Orientador: Paulo Roberto Gardel Kurka / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-07-24T15:32:08Z (GMT). No. of bitstreams: 1 Mathias_MauroHugo_D.pdf: 7532948 bytes, checksum: 3f7d919ebab4f2d9d68fbf29915d517a (MD5) Previous issue date: 1998 / Resumo: Esta tese trata do estudo de teorias, estratégias e metodologias de identificação de sistemas aplicado à análise de sinais de estruturas mecânicas. A abordagem do problema de identificação no contexto das áreas afins de análise de sinais, análise de séries temporais e análise modal é também discutida no trabalho. O enfoque central da pesquisa consiste em aplicar técnicas paramétricas do domínio do tempo na análise modal de estruturas mecânicas. Os procedimentos de identificação adotados descrevem o sistema estrutural através de modelos derivados do método Auto Regressivo de Médias Móveis (ARMA), correlacionando os parâmetros modais e coeficientes do modelo. Testes de simulação foram desenvolvidos para demonstrar as características dos métodos de identificação estudados. Finalmente um modelo modal experimental foi desenvolvido. Os parâmetros modais identificados do modelo foram estabelecidos a partir dos sinais de excitação e resposta medidos na estrutura através do procedimento experimental / Abstract: This thesis is related to system identification theories, strategies and methodologies applied to signal analysis of mechanical structures. The approach of the identification problem in the setting of signal analysis, time series models and modal analysis was also discussed in the work. The central subject of the research is outlined on the use of parametric time domain techniques applied to mechanical structural modal analysis. The identification procedures describes the structural system by models derived from an Auto Regressive Moving Average method (ARMA), highlighting the relations between modal parameters and model coefficients. Simulated test cases have been developed to demonstrate the characteristics of the identification methods studied. Finally an experimental modal model has been developed. The identified modal parameters were established from the excitation and response signals measured on the structures through the experimental test / Doutorado / Mecanica dos Sólidos e Projeto Mecanico / Doutor em Engenharia Mecânica

Orientador: Paulo Roberto Gardel Kurka / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-08-04T14:31:42Z (GMT). No. of bitstreams: 1 AmaroBaldeon_RobertoPedro_D.pdf: 4773363 bytes, checksum: d0f431ee3b99fa29f96a302fb22a01c1 (MD5) Previous issue date: 2004 / Resumo: O trabalho apresenta os modelos de series temporais aplicados na identificação de sistemas mecânicos. A técnica de Máxima Verossimilhança (ML) é aplicada na estimação dos parâmetros dos modelos de series temporais a fim de melhorar a precisão na estimação dos parâmetros modais. O algoritmo de Spliid é usado na estimação de valores iniciais para iniciar o processo iterativo da técnica ML. A performance da técnica ML é verificada simulando um sistema de três graus de h"berdade com duas entradas e duas saídas, é adicionado ruído no sinal de saída a fim de se verificar a eficiência dos modelos de series temporais na presença de ruído estocástico. Dados provenientes de teste de vibração de um protótipo de asa de avião são usados para comparar as técnicas propostas com os resultados obtidos usando o Ideas/Test / Abstract: This work presents the Multivariate Time Series Models in the identification ( mechanica1 systems. The maximum likelihood technique (ML) is applied to estimate tl1 parameters of the time series models in order to improve the precision in the estimation ( modal parameters. The Spliid's algorithm is used to estimate initial values to start tt iterative process of the ML technique. The perfoimance of the ML technique is verified j a three degree fteedom simulated system with two inputs and two outputs. Stochastic noh is added to the outputs in order to verify the performance of time series models when ti output is influenced by stochastic noise. Vibrating test data of a wing prototype is used 1 compare the proposed techniques with the results obtained experimentaly from Ideas/ Test / Doutorado / Mecanica dos Sólidos e Projeto Mecanico / Doutor em Engenharia Mecânica

