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Viszlay, Viliam. "Ohýbaná tělesa: Numerická podpora v software ANSYS." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2016. http://www.nusl.cz/ntk/nusl-240183.
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The aim of the thesis is the investigation of fracture-mechanics parameters on specimens made of quasi-brittle materials. The principles of two-parameter fracture mechanics are used. Couple of numerical simulations were done and their outputs are used for two main analysed specimen geometries. For simulations the finite element method software ANSYS is used. In the first part, the thesis focuses on bended specimens. The influence of different geometric parameters on fracture mechanics behaviour of cracked specimen is investigated. For model calibration the outputs of other authors are used. In the second part the specimens for modified compact-tension test (CT test) are analysed. Similar to the first part, the influence of geometric parameters of the specimen (in this case, the specimen size) on fracture mechanics parameters were investigated. The modified CT test was derived from CT test which is commonly used for metal materials testing as the suitable geometry for cement-based composite materials testing. The outputs of both parts are calibration polynomials, which are expressions obtained for different specimen geometries, giving the value of fracture mechanics parameter as the function of specimen geometry. As the example, calibration curves are used to obtain fracture toughness of tested material using the outputs from recent experiment.
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Maia, Filipe Martim Esteves. "Análise paramétrica e optimização estrutural utilizando o software comercial ANSYS." Master's thesis, FCT-UNL, 2011. http://hdl.handle.net/10362/6679.
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Rinaldi, Elisa. "3D Finite Element Analysis of Wheel/Rail normal contact problem using ANSYS software." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018.
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La meccanica del contatto fra ruota ferroviaria e rotaia, è una delle più importanti aree di studio nell’Ingegneria Ferroviaria. Ad oggi, un vasto numero di formulazioni analitiche sono state proposte dai ricercatori, con lo scopo di valutare i parametri di contatto tra ruota e rotaia ed arrivare ad una descrizione affidabile delle forze che agiscono nell’area di contatto. Comunque, solo alcuni dei metodi disponibili permettono di considerare, nelle loro elaborazioni, la reale geometria di contatto tra ruota e rotaia o la non linearità delle proprietà dei materiali impiegati. Un’alternativa ai metodi analitici per descrivere la fisica del contatto tra ruota e rotaia e di fare uso di tecniche computazionali numeriche quale l’Analisi agli Elementi Finiti (FEA – Finite Element Analysis). Il vantaggio di questo metodo è dato dalla possibilità di poter modellare complesse geometrie che permettono di simulare più accuratamente il contatto tra ruota e rotaia e determinare l’ampiezza degli stress e la loro distribuzione, oltre alla dimensione e forma dell’area di contatto.
Per questa ragione, un modello agli Elementi Finiti tridimensionale della ruota ferroviaria e della rotaia è stato creato utilizzando Ansys Parametric Design Language di ANSYS per studiare il problema di contatto normale. Per verificare l’accuratezza dei risultati forniti dal modello, questo è stato validato in confronto alla teoria di Hertz sul contatto elastico. Questa teoria rappresenta la base sulla quale la maggior parte dei modelli computazionali vengono sviluppati.
Il principali scopi di questa tesi sono quindi di studiare i problemi del contatto tra ruota e rotaia e di valutare l’influenza dei parametri operativi quali il coefficiente di frizione, lo spostamento laterale della sala montata e l’inclinazione della rotaia sul piano orizzontale, sulla fisica del contatto.
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Alarcon, Ayala Igor Carlos. "Customização do software ANSYS para análise de lajes de concreto protendido pelo método dos elementos finitos." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2017. http://hdl.handle.net/10183/163329.
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A necessidade por aprimorar sistemas e materiais na indústria da construção civil derivou no uso da protensão como uma alternativa de reforço para estruturas de concreto. As vantagens técnicas e econômicas encontradas no projeto e execução de estruturas de concreto fizeram com que este sistema venha ganhando preferência frente ao sistema convencional de concreto armado. Nesse contexto, este trabalho visa contribuir desenvolvendo um modelo computacional no software ANSYS, versão 16.0, por meio da ferramenta de customização UPF (User Performance Features), para o estudo de lajes de concreto armado e protendido, com ou sem aderência. A implementação do modelo computacional, baseado no método dos elementos finitos, tem ênfase na não-linearidade física dos materiais através de um modelo elasto-viscoplástico que inclui dois procedimentos de análise: a resposta instantânea da estrutura considera um comportamento elastoplástico e a resposta diferida da estrutura assume um comportamento viscoelástico. A modelagem das lajes é feita a partir da ideia de elementos reforçados, assim, são utilizados elementos finitos de casca de ordem superior SHELL281 como elementos base de concreto. Enquanto que a armadura passiva é modelada com elementos de reforço REINF264, considerando-as como uma linha de material mais rígido com aderência perfeita no interior dos elementos de casca, ou seja, como armadura incorporada. Por sua vez, para modelar a armadura ativa não-aderente utiliza-se elementos finitos unidimensionais LINK180 que funcionam como armadura discreta, a condição de não-aderência é satisfeita pelo comando CP. Destaca-se que a não-linearidade geométrica é inerente nos elementos finitos utilizados e que os mesmos são compatíveis entre si e com a ferramenta de customização UPF. Para validar a eficiência do modelo computacional, comparam-se resultados numéricos com valores experimentais disponíveis na literatura. A comparação dos resultados mostra que os modelos representam corretamente o comportamento das lajes ensaiadas experimentalmente. O baixo custo computacional de tempo, a boa precisão dos resultados e as ferramentas de processamento do ANSYS tornam-no em uma alternativa eficiente.<br>The need for improvement of systems and materials of the construction industry resulted in the use of prestressing as an alternative to reinforce concrete structures. The technical and economic advantages found in the design of concrete structures caused that this system has been gaining preference against the conventional system of reinforced concrete. In this sense, this work aims to contribute developing a computational model in ANSYS software, version 16.0, through the customization tool UPF (User Performance Features), to the study of reinforced and, bonded or unbonded, prestressed concrete slabs. The computational model implementation, based on the finite element method, has emphasis on the physical materials nonlinearity with an elasto-viscoplastic model that includes two analysis procedures: the instantaneous response of the structure considers an elastoplastic behavior and the delayed response of the structure assumes a viscoelastic behavior. The slab models are based in reinforcement elements, thus higher order shell finite elements SHELL281 are used as base elements of concrete. The reinforcement is modeled with reinforcing elements REINF264, as a line of more rigid material with perfect bonding inside the concrete elements, it is, as incorporated reinforcement. On the other hand, the finite elements LINK180 that work as discrete reinforcement are used to simulate prestressing tendons, CP command satisfies the absence of non-adherence. It is noteworthy that the geometrical nonlinearity is inherent to the finite element used and that they are compatible between them and with the customization tool UPF. To validate the computational model efficiency, numerical results are compared with experimental values available in the literature. The results comparison shows that the models represent correctly the behavior of experimentally tested slabs. The low computational cost of time, the good precision of results and the ANSYS processing tools make it an efficient alternative.
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Гудков, Сергій Миколайович, Сергей Николаевич Гудков, Serhii Mykolaiovych Hudkov та И. В. Мазуренко. "Исследование динамики ротора безвального насоса с использованием программного комплекса ANSYS". Thesis, Сумский государственный университет, 2014. http://essuir.sumdu.edu.ua/handle/123456789/40528.
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Осевые силы, действующие на роторы насосов, измеряются десятками тонн. Уравновешивание этих сил достигается с помощью автоматических устройств. Основными элементами систем авторазгрузки ротора являются цилиндрический и торцовый дроссели, разделенные камерой. Проводимости цилиндрического и торцевого дросселя зависят соответственно от радиальных и осевых колебаний
ротора. С этого можно сделать вывод о взаимосвязи радиальных и осевых колебаниях ротора, которую необходимо учитывать на стадии расчета и проектирования уравновешивающих устройств.
