Theoretical, numerical and experimental investigations have been successfully carried out to characterise the thermal performance of an air-to-water multi-pass heat exchanger equipped with thermosyphon technology. Air and water are the heat source and the heat sink on the evaporator and condenser, respectively. Evaporator and condenser are connected by six thermosyphons, through which thermal energy is transferred. The investigation was performed for two multi-pass configurations at various inlet conditions: a range of air inlet temperatures (100, 150, 200 and 250°C) and mass flow rates (0.05, 0.08, 0.11 and 0.14 kg/s). The water inlet conditions were kept constant (a temperature of 15°C and a mass flow rate of 0.08 kg/s). The theoretical model was built by applying the thermal resistance analogy with the aid of convection, boiling and condensation correlations found in the literature. It was found that the thermal resistances in the first pass act in parallel mode along the ones in the second pass. Similarly, in the case of three passes. Also, the external convective thermal resistance were found to be the major contributor to the overall thermal resistance in the entire heat exchanger. ANSYS Fluent was the numerical tool used to investigate the shell-side convective heat transfer for two multi-pass configurations. The CFD model has been experimentally validated. The two-phase change processes inside the thermosyphons were not modelled during the simulation. Instead, the thermosyphons were treated as solid rods with a constant thermal conductivity, which was calculated. The overall rate of heat transfer was obtained by both CFD and a theoretical model, and the results lay within 15% of the experimental data. The numerical predictions demonstrated that the K-ε Realizable turbulence model with scalable wall function is a reliable tool for predicting heat transfer and fluid flow in such types of heat exchangers. This investigation will add a great knowledge to the academia in terms of both experimentation and modelling in the area of multi-pass thermosyphons-based heat exchangers. Also, it provides the industries with a cost effect design tool for future modelling of similar heat exchanger systems.

The purpose of this study was to investigate the fatigue life of an endosseous root-form dental implant using finite element analysis. A conventional Brånemark dental implant system was redesigned to utilize the biocompatible, lightweight magnesium alloy coating which promotes bone growth. ANSYS Workbench 11.0 was used to generate a three-dimensional mesh of a model created in Pro Engineer with the actual size specifications. Regulations and schematic of test set-up from ISO 14801 - "Fatigue test for endosseous dental implants" were strictly followed to simulate the fatigue test. To validate the credibility of calculated fatigue life, actual prototypes were built with the design specifications and tested using Material Test System 810. The main advantages of performed computer simulations are that it is fast, efficient and cheap. A comparison of the calculated fatigue life with experimental fatigue life data displayed the accuracy and reliability of the computer simulation method.

Ingeniero Civil Mecánico / El Ministerio de Energía de Chile, en su plan Energía 2050, establece los lineamientos para el desarrollo energético del país hacia el año 2050, con énfasis en la ampliación de la red actual en capacidad y accesibilidad. Este plan incluye la energía hidroeléctrica como una de las principales, ya que es una energía renovable, limpia, eficiente y existe un alto potencial energético en la zona centro sur del país. En este contexto, el Departamento de Ingeniería Mecánica de la Universidad de Chile desarrolló un prototipo de turbina Pelton de microgeneración, con una potencia hidráulica disponible de 13,69 [kW], y un rendimiento teórico global de 70%. Sin embargo, la potencia generada en las pruebas fue de 8,189 [kW], con un rendimiento global de 59,34%, debido a problemas de subida de agua dentro del housing por su diseño. El objetivo general de este trabajo es realizar y evaluar un nuevo diseño del housing para el prototipo de laboratorio de la turbina Pelton del Departamento de Ingeniería Mecánica de la Universidad de Chile. Con este propósito, se desarrolla en primera instancia un modelo 3D de la turbina, donde el nuevo diseño del housing se realiza utilizando fundamentos de la teoría hidráulica de turbinas Pelton de microgeneración. Además, se modelan los elementos exteriores a la turbina, como rodamientos, generador, acoples, etc. Con el