TY - JOUR A1 - Pecqueur, Sébastien A1 - Maltenberger, Anna A1 - Petrukhina, Marina A. A1 - Halik, Marcus A1 - Jaeger, Arndt A1 - Pentlehner, Dominik A1 - Schmid, Günter T1 - Wide Band-Gap Bismuth-based p-Dopants for Opto-Electronic Applications JF - Angewandte Chemie International Edition N2 - Ten new efficient p‐dopants for conductivity doping of organic semiconductors for OLEDs are identified. The key advantage of the electrophilic tris(carboxylato) bismuth(III) compounds is the unique low absorption of the resulting doped layers which promotes the efficiency of OLED devices. The combination of these features with their low fabrication cost, volatility, and stability, make these materials very attractive as dopants in organic electronics. KW - p-Dopants KW - Bismuth KW - OLED Y1 - 2016 IS - 55 PB - Wiley-VCH Verlag CY - Weinheim ER - TY - JOUR A1 - Hirschmüller, Sebastian A1 - Pravida, Johann A1 - Marte, Roman A1 - Flach, Michael T1 - Long‐term material properties of circular hollow laminated veneer lumber sections under water saturation and cement alkaline attack JF - Wood Material Science and Engineering N2 - Innovative beech laminated veneer lumber (LVL) circular hollow sections for the use as temporary geotechnical soil nailing systems are currently being developed. Due to the permanent subsoil cement embedment, combined with high water saturation and permanent loading, the timber sections will lose strength and stiffness over time to a degree currently unknown. This paper presents the tensile and bending material properties of flat and curved beech LVL under various periods of immersion in a water–cement grout solution aiming at inducing both water saturation and long-term alkaline attack of the timber. In total, 824 and 279 samples were tested in tension and bending, respectively. Results show that samples manufactured from 3 mm thick veneers result in tensile strength and stiffness 17% and 24% higher, respectively, than samples manufactured from 2 mm thick veneers. A reduction in the initial bending and tensile strength of up to 70% was found after 90 days of water saturation and cement contact. Taking into account a duration of load factor for permanent loading of two years, it is recommended to reduce the short-term tensile and bending strength of beech circular hollow sections to be used as geotechnical anchors by 80%. KW - Timber engineering KW - Laminated veneer KW - Water saturation KW - Cement alkaline attack Y1 - 2019 UR - https://doi.org/10.1080/17480272.2018.1434830 VL - 14 IS - 3 SP - 142 EP - 156 ER - TY - JOUR A1 - Schemme, Michael T1 - Longfibre reinforced thermoplastics – status and perspectives JF - Plastics, Additives and Compounding KW - FVK Y1 - 2008 UR - https://doi.org/10.1016/S1464-391X(08)70060-6 VL - 10 IS - 2 SP - 38 EP - 43 ER - TY - JOUR A1 - Schemme, Michael T1 - LFT – development status and perspectives JF - Reinforced Plastics KW - FVK Y1 - 2008 UR - https://doi.org/10.1016/S0034-3617(08)70036-5 VL - 52 IS - 1 SP - 32 EP - 39 ER - TY - JOUR A1 - Hirschmüller, Sebastian A1 - Marte, Roman A1 - Pravida, Johann A1 - Flach, Michael ED - Springer, T1 - Inhibited wood degradation of cement‐coated beech Laminated Veneer Lumber (LVL) for temporary in‐ground applications. JF - European Journal of Wood and Wood Products N2 - This paper investigates the long-term tensile properties of laminated veneer lumber (LVL) beech sections coated with cement and exposed to fungal decay. A set of LVL coupon (dog-bone) samples was stored in compost, tested in tension after 6 and 12 months and compared to reference samples stored at 20 °C and 65% relative humidity. Results showed that after 26 weeks of compost exposure, a fungus of the Ascomycota genus was identified in cement-coated samples using a molecular biology polymerase chain reaction (PCR) technique, which analyses the internal transcribed spacer (ITS) region of the ribosomal DNA. However, no visual deterioration was noticed. Still in cement-covered samples and after 12 months of exposure, a common white rot fungus was determined by DNA chip technology, but no fungal wood decay was visible in areas where the applied coating had a thickness of at least 5 mm. Decay in uncoated LVL samples was significant with the samples having an average residual strength equal to 7%. This compares to the tensile strength of coated samples, which only decreased by 65% relative to the reference samples. Strength and stiffness of coated samples did not differ significantly between 6 and 12 months of exposure. Preliminary investigations tend to show that the strength reduction in cement-coated samples is due to an