Die Anwendung des Verfahrens der inversen Parameteridentifikation auf die Nanoindentation mit einer neuen Materialklasse (amorphe Legierungen) ist Hauptgegenstand der vorliegenden Arbeit. Um die Methode auf ihre Zuverlässigkeit hin zu überprüfen, werden darüber hinaus die drei Härtevergleichsplatten HV240, HV400 und HV720 sowie das oxidische Glas BK7, deren Nanoindentationsmessungen von Dipl.-Ing. André Clausner schon zu einem früheren Zeitpunkt vorgenommen wurden, zur Berechnung herangezogen. Die Auswahl der Materialien erfolgte so, dass diese einen möglichst großen Bereich von Y abdecken, von BK7 bis hin zu HV240. Damit soll gezeigt werden, dass das Verfahren der inversen Parameteridentifikation für einen großen Bereich von natürlich vorkommenden Materialien genutzt werden kann. Der Schwerpunkt liegt dabei auf der Bestimmung des Fließverhaltens, das durch die Parameter Fließgrenze1 Y und Verfestigungsexponent n erfolgt. Ziel ist es, in Zukunft auf weitere Experimente, die bisher zur Bestimmung der mechanischen Materialeigenschaften genutzt wurden und häufig zur Zerstörung der Proben führten, verzichten zu können. Für viele Gläser, z.B. BK7, sind derartige zerstörende Versuche nicht anwendbar, weil spröde Materialien splittern statt plastisch zu fließen. Dieser Arbeit liegt die Methode der Finiten-Elemente zugrunde, um eine inverse Parameteridentifikation zu realisieren. Sie wird hier eingesetzt, weil es sich bei plastischer Verformung um einen nichtlinearen Prozess2 handelt, der analytisch nicht mehr geschlossen gelöst werden kann. Die Simulationssoftware ANSYS R und ein Optimierungsmodul (SPC-OPT) der Fakultät für Maschinenbau dienen zur Berechnung. Bei der Simulation werden dabei ein zweidimensionales Modell und ein realitätsnahes dreidimensionales Modell eingesetzt.

In einer Einleitung werden verschiedene Möglichkeiten der Kopplung unterschiedlicher physikalischer Domänen diskutiert. Begriffe wie Kopplung auf Systemebene über Terminals und auf Feldebene über Lastvektor oder Matrixkopplung werden zugeordnet. Wie diese Kopplungsmöglichkeiten sich in der ANSYS Simulationsumgebung wiederfinden, wird aufgezeigt. Am Beispiel eines Akuators wird erläutert, welche physikalischen Domänen gekoppelt betrachtet werden müssen, um die hier vorhandenen temperaturabhängigen Materialeigenschaften zu berücksichtigen. In einem Beispiel zu einer Steckverbindung wird aufgezeigt, wie eine vom Kontaktdruck abhängige Leitfähigkeit berücksichtigt wird und Ergebnisse aus dieser Simulation werden diskutiert.

Neuartige funktionsbedingte Bauteilgeometrien in geringen Stückzahlen lassen sich mit verschiedenen Methoden der additiv, generativen Fertigung, populärwissenschaftlich 3D- Druck genannt, effizient herstellen. Für den Konstrukteur solcher Bauteile bedeutet dies ebenfalls neuartige Methoden als bisher anzuwenden. Bauteilgeometrien, die hinsichtlich einer Zielgröße optimiert sind, können mit der Topologieoptimierung auf Basis eines FE- Modells rechnerisch ermittelt werden. Während die Topologieoptimierung schon seit längerem bekannt und etabliert ist, war die durchgängige Nutzung einer gemeinsamen Datenbasis häufig durch Hindernisse geprägt. Im vorliegenden Artikel werden die heutigen Möglichkeiten anhand des FE-Systems ANSYS aufgezeigt und hinsichtlich des effizienten praktischen Einsatzes bewertet. / Innovative function-related component geometries in small quantities can be produced efficiently with different methods of additive, generative manufacturing, in a popular science known as 3D printing. For the designer of such components it also means to use other methods as usual. Component geometries optimized regarding to a target size can be calculated using topology optimization based on a FE model. While topology optimization has been known and established for a long time, the consistent use of a common database was often characterized by obstacles. In this article today's possibilities are shown with the FE system ANSYS and evaluated with regard of the efficient practical use.

In einer Einleitung werden verschiedene Möglichkeiten der Kopplung unterschiedlicher physikalischer Domänen diskutiert. Begriffe wie Kopplung auf Systemebene über Terminals und auf Feldebene über Lastvektor oder Matrixkopplung werden zugeordnet. Wie diese Kopplungsmöglichkeiten sich in der ANSYS Simulationsumgebung wiederfinden, wird aufgezeigt. Am Beispiel eines Akuators wird erläutert, welche physikalischen Domänen gekoppelt betrachtet werden müssen, um die hier vorhandenen temperaturabhängigen Materialeigenschaften zu berücksichtigen. In einem Beispiel zu einer Steckverbindung wird aufgezeigt, wie eine vom Kontaktdruck abhängige Leitfähigkeit berücksichtigt wird und Ergebnisse aus dieser Simulation werden diskutiert.