diseño de las partes, se presenta la configuración final de la turbina y sus componentes, y los materiales y tratamientos necesarios a utilizar en su fabricación. Se realiza un análisis computacional del comportamiento del agua dentro del nuevo housing de la turbina en sus condiciones de diseño con el fin de evaluar el nuevo diseño propuesto. El análisis utiliza el modelo Volume Of Fluid (VOF) para estudios multifásicos, a través del programa Ansys FLUENT. Los resultados del análisis muestran que no se generan problemas de subida de agua, por lo cual no se esperan bajas de rendimiento en el nuevo diseño del housing. El costo de fabricación del nuevo housing es de $470.000 CLP, lo que se encuentra por debajo del housing existente, con un total de $625.000, sin considerar los componentes adicionales de la turbina. / 05/06/2022

Orogene Prozesse in kontinentalen Kollisionszonen werden in zwei- und dreidimensionalen numerischen Modellen auf Basis der Finite-Elemente Methode (FEM) untersucht. Dabei stehen die Verteilung der Deformation innerhalb der Modellkruste, die korrespondierenden Spannungsfelder und die aus Temperaturfelddaten und Partikelpfaden abgeleitete metamorphe Entwicklung von Krustengesteinen im Vordergrund. Die Studie gliedert sich in einen methodischen Teil, umfangreiche Parameterstudien und spezielle Anwendungen auf fossile und rezente Orogene. Kontinentale Kollisionszonen sind - insbesondere in den tieferen Krustenstockwerken – durch hohe Beträge penetrativer Deformation gekennzeichnet. Im methodischen Teil der Arbeit wird eine Technik vorgestellt, mit deren Hilfe Verformungen des beobachteten Umfangs mit dem auf rein LAGRANGEscher Formulierung basierenden kommerziellen FE-Programmpaket ANSYS® modelliert werden können. Die speziell für Fragestellungen orogener Krustendynamik entwickelten Programmpakete OROTRACK bzw. OROTRACK3D umfassen Neuvernetzungs- und Ergebnisverwaltungsalgorithmen, die eine Modellierung von Konvergenzbeträgen bis zu mehreren hundert Kilometern erlauben. Zusätzlich können mittels einer Schnittstelle zu Oberflächenmodellen die Folgen exogener Prozesse auf die orogene Dynamik berücksichtigt werden. Weitere Charakteristika der Modellierungstechnik sind eine vollständige thermomechanische Kopplung, die Anwendung differenzierter Materialeigenschaften für verschiedene Krustenstockwerke sowie die Möglichkeit, die Deformation - den lokal herrschenden Druck- und Temperaturbedingungen entsprechend - entweder durch spröde oder duktile Materialgesetze zu approximieren. Die zur Beschreibung eines Kollisionsszenarios aufgebrachten Randbedingungen basieren auf den Grundlagen eines Mantelsubduktionsmodells (Willett et al. 1993). In 2D-Modellen wird ebene Verformung in einem Schnitt durch die kontinentale Kruste zweier kollidierender Platten modelliert, die basal einer vom lithosphärischen Mantel aufgeprägten Verschiebung unterliegen. Wird der lithosphärische Mantel der linken Platte an einem Punkt S unter die rechte Platte subduziert, ergibt sich für den linken Modellteil eine horizontale Verschiebung der Modellbasis nach rechts, während im rechten Modellteil keine Verschiebung der Modellbasis erlaubt ist. Im Bereich des Punktes S kommt es zu einer Diskontinuität der basalen Geschwindigkeit und somit zu maximaler Deformation. In publizierten Kollisionsmodellen, die auf ähnlichen Ansätzen beruhen, wird häufig rein sprödes Materialverhalten angenommen oder der duktile Anteil der Kruste durch geringe Krustentemperaturen klein und hochviskos gehalten. Unter diesen Bedingungen kann eng auf das Orogenzentrum lokalisierte Deformation mit einem typischerweise bivergenten Strukturmuster abgebildet werden (Willett et al. 1993 u.a.). Demgegenüber beweist eine erste Reihe zweidimensionaler Parameterstudien eine starke Abhängigkeit des beobachteten Deformationsmusters von den herrschenden Krustentemperaturen und der Konvergenzrate. Bei höheren Krustentemperaturen bildet sich demnach ein Entkopplungshorizont an der Krustenbasis, der für die oberen Krustenstockwerke eine verbreiterte und diffuse Deformationszone bedingt und die erzielte Krustenverdickung limitiert. Über die Verformungsratenabhängigkeit des duktilen Materialverhaltens und den unterschiedlichen Grad thermischer Reequilibrierung innerhalb der verdickten Kruste haben Variationen der Konvergenzrate ähnliche Auswirkungen auf das orogene Deformationsmuster. Verbesserte Modelle mit Neuvernetzungstechnik werden in Parameterstudien getestet, die den Einfluss unterschiedlicher Temperatur-Viskositätsfunktionen auf die Lokalisierung der Deformation und die resultierende synkonvergente