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  1. Article ; Online: An Edge-Filtered Optical Fiber Interrogator for Thermoplastic Polymer Analysis.

    Backmann, Vincent / Dorner, Felix / Drechsler, Klaus

    Sensors (Basel, Switzerland)

    2023  Volume 23, Issue 6

    Abstract: The present paper deals with the determination of thermodynamic quantities of thermoplastic polymers by using an optical fiber interrogator. Typically, laboratory methods such as differential scanning calorimetry (DSC) or thermomechanical analysis (TMA) ... ...

    Abstract The present paper deals with the determination of thermodynamic quantities of thermoplastic polymers by using an optical fiber interrogator. Typically, laboratory methods such as differential scanning calorimetry (DSC) or thermomechanical analysis (TMA) are a reliable state-of-the-art option for thermal polymer analysis. The related laboratory commodities for such methods are of high cost and are impractical for field applications. In this work, an edge-filter-based optical fiber interrogator, which was originally developed to detect the reflection spectrum of fiber Bragg grating sensors, is utilized for the detection of the boundary reflection intensities of the cleaved end of a standard telecommunication optical fiber (SMF28e). By means of the Fresnel equations, the temperature-dependent refractive index of thermoplastic polymer materials is measured. Demonstrated with the amorphous thermoplastic polymers polyetherimide (PEI) and polyethersulfone (PES), an alternative to DSC and TMA is presented as the glass transition temperatures and coefficients of thermal expansion are derived. A DSC alternative in the semi-crystalline polymer analysis with the absence of a crystal structure is shown as the melting temperature and cooling-rate-dependent crystallization temperatures of polyether ether ketone (PEEK) are detected. The proposed method shows that thermal thermoplastic analysis can be performed with a flexible, low-cost and multipurpose device.
    Language English
    Publishing date 2023-03-21
    Publishing country Switzerland
    Document type Journal Article
    ZDB-ID 2052857-7
    ISSN 1424-8220 ; 1424-8220
    ISSN (online) 1424-8220
    ISSN 1424-8220
    DOI 10.3390/s23063300
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article: Foundational Investigation on the Characterization of Porosity and Fiber Orientation Using XCT in Large-Scale Extrusion Additive Manufacturing.

    Tagscherer, Nevine / Schromm, Thomas / Drechsler, Klaus

    Materials (Basel, Switzerland)

    2022  Volume 15, Issue 6

    Abstract: The great potential of Extrusion Additive Manufacturing (EAM) for structural prototyping in the automotive industry is severely limited by the directional bias in the build direction. The layerwise fabrication leads to reduced mechanical properties at ... ...

    Abstract The great potential of Extrusion Additive Manufacturing (EAM) for structural prototyping in the automotive industry is severely limited by the directional bias in the build direction. The layerwise fabrication leads to reduced mechanical properties at the layer-to-layer interface compared to the bulk of the strand. Especially for the often-used semi-crystalline thermoplastics, the mechanical properties strongly depend on the processing parameters, even more so if short fibers are used as fillers. Therefore, ideal processing windows in which the mechanical strength and modulus in the z-direction reach their maximum can be identified for these parameters, resulting in a reduced directional bias. The influence of the EAM processing parameters on mechanical strength has already been investigated, correlating strength with thermal conditions during printing. However, these considerations did not distinguish between the thermal effect on the polymer properties, the formation of voids and pores at the layer interface, and the resulting fiber orientation for different strand proportions. Therefore, in this study, the effect of different processing temperatures and layer heights on the pore size and distribution, as well as the fiber orientation in the different regions of the mesostructure was investigated using X-ray Computed Tomography (XCT).
    Language English
    Publishing date 2022-03-20
    Publishing country Switzerland
    Document type Journal Article
    ZDB-ID 2487261-1
    ISSN 1996-1944
    ISSN 1996-1944
    DOI 10.3390/ma15062290
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article: Implementation of a viscoelastic material model to predict the compaction response of dry carbon fiber preforms

    Bublitz, Dennis / Colin, David / Drechsler, Klaus

    Composites. 2022 Feb., v. 153

    2022  

    Abstract: Determining the compaction behavior of fibrous material is essential for fiber reinforced composites manufacturing processes. The compression state directly influences both fiber volume content and tooling forces in closed mold processes. In this work, ... ...

    Abstract Determining the compaction behavior of fibrous material is essential for fiber reinforced composites manufacturing processes. The compression state directly influences both fiber volume content and tooling forces in closed mold processes. In this work, we present a viscoelastic material model which describes the compaction stress response. In its incremental formulation, the model is implemented into a finite element code, which makes it possible to calculate the thickness of force-controlled setups. We derived model parameters from compaction experiments with woven and non-crimp fabric carbon fiber preforms. The predicted compaction stress for both materials was in good agreement with the experimental data. Moreover, the model is capable of predicting creep and spring back behavior for force-controlled experiments. We proved that the developed model can be used to eliminate peak stresses during compaction and is also capable of predicting the time-dependent thickness response by means of a single set of formulas.
    Keywords carbon fibers ; fabrics ; finite element analysis ; models ; stress response ; viscoelasticity
    Language English
    Dates of publication 2022-02
    Publishing place Elsevier Ltd
    Document type Article
    ZDB-ID 2012223-8
    ISSN 1359-835X
    ISSN 1359-835X
    DOI 10.1016/j.compositesa.2021.106718
    Database NAL-Catalogue (AGRICOLA)