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Тесленко, О. С., та А. В. Хоменко. "Комп’ютерна механіка". Thesis, Сумський державний університет, 2015. http://essuir.sumdu.edu.ua/handle/123456789/43363.
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Комп’ютерна механіка – це комп’ютерні технології у всіх напрямках науки і техніки, зокрема в машинобудуванні, тепловій і атомній енергетиці, будівництві та біоінженерії. Особливістю «Комп'ютерної механіки» є те, що вона знайомить студентів з конструкцією, принципами роботи і фізичними процесами тих машин, які в подальшому доведеться створювати та досліджувати за допомогою комп'ютерних технологій.
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Лісовенко, Дмитро Володимирович, Дмитрий Владимирович Лисовенко, Dmytro Volodymyrovych Lisovenko, Андрій Васильович Загорулько, Андрей Васильевич Загорулько та Andrii Vasylovych Zahorulko. "Экспериментальное исследование торцовых затворных импульсных уплотнений". Thesis, Сумский государственный университет, 2014. http://essuir.sumdu.edu.ua/handle/123456789/40580.
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Гончарова, А. В. "Термогідродинамічний аналіз упорного підшипника зі скребками та охолодженням термонавантаженої зони колодки". Master's thesis, Сумський державний університет, 2018. http://essuir.sumdu.edu.ua/handle/123456789/71739.
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Об'єкт дослідження: упорний підшипник зі скребками та охолодженням термонавантаженої зони колодки.
Методи дослідження: дослідження механізму змащення в упорному колодковому підшипнику, моделювання сектору упорного підшипника за допомогою програмного комплексу ANSYS.
Упopнi пiдшипники кoвзaння являютьcя вaжливими кoмпoнентaми cучacних вiдцентpoвих кoмпpеcopiв тa iнших cилoвих уcтaнoвoк тa викopиcтoвуютьcя для пiдтpимки ocьoвих нaвaнтaжень poтopiв, щo oбеpтaютьcя. В ocтaннi poки бaгaтo дocлiджень cпpямoвaнi нa пiдвищення неcучoї здaтнocтi пiдшипникiв, aле зaпpoпoнoвaних зaхoдiв не зaвжди дocтaтньo, щoб в пoвнiй мipi зaбезпечити неoбхiднi poбoчi хapaктеpиcтики.
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González, Silva Germán. "Metodologia para aplicar LES ao craqueamento catalítico fluido em um reator riser industrial." [s.n.], 2012. http://repositorio.unicamp.br/jspui/handle/REPOSIP/266671.
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Previous issue date: 2012<br>Resumo: O objetivo principal desta tese é propor uma metodologia para aplicar simulação de grandes escalas (LES) em uma unidade de craqueamento catalítico industrial. Para atingir este objetivo, iniciou-se propondo uma metodologia para a construção da malha, sendo uma malha quase-uniforme. As malhas propostas foram implementadas para minimizar o esforço computacional e procedimento para a refinação uniforme no domínio do sistema. Inicialmente, foi estudada a fluidodinâmica de um leito fluidizado gás-sólido na escala de laboratório sem reação química, utilizando Simulação de Grandes Escalas. Com base nos resultados numéricos obtidos a partir de resultados da escala de laboratório foi aplicado o modelo cinético de 4 lump em uma simulação CFD tridimensional para um reator industrial FCC, utilizando LES para a fase gasosa, e considerando o catalisador como uma fase contínua (Euleriana). Os pacotes de simulação utilizados foram Ansys ICEM versão 13 para a construção da malha e Ansys CFX versão 13 para o pós-processamento dos resultados. No pós-processamento dos resultados foi proposta uma metodologia para determinar as médias azimutais das variáveis em planos perpendiculares ao escoamento e finalmente foram validadas as simulações com dados reportados na literatura. As principais conclusões do trabalho foram que foi possível diminuir o tamanho da malha e o tempo de processamento. Notou-se também que, ao usar malhas com discretização quase-uniforme não foi necessário fazer um refinamento de malha elevado, nem refinar perto da parede para o sistema gás-sólido<br>Abstract: The main objective of this thesis is to propose a methodology in how to apply Large Eddy Simulation (LES) on a unit of catalytic cracking. In order to achieve this, it was proposed an alternative way of constructing the computational mesh, by using quasi-uniform meshes. The proposed meshes were implemented to minimize the computational effort and procedure for refining them in the entire domain of the system. Initially it was studied the fluid dynamics of a lab scale gas-solid system without chemical reaction, using Large Eddy Simulation. Based on the numerical results obtained from lab scale results it was implemented the 4 lump kinetic model in a three dimensional CFD simulation of an FCC industrial reactor, using LES for the gas phase and considering the catalyst as a continuous phase (Eulerian). The simulation packages used were Ansys ICEM, version 13 for mesh construction and Ansys CFX 13 for computation and post-processing of the results. In the data post-processing it was proposed a methodology for calculating average values of fluctuating variables between two circular sections in the azimuthal direction. The results were compared with data reported in literature. The main conclusions of the results showed that it was possible to decrease the mesh size and the computational time. It was also noticed that by using quasi-uniform discretization it was not necessary to make a high mesh refinement near the wall for a gas-solid system<br>Doutorado<br>Desenvolvimento de Processos Químicos<br>Doutor em Engenharia Química
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Pavan, Kumar Maareddygari Pavan Kumar, and Bharadwaj Yellambalse Prem Kumar Anoop Anoop. "Design and Construction of Chassis for Uniti L7e Vehicle." Thesis, Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-32946.
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Chassis is the primary structural component of an automobile. It is the main supporting structure of a vehicle to which all other systems like braking, suspension and differential are attached. In this thesis, a methodology for L7e category vehicle chassis design and structural stability analysis is presented. The present car being developed at Uniti Sweden AB is classified as L7e category vehicle as per the European Union, therefore the chassis developed in this thesis considers the specific characteristics that vehicles under this category demands for. A literature study is carried out to review various existing designs of vehicle chassis, latest innovations and advanced materials used to manufacture the same. The various types of forces and stresses commonly acting on chassis structures are analyzed and their effects on the vehicle is understood. After completing literature study, several findings are listed in a systematic manner, by providing ample arguments to justify each of them. The pro-con analysis is conducted to evaluate merits and demerits of each alternative type of chassis and the material to manufacture it. The most essential design criteria are derived from the QFD (Quality function deployment) which then acts as important guidelines during the actual design process. Structural chassis frame is designed as per the design criteria, using the CAD software CATIAV5R19 and the structural stability of the same is tested and analyzed using ANSYS 15.0 software. From the results of these analysis tests the static structural stability of the design is confirmed.
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Karlíková, Adéla. "Modelling of flow and pressure characteristics in the model of the human upper respiratory tract under varying conditions." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2020. http://www.nusl.cz/ntk/nusl-413820.
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Cílem této diplomové práce je vytvořit 3D model horních dýchacích cest podle originálního modelu segmentovaného z CT dat, aplikovat různé podmínky na průtok vzduchu v modelu, a poté hodnotit změnu charakteristik rychlosti a tlaku. Model horních dýchacích cest byl vytvořen v prostředí softwaru ANSYS, který využívá výpočetní dynamiku tekutin, a byly použity Navier-Stokesovy rovnice pro modelování průtoku vzduchu v modelu. Nejprve byl vytvořen jednoduchý 2D model za účelem seznámení se s prostředím ANSYS. Dále byl zkonstruován 3D model horních dýchacích cest a byly modelovány charakteristiky rychlosti a tlaku za různých podmínek. Tyto podmínky zahrnují různé umístění a množství míst pro odběr vzorků v modelu a výběr různých kombinací vstupů. Nakonec byly prezentovány a hodnoceny výsledky spolu s ilustracemi modelů modelovaných za různých podmínek. 3D model lze považovat ze kompromis mezi výpočetní náročností a složitostí modelu a lze jej použít jako základ pro další výzkum.