[pt] A estabilidade de tensão tornou-se nos últimos anos tema de intensa pesquisa, envolvendo principalmente a identificação da natureza do problema e a busca de estratégias mais favoráveis para a operação e planejamento dos sistemas de potência. Este trabalho apresenta um relato da evolução da análise do fenômeno sendo, posteriormente descritos os detalhes de sua abordagem através da teoria das bifurcações em sistemas dinâmicos não-lineares. São caracterizados o limite de transmissão de potência à estabilidade de tensão e a geometria das trajetórias no espaço de estados em pontos de equilíbrio em suas proximidades. O estabelecimento de equivalência entre os modelos dinâmico e estático tornou possível o emprego de métodos baseados nas equações algébricas do fluxo de carga na determinação do limite de estabilidade de tensão e na avaliação do comportamento dinâmico local. Com base no algoritmo de fluxo de carga convencional, foi desenvolvido um programa computacional que emprega o método de continuação parametrizado. Os métodos de continuação permitem a obtenção do conjunto completo das soluções reais, relacionadas por um parâmetro escalar, de um sistema de equações. Mostra-se que a aplicação desses métodos em conjunto com as técnicas de análise modal resulta em uma forma eficiente para a seleção e localização de reforços visando aumentar a capacidade global de transmissão dos sistemas de potência. / [en] In the past few years voltage stabiity has become a subject of intense research involving the identification of the nature of this problem and the seek of suitable strategies for power systems operation and planning. In this work it is presented a report on the evolution in the analysis of this phenomena and it is described the details of its approach through the dynamic nonlinear systems bifurcation theory. The power transmission limit imposed by the voltage stability conditions is addressed and the geometry of the trajectories in state space considering the equilibrium points on the vicinity of this limit is deeply studied. The establishment of the equivalence conditions between the dynamic and static power system models made it possible to employ load-flow algebraic equations based methods on both the determination of the power transmission limit and the evaluation of local dynamic behaviour. A load-flow based computer program which uses the parameterized continuation method was developed. The continuation methods are widely known for providing the determination of whole set of a system s solutions which are related by a scalar parameter. In the closure, it is shown that the application of these methods, in a complementary basis with the modal analysis techniques, results in an efficient procedure to promote the choice and location of devices to improve the power system global tranmission capacity.

In this thesis a methodology for measuring vibrations has been produced andinvestigated for APID 60, a rotorcraft in a Vertical Take-off and landing remotelypiloted aircraft system (VTOL RPAS). A comparative study was carried out forthe purpose of identifying the methodology with respect to design modificationscommon to the APID 60. The pilot-study identified experimental modal analysis(EMA) as a feasible part of the methodology for experimentally extracting themodal parameters of a structure. The EMA was performed on the main frameof the APID 60 where an impact hammer test was chosen as the technique forextracting the response data. As a comparison a point mass was added to thestructure to alter the dynamic properties and the test was repeated.The results from the EMA was compared with a modal analysis performednumerically with a calculation software. Comparison of the results from EMAwith the modal analysis performed numerically indicates consistency. This confirmsa good reliability of the methodology produced. However, the structure onwhich the test were preformed is simple in terms of constant structural properties.Further work should therefore investigate whether this methodology of measuringvibrations could be successfully applied to a structure with higher complexity.

All structures have modal properties such as natural frequencies and damping. In engineeringit is often of interest to estimate these modal properties for certain structures, to be used whenmodelling for example fatigue. This is done by computing them from finite element models, by using experimental measurements or both. In the case of doing both, a finite elementmodel is usually established first and adjusted to fit measurements from experiments. Atlas Copco Rock Drills AB is the company where this thesis has been performed and the subject is experimental procedures related to estimating modal properties of the so calledpower pack, which essentially is a modularised engine and hydraulic power source of an Atlas Copco drill rig. Their current method for estimating these properties is a classical procedure which makes use of an impact hammer that an operator strikes the power pack with to induce excitation. Due to concealment of behind other parts the power pack when mounted inside the drill rig, the number of places where the operator is able to strike the power pack in is limited. Another problem with the current procedure is that it can be difficult to strike the power pack with a strong enough impulse to generate reliable results. In this thesis a new experimental procedure for Atlas Copco to use is suggested. It is based on operational modal analysis (OMA), which uses the machinery's excitation from its operational conditions to compute modal estimates. A comparison between different experimental procedures have been done and the suggested procedure is the following: excitation by engine sweep; modal identifcation by the PolyMAX method and mode shape scaling by the harmonic scaling method. An experiment was performed to compare two OMA procedures.The suggested procedure is the one that generated the better results of the two.

