Print Email Facebook Twitter Static ultrasonic welding of carbon fibre unidirectional thermoplastic materials and the influence of heat generation and heat transfer Title Static ultrasonic welding of carbon fibre unidirectional thermoplastic materials and the influence of heat generation and heat transfer Author Köhler, F. (TU Delft Aerospace Manufacturing Technologies; Composite Technology Center Stade) Villegas, I.F. (TU Delft Aerospace Structures & Computational Mechanics) Dransfeld, C.A. (TU Delft Aerospace Manufacturing Technologies) Herrmann, A. (Composite Technology Center Stade) Date 2021 Abstract Ultrasonic welding is a promising technology to join fibre-reinforced thermoplastic composites. While current studies are mostly limited to fabric materials the applicability to unidirectional materials, as found in aerospace structures, would offer opportunities for joining primary aircraft structures. However, due to the highly anisotropic flow of a molten unidirectional ply undesired squeeze flow phenomena can occur at the edges of the weld overlap. This paper investigates how the fibre orientation in the plies adjacent to the weld line influences the welding process and the appearance of edge defects. Ultrasonic welding experiments with different layups and energy director configurations were carried out while monitoring temperatures at different locations inside and outside the weld overlap. The joints were characterized by single lap shear tests, analysis of corresponding fracture surfaces and microscopic cross-sections. Results showed that the anisotropic flow and the anisotropic thermal conductivity of the plies adjacent to the weld line have a distinct effect on the appearance and location of edge defects. By using energy directors that cover only part of the weld overlap area a new approach was developed to mitigate edge defects caused by the highly directional properties of the unidirectional plies. Subject edge defectsenergy directorfusion bondingThermoplastic compositesunidirectional fibres To reference this document use: http://resolver.tudelft.nl/uuid:d15b0cac-133b-4f6a-8cda-1f2649d69d9b DOI https://doi.org/10.1177/0021998320976818 ISSN 0021-9983 Source Journal of Composite Materials, 55 (15), 2087-2102 Part of collection Institutional Repository Document type review Rights © 2021 F. Köhler, I.F. Villegas, C.A. Dransfeld, A. Herrmann Files PDF 0021998320976818.pdf 1.42 MB Close viewer /islandora/object/uuid:d15b0cac-133b-4f6a-8cda-1f2649d69d9b/datastream/OBJ/view