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Brahmachari, Koushik, of Western Sydney Hawkesbury University, of Science Technology and Agriculture Faculty, and School of Construction and Building Sciences. "Connection and flexural behaviour of steel RHS filled with high strength concrete." THESIS_FTA_CBS_BRAHMACHARI_K.xml, 1997. http://handle.uws.edu.au:8081/1959.7/526.
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Steel hollow section members filled with concrete have been frequently used in recent construction industry as columns and beams and beam-columns because of their superior performance and constructability. Previous research demonstrated that such system has large energy absorption capacity which is critical in the event of an earthquake. By filling steel RHS with concrete, the failure of the steel shell due to local buckling can be delayed and the ductility of the concrete core can be improved as a result of the confinement of the steel shell. This type of composite section may be used in various structures including frames of high rise buildings, bridges, offshore structures, cast-in-situ piles in foundation etc. Design methods for concrete-filled steel tubular sections are recommended in a number of code of practices. Due to the significant differences in the material properties between normal strength concrete and high strength concrete, there is a need to study the behaviour of composite sections with higher strength concretes. The study emphasises ultimate strength, ductility, post-failure strength reserve and interface bond. It also emphasises ductility and post-failure strength of the composite beams due to the brittle behaviour of higher strength concretes when compared to normal strength concrete. Spreadsheet graph were used to present the results such as load versus strains, load versus deflections etc. In this thesis analytical study is presented on the calculation of ultimate moment of resistance of the concrete-filled RHS beams. Among the main considerations of the derivation, the steel portion was assumed either elastic-perfectly plastic or perfectly plastic and concrete carries no strength in the tensile zone. At the interface both full bond and partial bond were assumed for comparison. Efforts were also made to calculate the midspan deflections of the composite beams. Simple analytical expressions derived from this study can be coded to a prgrammable calculator or in a small spreadsheet program for design use. Finite element studies were carried out by using a proprietorship software package ANSYS. In the analysis of concrete-filled, three types of elements with large deformation and nonlinear capabilities were used. A plastic shell element, a solid concrete element with cracking and crushing capabilities, and a nonlinear spring contact element were used to model the steel shell, the concrete core and the interface respectively.<br>Doctor of Philosophy (PhD)
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Альошин, Є. С. "Дослідження струмино-реактивної розширювальної турбомашини за допомогою програмного комплексу". Master's thesis, Сумський державний університет, 2019. http://essuir.sumdu.edu.ua/handle/123456789/76814.
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У роботі виконано моделювання течії газу за допомогою програмного комплексу ANSYS CFХ і дослідження впливу розмірів критичних перерізів підвідного та тягового сопла на параметри ефективності машини (пусковий момент і питомий пусковий момент) струминно-реактивної розширювальної турбомашини. Також було виконано порівняння отриманих результатів з результатами попередніх досліджень і верифікація результатів розрахунків у програмному комплексі ANSYS CFХ. Виконано дослідження параметрів течії газу в проточній частині машини при зміні кута розкриття дифузора. Розглянуті питання охорона праці<br>В работе выполнено моделирование течения газа с помощью программного комплекса ANSYS CFХ и исследования влияния размеров критических сечений подводного и тягового сопла на параметры эффективности машины (пусковой момент и удельный пусковой момент) струйно-реактивной расширительной турбомашины. Также было выполнено сравнение полученных результатов с результатами предыдущих исследований и верификация результатов расчетов в программном комплексе ANSYS CFХ. Выполнены исследования параметров течения газа в проточной части машины при изменении угла раскрытия диффузора. Рассмотрены вопросы охраны труда<br>The gas flow was simulated using the ANSYS CFX software package and the effect of the dimensions of the critical sections of the subsea and traction nozzle on the efficiency parameters of the machine (starting torque and specific starting torque) of a jet-reactive expansion turbomachine was studied. A comparison was also made of the results with the results of previous studies and verification of the calculation results in the ANSYS CFX software package. Investigations were made of the parameters of the gas flow in the flow part of the machine with a change in the opening angle of the diffuser. Occupational safety issues addressed
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Rezende, Rodrigo Alvarenga. "Analise de parametros fisicos e operacionais no fenomeno da cura localizada do processo termolitografico da prototipagem rapida." [s.n.], 2006. http://repositorio.unicamp.br/jspui/handle/REPOSIP/266294.
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Orientador: Rubens Maciel Filho<br>Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica<br>Made available in DSpace on 2018-08-09T08:31:02Z (GMT). No. of bitstreams: 1
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Previous issue date: 2006<br>Resumo: A Prototipagem Rápida consiste na reprodução física de objetos tridimensionais de geometria livre, a partir de um projeto inicial (design), modelado por auxílio de computador. A Prototipagem Rápida é uma tecnologia moderna que une métodos e equipamentos adequados a fim de oferecer, como principais atrativos, alta qualidade e redução de custos de produtos manufaturados. São diversos os métodos existentes e os materiais aplicáveis. Este trabalho apresenta um novo método de fabricação de protótipos, a Termolitografia. Baseada na irradiação de laser de CO2 na região espectral do
infravermelho sobre resinas termossensíveis, a Termolitografia oferece importantes vantagens quando comparada a outros processos, principalmente no que se refere ao estado físico da amostra logo após a irradiação do laser. Este processo apresenta duas grandes vantagens que são a não-contração da amostra após ser curada e a ausência de tratamento
pós-cura. A cura localizada é o fenômeno de confinamento da energia transmitida pelo laser realizando a cura do material somente em uma região desejada. O controle da cura localizada é a chave para o sucesso e para a garantia de protótipos de alta qualidade. Para ajustá-la e otimizá-la, é necessário o domínio de parâmetros físicos do material empregado
e de parâmetros operacionais do laser de CO2. O estudo da combinação dos efeitos, por exemplo, da variação da proporção dos componentes da amostra, da sua temperatura de cura, além de fatores operacionais como a velocidade de varredura, o diâmetro e a potência do feixe laser, é o alvo principal deste trabalho. As simulações facilitam a compreensão de
como cada variável pode interferir na construção do protótipo, e determinam faixas de valores para os parâmetros as quais implicam em melhores resultados no final do processo. O trabalho de seleção destes valores é importante para a futura continuidade de estudo experimental do processo termolitográfico<br>Abstract: Rapid Prototyping consists on a physical replication of three-dimensional objects with free geometry, from an initial design, modeled by computer assistance. Rapid Prototyping is a modern technology that unifies methods and suited equipments in order to offer as main attractive high quality and cost-reduction of manufactured products. There are many
techniques and raw materials applicable. This work presents a new method of prototypes fabrication, the Termolithography. Based on CO2 laser irradiation at the infrared spectral region onto thermosensitive resins, Thermolithography offers important advantages if compared with other processes, mainly those ones respected to the non-contraction effect of
the sample after being cured and the absence of a post cure treatment. The localized cure is the phenomenon of confinement of energy transmitted by laser beam performing the curing only on a desired region at the sample. The control of the localized cure is the key for the success and for the guarantee of high quality prototypes. In order to fit and optimize it, it is
necessary the domain of physical properties of the applied material and the domain of the CO2 laser operational parameters. The study of combination of the involved effects, for instance, the variation of amount of the components in the sample, the cure temperature, beside operational parameters as scanning velocity, the laser beam diameter and power, are the main target of this work. Simulations become easier the comprehension of how each variable can affect during the building of prototype and to determine the best range of values which implicate in better final result of the process. The selection of these values is
very important to the continuity of this work<br>Mestrado<br>Desenvolvimento de Processos Químicos<br>Mestre em Engenharia Química
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Baensch, Brose, Clauss, Dippmann, Mueller, Richter, Riedel, et al. "Mitteilungen des URZ 4/1996." Universitätsbibliothek Chemnitz, 1997. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-199700236.
