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Cyclic Superelastic Behavior of Iron-Based Fe-Ni-Co-Al-Ti-Nb Shape Memory Alloy
(2023-01-03)
Iron-based shape memory alloys came into focus as promising candidate materials for large-scale structural applications owing to their cost-efficiency. In the present work, the superelastic properties of a recently introduced Fe-Ni-Co-Al-Ti-Nb shape memory alloy are investigated. For 〈001〉-oriented single-crystalline material in aged condition (650 °C/6 h), an incremental strain test reveals excellent superelasticity at −130 °C with fully reversible strains up to about 6%. Under cycling loading at different test ...
Aufsatz
Ultra-high performance alkali-activated slag as a reusable mold for light metal casting
(2023-12-06)
Light metal die casting is usually performed using steel molds. However, these lead to a reduced quality of the casting due to the occurrence of metal corrosion on the surface and the incorporation of hydrogen into the casting as a result of required process chemistry. Ultra-high performance concrete based on alkali-activated slag can be used to produce mineral molds for aluminum casting. The use of reusable mineral molds not only enables the production of various thin-walled geometries. The risk of metal corrosion ...
Aufsatz
Numerical detection of synchronization phenomena in quasi-periodic solutions
(2023-10-05)
In science and technology, dynamical systems can show so-called quasi-periodic solutions. These solutions are composed of two or more base frequencies. The solution in the time domain can be represented by an invariant manifold. To parametrize the invariant manifold, we choose the hyper-time parametrization. If quasi-periodic solutions branches are continued by means of a path continuation, the phenomenon of synchronization may occur. This is important, because the hyper-time parametrization is only valid, as long ...
Aufsatz
Neural network interatomic potential for laser-excited materials
(2023-08-15)
Data-driven interatomic potentials based on machine-learning approaches have been increasingly used to perform large-scale, first-principles quality simulations of materials in the electronic ground state. However, they are not able to describe situations in which the electrons are excited, like in the case of material processing by means of femtosecond laser irradiation or ion bombardment. In this work, we propose a neural network interatomic potential with an explicit dependency on the electronic temperature. Taking ...
Aufsatz
Latent heat effects in inductive heating of shape memory alloy fibers
(2023-11-23)
Motivation of the present work is an inductive heating process, used in manufacturing a new kind of improved ultra-high performance concrete. In this novel material, fibers made out of shape memory alloys are used to increase the maximum possible fiber volume fraction, or to create an internal state of compressive stress. In contrast to other works, the underlying microstructure transformation from martensite to austenite is highlighted based on thermal analysis. Dynamic scanning calorimetry measurements are adapted ...
Aufsatz
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
Resistance of poly(lactic acid)/starch composites to weathering effects
(2023-10-06)
In order to produce a completely bio-based and cost-effective filled polymer, PLA and native potato starch as a filler were compounded by twin screw extrusion. Subsequently injection molded test specimens were manufactured and subjected to artificial weathering as well as different storages (high temperature, high humidity, freeze, water) for 504 h with a view to long-term resistance. Depending on the starch content a significant reduction of up to 100% in tensile strength can be seen, as the starch accelerates or ...
Aufsatz
Faserbewehrter UHPC auf Basis von alkalisch aktivierten Bindemittel
(2023-12-06)
Die mechanische Leistungsfähigkeit von faserverstärktem Ultrahochleistungsbeton auf der Grundlage alkalisch aktivierter Schlacke wurde untersucht, wobei der Schwerpunkt auf der Verwendung von Stahlfasern lag. Die Biegezugfestigkeit ist im Vergleich zu UHPC auf der Basis Portlandzement als Bindemittel erhöht. Die Korrelation der Biegezugfestigkeitsprüfung mit Faserauszugsversuchen ergab eine Verbesserung des Verbundverhaltens in der Grenzflächen-Übergangszone des AAM-UHPC im Vergleich zum OPC-UHPC. Bei Vergleichen von ...
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
A material model for thick, rate-dependent adhesives with delocalized softening
(2023-10-04)
This contribution is dedicated to the development and implementation of a material model to describe the deformation behaviour of assembly adhesives. These assembly adhesives are usually used with thicknesses of several millimetres up to centimetres in order to compensate for large relative displacements of joining parts. These large displacements can be resisted by assembly adhesives, since they have a low shear modulus and thus a high strain until failur above their glass transition temperature. As a basis, the ...