ISBN 978-3-8439-5751-9

978-3-8439-5751-9, Reihe Ingenieurwissenschaften

Philipp Picard
Transverse Flow Control in Advanced Process Chains for Tailored Carbon Fiber Reinforced Thermoplastics

267 Seiten, Dissertation Technische Universität München (2025), Softcover, A5

Zusammenfassung / Abstract

Tailored carbon fiber reinforced thermoplastics combine the high mechanical performance of continuous fiber reinforcements with the processing flexibility of thermoplastic materials and thus offer significant potential for lightweight structural applications. While melt-based processing enables efficient, multi-step process chains with short cycle times, existing processing routes for continuous fiber reinforced thermoplastics impose considerable restrictions on material and part design, hindering optimization with respect to material usage, cost efficiency, and structural performance.

The objective of this dissertation is the development of advanced process chains that enable tailored material and part designs while overcoming the limitations of conventional concepts. Based on a systematic analysis, two advanced concepts are derived: the manufacturing of near-net-shaped organo sheets by direct melt impregnation and the complete overmolding of local, load-adapted reinforcements in an injection molding process. Proof-of-concept investigations identify pressure-induced transverse material flow as a fundamental limitation, leading to insufficient impregnation and deformation of reinforcing structures.

Transverse flow is therefore analyzed experimentally using a squeeze flow test setup and analytically using a squeeze flow model. The studies consider combinations of unreinforced thermoplastic layers with dry or fully impregnated fiber layers, described as power-law fluids, and systematically examine the influence of the layer thickness ratio.

The results demonstrate that the height ratio between reinforced and unreinforced layers is the dominant parameter governing transverse flow. Based on these findings, processing concepts are derived and successfully applied to direct melt impregnation and complete overmolding of tailored reinforcements using adapted mold technologies and additive process steps.