alkaline degradation of the wood. The observed influence of the coating thickness on the visual fungal decay can probably be ascribed to the protection mechanism due to a physical fungal barrier with a high pH. KW - Timber engineering KW - cement‐coated beech Laminated Veneer Lumber KW - Wood and wood products Y1 - 2018 UR - https://doi.org/10.1007/s00107-018-1325-9 VL - 76 IS - 5 SP - 1483 EP - 1494 ER - TY - JOUR A1 - Krommes, Sandra A1 - Tomaschko, Florian T1 - Chance für mehr Ressourceneffizienz - Methode der Wert- und Stoffstromanalyse im Kontext der digitalen Transformation bestehender Fertigungsanlagen T1 - Opportunity for More Resource Efficiency JF - Zeitschrift für wirtschaftlichen Fabrikbetrieb (zwf) N2 - Die dynamische Wert- und Stoffstrommodellierung bildet die In- und Output-Ströme von Prozessen mittels Digitalisierungstechnologien ab. In einem aus fünf Schritten bestehenden methodischen Vorgehen kann der Einstieg in die Digitalisierung der Produktion für KMU mit bestehenden Anlagen- und Maschinenparks (Brownfield-Ansatz) gelingen: Ein digitaler Schatten ermöglicht ein echtzeit- und realdatenbasiertes Monitoring von Einzel- und Kleinserienfertigungen zur Steigerung der Ressourceneffizienz. Method of Value and Material Flow Analysis within the Digital Transformation of a Brownfield Approach. Dynamic value and material flow modeling maps input and output flows of processes by means of digitization. In a methodical approach consisting of five steps, SMEs with existing plant and machine parks (brownfield approach) can be successfully introduced to the digitization of production: A digital shadow of a defined process enables a real-time and real data-based monitoring and key figure system for individual and small series production. KW - Ressourcenefficienz KW - Digitalisierung KW - Industrie 4.0 KW - Wertstromanalyse KW - Stoffstromanalyse KW - digitaler Zwilling Y1 - 2021 UR - https://doi.org/10.1515/zwf-2021-0012 VL - 116 IS - 1-2 SP - 58 EP - 63 PB - De Gruyter CY - Berlin ER - TY - JOUR A1 - Lazar, Markus A1 - Jarre, F. T1 - Calibration by Optimization Without Using Derivatives JF - Optimization and Engineering N2 - Applications in engineering frequently require the adjustment of certain parameters. While the mathematical laws that determine these parameters often are well understood, due to time limitations in every day industrial life, it is typically not feasible to derive an explicit computational procedure for adjusting the parameters based on some given measurement data. This paper aims at showing that in such situations, direct optimization offers a very simple approach that can be of great help. More precisely, we present a numerical implementation for the local minimization of a smooth function f:Rn→R subject to upper and lower bounds without relying on the knowledge of the derivative of f. In contrast to other direct optimization approaches the algorithm assumes that the function evaluations are fairly cheap and that the rounding errors associated with the function evaluations are small. As an illustration, this algorithm is applied to approximate the solution of a calibration problem arising from an engineering application. The algorithm uses a Quasi-Newton trust region approach adjusting the trust region radius with a line search. The line search is based on a spline function which minimizes a weighted least squares sum of the jumps in its third derivative. The approximate gradients used in the Quasi-Newton approach are computed by central finite differences. A new randomized basis approach is considered to generate finite difference approximations of the gradient which also allow for a curvature correction of the Hessian in addition to the Quasi-Newton update. These concepts are combined with an active set strategy. The implementation is public domain; numerical experiments indicate that the algorithm is well suitable for the calibration problem of measuring instruments that prompted this research. Further preliminary numerical results suggest that an approximate local minimizer of a smooth non-convex function f depending on n≤300 variables can be computed with a number of iterations that grows moderately with n. KW - Engineering KW - Mathematical optimization Y1 - 2016 VL - 2016 IS - 17/4 SP - 833 EP - 860 PB - Springer ER - TY - JOUR A1 - Pecqueur, Sébastien A1 - Maltenberger, Anna A1 - Petrukhina, Marina A. A1 - Halik, Marcus A1 - Jaeger, Arndt A1 - Pentlehner, Dominik A1 - Schmid, Günter T1 - Bismut-haltige p-Dotanden mit großer Bandlücke für optoelektronische Anwendungen JF - Angewandte Chemie N2 - Zehn neue p‐Dotanden für die