Exhumierung metamorpher Gesteine quantifizieren. Ein rheologisches Verhalten, das eine effiziente mechanische Kopplung innerhalb des Krustenprofils gewährleistet, ist demzufolge nicht nur Voraussetzung für lokalisierte Krustenverdickung, sondern auch für rasche Exhumierung von Unterkrustengesteinen durch ein Zusammenspiel von Erosion und isostatischer Hebung. Die Modelle zeigen weiter, dass maximale Exhumierungsbeträge bei rheologisch vergleichsweise festem Verhalten der Unterkruste erzielt werden. Im Einzelnen kann die Variabilität der Versenkungs- und Exhumierungsgeschichte von Materialpunkten im Modellschnitt aus synthetischen PT-Pfaden ersehen werden. Der Wirkungskomplex um Krustentemperaturen, orogene Deformationslokalisierung und synkonvergente Exhumierung ist für die Kollisionsphase der variscischen Orogenese in Mitteleuropa von besonderer Bedeutung. Hochtemperaturmetamorphose und weitverbreitete granitoide Intrusionstätigkeit sind hier Ausdruck hoher Krustentemperaturen; dennoch sind an den Grenzen der klassischen tektonometamorphen Einheiten - im Bereich von Schwarzwald und Vogesen sowie der Mitteldeutschen Kristallinschwelle (MDKS) - eng lokalisierte Teilorogene mit bivergentem Strukturmuster sowie eine rasche synkonvergente Exhumierung amphibolitfazieller Gesteine dokumentiert. Ein solches Nebeneinander ist aus Sicht der Parameterstudien nur durch eine vergleichsweise hochviskose Unterkrustenrheologie zu erklären. In einer Fallstudie zur MDKS kommen in neueren experimentellen Arbeiten bestimmte Kriechparameter (Mackwell et al. 1998) zur Anwendung, mit denen ein derartiges Materialverhalten simuliert werden kann. Der in den reflexionsseismischen Profilen DEKORP 2N und 2S dokumentierte großmaßstäbliche Strukturbau im Bereich des rhenohercynischen Falten- und Überschiebungsgürtels, der MDKS und des saxothuringischen Beckens, sowie die an heute exhumierten Gesteine bestimmten metamorphen Maximalbedingungen können auf dieser Grundlage numerisch reproduziert werden. Eine Erweiterung der Modellierungstechnik auf dreidimensionale FE-Modelle dient der Berücksichtigung orogenparalleler Deformation, die im Randbereich von Kollisionszonen in effektivem Materialtransport resultieren kann; diese Prozesse sind u.a. als „tectonic escape“ (Burke & Sengör 1986) oder „lateral extrusion“ (Ratschbacher et al. 1991b) beschrieben worden. Unter der Annahme orthogonaler Konvergenz wird im 3D-Modell der Mantelsubduktionsansatz der 2D-Modelle zunächst in orogenparalleler Richtung extrudiert (Randbereich des Kollisionsorogens). Im angrenzenden, hinteren Teil des Modells (laterales Vorland des Kollisionsorogens) ist die Modellbasis dagegen keiner Verschiebung oder Fixierung unterworfen. Die Modellränder unterliegen hier einer sogenannten „no-tilt“-Bedingung, die eine differentielle Horizontalverschiebung initial übereinanderliegender Knoten verbietet. In einer Reihe von Parameterstudien werden das kinematische Muster, die räumliche Verteilung der Deformation und die zeitlichen Variationen des oberflächlichen Spannungsfelds untersucht, die sich bei modifizierten Randbedingungen ergeben. Laterale Extrusion ist demnach im Randbereich von Kollisionsorogenen trotz unterschiedlichster Modellszenarien stets präsent. Da die Lateralbewegungen zeitgleich mit der Kollision einsetzen und im Laufe der weiteren konvergenten Krustenverkürzung nur wenig beschleunigt werden, ist der von horizontalen Kräften ausgelöste „tectonic escape“ der dominierende Prozess, während gravitativ induzierte Bewegungen nur eine sekundäre Rolle spielen. Rigide Modellränder in Teilen des lateralen Vorlands modifizieren sowohl Umfang als auch Verteilung der Horizontalbewegungen, ihre Auswirkungen auf das Orogen selbst sind dagegen vergleichsweise gering. Variationen der Krustentemperaturen, der Konvergenzrate und der Unterkrustenrheologie beeinflussen dagegen sowohl die orogene Deformation als auch die des lateralen Vorlands. Unter der Annahme einer festen, isotropen Kopplung zwischen der Krustenbasis und dem bewegten lithosphärischen Mantel werden Extrusionsraten simuliert, die 30% der Konvergenzrate nicht überschreiten. Bis zu 70% können dagegen erreicht werden, wenn eine orogenparallele Beweglichkeit der Modellbasis gestattet wird. Die überragende Bedeutung dieser basalen Randbedingung erlaubt eine Interpretation des miozänen lateralen Extrusionsereignisses in den Ostalpen (z.B. Ratschbacher et al. 1991a). Wenn im Bereich der heutigen Ostalpen zu Beginn der lateralen Extrusion noch kein orogene Topographie bestand (Frisch et al. 1998), fand laterale Extrusion zeitgleich mit bedeutender