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Emission and Mechanical Properties of Glass and Cellulose Fiber Reinforced Bio-Polyamide Composites
(2023-06-07)
Climate change, access, and monopolies to raw material sources as well as politically motivated trade barriers are among the factors responsible for a shortage of raw materials. In the plastics industry, resource conservation can be achieved by substituting commercially available petrochemical-based plastics with components made from renewable raw materials. Innovation potentials are often not used due to a lack of information on the use of bio-based materials, efficient processing methods, and product technologies ...
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Prediction Model Based on DoE and FTIR Data to Control Fast Setting and Early Shrinkage of Alkaline-Activated Slag/Silica Fume Blended Cementitious Material
(2023-05-31)
This study aims to develop a material-saving performance prediction model for fast-hardening alkali-activated slag/silica fume blended pastes. The hydration process in the early stage and the microstructural properties after 24 h were analyzed using design of experiments (DoE). The experimental results show that the curing time and the FTIR wavenumber of the Si-O-T (T = Al, Si) bond in the band range of 900–1000 cm−¹ after 24 h can be predicted accurately. In detailed investigations, low wavenumbers from FTIR analysis ...
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Dissimilar Laser Beam Welding of Titanium to Stainless Steel Using Pure Niobium as Filler Material in Lap Joint Configuration
(2023-09-20)
In the present investigation, commercially pure titanium is welded to AISI 316L stainless steel by intermixing niobium as filler material in a lap joint configuration. For this purpose, a pulsed Nd:YAG laser with various pulse durations and pulse peak powers is employed to obtain different mixing conditions for the materials. It will be demonstrated that, despite the implementation of the filler material, the weld seams are characterized by a high affinity for cracking, which in turn can be attributed to the formation ...
Aufsatz
FEM–CM as a hybrid approach for multiscale modeling and simulation of ferroelectric boundary value problems
(2023-06-05)
Constitutive modeling of ferroelectrics is a challenging task, spanning physical processes on different scales from unit cell switching and domain wall motion to polycrystalline behavior. The condensed method (CM) is a semi-analytical approach, which has been efficiently applied to various problems in this context, ranging from self-heating and damage evolution to energy harvesting. Engineering applications, however, inevitably require the solution of arbitrary boundary value problems, including the complex multiphysical ...
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Dynamic tensile deformation behavior of AISI 316L stainless steel fabricated by laser-beam directed energy deposition
(2023-11-07)
The dynamic deformation behavior of metallic materials is the key to crash-safe design in many applications, e.g., in the automotive sector. However, in the field of additive manufacturing, dynamic deformation properties have only been scarcely studied. Based on the intrinsic interrelationships of process parameters, post-process heat treatments and the resulting microstructure, the present study seeks to provide a holistic overview of the dynamic tensile deformation properties of AISI 316L stainless steel, fabricated ...
Aufsatz
Verbesserung der CO₂-Bilanz von Kalksandsteinen durch den Einsatz von Sägeschlamm als Optimierungszuschlag
(2023-12-06)
Rund 20% der aus den Rohstoffen Kalk, Sand und Wasser hergestellten Kalksandsteine (KS) in KS-XL-Formaten werden zur Vorkonfektionierung gesägt. Dabei fallen in den KS-Werken insgesamt rd. 20.000 t Sägeschlämme pro Jahr an, die derzeit keiner gezielten Verwendung zugeführt werden. Allerdings handelt es sich dabei bereits unter Einsatz von CO₂-intensivem Branntkalk gehärtetes Material, welches als Optimierungszusatz genutzt werden kann.
Insgesamt 13 verschiedene Sägeschlämme (SäS) wurden hinsichtlich ihrer Eignung ...
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Topology optimization considering self-weight
(2023-11-10)
In civil engineering self-weight loading usually represents the preponderant load case and shall therefore be considered in structural optimization. The present study investigates numerical topology optimization of structural stiffness with a bound on disposable amount of material. A customized topology optimization routine based on Sequential Quadratic Programming was built and is examined by means of known benchmark problems complemented by consideration of self-weight. This study aims to highlight the relevance ...
Aufsatz
Spatially resolved in situ analyses of the adsorption behavior of different admixtures on binders
(2023-12-06)
Admixtures play a key role in improving the performance of the cement paste matrix. A more efficient matrix can allow a reduction the binder content while maintaining the same properties. There is currently a lack of knowledge about the spatial distribution of admixtures in situ on binder surfaces which would facilitate the use of admixtures in general in inorganic binder systems. Imaging techniques such as confocal laser scanning microscopy (CLSM) and fluorescence microscopy can be used to study the spatiotemporal ...
Aufsatz
PrOuD: Probabilistic Outlier Detection Solution for Time-Series Analysis of Real-World Photovoltaic Inverters
(2023-12-21)
Anomaly detection methods applied to time series are mostly viewed as black boxes that solely provide a deterministic answer for the detected target. Without a convincing explanation, domain experts can hardly trust the detection results and must conduct further time-series diagnoses in real-world applications. To overcome this challenge, we mathematically analyzed the sources of anomalies and novelties in multivariate time series as well as their relationships from the perspective of Gaussian-distributed non-stationary ...
Aufsatz
Mechanically induced dye-release from polyurea microcapsules in a rubbery adhesive
(2023-07-13)
Especially in the building industry the demand for in situ monitoring concepts of adhesive joints persists. In a new approach, microcapsules filled with special dyes, are added into a rubbery adhesive. Certain stress levels within the adhesive lead to a breakage of the capsules, which release their liquid cores. This results in a detectable colour change and thus, enables non-destructive condition monitoring of the bond. Dye-filled polyurea microcapsules were produced by interfacial polymerization by varying synthesis ...