Leitfähigkeitsdotierung von organischen Halbleitern wurden identifiziert. Der wesentliche Vorteil der elektrophilen Tris(carboxylato)‐Bismut(III)‐Verbindungen ist die niedrige Absorption der damit dotierten Schichten. Diese Eigenschaft zusammen mit ihren niedrigen Herstellungskosten sowie der guten Verdampfbarkeit und Stabilität macht diese Dotanden sehr attraktiv für Anwendungen in der organischen Elektronik. KW - p-Dotanden KW - Organische Halbleiter KW - Bismut Y1 - 2016 IS - 128(35) PB - Wiley-VCH Verlag CY - Weinheim ER - TY - JOUR A1 - Hummel, Sabine A1 - Obermeier, Katharina A1 - Zier, Katja A1 - Krommes, Sandra A1 - Schemme, Michael A1 - Karlinger, Peter T1 - Analysis of Mechanical Properties Related to Fiber Length of Closed-Loop-Recycled Offcuts of a Thermoplastic Fiber Composites (Organo Sheets) JF - Materials N2 - Increasing demand for energy-efficient means of transport has steadily intensified the trend towards lightweight components. Thermoplastic glass fiber composites (organo sheets) play a major role in the production of functional automotive components. Organo sheets are cut, shaped and functionalized by injection molding to produce hybrid components, such as those used in car door modules. The cutting process produces a considerable amount of production waste, which has thus far been thermally recycled. This study develops a closed mechanical recycling process and analyzes the different steps of the process. The offcuts were shredded using two shredding methods and implemented directly in the injection-molding process. Using tensile tests and impact bending tests, the material properties of the recycled materials were compared with the virgin material. In addition, fiber length degradation via the injection-molding process and the influence of the waterjet-cutting process on the mechanical properties are investigated. Recycled offcuts are both comparable to new material in terms of mechanical properties and usability, and are also economically and ecologically advantageous. Recycling polypropylene waste with glass fiber reinforcement in a closed loop is an effective way to reduce industrial waste in a sustainable and economical production process. KW - sustainability KW - fiber composites KW - recycling KW - renewable materials KW - manufacturing process KW - resource efficiency KW - emissions KW - degradation KW - characterization Y1 - 2022 UR - https://doi.org/10.3390/ma15113872 VL - 15 IS - 11 SP - 3872 ER - TY - JOUR A1 - Hirschmüller, Sebastian A1 - Pravida, Johann A1 - Marte, Roman A1 - Flach, Michael ED - Springer, T1 - Adhesive properties of laminated veneer lumber poles for use in temporary soil nailing: development and evaluation of a test method for curved structures in a high‐alkaline environment JF - Wood Science and Technology N2 - Innovative circular, hollow, laminated veneer lumber (LVL) beech sections for use as temporary geotechnical soil reinforcement members are currently being developed. Appropriate surface gluing quality between the veneers is fundamental to this subsoil application of the permanently cement-embedded, engineered timber product. The circular cross-section geometry and the permanently high-alkaline environment of the structural member is not covered by presently standardized testing and conditioning methods for examining LVL surface bond line quality. The sample conditioning and tensile shear test method compliant with EN 302-1 (Adhesives for load-bearing timber structures—test methods—part 1: determination of longitudinal tensile shear strength, European Committee for Standardization, Brussels, 2013) was modified to determine bonding parameters for circular, hollow LVL sections. Bond line curvature, groove cutting depth and sample geometry were found to greatly influence stress distribution, percentage of wood failure and tensile shear strength. Short-term alkaline treatment of test samples did not significantly influence the bonding performance, wood failure percentage, tensile shear strength and fracture patterns. To improve tensile shear strength, adhesives with different material rigidities were used and compared. An orthotropic, elastic numerical analysis revealed a greater influence of adherent elasticity than adhesive elasticity on the stress distribution within the bond line. With regard to determining the bond line integrity of curved veneer poles, a sample geometry compliant with EN 302-1 (2013) was developed and numerically evaluated. KW - Timber engineering KW - Laminated veneer KW - Temporary soil nailing Y1 - 2018 UR - https://doi.org/10.1007/s00226-018-0997-y VL - 52 IS - 4 SP - 1061 EP - 1092 ER -