Der mit flüssigem Natrium gefüllte Druckbehälter eines Präzessionsexperimentes unterliegt im Betrieb einer Vielzahl an Belastungen. Neben den aus der Rotation und Präzession resultierenden Fliehkräften und dem gyroskopischen Moment müssen ebenfalls die fertigungsbedingten Unwuchten sowie die Fluid-Struktur-Interaktion berücksichtigt werden. Darüber hinaus stellen die bei der Erwärmung bzw. Abkühlung auftretenden thermischen Spannungen eine wesentliche Beanspruchung dar. Es wird ein Algorithmus vorgestellt, der es ermöglicht, alle diese transienten und winkelabhängigen Lasten bei minimalem Rechenaufwand in den Berechnungsprozess einzubeziehen und die für den statischen und zyklischen Festigkeitsnachweis nach FKM-Richtlinie maßgeblichen Beanspruchungen zu identifizieren. Dies ermöglicht die vollflächige Berechnung des Auslastungsgrades in ANSYS Workbench.

Aufgrund von steigenden Energiekosten und einer sukzessive steigenden öffentlichen sowie politischen Forderung nach Umweltbewusstsein und Nachhaltigkeit, ist die Effizienzsteigerung von Gesamtsystemen einer der treibenden Kräfte für innovative, technologische Neuheiten geworden. Besonders bei der Entwicklung von verbrennungsmotorisch angetriebenen Fahrzeugen wurden z.B. durch die Hybridisierung von Antriebssträngen, die die Rekuperation von kinetischer Energie ermöglichen, Technologien zur Energieeinsparung etabliert. Da bei Verbrennungsmotoren ein hoher Anteil der im Kraftstoff gespeicherten Energie technologiebedingt als Abwärme im Abgas verloren geht, bietet die Wärmerekuperation ein weiteres hohes Potential für weitere Einsparungen. Diese ist z.B. mit Hilfe von thermoelektrischen Generatoren (TEG) möglich, die einen Wärmestrom direkt in elektrische Energie umwandeln. Zur effizienten TEG-Systemgestaltung ist ein hoher Temperaturgradient über dem thermoelektrisch aktivem Material notwendig, der wiederum zu kritischen thermomechanischen Spannungen im Bauteil führen kann. Diese werden zum einen durch die unterschiedlichen Temperaturausdehnungskoeffizienten der verschiedenen Materialien und zum anderen durch die mechanische Anbindung auf der heißen und kalten Seite des TEG verursacht. Somit liegt ein Zielkonflikt zwischen dem thermoelektrischen Systemwirkungsgrad und der mechanischen Festigkeit des Bauteils vor. In dieser Arbeit wird mit Hilfe einer mehrkriteriellen Parameteroptimierung eines vollparametrisierten FE-Modells des TEG in ANSYS WORKBENCH eine Methode vorgestellt, den thermoelektrischen Wirkungsgrad bei gleichzeitiger Reduktion der thermomechanischen Spannungen zu optimieren. Zur Optimierung kommt dabei ein genetischer Algorithmus der MATLAB GLOBAL OPTIMIZATION TOOLBOX zum Einsatz. Der Modellaufbau wird in ANSYS WORKBENCH mit der Makro-Programmiersprache JSCRIPT realisiert. Als Ziel- und Bewertungsfunktionen wird die mechanische Belastung jedes Bauteils im TEG ausgewertet und dessen elektrische Leistungsdichte berechnet. Die Ergebnisse zeigen, dass mit Hilfe der vorgestellten Methodik eine paretooptimale Lösung gefunden werden kann, die den gestellten Anforderungen entspricht.

To avoid the large amount of damage that floods can cause, spillway tunnels are used to control water levels. To ensure the safety of water transportation through spillway tunnels, the behaviour of the water throughout the tunnel is important to know. Physical experiments are time consuming and expensive, hence CFD simulations are a profitable option for investigating the performance of the spillway tunnel. In this project, simulations of water flow in a spillway tunnel were executed. A three dimensional model of the spillway tunnel in Zipingpu Water Conservancy Project was created in the software ANSYS Gambit. A coarse, middle and fine mesh with both hexahedral- and tetrahedral elements were also created for the model in ANSYS Gambit. The meshes were imported to ANSYS Fluent where the simulations, and a convergence analysis were made. The water flow was set to be described by the Reynolds-Averaged Navier-Stokes model, using the pressure solver, k-epsilon model and the VOF model. Physical experiments had previously been performed, and the simulated results were compared to these, in an attempt to find the parameters to replicate the experimental results to the greatest extent possible. The inlet velocity of the tunnel was known and the inlet boundary was set as a velocity inlet. The ceiling of the tunnel was set as a pressure inlet, the floor and walls were set as wall, and the outlet was set as pressure outlet. The simulated results showed similar behavior as the experimental results, but all differed from the experimental results. The grid convergence index, estimating the results' dependency on the mesh was 6.044 %. The flow was analyzed, and where the flow had unfavorable characteristics, such as a high cavitation number, the geometry of the spillway was altered in ANSYS Gambit to investigate if an improved geometry for the spillway tunnel could be found. The water flow in the revised geometry was simulated in ANSYS Fluent, and results showing flow with lower cavitation numbers was found.

