The paper treats the question of feasibility of measuring intrinsic thin film stresses due to nanoindentation. A variety of different methods is proposed and analysed with respect to their applicability. As this accuracy-estimation results in boundary conditions for the measurements which can not be fulfilled yet, the whole topic is considered from a purely academic point of few. With the help of a special software package [25] the following methods are considered: 1. Taking the moment of beginning plastic flow within the substrate as indictor, 2. Taking the moment of beginning plastic flow within the film as indictor, 3. Applying mixed loads (normal and lateral forces), 4. Applying the concept of the effectively shaped indenter. While the methods 2 to 4 appear to be in principle feasible, method 1 can completely be ruled out as being of no practical use. The mentioned software package (FilmDoctor prototype) is part of the supplemental material of this study.

Redundant parallel kinematic machines are parallel mechanisms to which one or more kinematic branch is added in order to improve their mechanical properties, in particular, their stiffness. Redundant parallel kinematic machines have then more actuators than their degree of freedom. New calibration methods are developed in this thesis in order to deal with the particularities related to the actuation redundancy. First, calibration methods using geometrical models are tested. Several measurement systems and control models are compared. A self-calibration is also carried out, where the redundant branches are switched to a passive mode. Thus, they play the role of the measurement system and the mechanism can be calibrated without the help of extra sensors. Geometrical calibration methods, however, do not take into account the internal constraints due to the redundancy. Elastic deformations are neglected although they are shown to have an influence on the positioning accuracy after the calibration. Modeling methods are then developed that take into account the geometry of the mechanism as well as the stiffness of its elements to improve the accuracy of the calibration. With such modeling methods, it is possible to determine the tool-center-point position for redundantly actuated parallel mechanisms from geometrical and stiffness parameters and given positions for all actuators. The modeling methods are first demonstrated on a simple mechanism. They are then tested on a real machine and used in calibration processes. / Mechanismen mit redundanter Parallelkinematik sind Parallelmechanismen, denen eine oder mehrere kinematische Ketten zugefügt werden, um die mechanischen Eigenschaften, insbesondere die Steifigkeit, zu verbessern. Maschinen mit redundanter Parallelkinematik besitzen dann mehr Antriebe als ihr Freiheitsgrad erfordern würde. In dieser Dissertation werden neue Kalibrierungsmethoden entwickelt, um die mit der Antriebsredundanz gebundenen Besonderheiten zu betrachten. Zuerst werden Kalibrierungsmethoden basierend auf geometrischen Modellen getestet. Verschiedene Messmethoden und Messsysteme werden verglichen. Eine Selbstkalibrierung wird durchgeführt. Bei dieser Kalibrierungsmethode werden die redundanten Antriebe freigeschaltet und als Messsystem genutzt. Die Maschine kann dadurch ohne externes Messsystem kalibriert werden. Dennoch betrachten geometrische Kalibrierungsmethode keine internen Verspannungen, die mit der Redundanz verbunden sind. Die elastischen Verformungen werden vernachlässigt, obwohl gezeigt wird, dass sie einen Einfluss auf die Positioniergenauigkeit nach der Kalibrierung haben. Es werden deshalb Modellierungsmethoden entwickelt, die sowohl die Geometrie des Mechanismus als auch die Elementsteifigkeit betrachten, um die Genauigkeit der Kalibrierung zu verbessern. Mit solchen Methoden ist es möglich, die Werkzeugposition redundanter Parallelkinematiken aus den Geometrie- und Steifigkeitsparametern und allen Antriebspositionen zu bestimmen. Die Modellierungsmethoden werden zuerst an einem einfachen Mechanismus angewandt. Sie werden danach an einer realen Maschine getestet und in einem Kalibrierungsprozess genutzt / Les mécanismes à cinématique parallèle redondante sont des mécanismes parallèles auxquels a été ajoutée une branche cinématique, ou plus, dans le but d'améliorer leurs propriétés mécaniques, en particulier, leur rigidité. Les mécanismes à cinématique parallèle redondante possèdent donc plus d'actionneurs que leur degré de liberté. De nouvelles méthodes d'étalonnage sont développées dans cette thèse afin de prendre en compte les spécificités liées à la redondance d'actionnement. Les méthodes d'étalonnage utilisant des modèles géométriques sont d'abord testées. Plusieurs systèmes de mesure et plusieurs modèles de contrôle sont comparés. Un auto-étalonnage est aussi réalisé. Pour cette méthode d'étalonnage, les actionneurs redondants sont mis en mode passif et jouent le rôle de système de mesure. Le mécanisme peut être étalonné sans ajout de codeurs. Cependant, les méthodes d'étalonnage géométriques ne prennent pas en compte les contraintes internes liées à la redondance. Les déformations élastiques sont négligées bien qu'il soit montré qu'elles ont une influence sur la précision de positionnement après étalonnage. Des méthodes de modélisation qui prennent en compte la géométrie du mécanisme ainsi que la rigidité des éléments sont donc développées pour améliorer la précision de l'étalonnage. Avec de telles méthodes, il est possible de déterminer la position de l'outil des mécanismes à redondance d'actionnement à partir de paramètres géométriques et élastiques et de la position de tous les actionneurs. Les méthodes de modélisation sont d'abord appliquées sur un mécanisme simple. Elles sont ensuite testées sur une machine réelle et utilisées dans des processus d'étalonnage.