Krustenverdickung statt; dies spricht für eine Dominanz des von horizontalen Kräften induzierten Prozesses „tectonic escape“ über gravitatives Kollabieren. In jedem Fall legt das in etwa ausgeglichene Verhältnis zwischen Plattenkonvergenz und lateraler Extrusion die Existenz eines basalen Entkopplungshorizonts nahe. Andere Faktoren, die zur Erklärung des Extrusionsereignisses herangezogen werden, z.B. die Indentation der Südalpen oder ein extensives Regime im Bereich des Pannonischen Beckens, können das Deformationsmuster beeinflusst haben, die beobachteten Verschiebungsbeträge sind damit jedoch aus Sicht der Modellstudien nicht plausibel zu machen. Aufgrund ihres großen Maßstabs lassen sich die Verhältnisse bei der Kollision Indiens mit der Eurasischen Platte bislang nur phänomenologisch mit den Modellergebnissen vergleichen. Eine skalierte Fallstudie bleibt somit eine Herausforderung für zukünftige FE-Modelle. / Orogenic processes in continental collision zones are studied by means of two- and three-dimensional numerical models based on the finite-element method (FEM). Special emphasis is laid on the crustal strain distribution, the corresponding stress field, and the metamorphic evolution of crustal rocks which can be determined by analyzing particle paths and temperature field data. The study comprises the description of a new modelling approach based on commercial software, extensive parameter studies and implications for fossil and recent orogens. The methodical part of the work focuses on the task to handle large penetrative deformation observed during orogenies using the commercial FE software package ANSYS® which is based on an updated Lagrangian formulation. Limitations inherited by this approach are overcome by using a remeshing technique. The software package OROTRACK and OROTRACK3D is developed to model orogenic deformation and comprises remeshing, mapping and tracking algorithms. Combined with ANSYS® they are capable of describing total plate convergence up to amounts of several hundreds of kilometers. A surface model inteface allows taking into consideration the effect of erosion on collisional mechanics. Additionally, the models presented in this study are characterized by full thermomechanical coupling, specific material properties describing different crustal layers, and the capability to switch between brittle and ductile material laws depending on current stress and temperature conditions. 2d models represent a vertical section cutting the continental crust of two colliding plates at an orientation perpendicular to the evolving orogen. Based on the mantle subduction approach (Willett et al. 1993) the lithospheric mantle which is not a part of the model itself exerts a basal velocity boundary condition on the crustal scale model. Assuming an asymmetric subduction of the lithospheric mantle of the left plate beneath the right plate’s mantle taper occurring at a point S, the basal FE nodes of the left model half are moved by a horizontal displacement whereas the right part basal nodes are fixed horizontally. The discontinuity of the basal boundary condition at S typically results in a local high strain area. Published modelling studies with similar boundary conditions frequently are based on the assumption of purely brittle deformation (analog models) or keep the ductile domain small and highly-viscous by low crustal temperatures. Under these conditions, orogenic deformation is highly localized and typically shows a bivergent pattern rooting in S and forming the boundary of a central pop-up structure. In contrast, a number of model runs performed without applying the remeshing option demonstrates that raised crustal temperatures result in a decoupling layer at the base of the crust, a widened and indistinct zone of mid to upper crustal deformation, and, subsequently, in only small amounts of crustal thickening. Variations of convergence rates show a similar effect on strain localization which is caused by the strain rate dependence of power law creep and variable degrees of thermal reequilibration in the thickened domain. Improved models with remeshing technique are evaluated during parameter variations quantifying the influence of different temperature-viscosity functions on strain localization and the resulting syncollisional exhumation of metamorphic rocks. It is shown that a rheological behaviour which promotes efficient mechanical coupling all over the crustal profile is a requirement not only for localized crustal thickening but also for rapid exhumation of lower crustal rocks by an interaction of isostatic