Numerical and Experimental Modal Control of Flexible Rotor Using Electromagnetic Actuator

The present work is dedicated to active modal control applied to flexible rotors. The effectiveness of the corresponding techniques for controlling a flexible rotor is tested numerically and experimentally. Two different approaches are used to determine the appropriate controllers. The first uses the linear quadratic regulator and the second approach is the fuzzy modal control. This paper is focused on the electromagnetic actuator, which in this case is part of a hybrid bearing. Due to numerical reasons it was necessary to reduce the size of the model of the rotating system so that the design of the controllers and estimator could be performed. The role of the Kalman estimator in the present contribution is to estimate the modal states of the system and to determine the displacement of the rotor at the position of the hybrid bearing. Finally, numerical and experimental results demonstrate the success of the methodology conveyed

Uncertainty Analysis Techniques Applied to Rotating Machines

This chapter presents the modeling procedure, numerical application, and experimental validation of uncertain quantification techniques applied to flexible rotor systems. The uncertainty modeling is based both on the stochastic and fuzzy approaches. The stochastic approach creates a representative model for the flexible rotor system by using the stochastic finite element method. In this case, the uncertain parameters of the rotating machine are characterized by homogeneous Gaussian random fields expressed in a spectral form by using the Karhunen-Loève (KL) expansion. The fuzzy approach uses the fuzzy finite element method, which is based on the α-level optimization. A comparative study regarding the numerical and experimental results obtained from a flexible rotor test rig is analyzed for the stochastic and fuzzy approaches

IDENTIFICAÇÃO DE FALHAS EM UMA EMPENAGEM VERTICAL USANDO IMPEDÂNCIA ELETROMECÂNICA E SIMULAÇÃO DE MONTE CARLO COM REDES NEURAIS PROBABILÍSTICAS

Nos últimos anos algumas técnicas experimentais de integridade estrutural têm recebido maior atenção devido ao desenvolvimento de dispositivos e métodos. Dentre estes procedimentos destaca-se o monitoramento da integridade estrutural baseado em sinais de impedância eletromecânica. Uma desvantagem do uso desta técnica é a variabilidade dos sinais medidos devido a frequências elevadas e sensíveis, temperatura, pressão, ruídos de circuitos, etc. Assim, um estudo da confiabilidade do sistema de identificação de falhas é proposto neste trabalho para se avaliar o monitoramento de falhas de uma empenagem vertical de um Veículo Aéreo Não Tripulado. Foram utilizadas adições de massas em algumas posições enquanto dois sensores são utilizados para a aquisição dos sinais de impedância. Um modelo baseado em redes neurais probabilísticas foi criado para modelar o processo de identificação de falhas na empenagem. Após isto, uma análise da variabilidade dos sinais reais foi feita e uma simulação de Monte Carlo foi realizada para a geração de sinais virtuais de impedância que foram avaliados pela rede neural inicial para identificação das falhas. Por fim, é importante ressaltar a importância da adição do comportamento estocástico ao modelo baseado em dados experimentais de uma estrutura real para compreensão da confiabilidade do uso do modelo.&nbsp

Monitoreo de salud estructural de aeronaves basado en mediciones de impedancia electromecánica

The structural Health Monitoring (SHM) is theprocess of damage detection in many areas ofengineering, like aerospace, civil and mechanics.One of SHM techniques is based on theelectromechanical impedance measurement. Thistechnique monitors the mechanical impedancevariation of the structure, caused by the presenceof damage, through measurements of theelectrical impedance signal of the piezoelectricmaterial bonded on the surface of the monitoredstructure. As the electrical impedance of thePZT patches is directly related to the mechanicalimpedance of the structure, the impedancemeasurements can be used for damage detection.The quantification of the damage is done by ametric, which is attributed a characteristic scalarvalue. In this context, the project developed byFederal University of Uberlandia with partnershipwith EMBRAER, studied the feasibility of thestructural health monitoring technique based onthe electromechanical impedance measurements todetect incipient damage at inaccessible location inthe airplane. This paper presents the results of thistechnique obtained by UFU for the consolidationof this tool. Despite the method is still applied inlaboratory scale applications, it has shown a greatpotential to detect incipient damage in airplanes’structures, like a rivet loss and cracks. This worksalso describes an impedance measurement systemdeveloped at UFU.Se denomina Monitoreo de Salud Estructuralal proceso de detección de anomalías (dañoso degradación) en varias áreas de ingeniería,tales como, aeroespacial, civil y mecánica,principalmente. Una de las técnicas utilizadaspara monitorear la integridad de una estructuraes basada en la medición de impedanciaelectromecánica. Esta técnica monitorea lavariación de impedancia mecánica de unaestructura, causada por la existencia de uno o másdaños, por medio de la medición de la impedanciaeléctrica de las pastillas de material piezoeléctricoacopladas en la superficie de la estructura. Laimpedancia eléctrica de las pastillas piezoeléctricasestá directamente relacionada con la impedanciamecánica de la estructura, es por eso que a partir dela variación de las señales de impedancia medidasse puede concluir la presencia o no de un daño.La cuantificación del daño se hace por mediode una métrica que es especialmente definidapara atribuirle un valor escalar característico.En el marco del proyecto de investigación enconvenio con la EMBRAER, la UniversidadFederal de Uberlândia (UFU), estudia la viabilidaddel uso de la técnica de Monitoreo de SaludEstructural basada en mediciones de impedanciaelectromecánica como una herramienta dedetección de daños incipientes en lugares dedifícil acceso en aeronaves. El presente trabajopresenta los resultados obtenidos en la UFU parala consolidación de esta herramienta, los cualesa pesar de encontrarse todavía en aplicacionesa nivel de laboratorio han mostrado un granpotencial para la detección de daños incipientesen estructuras aeronáuticas, tales como, pérdida deun remache y fisuras. En este trabajo también serádescrito un sistema de medición de impedanciaelectromecánica desarrollado en la UFU

Urinary Excretion of Ecdysterone and Its Metabolites Following Spinach Consumption

Scope The phytosteroid ecdysterone is present in spinach. In this study, the urinary elimination of ecdysterone and its metabolites in humans is investigated following spinach consumption of two different culinary preparations. Methods and results Eight participants (four males, four females) ingested 950 (27.1) g sautéed spinach (average [±standard deviation (SD)]) and 912 (70.6) g spinach smoothie as second intervention after washout. Post-administration urines are analyzed by liquid chromatography tandem mass spectrometry (LC-MS/MS). After intake of both preparations, ecdysterone and two metabolites, 14-deoxy-ecdysterone, and 14-deoxy-poststerone, are excreted in urine. The maximum concentration of ecdysterone is ranging from 0.09 to 0.41 µg mL−1 after sautéed spinach and 0.08–0.74 µg mL−1 after smoothie ingestion. The total excreted amount (mean% [±SD]) in the urine as a parent drug plus the metabolites is only 1.4 (1.0) for both sautéed spinach and smoothie. The apparent sex related differences in 14-deoxy-poststerone excretion will need further investigations. Conclusion Only a small proportion of ecdysterone from spinach is excreted into urine. No significant differences are found in concentration and recovered amount (%) of ecdysterone, 14-deoxy-ecdysterone, and 14-deoxy-poststerone in urine between sautéed spinach and smoothie ingestion. A discrimination between ecdysterone from food or preparations will be challenging based on urinary concentrations only, at least for later post-administration samples