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Das Campusnetz - neue Strukturen und Funktionen
Neues vom WWW-Server
Umstellung der HOME-Verzeichnisse vom NFS ins AFS
AFS löst NFS ab!
Neue Rechnersysteme - zur allgemeinen Nutzung
Superskalarrechner - Inbetriebnahme und Nutzungsmöglichkeiten
PC-Integration via SAMBA-Server
CD-ROM im Netz
Die Programmpakete MATHEMATICA und ANSYS
Ueberblick ueber /uni/global-Software
Ein weihnachtliches Problem?
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SILVA, Akleino Silvestre da. "Modelagem e simulação da dessalinização de águas salobras usando um separador ciclônico térmico munido de bicos aspersores." Universidade Federal de Campina Grande, 2016. http://dspace.sti.ufcg.edu.br:8080/jspui/handle/riufcg/296.
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Previous issue date: 2016-09-29<br>O consumo de água doce vem crescendo muito no mundo inteiro e sua possível escassez tornou-se um dos temas mais discutidos na atualidade. Com isso há necessidade de desenvolver novas estratégias para suprir a falta de água potável. Dentre elas, destacam-se a dessalinização. Neste sentido, o presente trabalho tem por objetivo avaliar um ciclone convencional utilizado para dessalinização da água salgada com adição de cinco bicos injetores, localizados na parte superior do mesmo. O modelo matemático adotado considera escoamento tridimensional, turbulento, estacionário e não isotérmico para a fase gasosa, e a aplicação do modelo Lagrangeano para as partículas. As equações de conservação da massa, de momento linear, de energia e as do modelo de turbulência SST , bem como as equações constitutivas e as condições de contorno foram resolvidas com auxílio do software comercial Ansys CFX. São apresentados os resultados dos campos de pressão, temperatura,
velocidade e fração mássica, linhas de fluxo, trajetórias das partículas, perfis de velocidade, de pressão total e de temperatura total no interior do separador ciclônico térmico. Constatouse o caráter tridimensional do escoamento gás-partícula no interior do ciclone com presenças de regiões de zonas de recirculação e de inversão de fluxo. Os resultados mostraram que a variação das temperaturas na alimentação, tanto do ar como da água, influência na geração de vapor no interior do separador ciclônico. Porém é preciso um estudo cauteloso, como por exemplo, avaliar a influência do comprimento da parte cônica, tanto na fluidodinâmica quanto na cinética, para tentar aumentar o tempo de residência das partículas e com isso contribuir para o aquecimento da partícula.<br>The consumption of fresh water has been increasing worldwide and its possible
shortage has become one of the most discussed topics today. With this, there is a need to
develop new strategies to address the lack of potable water. Among them, desalination. In this sense, the present work aims to evaluate a conventional cyclone used for the desalination of salt water with the addition of five injector nozzles, located in the upper part of the same. The mathematical model adopted considers three-dimensional, turbulent, stationary and nonisothermal flow for the gas phase, and the application of the Lagrangian model to the particles. The equations of conservation of mass, linear momentum, energy and those of the SST w turbulence model, as well as the constitutive equations and the boundary conditions were solved with the commercial software Ansys CFX. The results of the fields of pressure, temperature, velocity and mass fraction, flow lines, particle trajectories, velocity profiles, total pressure and total temperature inside the thermal cyclone separator are presented. It was noted three-dimensional character of the gas-particle flow within the cyclone presence regions with recirculation zones and reverse flow. The results showed that the temperature variation in both air and water influences the generation of steam inside the cyclonic separator. However, a cautious study is required, for example, to evaluate the influence of the length of the conic part, both in fluid dynamics and kinetics, to try to increase the residence time of the particles and thereby contribute to the heating of the particle.
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Brahmachari, Koushik. "Connection and flexural behaviour of steel RHS filled with high strength concrete." Thesis, View thesis, 1997. http://handle.uws.edu.au:8081/1959.7/526.
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Steel hollow section members filled with concrete have been frequently used in recent construction industry as columns and beams and beam-columns because of their superior performance and constructability. Previous research demonstrated that such system has large energy absorption capacity which is critical in the event of an earthquake. By filling steel RHS with concrete, the failure of the steel shell due to local buckling can be delayed and the ductility of the concrete core can be improved as a result of the confinement of the steel shell. This type of composite section may be used in various structures including frames of high rise buildings, bridges, offshore structures, cast-in-situ piles in foundation etc. Design methods for concrete-filled steel tubular sections are recommended in a number of code of practices. Due to the significant differences in the material properties between normal strength concrete and high strength concrete, there is a need to study the behaviour of composite sections with higher strength concretes. The study emphasises ultimate strength, ductility, post-failure strength reserve and interface bond. It also emphasises ductility and post-failure strength of the composite beams due to the brittle behaviour of higher strength concretes when compared to normal strength concrete. Spreadsheet graph were used to present the results such as load versus strains, load versus deflections etc. In this thesis analytical study is presented on the calculation of ultimate moment of resistance of the concrete-filled RHS beams. Among the main considerations of the derivation, the steel portion was assumed either elastic-perfectly plastic or perfectly plastic and concrete carries no strength in the tensile zone. At the interface both full bond and partial bond were assumed for comparison. Efforts were also made to calculate the midspan deflections of the composite beams. Simple analytical expressions derived from this study can be coded to a prgrammable calculator or in a small spreadsheet program for design use. Finite element studies were carried out by using a proprietorship software package ANSYS. In the analysis of concrete-filled, three types of elements with large deformation and nonlinear capabilities were used. A plastic shell element, a solid concrete element with cracking and crushing capabilities, and a nonlinear spring contact element were used to model the steel shell, the concrete core and the interface respectively.
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PEREIRA, Evaldo Marcos Ascendino. "Secagem de mamona da variedade BRS energia: experimentação e simulação." Universidade Federal de Campina Grande, 2015. http://dspace.sti.ufcg.edu.br:8080/jspui/handle/riufcg/891.