La détermination des caractéristiques vibratoires est une étape cruciale lors du processus de certification d'une structure ou lors de l'évaluation de sa détérioration. Quelle que soit la technique utilisée, l'identification des modes d'une structure nécessite d'effectuer des essais de vibration. Durant ces essais, on effectue des mesures qui permettent d'observer la réponse du système à une excitation connue, partiellement connue ou inconnue. Les méthodes d'identification modale sont des méthodes globales. Elles permettent de déterminer les modes de la structure à partir d'un post-traitement des données mesurées. Certaines techniques d'identification modale, telles que les méthodes basées sur la minimisation d'erreur de modélisation ARX ou les méthodes sous-espaces, se sont fortement répandues dans le monde industriel ces quinze dernières années. Cependant, malgré ce succès, ces méthodes ne fourniront jamais les paramètres modaux exacts de la structure étudiée. En effet, à cause de nombreuses sources d'erreurs (e.g. bruits sur les capteurs, bruits environnementaux), l'identification modale à partir de données réelles ne peut mener qu'à des estimations des paramètres modaux. Une estimation est par définition entachée d'une erreur statistique, la variance. Le but de cette thèse est l'étude approfondie de l'estimation de cette erreur statistique. Le manuscrit est découpé en trois partie. La première concerne la description détaillée de deux familles d'identification modale (minimisation d'erreur de modélisation ARX et méthodes sous-espace). La seconde partie décrit le principe de l'estimation des incertitudes et fournit les chaînes de propagation des variances. La troisième partie présente une validation poussée de ces méthodes dans le but d'une utilisation opérationnelle. / Determinination of vibration characteristics is a crucial step for structure certification or health monitoring. Whatever the method, modes identification of a structure requires vibration tests. During these tests, measurements are made in order to observe responses of the system to known, partially known or unknown excitations. Modal identification methods are global methods. They allow the determination of modes from data post-treatment. Some modal identification methods, such as those based on ARX modelisation error minimisation or subspace methods, have been largely spread into the industry for about fifteen years. Despite this succes, these methods will never provide exact results. Indeed, due to numerous error sources (e.g. sensor noises, environmental noises), modal identifications based on measured data can only lead to modal parameters estimations. By definition, an estimation is subject to statistical errors, also called variances. The purpose of this thesis is to give an in-depth study of these statistical errors estimation. This document is divided in three parts. Firstly, a description of two kind of modal identification methods (ARX modelisation error minimisation and subspace methods) is given. Secondly, the uncertainty estimation principle is explained and propagation schemes of variances are given. Finally, the third part provides an in-depth validation of these methods in order to proceed to industrial utilisations.

In this work, a pioneering application of the Solution Structure Method (SSM) for structural dynamics problems is presented. Vibration analysis is an important aspect of any design-analysis cycle for which reliable computational methods are required. Unlike many meshfree methods, SSM is capable of {\it exact treatment of all prescribed boundary conditions}. In addition, the method is capable of using basis functions which do not conform to the shape of the geometric model. Together, this defines an unprecedented geometric flexibility of the SSM. This work focused on the development of numerical algorithms for 2D in-plane and 3D natural vibration analysis and 2D in-plane dynamic response. The convergence and numerical properties of the method were evaluated by comparing meshfree results with those obtained using traditional Finite Element Analysis implemented in Solidworks and ANSYS. The numerical experiments presented in this work illustrate that the Solution Structure Method possesses good convergence and in some cases, such as geometries with partially fixed boundaries, this method converges much more rapidly than traditional FEA. Finally, in addition to complex boundary conditions, this method can easily handle complex geometries without losing favorable convergence properties.

