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COB108 TORQUÍMETRO ELETRÔNICO PARA MEDIDA DE TORQUE EM EIXOS MECÂNICOS ROTATIVOS

Mário Ricardo Gongora Rúbio & João Dragojevic Bosko

Instituto de Pesquisas Tecnológicas do Estado de São Paulo, DITT, Cidade Universitária, A.S.O., Butantã, CEP - 05508-901, São Paulo, S.P., Brasil. e-mail: gongoram@ipt.br

A low cost, small wireless static and dynamic torque measurement strain gage based instrument was designed and implemented. This approach is specially suited for rotating shafts of ships, industrial & household machines and land vehicles. Strain associated to this measures is often very low, so we propose a method using semiconductor piezoresistor strain gages to obtain higher sensitivity with a simple compensation for apparent strain due to local temperature changes in shaft.

Keywords: Torsion -Measurement, Semiconductor Strain Gages, Telemetry, Temperature Compensation.

 

COB 153 MEASUREMENT OF RESIDUAL STRESSES BY THE INCREMENTAL HOLE-DRILLING TECHNIQUE USING THE TRANSMISSION FUNCTION METHOD

Gerard Chalant, Sylvie Idrissi, Theophile Mehinto

Laboratoire "Mécanique, Matériaux, Environnement", Faculté de Technologie de Guyane Université des Antilles et de la Guyane BP. 792, F-97337 CAYENNE cedex, Guiana Francesa, E-mail : gerard.chalant@univ-ag.fr

Residual stress state may exist in a large variety of mechanical parts of industrial mechanisms and is very common. The origins of this residual stress state are numerous and are mainly due to material elaboration processes and to body part shaping. Residual stress state must be well known in order to be able to make a proper calculation of mechanical resistance of the body part. Several experimental methods exist so that residual stress state determination can be performed. Those methods are surface ones (X-ray diffraction technique) or destructive and restricted to uniform stress states (hole-drilling technique). Methods suitable for determining stress gradient have been derived from hole-drilling technique but usually complex calculations are requested for this purpose. The method presented here is based on a normalized unique experimental strain variation function called Transmission Function. Once determined, this function allows easy step by step calculation of the stress gradient.

Keywords: Residual Stresses, Hole-Drilling Technique, Stress Gradient, Incremental Method, Transmission Function

 

Cob190 DELIMITAÇÃO DO CAMPO DE UTILIZAÇÃO DE UM GERADOR PERIÓDICO DE PRESSÃO / DELIMITATION OF THE FIELD OF APPLICATION OF A PERIODIC PRESSURE GENERATOR

Alberto C.G.C. Diniz, Fernando J. R. Neves & Danilo J. Santos

Departamento de Engenharia Mecânica , Universidade de Brasília, 70910-900 Brasília - DF - Brasil - E-mail: fernando@enm.unb.br

This presents recent results obtained for the characterization of a Periodic Pressure Generator developed for the dynamic calibration of pressure sensors and transducers in the range of up to 35 mbar, using a sinusoidal excitation signal. Continuing previous research on this pressure generator, the calibration procedures, and the dynamic characterization of the pressure generator were now done with the aid of a dynamic signal analyzer. Use of the analyzer showed that the operating range of the generator is larger than the results first presented indicated. On the other hand the reliability of the calibration procedure was increased, while the procedures themselves were simplified by the use of the analyzer.

Keywords: Instrumentação; Calibração; Metrologia Dinâmica; Sensores, Pressão / Instrumentation; Calibration; Dynamic Metrology; Sensors; Pressure

 

COB259 DESENVOLVIMENTO DE UM RADIÔMETRO ELIPSOIDAL DE ALTA SENSIBILIDADE / DEVELOPMENT OF A HIGH-SENSITIVITY ELLIPSOIDAL RADIOMETER

Amaury Roteger De Oliveira

IPT - Instituto de Pesquisas Tecnológicas do Estado de São Paulo S.A. - Divisão de Mecânica e Eletricidade - CEP 05508-901 - São Paulo - SP - Brasil - E-mail: arotger@ipt.br

Jurandir Itizo Yanagihara

EPUSP - Escola Politécnica da Universidade de São Paulo - Departamento de Engenharia Mecânica - CEP 05508-900 - São Paulo - SP - Brasil; E-mail: jiyanagi@usp.br

The main objective of this work is the development of a high-sensitivity and low-cost ellipsoidal radiometer for measurement of total radiation. The ellipsoidal cavity has an appropriate geometry and high-reflectivity surface so that all incident radiation is focused on a hemispheric sensor connected to a differential thermocouple. From the generated thermoelectric voltage it is possible to evaluate directly the incident radiation power through a calibration procedure conducted using a black-body cavity. We achieved a radiometer sensitivity that is three times larger than the similar instruments in the market. It is also worth noting that all material used in this instrument can be purchased anywhere with low cost. The main application for the radiometer is the measurement of total radiation in furnaces and other high-temperature industrial equipments.