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Previous issue date: 2015-05-29<br>CNPq<br>Subprodutos à base de óleo de rícino são utilizados na fabricação de vários produtos de base comercialmente importantes, tais como: surfactantes, lubrificantes, tintas, produtos farmacêuticos, cosméticos, poliésteres, polímeros, etc. A mamona tem na sua composição aproximadamente 50% de óleo, com especiais características, tais como elevada viscosidade, estabilidade ao calor e pressão, baixo ponto de congelamento e habilidade para formar substâncias cerosas após tratamentos químicos. A mamona é um candidato potencial para a produção de biodiesel; No entanto, este produto deve ser seco, a fim de reduzir o teor de umidade (10%), para o armazenamento seguro. A secagem é uma operação complexa, que envolve a transferência transiente de calor e de massa, que provoca transformações físicas e químicas do produto, o qual, por sua vez, pode causar alterações na qualidade do mesmo, bem como nos mecanismos de transferência de calor e de massa . Este trabalho apresenta um estudo experimental e numérico da secagem de frutos de mamona (Ricinus communis L., variedade "BRSEnergia"). Um modelo matemático tridimensional transiente é apresentado para predizer a transferência de massa e calor e simular a distribuição do teor de umidade e temperatura no interior do sólido, considerando as propriedades termofí sicas constantes, utilizando-se o software ANSYS CFX®. Para a validação da metodologia numérica foram realizados experimentos de secagem com frutos de mam ona da variedade BRS Energia. Nos experimentos, foram usadas temperaturas de secagem de 40, 50, 60, 70, 80, 90 e 100 ºC. Os dados experimentais de secagem foram ajustados ao modelo matemático empírico de Page, apresentando para todos os tratamentos coeficientes de determinação (R2) superiores a 99,60% e valores de desvio-padrão da estimativa (SE)
inferiores a 0,0165. As cinéticas de secagem de teor de umidade e temperatura obtidos
por meio do CFX® foram comparados com as cinéticas experimentais de secagem e uma boa aproximação foram obtidas. Coeficientes de massa difusivo foram obtidos para diferentes condições de secagem. Verificou-se que os coeficientes de transporte de massa difusivo tendem a aumentar com o aumento da temperatura do ar de secagem.<br>Castor oil-based by-products are used in the manufacture of several commercially
important commodities like surfactants, coatings, greases, pharmaceuticals, cosmetics,
polyesters, polymers, etc . The castor bean has in the compositions approximately 50%
oil, with special characteristics such as high viscosity, heat and pressure stability, low
freezing point and ability to form waxy substances after chemical treatments. The
castor bean is a potential candidate for the production of biodiesel; However, this
product must be dried, in order, to reduce moisture content (10%), for safe storage. Drying is a complex operation involving transient transfer of heat and mass that provokes physical and chemical transformations in the product, which, in turn, may cause changes in the quality thereof, as well as the mechanisms of heat and mass transfer. This work presents an experimental and numerical study of castor bean fruits drying (Ricinus communis L., variety "BRS Energia"). A three-dimensional transient mathematical model is presented to predict the heat and mass transfer and to simulate the distribution of temperature and moisture content inside the solid, considering the constant thermophysical properties, using ANSYS CFX® software. For validation of the numerical methodology were performed drying experiments with castor bean fruits of the variety BRS Energy. In the experiments, were used drying temperatures of 40, 50, 60, 70, 80, 90 and 100ºC. The experimental data of drying were adjusted to the empirical mathematical model of Page, presenting for all treatments, coefficients of
determination (R2) greater than 99.60% and standard deviation values of the estimate
(SE) lower than 0.0165. The drying kinetics of temperature and moisture content
obtained by CFX® were compared with the experimental drying kinetics and a good
approximation has been obtained. Diffusive mass coefficients were obtained for
different drying conditions. It was found that the diffusive mass transport coefficients
tend to increase with increasing drying air temperature.
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SANTOS, Tarcísio David KOnna Nunes. "Simulação em CFP de um reator CSTR para produção de biodíesel." Universidade Federal de Campina Grande, 2016. http://dspace.sti.ufcg.edu.br:8080/jspui/handle/riufcg/301.
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Previous issue date: 2016-03-23<br>Este trabalho propôs um modelo matemático para um reator do tipo CSTR (continuous stirred-tank reactor) partindo de dados experimentais da cinética da reação de transesterificação entre o óleo de soja e o acetato de metila, tendo como catalisador uma enzima, a Candida Antartica. Um volume foi proposto para reator para que o tempo médio de residência da mistura reacional fosse suficiente tal que o rendimento esperado, com base nos dados obtidos pelo Matlab®, fosse obtido na saída do reator. O estudo reacional fluidodinâmico foi feito utilizando o software comercial ANSYS® versão 15.0.
Duas configurações do reator foram propostas otimização, afim de tornar o processo o mais homogêneo possível, tentando atingir as configurações do reator de mistura perfeita. Os impelidores utilizados foram o tipo pás retas inclinadas e o ripo Ribbon (Âncora), afim de avaliar qual dos impelidores consegue o rendimento satisfatório com menor potência de operação. A potência requerida foi determinada através das equações para misturadores mecânicos, sendo avaliado apenas como variável a rotação das pás.<br>This work proposes a mathematical model to a reactor of CSTR-type
(Continuous Stirred-tank reactor) starting from experimental data of the kinetics
of transesterification of soybean oil and methyl acetate, with the catalyst
enzyme, Candida Antarctica. A reactor volume was proposed for the average
residence time of the reaction mixture was sufficient such that the expected
yield, based on data obtained by Matlab, was obtained in the reactor outlet. The
reaction fluid dynamic study was done using the commercial software ANSYS®
version 15.0. The optimization of the reactor was proposed by comparing the
reactor operation with two impellers separately in order to make the process
more homogeneous as possible, trying to achieve the perfect blend of reactor
configurations. The impellers used were the type inclined straight blades and
Ribbon RIPO (Anchor), to determine which of the impellers can the satisfactory
performance with lower power operation. The required power was determined
by the equations for mechanical mixers, being rated only as a variable rotation
of the blades
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Jindra, Daniel. "Stanovení požární odolnosti konstrukcí." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2019. http://www.nusl.cz/ntk/nusl-392030.
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Possibilities of modeling non-linear behavior of concrete within standard room temperatures and increased fire-load values using FEM software ANSYS are studied. Temperature dependences of material models are considered. Fire resistance of reinforced concrete and concrete-steel composite construction is analyzed. Fire loads are defined in accordance with relevant standards. Non-linear structural transient analyses are calculated after temperatures were determined by transient thermal analyses. Results obtained from analyses of simple reinforced concrete structure are compared with approach of isotherm 500 °C method.
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CURSINO, Gustavo Gomes Sampaio. "Influência da geometria da distribuição de temperatura em um combustor vertical de leito fluidizado a óleo combustível." Universidade Federal de Campina Grande, 2016. http://dspace.sti.ufcg.edu.br:8080/jspui/handle/riufcg/309.
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Previous issue date: 2016-04-18<br>Este trabalho teve o propósito de determinar o comportamento dos gases na seção de
radiação de um combustor de ar que pertence a uma planta industrial. O corpo metálico
do equipamento rompeu em seu primeiro ano de operação, devido a um problema
conceitual em sua geometria. A fluidodinâmica computacional (CFD), por meio do
método dos volumes finitos, foi utilizada para desenvolver um modelo tridimensional
que pudesse reproduzir o perfil de temperatura e o comportamento do fluxo do ar de
combustão no equipamento. Na simulação, através do uso do software ANSYS CFX,
foram utilizados: (i) o modelo de turbulência Reynolds Stress Model (RSM); (ii) as
malhas hexaédrica, tetraédrica e prismática; (iii) o modelo de radiação P-1; e (iv) o
modelo de combustão Eddy Dissipation Concept (EDC). Como resultado, foram
apresentadas quatro possíveis mudanças na geometria do combustor de ar que, caso
adotadas, eliminariam os riscos de novas falhas e garantiriam a continuidade
operacional da unidade de processo.<br>This paper has the objective to describe the behavior of the flow and temperature of the
flue gas in the radiation section of the vessel used to preheat air in a combustor. The
equipment failed in its first operational year, due to a conceptual problem in its
geometry. The CFD code based on finite volume method was applied to simulate the
physical model of combustor using the ANSYS CFX software, reproducing the main
features of the preheater. The simulation had considered: (i) Reynolds Stress Model
(RSM) as turbulence model, (ii) The meshes applied were the hexahedral, tetrahedral
and prismatic, (iii) P-1 was used as the radiation model and (iv) Eddy Dissipation
Concept (EDC) as combustion model. Through the simulation was possible to propose
four different kind of combustor geometry modification, that the application of anyone of
them would eliminate the risk of new failures, ensuring the unit production availability.
22
Urbano, Díaz Elisa. "Análisis de un patrón de relación conflictiva entre padres e hijos desde una perspectiva relacional: Proceso reconstructivo con una nueva estructuración del tiempo." Doctoral thesis, Universitat Ramon Llull, 2013. http://hdl.handle.net/10803/108092.
Full textAbstract:
El problema a investigar és l'ocupació del limitat temps disponible dedicat al nucli familiar. Requereix una distribució conscient, orientant cap a uns objectius concrets. Examinem la interacció en un cas únic familiar gravat en vídeo, utilitzant la metodologia Grounded Theory, mitjançant el programari informàtic Atlas.tu.