Submitted by JOSIANE SANTOS DE OLIVEIRA (josianeso) on 2018-04-25T13:02:31Z No. of bitstreams: 1 Rodrigo Comin_.pdf: 9770505 bytes, checksum: 7fab41aa9f91c2809d6d8bc966015c61 (MD5) / Made available in DSpace on 2018-04-25T13:02:32Z (GMT). No. of bitstreams: 1 Rodrigo Comin_.pdf: 9770505 bytes, checksum: 7fab41aa9f91c2809d6d8bc966015c61 (MD5) Previous issue date: 2017-09-29 / Nenhuma / O setor automotivo nacional, no segmento de fabricação de carrocerias para ônibus, vem buscando melhorar a qualidade de produção de seus veículos, visando atender as exigências do mercado interno e externo, por meio de especificações de projetos eletrônicos seguindo normas internacionais. Neste contexto, as normas de compatibilidade eletromagnética destacam-se, pois, possuem um papel importante para garantir que os equipamentos possam operar de forma segura, sem gerar ou sofrer interferências. Este trabalho tem como objetivo desenvolver uma metodologia para projetar produtos eletrônicos que necessitam atender normas de compatibilidade eletromagnética, por meio de estudos de técnicas de emissões radiadas e conduzidas, e uso de ferramentas computacionais para simulação da placa de circuito impresso. A partir deste estudo, pode-se diminuir investimentos com laboratórios de testes, tempo de desenvolvimento e disponibilizar produtos ao mercado de forma mais eficiente. O uso de técnicas apropriadas e boas práticas em projetos são meios adequados para atender requisitos de normas, porém a evolução das tecnologias e adição de mais circuitos em áreas menores torna necessário avançar nos conhecimentos. Assim, deve-se compreender de forma detalhada as técnicas para emissões de modo comum e diferencial, desenvolver simulações que possam prever resultados em testes de laboratórios e propor alterações em projeto mecânico ou eletrônico que atendam os limites determinados em normas. / The national automotive division, more precisely in the bus manufacturing segment, efforts are being deposited to improve the manufacturing quality of its vehicles in order to meet the requirements of the internal and external market through electronic projects based on international standards. Furthermore, the electromagnetic compatibility standards stand out because they have a major importance ensuring that electronic devices are able to provide safety to its users, without interfering or being interfered by other devices. The objective of this research is to develop a methodology to design electronic devices which must meet the standards requirements of electromagnetic compatibility. This goal is achieved through the study of radiated and conducted emissions techniques, and using computational tools for simulation of printed circuit boards. From this study it will be possible to reduce costs with laboratory tests, reduce the time required for development, and provide products to the customers in an efficient way. The use of appropriated techniques and good practices during the designs process are the proper way to meet standards and requirements. However, with the evolution of technology and addition of more electronic circuits in smaller areas requires to acquire more knowledge and go deeper in this study. Thus, it is necessary to understand in details the common mode and differential emissions technics, develop simulations which can provide a preview of what the laboratory tests may result, and propose changes in the mechanic and electronic project design in order to meet the limits of the requirements determined in the standards.

