Authors Spickenheuer, A. ; Scheffler, C. ; Bittrich, L. ; Haase, R. ; Garray, D. ; Heinrich, G.
Title Tailored fiber placement in thermoplastic composites
Date 19.09.2017
Number 53743
Abstract The development of fiber-reinforced composites has opened up high strength, stiffness and lightweight potential. To utilize the full performance capabilities, the orientation of the anisotropic fibers has to match the specific load case. New Fiber path optimization methods [1] combined with Tailored Fiber Placement (TFP) provides the optimum correlation between load case and fiber orientation and therefore leads to unmatched component performance with composite materials. The mechanical potentials of a so called vaiable-axial TFP preform design and the manufacturing quality are strongly depending on the grade of the reinforcing filaments that are involved in the composite manufacturing process. Currently, TFP preforms are mostly made of dry reinforcing filaments that are impregnated afterwards with thermoset resins. However, for conventional multiaxial composites the current trend shows a wider usage of thermoplastic (TP) resin as matrix material, e.g. organo sheets. The aim of the current research is the set-up of an innovative, resource-efficient technology for the fabrication of optimized TP / hybrid composite structures through strict load-oriented design of the reinforcing fibers and low cost tooling capabilities [2]. At present most common hybrid yarns are mainly based on PP (polypropylene) or PA (polyamide). Most of the available hybrid yarns reveal low commingling quality; furthermore, the sizings are not adapted to the thermoplastic component and their high consolidation temperature. Also the wax or oil containing spin finish of the thermoplastic yarn might lead to reduced fiber-matrix interaction. Hybrid yarns of high performance thermoplastics as PBT (polybutylene therephthalate) and glass or carbon fibers are mainly available as air-jet textured hybrid yarn on the market resulting in significant lower composite quality compared to online commingled hybrid yarns [3]. The development of new glass/PBT SpinCom yarns for high-performance composites is therefore focused on the manufacturing of simultaneously spun hybrid yarns with no damage of the reinforcing filaments with applied temperature resistant sizings, improved filament distribution while avoiding a disadvantageously spin finish of thermoplastic filaments. In order to substitute cost intensive consolidation processes for TP / hybrid yarn based TFP preforms, such as autoclaving or hot pressing, as alternative solution a vacuum bag systems could be applied instead to increase the economic performance for small lot sizes as well as flexibility to design even complex shaped 3D parts. Furthermore, the opportunity of incremental steel metal forming technology to produce light and low cost tooling for small series also target economic advantages for the whole process. Also the reduced thermal capacity and therefore the low energy consumption for the consolidation process is addressed. The authors would like to thank the German Federation of Industrial Research Associations (AiF) for funding the project “Tailored Fiber Placement in Thermoplastic Composites” (AiF-Cornet 164-EBR "TailComp").
Publisher Technologies for Lightweight Structures
Citation Technologies for Lightweight Structures (2017) 13 Seiten

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