[EN] Modern communications systems impose stringent requirements on the equipment that operates at microwave frequency, especially in the case of wireless communications. The design of passive components for these applications is contingent upon the availability of accurate electromagnetic (EM) modeling tools that can efficiently handle the complex geometry of these components. Despite the widespread use of mesh-based general-purpose computer-aided engineering (CAE) tools to perform final design verifications, their application during the optimization process is limited. Optimum designs require a large number of simulations, which are computationally expensive when performed by general purpose tools. Instead, microwave designers prefer to employ faster software tools tailored to specific geometries, such as waveguide components, multilayered structures, etc. Therefore, the development of faster and more efficient specialized EM tools has a direct impact on the design of microwave components, both quantitatively and qualitatively. Increasingly complex geometries are modeled more accurately, and may be incorporated into novel designs without penalizing development time and its associated costs. By doing so, passive components become more advanced and are able to fulfill stricter requirements. At the same time, new research and development opportunities arise in order to address the challenges posed by these advanced structures. The present thesis is focused on a specific type of waveguide cavity geometry: bi-dimensional structures of arbitrary shape. Most microwave components based on rectangular waveguides include these elements (bends, T-junctions, tapers, power-dividers, etc.), thus the scope of this work is wide. To characterize these structures, an efficient full-wave modal formulation is developed. Taking into account common properties of bi-dimensional structures, such as its electromagnetic symmetry, the resulting technique is very efficient and accurate. Thanks to the integration of this formulation into a CAE tool, a designer is able to solve complex systems that combine this type of element with components of vastly different shapes. The developed formulation is first applied to the analysis and design of passive components, such as filters, multiplexers and orthomode transducers. These examples are employed to validate the results, as well as to demonstrate the improvement that the proposed analysis technique represents over well-known commercial EM packages. Likewise, this formulation is combined with the tool SPARK3D to predict RF breakdown (multipactor and corona) in selected bi-dimensional structures. Then, novel implementations of waveguide quasi-elliptic filters, based on the interconnection of bi-dimensional cavities, are proposed. Special attention is paid to the realization of multiple transmission zeros (TZs) with tuning-less compact structures. First, a novel family of filters, known as hybrid-folded rectangular waveguide structures, is studied. Simple and flexible methods to prescribe the location of the transmission zeros realized by these structures are presented. Practical aspects related to their physical implementation are also discussed. Secondly, a compact and purely capacitive obstacle, capable of realizing multiple TZs, is presented and discussed. In both cases, multiple examples are given to illustrate the step-by-step process involved in the design of these structures. Finally, a systematic procedure for the design of wideband manifold-coupled multiplexers is proposed. To preven the generation of undesired resonances, stubs that connect the filters to the manifold are removed. Likewise, the manifold length is kept as short as possible. Following a simple procedure, based on analytical formulas and EM simulations, a good starting point for the final optimization of these structures is obtained. It has been applied to a wideband quadruplexer for passive intermodulation measurement at C-band. / [ES] Actualmente, los sistemas de comunicaciones imponen unos requisitos muy estrictos sobre el equipamiento en la banda de microondas. El diseño de estos componentes está supeditado, frecuentemente, a la disponibilidad de herramientas de modelado electromagnético (EM) que sean capaces de analizar geometrías complejas. A pesar del amplio uso de herramientas CAE (computer-aided engineering) de propósito general para la verificación final de prototipos, su potencial aplicación durante el proceso de diseño es limitada. Los diseños óptimos exigen realizar una gran cantidad de simulaciones EM. Dado que las simulaciones con estas técnicas tienen un alto coste computacional, los diseñadores suelen optar por emplear herramientas software especializadas en las estructuras que diseñan. Por tanto, el desarrollo de nuevas herramientas más precisas y eficientes ayudará a reducir el tiempo de diseño de estos productos, y con ello los costes asociados. Además, permitirá abrir nuevas líneas de investigación para responder a los retos que plantean geometrías cada vez más complejas. Esta tesis se centra en el desarrollo de una herramienta de análisis EM para un tipo concreto de estructuras: cavidades bidimensionales de sección arbitraria. Es habitual encontrar este tipo de estructuras en la mayoría de componentes implementados en guía rectangular. Por tanto, el rango de aplicación de la teoría desarrollada en esta tesis es muy amplio. En concreto, se ha desarrollado una nueva formulación basada en métodos modales que permite realizar una caracterización de onda completa de estas estructuras de forma eficiente y precisa. Al aprovechar su simetría geométrica y electromagnética, la herramienta desarrollada puede minimizar los cálculos a realizar, consiguiendo grandes velocidades de computación pero manteniendo una alta precisión. Gracias a la integración de esta formulación dentro de una herramienta CAE basada en métodos modales, se ofrece la posibilidad a los diseñadores de resolver sistemas muy complejos que combinan este tipo de cavidades con otros componentes de geometrías distintas. Esta formulación se aplica, en primer lugar, al análisis y diseño de componentes