Apliquem l'Anàlisi Transaccional, observant què provoca problemes, com es transmeten valors, la imposició de límits, si el format utilitzat ha estat efectiu, i comparant-lo amb la teoria, quin és el motiu. Detectem els àmbits problemàtics i posteriorment realitzem una intervenció psicològica. Pretenem crear un sistema d'educar en els quatre valors bàsics proposats, sobre la base de la utilització d'una estructura del temps basada en tres eixos: temps, comunicació i valors.<br>El problema a investigar es el empleo del limitado tiempo disponible dedicado al núcleo
familiar. Requiere una distribución consciente, orientando hacia unos objetivos
concretos. Examinamos la interacción en un caso único familiar grabado en video,
utilizando la metodología Grounded Theory, mediante el software informático Atlas.ti.
Aplicamos el Análisis Transaccional, observando qué provoca problemas, cómo se
transmiten valores, la imposición de límites, si el formato utilizado ha sido efectivo, y
comparándolo con la teoría, cuál es el motivo. Detectamos los ámbitos problemáticos y
posteriormente realizamos una intervención psicológica. Pretendemos crear un sistema
de educar en los cuatro valores básicos propuestos, en base a la utilización de una
estructura del tiempo basada en tres ejes: tiempo, comunicación y valores.<br>The issue under research is the use of limited available time devoted to family. Time
distribution requires a conscious, moving towards specific targets. We examined the
interaction in a single case family videotaped using Grounded Theory methodology,
computer software Atlas.ti is used. We apply Transactional Analysis, looking at the
causes of problems, how values are transmitted, the imposition of limits, if the format
has been effective, and compared with theory, what are the reasons. We identify
problem areas and accomplish a psychological intervention. We want to create a system
of education in the proposed four core values, based on the use of a time structure based
on three axes: time, communication and values.
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BOON, SIDDHARTH. "CRANKSHAFT ANALYSIS AND MODELING USING ANSYS SOFTWARE." Thesis, 2020. http://dspace.dtu.ac.in:8080/jspui/handle/repository/18306.
Full textAbstract:
The reliability of any system, during which the linear displacement of a piston is regenerate into
the rotation of a power transmission shaft, strongly depends on the reliability of the crankshaft.
The crankshaft is that the vital element and any damage occurring to the crankshaft might put the
system out of order. Crankshaft is massive volume production component with a complex
geometry within the ICE. This converts the reciprocating displacement of the piston into a rotation
of the crank. The crank shaft takes the power from piston that is generated because of combustion
method within the combustion chamber of the cylinder. Throughout the power transmission
method the load acts at a specific crank angle to the max and thus the connecting rod is analyzed
for the stress developed, due to load conditions and the changes mentioned. The existing works
design first the 3D model of the engine parts are built in the software ‘CATIA V5’ and are then
transferred to ‘ANSYS’. The analysis of crank throw distortion and stress provides a conceptual
support to enhance the design by weigh reduction. The proposed research works the 3D model of
crankshaft system, obtained from CATIA V5 software is analyzed in ANSYS to assess the motion
and loads acting on the crankshaft. Topology optimization is help to optimize the performance of
any machine. The present model is test in three different loading conditions 22624N, 32624N and
42624N load is applied in crank shaft. After analysis ad comparison of all present models it is seen
that the lowest stress, deformation and weight are found in model 3 in all loading condition. The
topology optimization process is help to reduce the material of workpiece without affecting the
performance.
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Chun-YuChang and 張群郁. "Analysis of 3D Member Structures by Software ANSYS WORKBENCH." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/86190500147217013424.
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碩士<br>國立成功大學<br>土木工程學系碩博士班<br>100<br>In recent years, building design and construction technology have been developed to enhance the strength and safety of the structures, including steel structures which are widely used in public works. Three dimensional truss-like steel frame which behaves with very high strength and stiffness is widely used.
Although it is already clear knowledge as structures vibrate in elastic stage, it will become much more complicated when it vibrate beyond elastic limit and the material goes into yielding stage. The structures behaves nonlinearly.
In order to investigate the dynamic behavior of the three dimensional truss-like steel frame, computer-aided engineering analysis software package ANSYS Workbench is used here in. Dynamic behaviors of the mentioned structure, such as stress, deflections, ultimate loads, and failure modes…etc. are detected in detail. It is expected to help engineers to face the design work in the future.
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Chen, Li-Yueh, and 陳立月. "A Study of Thermal and Flow Fields on Heat Sinks Using ANSYS Software." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/87595638664293534794.
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碩士<br>華梵大學<br>機電工程學系博碩專班<br>98<br>The thermal management of high heat flux electronic components for reliable and effective operation has drawn much attention. Among these cooling technologies, the use of air impingement has been widely used in industrial transport processes since air impingement cooling has the advantage of convenience, economy, stability, high efficiency and cleanness. In this thesis, a CFD software ANSYS CFX is used to investigate the characteristics of the heat sink design. The investigated topic includes the width and the height of the fins, the jet velocity, and the distance between the nozzle and the tip of the fins. The flow is assumed to be laminar and the square cross section of the impingement jet is specified. The research reveals that increasing the flow velocity of the impingement jet can increase the heat transfer of the heat sink. However, the enhancement of heat transfer decreases gradually as the Reynolds number increases. In addition, the thermal resistance decreases with increasing fin width at low Reynolds number while the heat transfer rate can be increased at high Reynolds number due to the effect of a large amount of flow rate. The decreased fin length is found to be able to enhance the heat transfer rate. Finally, the jet spread distance is dependent on the Reynolds number, which indicates that the selection of jet and heat sink configuration has to be compromised in order to reach an optimal performance of heat transfer rate.
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Alves, Pedro Rafael Lages. "Desenvolvimento de ferramenta numérica para o estudo de propagação de fendas por fadiga usando software comercial de elementos finitos." Master's thesis, 2016. http://hdl.handle.net/10400.26/18849.
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O fenómeno de fadiga é uma das principais causas de falha dos componentes mecânicos sujeitos
a cargas cíclicas. É um processo de alteração estrutural permanente, progressivo e localizado.
Este fenómeno é dividido em três etapas: i) nucleação e iniciação da fenda; ii) propagação
estável da fenda; iii) e rotura do material. Devido ao facto da fadiga ser um fenómeno bastante
complexo e depender de inúmeras variáveis, muita da investigação desenvolvida foca-se em
apenas uma das suas fases. Devido ao desenvolvimento da tecnologia informática, a aplicação
de métodos numéricos avançados, mais precisamente o método dos elementos finitos, tem-se
mostrado bastante eficaz, permitindo o desenvolvimento de ferramentas para estimar o tempo
de serviço de componentes, prevenindo assim a sua rotura. Uma das abordagens numéricas
mais eficientes é a técnica de remalhagem adaptativa. Contudo, esta técnica requer um conjunto
muito específico de sub-rotinas, relativamente complexas, que não se encontram disponíveis
nos principais softwares generalistas de elementos finitos.
O objetivo deste trabalho e o desenvolvimento de uma ferramenta numérica, baseada na técnica
de remalhagem adaptativa, para interação com o software comercial de elementos finitos
ANSYS que permita estudar, de forma simples e rápida, fenómenos de propagação de fendas
por fadiga, sem necessidade de conhecimentos específicos sobre a técnica numérica. Assim,
utilizando o software ANSYS, é criado um modelo tridimensional de elementos finitos, a partir
do qual se obtém o campo de deslocamentos da peça fissurada; depois, são calculados os
avanços nodais da frente de fenda; e, em seguida, é definida uma nova frente de fenda. Após o
desenvolvimento da ferramenta, procedeu-se à validação dos resultados, comparando as
previsões numéricas com as formas de fenda obtidas experimentalmente. Por fim, foi estudado
o efeito de diferentes variáveis na evolução da forma da fenda, nos fatores de intensidade de
tensão e na vida da fadiga.