forces and surface erosion. Exhumation becomes most powerful when a relatively low-viscous upper crust is combined with a relatively stiff lower crust. In detail, systematic variations of the burial and exhumation history of different marker points along the model section can be illustrated by synthetic PTt data. The correlation between crustal temperatures, orogenic strain localization and syncollisional exhumation is of great importance for the late collisional events in the Variscan orogeny in Central Europe. There, high temperature/ low pressure metamorphism and widespread granitoid intrusions document high crustal temperatures. On the other hand, localized bivergent orogenic structures mark the boundaries between the tectonometamorphic units at the region of Schwarzwald and Vosges as well as the Mid German Crystalline Rise (Mitteldeutsche Kristallinschwelle, MDKS). Strain localization and synconvergent exhumation of amphibolite grade metamorphic rocks in these areas can be only explained by assuming a lower crustal rheology much stiffer than previously estimated. Creep parameters determined in recent laboratory studies (Mackwell et al. 1998) are capable of supporting rheologies of that kind and are applied in a case study focusing on the MDKS. Under these assumptions, metamorphic peak pressures and temperatures from the Rhenohercynian fold and thrust belt, the MDKS itself, and the Saxothuringian basin as well as the main structural pattern derived from the reflection seismic profiles DEKORP 2N and 2S are well reproduced by the numerical model. An expansion of the modelling technique to 3d FE models aims at taking orogen-parallel deformation into consideration which can result in prominent transport of rocks towards the lateral foreland areas of collisional belts; these processes have been described as tectonic escape (Burke & Sengör 1986) or lateral extrusion (Ratschbacher et al. 1991b). Given the assumption of orthogonal convergence, the 2d mantle subduction model is extruded in orogen-parallel direction to build a three-dimensional crustal block (marginal area of the collision zone). In the adjacent rear part of the model (lateral foreland of the collison zone), basal nodes are no longer object of the velocity boundary condition or fixation, respectively. The model margins obey a no-tilt-requirement preventing differential horizontal displacements of nodes initially on top of each other. Depending on the geodynamic scenario characterizing the marginal area, further boundary conditions like plate boundary forces or rigid buttresses can be defined. A set of model runs is used to gain quantitative insight into the effect of different parameters and boundary conditions on the resulting kinematic pattern, the spatial distribution of strain as well as temporal variations of the surface stress field. According to the modelling results, lateral extrusion is a common process in the marginal area of orogenic belts since it is present in all modelled scenarios. As lateral motions start contemporaneously with the onset of collision and are only slightly accelerated during further convergence, tectonic escape driven by horizontal forces seems to be a more powerful process than gravitational spreading. Rigid model margins surrounding parts of the lateral foreland modify the amount as well as the distribution of horizontal motions but their effect on the orogen itself is rather small. Variations in crustal temperatures, convergence rates, and lower crustal rheology effect both orogenic and lateral foreland deformation. Assuming an isotropic coupling mechanism between the crust and the lithospheric mantle, extrusion rates no higher than 30% of the current convergence rate can be modelled. As much as 70% are reached when the model base is allowed to move laterally. The significance of this basal boundary condition allows to interpret the Miocene lateral extrusion event in the Eastern Alps (z.B. Ratschbacher et al. 1991a). If there was no mountaineous topography in the Eastern Alps area before the onset of lateral movements (Frisch et al. 1998), the lateral extrusion was contemporaneous with prominent crustal thickening and should be induced rather by tectonic escape than by gravitational collapse. In each case, the almost 1:1 ratio of convergence vs. lateral extrusion implies the existence of a basal decoupling horizon. Other proposed causes like the indentation of the Southern Alps or an extensive regime in the Pannonian basin could have modified the resulting structural pattern but fail to explain the dimension of lateral motions by a factor of 2. Due to the large scale of the Indian-Eurasian collision, modelling results can only be compared phenomenologically with tectonic escape in Eastern Asia. A scaled case study therefore remains a great challenge for future FE modelling.

