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Proceedings Paper

Laser-based surface treatment of CFRP and aluminum for adhesively bonded hybrid joints
Author(s): Jochen Schanz; Michael Gooßen; Dieter Meinhard; David Harrison; Anjali De Silva; Volker Knoblauch; Harald Riegel
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Paper Abstract

Carbon fiber reinforced polymer (CFRP) offers the highest potential for lightweight applications due to its excellent weight to strength ratio in comparison to other materials. However, it is cost-intensive and therefore rarely used monolithically. This makes pretreatment and joining processes so important. Hybrid connections of CFRP and metals can be made by riveting, bolting, stir joining and by adhesive. For adhesive bonding, a pretreatment of the materials is necessary. A laser pretreatment has the advantage, that it is automatable and contactless. This paper deals with the pretreatment of CFRP with different laser wavelengths in near-infrared (NIR, 1030 and 1064 nm) and ultraviolet (UV, 355 nm) range. The influence of the processing direction relative to the fiber layer and the influence of the energy density was investigated with a short pulsed NIR infrared laser. In addition, the influence of different surface structures on the mechanical strength was investigated. The treated CFRP surfaces were examined with a light microscope and a scanning electron microscope. The tensile shear strengths were determined using CFRP and aluminum substrates, joined with a 2-part epoxy adhesive. As a comparison, UV laser treated specimens were also mechanically tested. An ultra-short pulsed NIR laser system was used to generate periodic structures on the CFRP to maximize the surface area without fiber damage and breakage. The investigations on the influence of the machining direction with NIR relative to the fiber layer showed insignificant differences in shear strengths. The variation of the energy density showed an influence on the ablation behavior of the CFRP matrix and the mechanical strength. The maximum strength with a cohesive failure in the adhesive was achieved with optimized short pulsed NIR laser parameter.

Paper Details

Date Published: 9 March 2020
PDF: 11 pages
Proc. SPIE 11268, Laser-based Micro- and Nanoprocessing XIV, 1126819 (9 March 2020); doi: 10.1117/12.2546715
Show Author Affiliations
Jochen Schanz, Aalen Univ. (Germany)
Glasgow Caldonian Univ. (United Kingdom)
Michael Gooßen, Aalen Univ. (Germany)
Dieter Meinhard, Aalen Univ. (Germany)
David Harrison, Glasgow Caledonian Univ. (United Kingdom)
Anjali De Silva, Glasgow Caledonian Univ. (United Kingdom)
Volker Knoblauch, Aalen Univ. (Germany)
Harald Riegel, Aalen Univ. (Germany)

Published in SPIE Proceedings Vol. 11268:
Laser-based Micro- and Nanoprocessing XIV
Udo Klotzbach; Akira Watanabe; Rainer Kling, Editor(s)

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