Laserstrahl-Bohren von CFK-Preforms

Janssen, Stefan; Poprawe, Reinhart (Thesis advisor); Klocke, Fritz (Thesis advisor)

1. Auflage. - Aachen : Apprimus Verlag (2018)
Book, Dissertation / PhD Thesis

In: Ergebnisse aus der Lasertechnik
Page(s)/Article-Nr.: 1 Online-Ressource (VI, 156 Seiten) : Illustrationen

Abstract

The use of components made of carbon fiber-reinforced polymers (CFRP) is becoming increasingly important, especially in the automotive and aviation industries. The targeted weight savings are expected to reduce fuel consumption while maintaining the same mechanical load-bearing capacity of the components. The integration of force transmission elements for the detachable connection of CFRP components to a basic structure places special demands on production technology. Defects such as thermal damage and delamination must be avoided due to the still cost-intensive carbon fibers and the complex process chain for the production of CFRP components. For the drilling of holes for the integration of force transmission elements, both conventional and non-conventional manufacturing processes reach the limits of industrially relevant materialographic and geometric quality. The main reason for this are the different physical properties of the carbon fibers and the matrix. It therefore seems promising to drill the still unimpregnated carbon fiber textile and to infuse it with the matrix material after integration of the force transmission elements. Laser drilling enables mechanical contactless material processing to ensure an undisturbed textile setup. In order to evaluate the achievable geometric and materialographic drilling quality, the effects of laser radiation on the carbon fiber textile must be investigated. The use of long-pulsed laser radiation enables productive material processing. However, the high-energy laser pulses can cause significant thermal damage to the fibers. Alternatively, ultra-short pulsed laser radiation can be used to manufacture a thermally defect free bore, but often at the expense of productivity and aspect ratio. In the context of this work the damage phenomena and their mechanisms of action of laser-drilled, carbon fiber-based textile preforms are investigated. Process strategies are developed both for the processing of long-pulsed and ultra-short pulsed laser radiation in order to reduce or even avoid thermally induced damage. For long-pulsed laser processing, a scanning strategy is developed with which thermal damage can be minimized at high productivity. Furthermore, recommendations for action are being developed, especially for ultra-short pulsed laser radiation, in order to increase productivity and reduce conicity of the bore.

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