Thesis (M.S.)--State University of New York at Binghamton, Department of Mechanical Engineering, 2005. / Includes bibliographical references (p. 78-80).

Micro-motion devices may share a common architecture such that they have a main body of compliant material and some direct actuation elements (e.g., piezoelectric element). The shape of such a compliant material is designed with notches and holes on it, and in this way one portion of the material deforms significantly with respect to other portions of the material a motion in the conventional sense of the rigid body mechanism. The devices of this kind are called compliant mechanisms. Computer tools for the kinematical and dynamic motion analysis of the compliant mechanism are not well-developed. In this thesis a study is presented towards a finite element approach to the motion analysis of compliant mechanisms. This approach makes it possible to compute the kinematical motion of the compliant mechanism within which the piezoelectric actuation element is embedded, as opposed to those existing approaches where the piezoelectric actuation element is either ignored or overly simplified. Further, the developed approach allows computing the global stiffness and the natural frequency of the compliant mechanism. This thesis also presents a prototype compliant mechanism and a test bed for measuring various behaviors of the prototype mechanism. It is shown that the developed approach can improve the prediction of motions of the compliant mechanism with respect to the existing approaches based on a comparison of the measured result (on the prototype) and the simulated result. The approach to computation of the global stiffness and the natural frequency of the compliant mechanism is validated by comparing it with other known approaches for some simple mechanisms.

The world we are living in today is pushing the technology harder and harder. The products need to get better and today they also need to be friendlier to the environment. To get better products we need better analysis tools to optimize them and to get closer to the limit what the material can withstand. Siemens industrial Turbomachinery AB, at which thesis work is made, is constructing gas and steam turbines. Gas and steam turbines are important in producing power and electricity. Electricity is our most important invention we have and most of the people are just taking electricity for granted. One way to produce electricity is to use a gas turbine which is connected to a generator and by combing the turbine with a steam turbine the efficiency can be up to 60 %. That is not good enough and everybody want to get better efficiency for the turbines, meaning less fuel consumption and less impact on the environment. The purpose of this thesis work is to analyze a tool for rotor dynamics calculations. Rotor dynamics is important in designing a gas turbine rotor because bad dynamics can easily lead to disaster. Ansys Classic version 11 is the analyze program that is going to be evaluated for the rotor dynamic applications. Nowadays rotor dynamics is done with beam elements i.e. 1D models, but in this thesis work the beam elementsare going to be changed to solid elements. With solid elements a 3D model can be built and thanks to that more complex calculations and simulations can be made. For example, with a 3D model 3D effects can be shown and e.g. simulations with blade loss can be done. 3D effects are not any problem today but in the future the gas turbines have to get better and maybe also the rotational speed will increase. Ansys isn’t working perfectly yet, there are some problems. However Ansys have a good potential to be an additional tool for calculations of rotor dynamics, because more complex calculations and simulations can be done. More knowledge and time needs to form the rules to modeled a rotor and developing the analysis methods. Today the calculated lateral critical speeds are lower than the ones obtained from the in-house program Ardas version 2.9.3 which is used in Siemens Industrial Turbomachinery AB today. The difference between the programs are not so big for the four first lateral modes, only 3-8 %, but the next three lateral modes have a difference of 10-20 %. The torsion frequencies from Ansys are the same as the ones from Ardas, when the Solid186 elements are used to model the blades.

