Weber, David E.
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Weber, David E.
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Weber, David E.
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Weber, David
Weber, David Ernst
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Item-typ:Veröffentlichung, Naturfaserverstärkte Kunststoffe für strukturelle Anwendungen auf Basis drehungsfreier Bastfasergarne(Deutscher Fachverlag GmbH, 2021); ; ; ; Die größtmögliche Ausnutzung der Eigenschaften von Fasern ist das Ziel vieler Spinnverfahren. Bislang können die Eigenschaften von Bastfasern in Kurzstapelgarnen für die Verstärkung von Faserverbundwerkstoffen nur unvollständig ausgenutzt werden. Deshalb wird eine neuartige Garnstruktur mit kürzeren drehungsfreien Bastfasern im Garnkern für Halbzeuge und den Einsatz in naturfaserverstärkten Kunststoffen (NFK) für höherbelastete Strukturbauteile entwickelt. Dadurch sollen gute mechanische Eigenschaften der NFK erreicht werden und gleichzeitig der Preis infolge der Verwendung kostengünstigerer Verstärkungsfasern reduziert werden. Zielsetzung ist dabei nicht die reine Substitution der herkömmlichen glasfaserverstärkten Kunststoffe (GFK), sondern die Erschließung neuer Anwendungsfelder durch die Kombination von Glas- und Bastfasern. Um das Ziel umzusetzen haben sich Partner aus Industrie und Forschung zu einer Kooperation im Rahmen eines von der Fachagentur Nachwachsende Rohstoffe (FNR) finanzierten Projektes (NF-CompPlus) zusammengeschlossen. Die Partner sind so ausgewählt, dass alle Schritte in der Fertigungskette vom Rohstoff bis zum Faserverbundwerkstoff einschließlich durchzuführender Prüfungen abgebildet sind.Wissenschaftlicher ArtikelBand:64Heft:3240 - Some of the metrics are blocked by yourconsent settings
Item-typ:Veröffentlichung, Manufacturing of flax- and glass-fibre reinforced thin-walled tubes and measuring their interlaminar shear properties by torsion testsRecently, methods for determining interlaminar shear properties have been continuously developed to achieve homogeneous stress states and avoid edge effects. In this regard, the torsion test on tube specimens represents a setup with many advantages. Therefore, fibre composites made by a winding of glass and flax fibres were produced at a new type of mandrel, resulting in tubes with a wall thickness between 370 µm (glass) and 640 µm (flax). A new method for determining the shear strain is described in the context of the torsion test. The results are in line with analogous investigations, proving the validity of the new methodology.Wissenschaftlicher ArtikelHeft:319113 - Some of the metrics are blocked by yourconsent settings
Item-typ:Veröffentlichung, Novel Low-Twist Bast Fibre Yarns from Flax Tow for High-Performance Composite Applications(MDPI, 2020-12-29); ; ; ; The use of natural fibres for components subjected to higher mechanical requirements tends to be limited by the high price of high-quality semi-finished products. Therefore, the present study deals with the development of more cost-effective staple fibre yarns made from flax tow. In the subsequent processing stage, the yarns were processed into quasi-unidirectional (UD) fabrics. The results of the fibre characterisation along the process chain have shown that no significant mechanical fibre damage occurs after slivers' production. Fibres prepared from yarns and fabrics show comparable characteristics. The yarns were processed to composites by pultrusion to verify the reinforcement effect. The mechanical properties were comparable to those of composites made from a high-quality UD flax roving. The fabrics were industrially processed into composite laminates using a vacuum infusion and an autoclave injection process (vacuum injection method in an autoclave). While impact strength compared to a reference laminate based on the UD flax roving was achieved, tensile and flexural properties were not reached. An analysis showed that the staple fibre yarns in the fabric show an undulation, leading to a reorientation of the fibres and lower characteristic values, which show 86-92% of the laminate made from the flax roving. Hybrid laminates with outer glass and inner flax layers were manufactured for the intended development of a leaf spring for the bogie of a narrow-gauge railroad as a demonstrator. The hybrid composites display excellent mechanical properties and showed clear advantages over a pure glass fibre-reinforced composite in lightweight construction potential, particularly flexural stiffness.Wissenschaftlicher ArtikelBand:14Heft:187 - Some of the metrics are blocked by yourconsent settings
Item-typ:Veröffentlichung, Hemp From disordered lines for new staple fibre yarns and high-performance composite applications(Frontiers Media, 2022-01-28); ; ; ; The use of natural fibre-reinforced plastics for higher-stressed applications is currently often limited by the high price of high-quality semi-finished products. Therefore, the present study deals with developing yarns from cost-effective hemp from a disordered separation process (total fibre line) for composite reinforcements. Composites were fabricated using a miniature pultrusion process with thermosetting matrices from the yarns. The results show that around 90% of the flexural strength and flexural modulus of identically produced flax composites could be achieved with maximum values of 282 MPa for the flexural strength and 23.4 GPa for the flexural modulus. The yarns were additionally used to manufacture quasi-unidirectional fabrics to produce composite laminates using different manufacturing processes. The highest values were obtained for a laminate with 39 vol% fibre content, produced with a resin injection process in an autoclave, achieving a tensile strength of 155 MPa, Young's modulus of 19.4 GPa, a flexural strength of 174 MPa and bending modulus of 12.4 GPa. The characteristic values are sufficient to use the materials in applications with higher mechanical requirements.Wissenschaftlicher ArtikelBand:8141 - Some of the metrics are blocked by yourconsent settings
Item-typ:Veröffentlichung, A Competitive Study of the Static and Fatigue Performance of Flax, Glass, and Flax/Glass Hybrid Composites on the Structural Example of a Light Railway Axle Tie(Frontiers Media, 2022-04-13); ; ; ; The most common studies in the literature are those analyzing fatigue life under cyclic loading for flax fiber-reinforced composites. A novel type of staple fiber yarn made from flax tow with almost unidirectional fiber orientation and a quasi-unidirectional fabric was developed for composite applications. Additionally, a hybrid material made of flax and glass was produced for a demonstrator component (an axle tie of a narrow-gauge railway). For such an application, the investigation of fatigue strength is of particular importance. Therefore, the fatigue behavior of flax, glass, and hybrid flax/glass composites was investigated in the high cycle fatigue range. A total of 106 load cycles were carried out. From about 7³ to 8³ loading cycles, the flax laminate was found to have higher fatigue strength than the glass fiber-reinforced composite. The hybrid materials tend to show a higher fatigue strength than the glass type from approximately 2 × 105 load cycles. Results based on a finite element method also demonstrate better fatigue properties at an increased number of load cycles for flax-based composites than the glass fiber-reinforced component. The flax/glass component’s fatigue strength ranged between the flax values and the glass fiber-reinforced composites. Overall, the hybrid material shows significantly better static bending and impact characteristics than flax and considerably better fatigue properties than the glass fiber-reinforced composite making the hybrid material attractive for an application in an axle tie.Wissenschaftlicher ArtikelBand:9144