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  4. Book ; Online ; Thesis: A material model for the compaction process simulation of carbon fiber preforms

    Bublitz, Dennis Verfasser] / [Drechsler, Klaus [Akademischer Betreuer] / Binetruy, Christophe Gutachter] / [Drechsler, Klaus [Gutachter]

    2023  

    Author's details Dennis Bublitz ; Gutachter: Christophe Binetruy, Klaus Drechsler ; Betreuer: Klaus Drechsler
    Keywords Technische Chemie ; Technical Chemistry
    Subject code sg660
    Language English
    Publisher Universitätsbibliothek der TU München
    Publishing place München
    Document type Book ; Online ; Thesis
    Database Digital theses on the web

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  5. Book ; Online ; Thesis: Entwicklung eines Messsystems für die transversale Permeabilität von Faserhalbzeugvorformlingen und dessen Validierung anhand relevanter Material-, Design- und Prozessparameter

    Graupner, Robert [Verfasser] / Drechsler, Klaus [Akademischer Betreuer] / Drechsler, Klaus [Gutachter] / Horn, Siegfried R. [Gutachter]

    2023  

    Author's details Robert Graupner ; Gutachter: Klaus Drechsler, Siegfried R. Horn ; Betreuer: Klaus Drechsler
    Keywords Technische Chemie ; Technical Chemistry
    Subject code sg660
    Language German
    Publisher Universitätsbibliothek der TU München
    Publishing place München
    Document type Book ; Online ; Thesis
    Database Digital theses on the web

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  6. Article ; Online: Prediction of consolidation quality in laser-assisted AFP and effect of blank quality on stamp forming

    Seefried, Kilian / Bezerra, Renato / Drechsler, Klaus

    2023  

    Abstract: This paper presents a parameter study into the thermoplastic-automated fibre placement process. The material used was carbon fibre-reinforced LM-PAEK unidirectional tape. The overall objective of this investigation was the derivation of regression models ...

    Abstract This paper presents a parameter study into the thermoplastic-automated fibre placement process. The material used was carbon fibre-reinforced LM-PAEK unidirectional tape. The overall objective of this investigation was the derivation of regression models to describe and predict the consolidation quality of laminates in dependence on the main process parameters of the lay-up process. Furthermore, post-consolidation by stamp forming was investigated to analyse the impact of the initial quality of the blank on post-forming laminate quality. With the parameter study performed, prediction models for the degree of bonding and crystallinity could be derived. In addition, a more comprehensive understanding of the process parameter influences and the definition of parameter limits to distinguish between rapid and in situ lay-up processes was achieved. Furthermore, the potential of the process chain consisting of rapid lay-up and stamp forming for producing high-quality laminates was demonstrated for the investigated LM-PAEK tape.

    Online First
    Keywords LM-PAEK ; microstructural analysis ; automated fibre placement ; stamp forming ; short beam strength test ; low-melt polyaryl ether ketone ; carbon fiber reinforcement ; DDC::600 Technik ; Medizin ; angewandte Wissenschaften::620 Ingenieurwissenschaften
    Subject code 670
    Language English
    Publishing country de
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  7. Article ; Online: A novel polysaccharide/zein conjugate as an alternative green plastic.

    Tallawi, Marwa / Amrein, Danial / Gemmecker, Gerd / Aifantis, Katerina E / Drechsler, Klaus

    Scientific reports

    2023  Volume 13, Issue 1, Page(s) 13161

    Abstract: The flax seed cake is a waste product from flax oil extraction. Adding value to this wasted material aligns with the concept of circularity. In this study, we explored zein protein conjugation with flax mucilage for packaging material development. ... ...

    Abstract The flax seed cake is a waste product from flax oil extraction. Adding value to this wasted material aligns with the concept of circularity. In this study, we explored zein protein conjugation with flax mucilage for packaging material development. Although both flax mucilage and zein have excellent film-forming properties, they lack the required mechanical properties for industrial processing and are sensitive to high humidity. We present a simple and non-toxic one-pot method for developing the novel flax mucilage/zein conjugate. Where the flax mucilage undergoes oxidation to form aldehyde groups, which then react with zein's amino groups in a glycation process. The conjugates were analyzed using different techniques. The flax mucilage conjugate had a water-holding capacity of 87-62%. Increasing the zein content improved the surface smoothness of the films. On the other hand, higher levels of zein led to a significant decrease in film solubility (p < 0.05). The flax mucilage conjugate exhibited thermoplastic and elastic properties; revealing Young's modulus of 1-3 GPa, glass transition temperature between 49 °C and 103 °C and excellent processability with various industrial techniques. Showing its potential as a sustainable alternative to traditional plastics.
    Language English
    Publishing date 2023-08-12
    Publishing country England
    Document type Journal Article
    ZDB-ID 2615211-3
    ISSN 2045-2322 ; 2045-2322
    ISSN (online) 2045-2322
    ISSN 2045-2322
    DOI 10.1038/s41598-023-40293-4
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  8. Book ; Conference proceedings: Clinical image-based procedures

    Drechsler, Klaus

    from planning to intervention : international workshop, CLIP 2012, held in conjunction with MICCAI 2012, Nice, France, October 5, 2012 : revised selected papers

    (Lecture notes in computer science, ; 7761 ; LNCS sublibrary. SL 6, Image processing, computer vision, pattern recognition, and graphics.)