Accident conditions involving significant core degradation are termed severe accidents /IAEA: NS-G-2.15/. Despite the low probability of occurrence of such events, the investigation of severe accident scenarios is an important part of the nuclear safety research. Considering a hypothetical core melt down scenario in a VVER-1000 light water reactor, the early in-vessel phase focusing on the thermal-hydraulic phenomena, and the late in-vessel phase focusing on the melt relocation into the reactor pressure vessel (RPV) lower head, are investigated. The objective of this work is the assessment of severe accident management procedures for VVER-1000 reactors, i.e. the estimation of the maximum period of time available for taking appropriate measures and particular decisions by the plant personnel. During high pressure severe accident sequences it is of prime importance to depressurize the primary circuit in order to allow for effective injection from the emergency core cooling systems and to avoid reactor pressure vessel failure at high pressure that could cause direct containment heating and subsequent challenge to the containment structure. Therefore different accident management measures were investigated for the in-vessel phase of a hypothetical station blackout accident using the severe accident code ASTEC, the mechanistic code ATHLET and the multi-purpose code system ANSYS. The analyses performed on the PHEBUS ISP-46 experiment, as well as simulations of small break loss of coolant accident and station blackout scenarios were used to contribute to the validation and improvement of the integral severe accident code ASTEC. Investigations on the applicability and the effectiveness of accident management procedures in the preventive domain, as well as detailed analyses on the thermal-hydraulic phenomena during the early in-vessel phase of a station blackout accident have been performed with the mechanistic code ATHLET. The results of the simulations show, that the effectiveness of the procedures strongly depends on the ability of the passive safety systems to inject as much water as possible into the reactor coolant system. The results on the early in-vessel phase have shown potentially delayed RPV failure by depressurization of the primary side, as slowing the core damage gives more time and different possibilities for operator interventions to recover systems and to mitigate or terminate the accident. The ANSYS model for the description of the molten pool behaviour in the RPV lower plenum has been extended by a model considering a stratified molten pool configuration. Two different pool configurations were analysed: homogeneous and segregated. The possible failure modes of the RPV and the time to failure were investigated to assess the possible loadings on the containment. The main treated issues are: the temperature field within the corium pool and the RPV and the structure-mechanical behaviour of the vessel wall. The results of the ASTEC calculations of the melt pool configuration were applied as initial conditions for the ANSYS simulations, allowing a more detailed and more accurate modelling of the thermal and mechanical behaviour of the core melt and the RPV wall. Moreover, for the late in-vessel phase, retention of the corium in the RPV was investigated presuming external cooling of the vessel wall as mitigative severe accident management measure. The study was based on the finite element computer code ANSYS. The highest thermomechanical loads are observed in the transition zone between the elliptical and the vertical vessel wall for homogeneous pool and in the vertical part of the vessel wall, which is in contact with the molten metal in case of sub-oxidized pool. Assuming external flooding will retain the corium within the RPV. Without flooding, the vessel wall will fail, as the necessary temperature for a balanced heat release from the external surface via radiation is near to or above the melting point of the steel.

[pt] Otimização estrutural sujeita a carregamentos dinâmicos é um problema desafiador em vários aspectos, a começar pelo grande número de restrições que devem ser atendidas em todos os instantes de tempo. Além disso, o custo computacional para avaliar os gradientes destas restrições é bastante elevado e requer um grande espaço de armazenamento. Na literatura, alguns métodos reduzem o número de restrições avaliando em instantes de tempo selecionados, como o pior caso por exemplo, ou ainda constroem um funcional equivalente, integrando as restrições violadas ao longo do tempo, assim eliminando essa dependência. Nesta dissertação, o método do Carregamento Estático Equivalente (ESL) é utilizado, no qual o problema dinâmico original é transformado em uma sequência de subproblemas de otimização linear estática com múltiplos casos de carga. Um atrativo deste método é a possibilidade da solução de problemas não lineares, evitando o alto custo devido às repetidas análises estruturais e cálculos das restrições. Problemas clássicos de treliças planas submetidas a carregamentos dinâmicos são resolvidos utilizando o método ESL. A função a ser minimizada é a massa da treliça, que está sob restrições de tensão e deslocamento, onde as variáveis de projeto são as áreas da seção transversal dos membros. Além disso, uma interface utilizando ANSYS e MATLAB é desenvolvida para uma abordagem modular, na qual a análise via elementos finitos e a otimização possam ser realizadas separadamente. Este processo viabiliza a otimização de estruturas que apresentam comportamentos não lineares a partir da utilização de diversos softwares comerciais disponíveis no mercado. / [en] Structural optimization subject to dynamic loading is a challenging problem in many aspects, starting with the large number of constraints that must be respected at all instants of time. Furthermore, the computational cost to evaluate the gradients of these constraints is significantly high and requires a large storage space. In the literature, some methods reduce the number of constraints evaluating at selected instants of time, such as the worst case. Alternatively, a single equivalent functional is constructed to eliminate the time dependence by integrating the violated constraints over time. In this work, the Equivalent Static Load (ESL) method is used, in which the original dynamic problem is reduced into a number of static linear optimization problems with multiple load cases. An attractive feature of this method is the possibility of solving non-linear problems, avoiding the high cost due to repeated structural analyzes and constraint calculations. Classical problems of plane trusses subjected to dynamic loads are solved using the ESL method. The function to be minimized is the truss mass, which is subjected to stress and displacement constraints, where the design variables are the cross-sectional areas of the members. In addition, an interface using ANSYS and MATLAB was developed for a modular approach, in which finite element analysis and optimization can be performed separately. This process makes possible the optimization of structures that present non-linear behavior from the use of most structural analysis software packages available on the market.