pasivos comunes, tales como filtros, multiplexores y OMTs. Estos ejemplo validan la herramienta desarrollada, y demuestran la significativa mejora que supone el uso de esta nueva técnica con respecto a otros paquetes software de análisis electromagnético. Asimismo, al combinar esta formulación con la herramienta SPARK3D se abre la posibilidad de predecir la aparición de fenómenos de descarga de alta potencia en determinadas estructuras bidimensionales. A continuación, se proponen nuevas formas de implementar filtros cuasi-elípticos basados en la interconexión de cavidades bi-dimensionales. Se hace especial hincapié en la realización de múltiples ceros de transmisión mediante estructuras compactas que no requieran sintonía. Por una parte se estudian los filtros hybrid-folded rectangular waveguide. Este trabajo incluye una discusión en profundidad sobre distintas implementaciones de este tipo de filtros. En ella se consideran aspectos prácticos relacionados con su uso e implementación física, que ofrecen al diseñador unos criterios claros para elegir la estructura que más se ajuste a sus especificaciones. Por otra parte se presenta un nuevo obstáculo de naturaleza capacitiva muy compacto, que permite la realización de múltiples ceros de transmisión incluso en estructuras en línea. En ambos casos se incluyen ejemplos de aplicación y se describe la metodología seguida para su diseño. Finalmente, se expone un procedimiento sistemático para diseñar multiplexores de banda ancha. Para prevenir la generación de resonancias indeseadas se evitan, en la medida de lo posible, las interconexiones mediante tramos cortos de guía. Siguiendo una metodología simple se consigue un excelente punto inicial para su optimización. La te / [CAT] Els actuals sistemes de comunicacions sense fils imposen uns requisits molt estrictes sobre l'equipament de la banda de microones. El disseny d'aquests components està supeditat, frequentment, a la disponibilitat de ferramentes de modelatge electromagèntic (EM) que siguen capaços de gestionar geometries complexes. Tot i l'ampli ús de ferramentes CAE (computer-aided engineering) de propòsit general per a la verificació final de prototips, la seua aplicació durant el procés de disseny és limitada. Els dissenys òptims exigeixen realitzar una gran quantitat de simulacions. Les simulacions amb aquestes tècniques tenen un alt cost computacional, per tant els dissenyadors solen optar per utilitzar ferramentes software especialitzades en les estructures que dissenyen. Per tant, el desenvolupament de noves tècniques d'anàlisi més precises i eficients ajudarà a reduir el temps de desenvolupament d'aquests productes, i dels seus costos associats. A més permetrà obrir noves línies d'investigació per respondre els reptes que plantegen geometries cada vegada més complexes. Aquesta tesi es centra en el desenvolupament d'una ferramenta d'anàlisi EM per a un tipus concret d'estructures: cavitats bidimensionals de forma arbitraria. És habitual trobar aquestes estructures en la majoria de components implementats en guia rectangular. Per tant, l'àmbit d'aplicació de la teoria presentada en esta tesi és molt ampli. En concret, s'ha desenvolupat una nova formulació basada en mètodes modals que permet realitzar una caracterització d'ona completa d'aquestes estructures de forma eficient i precisa. Aprofitant la seua simetria geomètrica i electromagnètica, la ferramenta desenvolupada pot minimitzar els càlculs a realitzar, aconseguint grans velocitats de càlcul mantenint una alta precisió. Gràcies a la integració d'aquesta formulació dins d'una ferramenta CAE basada en mètodes modals, s'ofereix la possibilitat als dissenyadors de resoldre sistemes molt complexos que combinen aquest tipus de cavitats amb altres components de diferent geometria. Aquesta formulació s'aplica, en primer lloc, a l'anàlisi i disseny de components passius comuns: filtres, multiplexors i OMTs. Aquests exemples serveixen per a validar la ferramenta desenvolupada, així com demostrar la significativa millora que suposa l'ús d'aquesta nova tècnica respecte d'altres paquets software d'anàlisi electromagnètic. Així mateix, mitjançant la combinació d'aquesta formulació amb la ferramenta SPARK3D s'obri la possibilitat de predir l'aparició de fenòmens de descàrrega d'alta potència en estructures bidimensionals. A continuació, es proposen noves formes d'implementar filtres quasi el-líptics en guia d'ona basats en la interconnexió de cavitats bidimensionals. Es fa especial èmfasi en la realització de múltiples zeros de transmissió mitjançant estructures compactes que no requereixen de sintonia. D'una banda s'estudien els filtres hybrid folded rectangular waveguide. Aquest treball inclou una discussió en profunditat sobre diferents implementacions d'aquest tipus de filtres. S'hi consideren aspectes pràctics relacionats amb el seu ús i implementació física, que ofereixen al dissenyador uns criteris clars per triar l'estructura que més s'ajuste a les seues especificacions. D'altra banda es presenta un nou obstacle de naturalesa capacitiva extremadament compacte, que permet la realització de múltiples zeros de transmissió fins i tot en estructures en línia. En els dos casos s'inclouen exemples d'aplicació i es descriu la metodologia seguida per al seu disseny. Finalment, s'exposa un procediment sistemàtic per dissenyar multiplexors de banda ampla. Per prevenir la generació de ressonàncies no desitjades s'eviten les interconnexions amb trams de guia curts. Seguint una metodologia simple, basada en fórmules analítiques i simulacions electromagnètiques, s'aconsegueix un excel-lent punt inicial per a l'optimització. / Carceller Candau, C. (2016). Full-wave characterization of bi-dimensional cavities and its application to the design of waveguide filters and multiplexers [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/64089 / TESIS

This master´s thesis deals with the acoustic emission of the gearbox housing. It contains a description of the procedure of solving individual numerical approaches and their results. Finally, it compares the influence of design modifications on acoustic emission.

No description available.