    2013  

    Event/congress CLIP (Workshop) (2012, NiceFrance) ; International Conference on Medical Image Computing and Computer-Assisted Intervention (15th, 2012, NiceFrance)
    Author's details Klaus Drechsler, Marius Erdt, Marius George Linguraru, Cristina Oyarzun Laura, Karun Sharma, Raj Shekhar, Stefan Wesarg (eds.)
    Series title Lecture notes in computer science, ; 7761 ; LNCS sublibrary. SL 6, Image processing, computer vision, pattern recognition, and graphics.
    MeSH term(s) Diagnostic Imaging/methods ; Image Processing, Computer-Assisted ; Computer Simulation
    Language English
    Dates of publication 2013-2013
    Size x, 132 pages :, illustrations. ;, 24 cm.
    Document type Book ; Conference proceedings
    ISBN 9783642380785 ; 3642380786 ; 9783642380792 ; 3642380794
    Database Catalogue of the US National Library of Medicine (NLM)

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  9. Book ; Conference proceedings ; Audio / Video: Composites in automotive and aerospace

    Drechsler, Klaus

    9. Internationaler Composites Kongress, 16. - 17. Oktober 2013, Neue Messe München ; [im Rahmen der] Materialica 2013, [16. Internationale Fachmesse für Werkstoffanwendungen, Oberflächen und Product Engineering]

    2013  

    Title variant International conference
    Institution Munich Expo GmbH
    Event/congress Composites in Automotive and Aerospace Conference (9, 2013.10.16-17, Munich) ; International Composites Conference (9, 2013.10.16-17, Munich) ; Internationale Fachmesse für Werkstoffanwendungen, Oberflächen und Product Engineering (16, 2013.10.16-17, München) ; Internationaler Composites Kongress (9, 2013.10.16-17, München) ; Materialica (16, 2013.10.16-17, München)
    Author's details Munich Expo
    Language German ; English
    Size 1 CD-ROM
    Publishing place Munich
    Document type Book ; Conference proceedings ; Audio / Video
    Note Beitr. teilw. dt., teilw. engl. ; Enth. überw. Präsentationsfolien und Abstracts der Tagungsbeiträge
    Database Library catalogue of the German National Library of Science and Technology (TIB), Hannover

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  10. Book ; Online: Flexible intelligente Bearbeitungstechnologien für komplexe Faserverbundbauteile

    Drechsler, Klaus

    2016  

    Abstract: Für die Bearbeitung der Hochleistungsfaserverbundstrukturen wurden neueste Technologien zur Bauteil-Aufspannung und -Bearbeitung (Fräsen, Laserprozess), Robotersteuerung, Prozesssimulation und Qualitätssicherung miteinander kombiniert. Die beteiligten ... ...

    Abstract Für die Bearbeitung der Hochleistungsfaserverbundstrukturen wurden neueste Technologien zur Bauteil-Aufspannung und -Bearbeitung (Fräsen, Laserprozess), Robotersteuerung, Prozesssimulation und Qualitätssicherung miteinander kombiniert. Die beteiligten Unternehmen deckten von den Werkzeug-, Roboter-, Anlagen- und Bauteilherstellern über Qualitätssicherung und Prozesssimulation bis zur Endanwendung das gesamte hierzu nötige industrielle Know-how ab. Abgerundet wurde dieses Know-how durch die Expertise von namhaften Forschungseinrichtungen auf dem Gebiet der Automatisierungstechnik und Prozessanalyse für Composites. Durch eine intelligente Kombination von Bearbeitungsverfahren und durch die Erhöhung des Automatisierungsgrades wird ein wesentlicher Beitrag zur zukünftigen Bereitstellung von wirtschaftlichen Composite-Produktionsprozessketten und damit einhergehend zur Verbesserung der im internationalen Wettbewerb maßgeblichen Faktoren Produktivität und Flexibilität für die gesamte Anwenderbranche von Faserverbundbauteilen geleistet. FlexiCut trägt damit zur Verbesserung des Forschungs- und Produktionsstandtortes Deutschland bei.
    Keywords production engineering ; materials science ; Faserverbundwerkstoff ; Endbearbeitung ; Robotersteuerung ; Prozesssimulation ; Qualitätssicherung ; Faserverbundtechniker ; Verarbeitungsingenieure ; Verfahrensingenieure ; Bearbeitungstechniker ; Programmierer ; Steuerungsingenieure ; Qualitätssicherungsingenieure ; 660
    Subject code 670
    Language German
    Publisher Fraunhofer Verlag
    Publishing country de
    Document type Book ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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