In the simulation of deformations of plates it is well known that we have to use a special treatment of the thickness dependence. Therewith we achieve a reduction of dimension from 3D to 2D. For linear elasticity and small deformations several techniques are well established to handle the reduction of dimension and achieve acceptable numerical results. In the case of large deformations of plates with non-linear material behaviour there exist different problems. For example the analytical integration over the thickness of the plate is not possible due to the non-linearities arising from the material law and the large deformations themselves. There are several possibilities to introduce a hypothesis for the treatment of the plate thickness from the strong Kirchhoff assumption on one hand up to some hierarchical approaches on the other hand.

We give an alternate description of the usual shell equation that does not depend on the special mid surface coordinates, but uses differential operators defined on the mid surface.

Zugl.: Stuttgart, Univ., Diss., 2001.

Zugl.: Stuttgart, Univ., Diss., 2003. / Print-Ausg. bei Shaker, Aachen erschienen.

Techn. Universiẗat, Diss., 2003--Berlin.

The use of composite materials in engineering practice and in particular nonmetallic composite materials in the preparation of elastic couplings (clutches) requires modeling of their mechanical behavior. The production of elastic couplings with a elastic element having reinforced polymer materials require studying the behavior of those materials for loads which are typical for their operation. In many modern structures of elastic clutches are used multilayer reinforced composites. This kind of materials are composed of separate layers with different orientation of reinforcing fibers. Several authors have studied the behavior of this type of laminated materials (Yongming L. 2005, Zhang Y.X., 2009). Factors,which determine the stress and deformation state of this type of elastic elements are: — structure and mechanical characteristics — matrix and reinforced material — connection between matrix and reinforced material — orientation of reinforcement. The aim of this paper is to investigate stress and strain state of elastic element of coupling, creating a model for determination of the state of threelayers nonmetallic material for manufacturing of nonmetallic elastic elements.

Data stream processing systems are used to process data from high velocity data sources like financial, sensor, or logistics data. Many use cases force these systems to use a distributed setup to be able to fulfill the strict requirements regarding expected system throughput and end-to-end latency. The major challenge for a distributed data stream processing system is unpredictable load peaks. Most systems use overprovisioning to solve this problem, which leads to a low system utilization and high monetary cost for the user. This doctoral thesis studies a potential solution to this problem by automatic scaling in or out based on the changing workload. This approach is called elastic scaling and allows a cost-efficient execution of the system with a high quality of service. In this thesis, we present our elastic scaling data stream processing system FUGU and address three major challenges of such systems: 1) consideration of user-defined end-to-end latency constraints during the elastic scaling, 2) study of different auto-scaling techniques, and 3) combination of elastic scaling with different fault tolerance techniques. First, we demonstrate how our system considers user-defined end-to-end latency constraints during the scaling decisions. Each scaling decision causes short latency peaks, because the processing needs to be paused while operators are moved. FUGU estimates the latency peaks for different scaling decisions, tries to minimize the created latency peak and at the same time to achieve similar monetary costs like alternative approaches. Second, we study different auto-scaling techniques for elastic-scaling data stream processing systems. Auto-scaling techniques are a very important part of such systems as they derive the scaling decisions. In this thesis, we study three auto-scaling techniques: Threshold-based Scaling, Reinforcement Learning and the novel Online Parameter Optimization. The Online Parameter Optimization overcomes the shortcomings of the two other approaches by avoiding manual tuning and being robust towards different workload patterns. Finally, we present an integration of an elastic scaling with different replication techniques for high availability to allow to minimize the spent monetary cost and to ensure at the same time a maximal recovery time. We leverage two replication approaches in FUGU and evaluate a trade-off between recovery time and overhead. FUGU estimates the recovery time and adaptively optimizes the used replication technique for each operator. All these contributions are carefully evaluated in three real-world scenarios and we discuss the relationship of our contributions towards related work.

We give an alternate description of Koiter's shell equation that does not depend on the special mid surface coordinates, but uses differential operators defined on the mid surface.:1. Introduction 2. Basic differential geometry 3. The strain tensor and its simplifications 4. Linearization to small strain and coordinate free description 5. The resulting Koiter energy