and nugget pull-out. Fracture surfaces exhibited broken fibers. The depth of the joint was found to play a crucial role in determining the failure mode, with interfacial shear failure resulting in higher lap shear strength. Thermal analyses conducted on the produced joints showed no evidence of thermal degradation, which aligns with the temperature measurements during the process, as they remained below the melting temperature of CF-PPS.

KW - Refill FSSW

KW - Thermoplastic composites

KW - Solid-state welding

KW - Polymer joint

KW - CF-PPS

KW - Engineering

UR - http://www.scopus.com/inward/record.url?scp=85169899624&partnerID=8YFLogxK

U2 - 10.1016/j.tws.2023.111037

DO - 10.1016/j.tws.2023.111037

M3 - Journal articles

VL - 191

JO - Thin-Walled Structures

JF - Thin-Walled Structures

SN - 0263-8231

M1 - 111037

ER -