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Funktionalisierung faserverstärkter Hochleistungsbetone mittels Formgedächtnislegierungen
(2023-12-06)
Faserverstärkte (Ultra-)Hochleistungsbetone ((U)HPC) werden bereits seit den 1970er Jahren in großen Mengen für die Herstellung von Betonfertigteilen verwendet. Fasern werden eingesetzt, um die Zugfestigkeit zu erhöhen und sprödes Versagen in duktiles Nachbruchverhalten umzuwandeln. Funktionale Formgedächtnislegierungen (FGL) als Bewehrung haben das Potenzial, in Form von Vorspannelementen im erhärteten Beton zu wirken und die Frischbetoneigenschaften zu verbessern.
FGL haben die Eigenschaft, sich an eine eingeprägte ...
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
Fracture behavior of ultra-high performance lightweight concrete: In situ investigations using μ-CT
(2023-12-06)
In various research projects at the University of Kassel, the concept of lightweight concrete has been combined with that of ultra-high performance concrete (UHPC). Due to the high performance of the UHPC matrix, lightweight concretes (UHPLC) with strengths of 60-130 MPa and bulk density of 1.5-1.9 kg/m³ were developed. This material can be used in many applications because of its low thermal conductivity, low weight and thus easy to transport, recyclable and can be prefabricated. Thus, it meets today's multifunctional ...
Aufsatz
Analysis of the Machine-Specific Behavior of Injection Molding Machines
(2023-12-22)
The performance of an injection molding machine (IMM) influences the process and the quality of the parts manufactured. Despite increasing data collection capabilities, their machine-specific behavior has not been extensively studied. To close corresponding research gaps, the machine-specific behavior of two hydraulic IMMs of different sizes and one electric IMM were compared with each other as part of the investigations. Both the start-up behavior from the cold state and the behavior of the machine at different ...
Aufsatz
Characterization of films and film-forming solutions of chitosan/thermoplastic rice starch associations: Role of starch oxidation and plasticizer type in the molecular interactions
(2023-09-29)
Polysaccharide films are alternative sources to replace fossil-based compounds. This study aimed to use rice starch modified by gelatinization and oxidation processes. Different properties were observed after blending it with chitosan and polyols, as evaluated on the film-forming solutions by rheology. The interaction between chitosan and oxidized starch appeared higher, as the plasticizers exhibited a low effect on the rheological behavior. Polyols played an essential role in chitosan/gelatinized associations, driven ...
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 ...
Aufsatz
High-Strength Dissimilar Welds Between a NiTi Shape Memory Alloy and Titanium Obtained by Intermixing Niobium Using Pulsed Laser Beam Welding
(2023-11-17)
Joining of NiTi shape memory alloys with commercially pure titanium (Ti) is of great interest for manifold industrial applications. However, dissimilar fusion welding of these materials is associated with the formation of extremely brittle intermetallic compounds, e.g., Ti2Ni and TiNi3, which drastically limit the mechanical properties of NiTi/Ti joints. The present investigation seeks to improve both chemical compatibility and mechanical performance through intermixing of a niobium foil as filler material into a ...