27
Roychowdhury, Anish. "Numerical Modelling and Software Development for Analysing Squeeze Film Fffect in MEMS." Thesis, 2015. http://etd.iisc.ac.in/handle/2005/3650.
Full textAbstract:
The goal of the current study was to develop a computational framework for modelling
the coupled fluid-structure interaction problem of squeeze films often encountered in
MEMS devices. Vibratory MEMS devices such as gyroscopes, RF switches, and 2D
resonators often have a thin plate like structure vibrating transversely to a Fixed substrate, and are generally not perfectly vacuum packed. This results in a thin air film being trapped between the vibrating plate and the fixed substrate which behaves like a squeeze film offering both stiffness and damping to the vibrating plate. For accurate modelling of the squeeze film effect, one must account for the coupled
fluid-structure interaction. The majority of prior works attempting to address the coupled problem either approximate the mode shape of the vibrating plate or resort to cumbersome iterative solution strategies to address the problem in an indirect way. In the current work,
we discuss the development of a fully coupled finite element based numerical scheme to
solve the 2D Reynolds equation coupled with the 3D plate elasticity equation in a single
step. The squeeze film solver so developed has been implemented into a commercial
FEA package NISA as part of its Micro-Systems module. Further, extending on a prior
analytical work, the effect of variable
ow boundaries for an all sides clamped plate on squeeze film parameters has been thoroughly investigated. The developed FEM based numerical scheme has been used to validate the results of the prior analytical study. The developed numerical scheme models the 2D Reynolds equation thus limiting the model to account for the effects of the
fluid volume strictly confined between the structure and the substrate. To study the effect of surrounding fluid volume ANSYS FLOTRAN simulations have been performed by numerically solving the full 3D Navier Stokes equation in the extended fluid domain for the different flow boundary scenarios. Cut-off frequencies are established beyond which one can consider a 2D fluid domain without considerable loss of accuracy.
First, a displacement based finite element formulation is presented for the 2D Reynolds
equation coupled with the 3D elasticity equation. Both lower order 8 node and higher
order 27 node 3D elements are developed. Only a single type of 3D element is used for
modelling along with a 2D fluid layer represented by the \wet" face of the 3D structural domain. The results from our numerical model are compared with experimental data from literature for a MEMS cantilever. The results from the 27 node displacement based elements show good agreement with published experimental data. The results from the lower order 8 node displacement based elements however show huge errors even for relatively fine meshes due to locking issues in modelling high aspect ratio structures. This limits the implementation of the displacement based solver in commercial FE packages where the available mesh generators are generally restricted to lower order 3D elements.
In order to overcome the limitations faced by lower order elements (primarily locking
issues) in modelling high aspect ratio MEMS geometries, a coupled hybrid formulation is
developed next. A thorough performance study is presented considering both the hybrid
and displacement based elements for lower order 8 node and higher order 27 node ele-
ments. The optimal element choice for modelling squeeze film geometries is determined based on the comparative studies. The effect of element aspect ratio for hybrid and displacement based elements are studied and the superiority of hybrid formulation over displacement based formulations is established for lower order 8 node elements. The coupled hybrid nite element formulation developed for lower order elements is implemented in the commercial FEA package NISA.
The implementation scheme to integrate the developed coupled hybrid 8 node squeeze
film solver into the commercial FEA package is discussed. The pre-integration analysis
and subsequent requirement gaps are first investigated. Based on the gap analysis, certain GUI modifications are undertaken and parser programs are developed to re-format data according to NISA input requirements. Certain special features are included in the
package to aid in post processing data analysis by MEMS designers such as \frequency
sweep" and \node of interest" selection. As a case study for validation, we also present
the modelling of a MEMS cantilever and show that the simulation results from our
software are in good agreement with experimental data reported in the literature.
Finally as a case study, an extension of a prior analytical work, which studies the
effect of varying flow boundaries on squeeze film parameters, is discussed. Explanations
are provided for the findings reported in the prior analytical work. The concept of using
variation in flow boundaries as a frequency tuning tool is introduced. The analytical
results are validated with the coupled numerical scheme discussed before, by considering imposed mode shape for an all sides clamped plate as prescribed displacement to the fluid domain. The simulated results are used to study the intricacies in squeeze film damping and stiffness variations with respect to spatial changes in the fluid flow boundary
conditions. In particular, it has been shown that the boundary venting conditions can
be used effectively to tune the dynamic response of a micromechanical structure over a fairly large range of frequencies and somewhat smaller range of squeeze film damping.
Next, the effect of the surrounding
fluid volume for various venting conditions is studied.
ANSYS FLOTRAN is used to solve for the full 3D Navier Stokes equation over the
extended fluid domain. Results from the extended domain study are used to determine
cut-off frequencies beyond which one need not resort to an extended mesh study, and
yet be within 5% accuracy of the full extended mesh model.
28
Roychowdhury, Anish. "Numerical Modelling and Software Development for Analysing Squeeze Film Fffect in MEMS." Thesis, 2015. http://etd.iisc.ernet.in/2005/3650.
Full textAbstract:
The goal of the current study was to develop a computational framework for modelling
the coupled fluid-structure interaction problem of squeeze films often encountered in
MEMS devices. Vibratory MEMS devices such as gyroscopes, RF switches, and 2D
resonators often have a thin plate like structure vibrating transversely to a Fixed substrate, and are generally not perfectly vacuum packed. This results in a thin air film being trapped between the vibrating plate and the fixed substrate which behaves like a squeeze film offering both stiffness and damping to the vibrating plate. For accurate modelling of the squeeze film effect, one must account for the coupled
fluid-structure interaction. The majority of prior works attempting to address the coupled problem either approximate the mode shape of the vibrating plate or resort to cumbersome iterative solution strategies to address the problem in an indirect way. In the current work,
we discuss the development of a fully coupled finite element based numerical scheme to
solve the 2D Reynolds equation coupled with the 3D plate elasticity equation in a single
step. The squeeze film solver so developed has been implemented into a commercial
FEA package NISA as part of its Micro-Systems module. Further, extending on a prior
analytical work, the effect of variable
ow boundaries for an all sides clamped plate on squeeze film parameters has been thoroughly investigated. The developed FEM based numerical scheme has been used to validate the results of the prior analytical study. The developed numerical scheme models the 2D Reynolds equation thus limiting the model to account for the effects of the
fluid volume strictly confined between the structure and the substrate. To study the effect of surrounding fluid volume ANSYS FLOTRAN simulations have been performed by numerically solving the full 3D Navier Stokes equation in the extended fluid domain for the different flow boundary scenarios. Cut-off frequencies are established beyond which one can consider a 2D fluid domain without considerable loss of accuracy.
First, a displacement based finite element formulation is presented for the 2D Reynolds
equation coupled with the 3D elasticity equation. Both lower order 8 node and higher
order 27 node 3D elements are developed. Only a single type of 3D element is used for
modelling along with a 2D fluid layer represented by the \wet" face of the 3D structural domain. The results from our numerical model are compared with experimental data from literature for a MEMS cantilever. The results from the 27 node displacement based elements show good agreement with published experimental data. The results from the lower order 8 node displacement based elements however show huge errors even for relatively fine meshes due to locking issues in modelling high aspect ratio structures. This limits the implementation of the displacement based solver in commercial FE packages where the available mesh generators are generally restricted to lower order 3D elements.
In order to overcome the limitations faced by lower order elements (primarily locking
issues) in modelling high aspect ratio MEMS geometries, a coupled hybrid formulation is
developed next. A thorough performance study is presented considering both the hybrid
and displacement based elements for lower order 8 node and higher order 27 node ele-
ments. The optimal element choice for modelling squeeze film geometries is determined based on the comparative studies. The effect of element aspect ratio for hybrid and displacement based elements are studied and the superiority of hybrid formulation over displacement based formulations is established for lower order 8 node elements. The coupled hybrid nite element formulation developed for lower order elements is implemented in the commercial FEA package NISA.
