Siegen, Universiẗat, Diss., 2004.

Master-Arbeit Univ. St. Gallen, 2008.

Zugl.: Hannover, Universiẗat, Diss., 1994.

TiC particulate reinforced Ti6Al4V metal matrix composites (Ti6Al4V 10 wt.% TiC) have high strength-to-weight ratio and good high temperature properties. Although this class of composite clearly perform better than the matrix alloy itself, the successful application of such particulate-reinforced materials depends on the availability of proven joining techniques that can produce high quality joints. Due to the high chemical reactivity of titanium that may lead to a chemical interaction with the reinforcing material a poor fusion welding performance is commonly observed in these materials making solid-state diffusion bonding and rotary friction welding potential processes to produce complex structural components. Despite recent advances in processing and manufacturing technology of Ti6Al4V 10 wt.% TiC there is still a lack of understanding in the solid state joining possibilities and its microstructural changes and mechanical properties. The main objective of this work is to investigate and analyse the feasibility of joining the particulate-reinforced composite alloy by rotary friction welding and diffusion bonding processes. It is also aimed the determination and establishment of the microstructure/properties relationships of the resultant welds as well as to investigate the bonding mechanisms and understand the weldability aspects of friction welded and diffusion bonded Ti6Al4V 10 wt.% TiC. Metallurgical characterization of both base material and welded joints was performed using Optical and Scanning Electron Microscope. Mechanical assessment was accomplished using tensile, microflat tensile and fracture toughness tests. A microstructural examination of the friction-welded joints has revealed two distinct welding zones (transformed and recrystallized zone as well as heat affected zone); while no metallurgical transformation has occurred in the diffusion bonding process. In the case of rotary friction welding best results were associated with low rotational speed and low friction pressure; while in the diffusion bonding process the best results were associated with a bonding temperature and pressure of 1000C and 5MPa together with bonding times ranging from 35 and 60 minutes.

In the frame of the current work the incremental EVICD(EVent Independent Continuous Damage) crack initiation life prediction method for arbitrary multiaxial loading was consequently further developed. A modular concept was established to account also for an application of the EVICD method in the engineering practise. Numerous comparisons of EVICD predictions and experimental results have shown satisfactory prediction results of the EVICD method which is recommended in its present stage as a high-grade crack initiation life prediction tool for engineering practise.

This work describes the development of a framework for numerical simulation software, using the finite volume method. A major guideline has been flexibility. The framework is written in C++, making strong use of its object-oriented capabilities. Outlined are the benefits, as well as the pitfalls related to object-oriented programming, if used for numerical simulations. The text explains that flexibility has not only been tried to achieve in terms of software design, but also with respect to the numerical approaches used. The field of application in the scope of this work is computational fluid dynamics. Thus a brief overview over the necessary equations and the employed numerical techniques is given. Furthermore a number of example computations can be found in this text. An important part of this work deals with a novel approach for unstructured mesh generation. The approach is based on multi element type grids and uses level-sets as input to describe the geometry. It is well suited to create anisotropic layers, such as boundary layer grids for fluid dynamics problems. Furthermore it can deal with moving and even topologically changing geometries. In the scope of this work it is limited to two-dimensional problems.

Augsburg, Univ., Diss., 2008.

No description available.

4 mal im Jahr erscheinende Zeitschrift über aktuelle Themen der TU Chemnitz

Am Anfang einer jeden Forschungsarbeit steht das Literaturreview, das heißt die systematische Aufarbeitung des Stands der Wissenschaft, Forschung und Technik. Im wissenschaftlichen Umfeld wohnt diesem Teil der wissenschaftlichen Arbeit aufgrund der rapide ansteigenden Anzahl von Publikationen weltweit eine größer werdende Herausforderung inne. Um diesen Schritt so effektiv und effizient wie möglich zu gestalten, ist der Einsatz eines strukturierten, nachvollziehbaren und methodischen Vorgehens wichtiger. Vor allem im medizinischen und sozialwissenschaftlichen Forschungsbereich hat sich die Durchführung von systematischen Literaturreviews etabliert. Während in den genannten Forschungsdisziplinen diese Methode im Rahmen verschiedener Publikation diskutiert und determiniert ist, existiert im ingenieurwissenschaftlichen Bereich eine hohe Heterogenität in angewendeten Methoden und deren Qualität. Im folgenden Artikel wird das methodische Vorgehen des systematischen Literaturreviews auf den ingenieurwissenschaftlichen Bereich übertragen und als praktischer Handlungsleitfaden dargestellt. Dafür wird zunächst der wissenschaftliche Stand der methodischen Vorgehensweise des systematischen Literaturreviews aufgezeigt. Die überblickende Beschreibung des Gesamtprozesses schließt sich an, gefolgt von der Detailierung der zugehörigen Subprozesse. Jede Prozessbeschreibung wird zum besseren Verständnis durch eine Prozessdarstellung unterstützt. Finalisiert wird der Artikel durch eine Betrachtung von Grenzen der beschriebenen Methodik sowie durch ein Fazit.:Abstract 1 Einleitung 2 Stand von Wissenschaft und Forschung 3 Beschreibung des Gesamtprozesses 4 Dokumentation (A) 5 Konzeptionierung (B) 6 Literatursuche (C) 7 Literaturanalyse und -auswahl (D) 8 Erweiterte Literatursuche (E) 9 Kritik und Limitierung 10 Fazit Literaturverzeichnis / At the beginning of any research work you have to do a literature review, the systematic review of the state of the art in science, research and technology. In the scientific environment, this part of scientific work is increasingly challenging due to the rapidly growing number of publications worldwide. To make this step as effective and efficient as possible, the use of a structured, comprehensible and methodical approach is crucial. Especially in the medical and social science research fields, the implementation of systematic literature reviews has become established. In the mentioned research disciplines this method is discussed and determined in the context of different publications, whereas in the engineering field there is a high heterogeneity in applied methods and their quality. In the following article, the methodological procedure of systematic literature reviews is transferred to the field of engineering and presented as a practical guideline. For this purpose, the scientific state-of-the-art of the methodological approach of systematic literature reviews is first presented. The overview description of the overall process follows, after which the details of the associated sub-processes are presented. Each process description is supported by a process chart for better understanding. The article is finalized by a consideration of limitations of the described methodology as well as by a conclusion.:Abstract 1 Einleitung 2 Stand von Wissenschaft und Forschung 3 Beschreibung des Gesamtprozesses 4 Dokumentation (A) 5 Konzeptionierung (B) 6 Literatursuche (C) 7 Literaturanalyse und -auswahl (D) 8 Erweiterte Literatursuche (E) 9 Kritik und Limitierung 10 Fazit Literaturverzeichnis