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Item type:Publication, Access status: without files , Full-field multi-scale analyses embedding fiber-matrix interfaces in short fiber reinforced thermoplasticsThis contribution presents a comprehensive full-field multi-scale modeling strategy for Short Fiber Reinforced Thermoplastics (SFRTs), with a particular focus on degradation at the fiber-matrix interfaces. The proposed approach combines nonlinear matrix behavior, cohesive interface degradation, and complex, large-scale randomized periodic Representative Volume Elements (RVEs) whose fiber orientations are derived from an experimentally determined Orientation Distribution Function (ODF). By integrating these aspects within a single framework, the model captures a level of mechanical and microstructural complexity that is rarely addressed in existing SFRT simulations. The model is applied to PA66GF30 to investigate how interface properties influence the macroscopic response of the composite in connection with the development of local damage mechanisms. Interface parameters are calibrated to reproduce experimental results, leading to good agreement with the measured overall behavior. In addition, the predicted local damage patterns are consistent with mechanisms reported in the literature, highlighting the ability of the approach to link interface degradation, microstructural morphology, and overall SFRT behavior.Publicationtype: Journal Article40 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , A workflow for designing stiffness-optimized structures in the context of additive manufacturing of endless fiber-reinforced composites(Sage Publications, 2025-08); ; ; This paper investigates the interface between structural optimization for anisotropic materials and modern additive manufacturing methods by presenting and evaluating a workflow for the design of structures for fused filament fabrication using endless fiber-reinforced filament. The process chain consists of optimizing the material orientations and topology of the anisotropic structure simultaneously, non-planar slicing and load-oriented path planning for additive manufacturing. The design workflow is demonstrated using an academic example and validated by a more practical example including mounting regions for bolts and multiple load cases. The results expose requirements for additive manufacturing of continuously fiber-reinforced structures that have to be considered by the optimization process for narrowing the gap between optimization results and simulated performance of the manufactured parts. At the same time, the potential of the presented workflow for designing parts while taking manufacturability into account is demonstrated successfully.Publicationtype: Journal Article92 17 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , A workflow for designing stiffness-optimized structures in the context of additive manufacturing of endless fiber-reinforced composites(Sage Publications, 2025-06-01); ; ; This paper investigates the interface between structural optimization for anisotropic materials and modern additive manufacturing methods by presenting and evaluating a workflow for the design of structures for fused filament fabrication using endless fiber-reinforced filament. The process chain consists of optimizing the material orientations and topology of the anisotropic structure simultaneously, non-planar slicing and load-oriented path planning for additive manufacturing. The design workflow is demonstrated using an academic example and validated by a more practical example including mounting regions for bolts and multiple load cases. The results expose requirements for additive manufacturing of continuously fiber-reinforced structures that have to be considered by the optimization process for narrowing the gap between optimization results and simulated performance of the manufactured parts. At the same time, the potential of the presented workflow for designing parts while taking manufacturability into account is demonstrated successfully.Publicationtype: Journal Article100 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: Embargo , Recommendations to improve the usability of research results as reference system elements addressing corporate engineers, researchers, and policymakers(Sage Publications, 2025-02-13); ; ; Haberkern, PatrickProduct engineering is a highly complex process faced with many challenges. To meet today’s challenges of society, such as climate change, energy production and demands, and demographic shifts, and to achieve economic success for companies, technical solutions in products and systems must evolve and advance. Hereby, university research provides a potent source of cutting-edge technologies and knowledge that companies can use as input to advance their solutions. However, many challenges and barriers hinder the process of transferring new technologies, concepts, and knowledge from research to corporate engineering. In this article, we present 22 recommendations to improve the usability of research results for the activities and processes of corporate product engineering. These recommendations address the three relevant target groups: (I) corporate engineers and companies, (II) researchers and research facilities, and (III) funding agencies and (research) policymakers. First, we offer recommendations for corporate engineers and companies to integrate research results more efficiently. Second, we present recommendations for researchers and