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Dissertation
Einfluss mesoskopischer und mikroskopischer Phasenverteilungen auf das Wachstumsverhalten physikalisch kurzer Risse
(2017-09-28)
Im Rahmen der vorliegenden Arbeit wird der Einfluss der meso- und mikroskopischen Phasenverteilung auf das Wachstumsverhalten physikalisch kurzer Risse unter Ermüdungsbelastung in metallischen Werkstoffen untersucht. Dazu werden physikalisch kurze Risse in einem Stahl und einer Aluminiumlegierung gezielt initiiert und bei einer definierten Belastung wachsen gelassen,
um die Interaktion des Risses mit den unterschiedlichen Phasenverteilungen analysieren zu können.
Zur Analyse des mesoskopischen Phaseneinflusses ...
Dissertation
Bruchmechanische Charakterisierung physikalisch kleiner Ermüdungsrisse
(2017-05-05)
Im Rahmen dieser Arbeit wurden das Wachstumsverhalten und der Belastungszustand physikalisch kleiner Ermüdungsrisse bei mechanisch monotoner und zyklischer Belastung unter Berücksichtigung der Mikrostruktur in-situ untersucht.
Das Wachstumsverhalten kleiner Risse hat im Bereich der bruchmechanischen Rissanalyse in der jüngsten Vergangenheit ein besonderes Interesse erfahren, vor allem weil diese Risse einen wesentlichen Anteil der Lebensdauer ausmachen. Kleine Risse in der Größenordnung der Mikrostruktur (Korngrößen, ...
Dissertation
Mechanismenorientierte Lebensdauervorhersage für eine thermo-mechanisch hergestellte Flanschwelle mit gradiertem Gefüge
(2010-02-09)
Im Rahmen der vorliegenden Arbeit wird ein Konzept zur mechanismenorientierten Lebensdauervorhersage entwickelt und auf eine Flanschwelle mit gradiertem Gefüge übertragen.
Das Konzept wird in Form eines Computercodes (LOCC) zur Anwendung gebracht. Basierend auf lokalen Spannungen wird für jedes Element eines FE-Modells eine bedingte Versagenswahrscheinlichkeit berechnet. Mithilfe bruch- und ggf. mikromechanischer Modelle werden lokale kritische Risslängen und die bei gegebener Lebensdauer zugehörigen Anfangsrisslängen ...
Konferenzveröffentlichung
Influence Of The Fiber-Matrix-Interaction On The Fracture Behavior Of Regenerated Cellulose Fiber Reinforced Polypropylene
(Society of Plastics Engineers, 2017)
This investigation focuses on the fiber-matrix-interaction of man-made cellulose fibers (RCF) in a PP matrix with an additional MAPP content using an energetic evaluation of the single fiber pull-out test (SFPT). Furthermore glass fibers were characterized for reference purposes. With the SFPT the interfacial shear strength (IFFS) and the critical fiber length (lc) as well as the consumed energy of a fiber pull-out and a fiber rupture were determined. In a following step the resulting values of lc were related to the ...
Konferenzveröffentlichung
Joining Investigations of Polymer-Metal-Hybrids for Permanantly Non-Leaking Applications
(Society of Plastics Engineers, 2016)
The demand for light-weight construction and economic efficiency has led to the development of light-weight construction strategies, i.e., multi-material design, in many areas of industry. Here, the property profiles of the composite partners are utilized synergetically. Plastic-metal hybrid composites possess a large amount of potential in this regard owing to the weight reduction that can be achieved in the composite and the simultaneous enhancement of the mechanical properties.
Hybrid components have already ...
Konferenzveröffentlichung
Development of a Flexible Polymer Joining Center Capable of Performing Multiple Joining Processes Using Different Methods in a Single Cycle
(Society of Plastics Engineers, 2016)
Goal of this research and innovation project is the implementation of a flexible polymer joining center as a prototype machine integrating different friction welding methods. This prototype joining cell combines (a) flexibility by being capable of performing joining processes in any order in a single flow with (b) modularity by integrating unified interfaces for exchanging joining modules, and (c) scalability by offering a wide range of setups for smaller to larger work pieces. Corresponding interfaces to up- and ...
Konferenzveröffentlichung
The Influence of different die geometries on the Extrusion Process of High-Consistency Silicone Rubber
(Society of Plastics Engineers, 2019)
Silicone Rubber and especially High-Consistency Silicone Rubber (=HCR), are typically processed in the extrusion process. Due to the high requirements in terms of the ma-terial properties and the geometric dimensions, a funda-mental knowledge of the whole process including experi-ences in tool design are essential.
In this study, HCR with different Shore-hardnesses are extruded on a vertical silicone extrusion line with various breaker plates with different length to diameter ratios (=L/D-ratio) in order to analyze ...
Konferenzveröffentlichung
Pull and Foam - Injection moulding method: Foamed ribs for stiffening plane components
(Society of Plastics Engineers, 2012)
The pull and foam method is a foam injection moulding method which is currently being developed at the Institut für Werkstofftechnik (IfW) (Institute of Materials Engineering) at the University of Kassel. The processing principle represents an alternative to the existing foam injection moulding special procedures and introduces the possibility to partially foam a component. In so doing, thin-walled, hardly foamed components with foamed ribs can be made in one processing step, thus also components with graded ...
Konferenzveröffentlichung
UV light irradiation of fibers in thermoplastic pultrusion for higher surface energy
(Society of Plastics Engineers, 2018)
Pultrusion is a common way to produce thermoplastic composites reinforced with different kinds of fibers. There are many different opportunities to improve the properties of a thermoplastic material. Different kind of fibers where pultruded in combination with different thermoplastic materials. The fiber content was set to 30wt% comparing the roving strain with the pultruded strain. UV-C light was used in the process to improve the fiber matrix adhesion. The pultruded strain was granulated and injection molded to ...
Konferenzveröffentlichung
Natural fiber reinforced technical (bio-) composites modified with halogen-free flame retardants
(Society of Plastics Engineers, 2019)
Under the aspect of sustainability and the use of alternative materials, engineering thermoplastics such as polybutylene terephthalate (PBT) will be reinforced with renewable raw materials such as regenerated cellulose fibers.
The University of Kassel is developing cellulose regenerated fiber reinforced technical thermoplastics in a state-funded project with further companies. Since pure natural fibers cannot withstand the high operating temperature of engineering thermoplastics (Ts>230°C), regenerated cellulose ...