Micro-motion devices may share a common architecture such that they have a main body of compliant material and some direct actuation elements (e.g., piezoelectric element). The shape of such a compliant material is designed with notches and holes on it, and in this way one portion of the material deforms significantly with respect to other portions of the material a motion in the conventional sense of the rigid body mechanism. The devices of this kind are called compliant mechanisms. Computer tools for the kinematical and dynamic motion analysis of the compliant mechanism are not well-developed. In this thesis a study is presented towards a finite element approach to the motion analysis of compliant mechanisms. This approach makes it possible to compute the kinematical motion of the compliant mechanism within which the piezoelectric actuation element is embedded, as opposed to those existing approaches where the piezoelectric actuation element is either ignored or overly simplified. Further, the developed approach allows computing the global stiffness and the natural frequency of the compliant mechanism. This thesis also presents a prototype compliant mechanism and a test bed for measuring various behaviors of the prototype mechanism. It is shown that the developed approach can improve the prediction of motions of the compliant mechanism with respect to the existing approaches based on a comparison of the measured result (on the prototype) and the simulated result. The approach to computation of the global stiffness and the natural frequency of the compliant mechanism is validated by comparing it with other known approaches for some simple mechanisms.

The aim of this thesis is to investigate Ti/APC-2 nanocomposite laminates mechanical properties after low velocity impact. The finite element analysis with software ANSYS/LS-DYNA is used to analyze the size of damage and plastic zone and internal energy of laminates during low velocity impact. Finally, the numerical results and experimental data are in good agreement. The work can be divided into two parts: the first is to fabricate the hybrid composite laminates and place the samples on the floor, subjected to the free drop of a rigid steel ball of 1m and 2m high. Then, the samples after impact were due to static tensile and fatigue tests to obtain mechanical properties. Using the optical microscopy the impact defects of laminate surface were measured. The second, ANSYS/LS-DYNA was used to simulate a laminate impacted by a steel ball. The energy change of steel ball impact and internal energy of laminates during impact were also discussed. From the experimental data, the mechanical properties, such as ultimate strength and stiffness, of virgin samples are better than those of impacted samples due to free drop. In addition, no matter the laminates were added nanoparticles SiO2 or not, the strength of laminates reduces after impact, however, the fatigue resistance of impacted samples does not lose much. Compare with the data of penetration depth and plastic zone due to free drop. The errors of numerical results are 5.4%~12.4% for the penetration depth and the errors 5.21%~8.98% for plastic zone respectively. That is acceptable. The numerical method ology provides a reference to realize the energy change in laminates after impact. Also, from the experimental measurement it is obvious to see damage area after impact and the mechanical properties do not reduce significantly due to low velocity impact generally in Ti/APC-2 composite laminates.

Abstract The thesis is aimed to analyze the flip chip in chip scale package (CSP) by finite element method incorporated with software ANSYS due to thermally cyclic loading. The coefficient of thermal expansion (CTE) of underfill and different mechanical properties of four kinds underfill-A, B, C, D and with/without metal cap are considered as parameters. The effects of above-mentioned parameters on package¡¦s displacement, strain and stress fields are studied. The results show that the maximum equivalent strain and stress take place at the interface between chip and underfill far away from the center of the whole package and on the top of the most outside solder bump in the solder joint. The larger the CTE of underfill is, the larger the maximum equivalent strain and stress are. Package with metal cap can reduce the displacement to almost half or more of that without cap, but increase the values of maximum equivalent strain and stress. No matter with metal cap or not, the underfill D is the best choice. Hence, the underfill material properties possess lower CTE and larger Young¡¦s modulus than those of solder bump.