research facilities to support the promotion and transferability of their research results. Third, we provide recommendations for funding agencies and (research) policymakers to positively influence the usability of research results in corporate engineering. We expect that implementing one or more of our recommendations will enhance the efficiency of knowledge and technology transfer into corporate product engineering. We anticipate this will lead to faster technological advancements for companies and social benefits by addressing today’s major challenges more effectively.Publicationtype: Journal Article53 22 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Electrical characterization of polyethylene oxide-alumina composite(Sage Publications, 2013-03-01); ; ; ; This study deals with the electrical characterization of polyethylene oxide (PEO) – alumina (Al2O3) composites at several concentrations, 0%, 5%, 10%, and 15% by weight Al2O3. The alternating current electrical properties were studied as a function of frequency in the range from 20 Hz to 1 MHz and studied with filler concentrations. Transmission light microscopy (TLM) and scanning electron microscopy (SEM) revealed that the dispersed Al2O3 particles were randomly distributed within the PEO matrix with some surface contacts between them and also revealed that the ceramic particles are tightly held by the host matrix material. The melting temperature, T m, was determined for the composites via differential scanning calorimetry (DSC). The AC electrical properties (impedance, real part of impedance, imaginary part of impedance, dissipation factor, dielectric constant, real part of electric modulus, imaginary part of electric modulus, electrical conductivity, and relaxation time) were determined. It was found that the applied frequency and filler concentrations affected the AC electrical properties of the composites. The universal power-law of alternating current conductivity wasobserved in the PEO/Al2O3 composites. The calculated power exponent is physically acceptable within this applied model.Publicationtype: Journal Article61 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Design and fabrication of an on-line consolidation facility for thermoplastic compositesAn experimental apparatus that utilizes continuous fiber reinforced thermoplastics to wind rings and short tubes has been developed. Termed an on-line consolidation facility, preimpregnated tow is consolidated while the ring is being wound. The three most important parameters for the consolidation process are time, temperature, and pressure, and the facility is designed to establish their optimum combination. Therefore, each component of the apparatus provides maximum flexibility and variability in terms of these parameters. This article describes the basic concept of the process and then shows how the concept can be realized. The technique for heating the impregnated tow utilizes infrared radiation. However, additional heat sources are used to provide optimum temperature control at the nip point. Finally, several types of preimpregnated tow are used to produce samples that prove the feasibility of the process and establish acceptable ranges on the parameters.Publicationtype: Journal Article237 705 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Interlaminar Fracture Energy of Laminates Made of Thermoplastic Impregnated Fiber BundlesInterlaminar mode I- and II-fracture energy measurements (in terms of the strain energy release rate) were carried out with different laminates of a glass fiber/thermoplastic PA 12- and aramid fiber/PA 12-composite system. Specimens were prepared from fiber bundles interspersed with polymer powder and a polymer sheath around them. The results, obtained from two different test procedures and data reduction methods, reflect a good interlaminar fracture toughness of the different laminates. This can be attributed to the large damage zone size due to the tough matrix and a big amount of fiber bridging, which is highlighted by micrographs achieved with SEM-analysis.Publicationtype: Journal Article234 477 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Fracture toughness of short fiber/thermoplastic matrix composites, compared on the basis of different test methods(1988-01-01); ; ; A variety of thermoplastic matrices, including Polyethersulfone (PES), Polyoxymethylene (POM), and toughness modified Polyethylenterephthalate (PET), and their short glass fiber reinforced composites have been tested with respect to their impact resistance. Test methods applied, all characterize in some respects the "toughness" of these materials. It turns out, however, that the ranking order of their toughnesses varies quite remarkably, depending on the particular testing procedure. In a fracture mechanics test with compact tension specimens, the fracture toughness of Polyethersulfone, for instance, is very low compared to the other thermoplastics and to their short fiber reinforced versions. This is due to the very sharp notches used in this kind of toughness test, and due to the high notch sensitivity of PES. In a falling dart test with a CEAST® modular falling weight device, and the use of unnotched plates, PES proves to be, on the other hand, much better than all the other competitive materials. The results are discussed with respect to the content of infor mation of the individual tests on the "toughness" profile of the different polymers and com posite materials studied.Publicationtype: Journal Article254 421