The implementation scheme to integrate the developed coupled hybrid 8 node squeeze
film solver into the commercial FEA package is discussed. The pre-integration analysis
and subsequent requirement gaps are first investigated. Based on the gap analysis, certain GUI modifications are undertaken and parser programs are developed to re-format data according to NISA input requirements. Certain special features are included in the
package to aid in post processing data analysis by MEMS designers such as \frequency
sweep" and \node of interest" selection. As a case study for validation, we also present
the modelling of a MEMS cantilever and show that the simulation results from our
software are in good agreement with experimental data reported in the literature.
Finally as a case study, an extension of a prior analytical work, which studies the
effect of varying flow boundaries on squeeze film parameters, is discussed. Explanations
are provided for the findings reported in the prior analytical work. The concept of using
variation in flow boundaries as a frequency tuning tool is introduced. The analytical
results are validated with the coupled numerical scheme discussed before, by considering imposed mode shape for an all sides clamped plate as prescribed displacement to the fluid domain. The simulated results are used to study the intricacies in squeeze film damping and stiffness variations with respect to spatial changes in the fluid flow boundary
conditions. In particular, it has been shown that the boundary venting conditions can
be used effectively to tune the dynamic response of a micromechanical structure over a fairly large range of frequencies and somewhat smaller range of squeeze film damping.
Next, the effect of the surrounding
fluid volume for various venting conditions is studied.
ANSYS FLOTRAN is used to solve for the full 3D Navier Stokes equation over the
extended fluid domain. Results from the extended domain study are used to determine
cut-off frequencies beyond which one need not resort to an extended mesh study, and
yet be within 5% accuracy of the full extended mesh model.
29
Kirana, Kumara P. "Studies On The Viability Of The Boundary Element Method For The Real-Time Simulation Of Biological Organs." Thesis, 2016. https://etd.iisc.ac.in/handle/2005/2553.
Full textAbstract:
Realistic and real-time computational simulation of biological organs (e.g., human kidneys, human liver) is a necessity when one tries to build a quality surgical simulator that can simulate surgical procedures involving these organs. Currently deformable models, spring-mass models, or finite element models are widely used to achieve the realistic simulations and/or the real-time performance. It is widely agreed that continuum mechanics based numerical techniques are preferred over deformable models or spring-mass models, but those techniques are computationally expensive and hence the higher accuracy offered by those numerical techniques come at the expense of speed. Hence there is a need to study the speed of different numerical techniques, while keeping an eye on the accuracy offered by those numerical techniques. Such studies are available for the Finite Element Method (FEM) but rarely available for the Boundary Element Method (BEM). Hence the present work aims to conduct a study on the viability of BEM for the real-time simulation of biological organs, and the present study is justified by the fact that BEM is considered to be inherently efficient when compared to mesh based techniques like FEM. A significant portion of literature on the real-time simulation of biological organs suggests the use of BEM to achieve better simulations. When one talks about the simulation of biological organs, one needs to have the geometry of a biological organ in hand. Geometry of biological organs of interest is not readily available many a times, and hence there is a need to extract the three dimensional (3D) geometry of biological organs from a stack of two dimensional (2D) scanned images. Software packages that can readily reconstruct 3D geometry of biological organs from 2D images are expensive. Hence, a novel procedure that requires only a few free software packages to obtain the geometry of biological organs from 2D image sequences is presented. The geometry of a pig liver is extracted from CT scan images for illustration purpose. Next, the three dimensional geometry of human kidney (left and right kidneys of male, and left and right kidneys of female) is obtained from the Visible Human Dataset (VHD). The novel procedure presented in this work can be used to obtain patient specific organ geometry from patient specific images, without requiring any of the many commercial software packages that can readily do the job. To carry out studies on the speed and accuracy of BEM, a source code for BEM is needed. Since the BEM code for 3D elasticity is not readily available, a BEM code that can solve 3D linear elastostatic problems without accounting for body forces is developed from scratch. The code comes in three varieties: a MATLAB version, a Fortran version (sequential version), and a Fortran version (parallelized version). This is the first free and open source BEM code for 3D elasticity. The developed code is used to carry out studies on the viability of BEM for the real-time simulation of biological organs, and a few representative problems involving kidneys and liver are found to give accurate solutions. The present work demonstrates that it is possible to simulate linear elastostatic behaviour in real-time using BEM without resorting to any type of precomputations, on a computer cluster by fully parallelizing the simulations and by performing simulations on different number of processors and for different block sizes. Since it is possible to get a complete solution in real-time, there is no need to separately prove that every type of cutting, suturing etc. can be simulated in real-time. Future work could involve incorporating nonlinearities into the simulations. Finally, a BEM based simulator may be built, after taking into account details like rendering.<br>This is the final version of the thesis, i.e., the version after the thesis defense (oral examination) is successfully completed.
30
Kirana, Kumara P. "Studies On The Viability Of The Boundary Element Method For The Real-Time Simulation Of Biological Organs." Thesis, 2016. http://etd.iisc.ernet.in/handle/2005/2553.
Full textAbstract:
Realistic and real-time computational simulation of biological organs (e.g., human kidneys, human liver) is a necessity when one tries to build a quality surgical simulator that can simulate surgical procedures involving these organs. Currently deformable models, spring-mass models, or finite element models are widely used to achieve the realistic simulations and/or the real-time performance. It is widely agreed that continuum mechanics based numerical techniques are preferred over deformable models or spring-mass models, but those techniques are computationally expensive and hence the higher accuracy offered by those numerical techniques come at the expense of speed. Hence there is a need to study the speed of different numerical techniques, while keeping an eye on the accuracy offered by those numerical techniques. Such studies are available for the Finite Element Method (FEM) but rarely available for the Boundary Element Method (BEM). Hence the present work aims to conduct a study on the viability of BEM for the real-time simulation of biological organs, and the present study is justified by the fact that BEM is considered to be inherently efficient when compared to mesh based techniques like FEM. A significant portion of literature on the real-time simulation of biological organs suggests the use of BEM to achieve better simulations. When one talks about the simulation of biological organs, one needs to have the geometry of a biological organ in hand. Geometry of biological organs of interest is not readily available many a times, and hence there is a need to extract the three dimensional (3D) geometry of biological organs from a stack of two dimensional (2D) scanned images. Software packages that can readily reconstruct 3D geometry of biological organs from 2D images are expensive. Hence, a novel procedure that requires only a few free software packages to obtain the geometry of biological organs from 2D image sequences is presented. The geometry of a pig liver is extracted from CT scan images for illustration purpose. Next, the three dimensional geometry of human kidney (left and right kidneys of male, and left and right kidneys of female) is obtained from the Visible Human Dataset (VHD). The novel procedure presented in this work can be used to obtain patient specific organ geometry from patient specific images, without requiring any of the many commercial software packages that can readily do the job. To carry out studies on the speed and accuracy of BEM, a source code for BEM is needed. Since the BEM code for 3D elasticity is not readily available, a BEM code that can solve 3D linear elastostatic problems without accounting for body forces is developed from scratch. The code comes in three varieties: a MATLAB version, a Fortran version (sequential version), and a Fortran version (parallelized version). This is the first free and open source BEM code for 3D elasticity. The developed code is used to carry out studies on the viability of BEM for the real-time simulation of biological organs, and a few representative problems involving kidneys and liver are found to give accurate solutions. The present work demonstrates that it is possible to simulate linear elastostatic behaviour in real-time using BEM without resorting to any type of precomputations, on a computer cluster by fully parallelizing the simulations and by performing simulations on different number of processors and for different block sizes. Since it is possible to get a complete solution in real-time, there is no need to separately prove that every type of cutting, suturing etc. can be simulated in real-time. Future work could involve incorporating nonlinearities into the simulations. Finally, a BEM based simulator may be built, after taking into account details like rendering.