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Now showing items 131-140 of 141
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
Influence of effluent particles and particle-bound micropollutants on the removal of micropollutants and UVA₂₅₄ in wastewater effluent ozonation
(2024-01-09)
This study systematically investigated the influence of effluent particles and activated sludge (AS) particles on the removal of micropollutants via wastewater effluent ozonation within typical effluent total suspended solids (TSS) concentrations. A series of batch experiments revealed that particle concentrations up to 30 mg/L had a minor impact on the removal of organic micropollutants (OMPs) in the aqueous phase. Moreover, the reduction of UV absorbance at 254 nm (UVA₂₅₄) was negatively correlated to the level of ...
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 ...
Aufsatz
Influence of deep rolling at different temperatures on near-surface and mechanical properties of a Maraging C250 steel
(2024-04-27)
Due to an outstanding combination of high strength and fracture toughness Maraging steels are used in numerous industries, e.g., in the aerospace sector. The high strength can be attributed to precipitation strengthening by conventional age-hardening heat treatments. However, as many of the envisaged applications will suffer from cyclic loadings, the fatigue properties are of significant interest in terms of a reliable use. Generally, Maraging steels are characterized by a relatively low fatigue strength limiting the ...
Aufsatz
The environmental performance of plastic packaging waste management in Germany
(2023-07-28)
Plastic is a popular packaging material, but also criticized as a symbol for the make-use-dispose economy because of its short lifespan, its dependency on fossil fuels, and its potential contribution to marine litter. To identify current and potential future key factors for the environmental performance of plastic packaging waste (PPW) management in Germany, a life cycle assessment considering five different pathways of PPW (including deposit-refund systems, separately collected lightweight packaging waste, and ...
Aufsatz
Bond strength, failure criteria and calculation methods for adhesively bonded timber–concrete composites
(2024-04)
The bond strength of adhesively bonded timber–concrete composites (ATCC) with prefabricated concrete elements is usually described using the shear strength of the timber. This approach, however, often fails to consider the actual failure modes of the bondline and also the interaction between shear stresses and stresses perpendicular to the bondline has not yet been comprehensively understood. To address this limitation, a reliable calculation method is required, where stress determination, failure criterion, and ...
Aufsatz
Solar driven liquid desiccant dehumidification system: Measurements and annual system simulations
(2024-01-17)
Liquid desiccant air conditioning (LDAC) systems are used for dehumidification of air to low dew point temperatures. In the presented study a TRNSYS model of a LDAC unit is developed and validated with laboratory measurements. This model is coupled with a solar thermal system that provides heating water for the regeneration process. With this model dynamic annual system simulations can be carried out to simulate the dehumidification of a building. The solar fraction is evaluated for various infiltration rates of the ...