Keywords: Thermal radiation, total hemispherical radiation, thermal radiometer, ellipsoidal radiometer, differential thermocouple. Radiação térmica, radiação total hemisférica, radiômetro térmico, radiômetro elipsoidal, termopar diferencial.

 

COB352 CALIBRAÇÃO SEMI-AUTOMÁTICA DE BALANÇAS PARA TÚNEIS DE VENTO EMPREGANDO REDES NEURAIS ARTIFICIAIS/ SEMI-AUTOMATIC CALIBRATION OF WIND TUNNEL BALANCES USING ARTIFICIAL NEURAL NETWORKS

Laurizete s. Camargo & Takashi Yoneyama

Divisão de Engenharia Eletrônica, Instituto Tecnológico de Aeronáutica - ITA

CEP 12.228-900 São José dos Campos - Brasil - e-mail: takashi@ita.cta.br

This work is concerned with a semi-automatic calibration procedure using artificial neural networks for wind tunnel balances. The adopted structure is suited to a large variety of wind tunnel balances, from one to six degrees of freedom. The proposed procedure was applied to a piramidal balance with six components, installed at the windtunnel TA-2 of Centro Técnico Aeroespacial. The estimates of the aerodynamic loading that appear on the test model are obtained directly as the output of an artificial neural network.

Keywords: Neural Networks, Non-Linear Identification, Instrument Calibration , Windtunnel, Balance, Redes Neurais, Identificação Não-Linear, Calibração de Instrumentos, Túnel de Vento, Balança.

 

COB527 wo-Phase Flow Tomography Using a 8-Electrode Electrical Capacitance Sensor

Luiz Felipe Mendes de Moura, Flavio Tambellini & Francisco Antonio Belo*

Departamento de Engenharia Térmica e de Fluidos, Faculdade de Engenharia Mecânica - UNICAMP/FEM CEP 13.083-970 Campinas, Brasil - E-mail: felipe@fem.unicamp.br

*Centro de Tecnologia, Universidade Federal da Paraíba - UFPb/CT João Pessoa, Brasil

This paper describes an electrical capacitance tomography (ECT) system for imaging of two-phase flows. The capacitance sensor was built with eight electrodes around an insulating pipe. In the proposed capacitance measurement system, when an electrode is an emitter, the seven other electrodes are receivers, leading to a parallel reading tomography type. For a 8-electrode sensor, there are 28 independent readings. In order to improve the measurement system time response, a new electronic transducer was developed that supports excitation frequency up to 10 MHz. The proposed ECT system was tested for both stratified and annular air-water flows. A linear back projection algorithm was used to reconstruct the cross section image of the two-phase flow from the measured capacitance values. The reconstructed flow images obtained using this algorithm were compared to the real two-phase flow distributions. Filtering techniques were applied to the back projection algorithm in order to improve the reconstructed flow image quality. Limitations and possible future improvements of this technique are also discussed.

Keywords: Two-phase flow, Tomography, Capacitance sensor

 

COB629 QUALIFICATION TESTS OF THE EMB-145 AIRCRAFT MAIN LANDING GEAR

Ivanil Elisiário Barbosa and Maurício Pazini Brandão

Instituto de Aeronáutica e Espaço - IAE, Centro Técnico Aeroespacial - CTA 12228-904, São José dos Campos, SP, Brazil

pazini@aer.ita.cta.br and

Clóvis Salvador Ribas

Divisão de Equipamentos - EMBRAER-EDE 12237-540, São José dos Campos, SP, Brazil

This paper presents the procedures, solutions and results found during the certification drop tests of the newest EMBRAER commercial aircraft, in order to define the gear dynamic behavior while absorbing and dissipating the airplane landing energy. Combined free drop conditions, referring to different landing weights and vertical sink speeds have been reproduced in the Aerospace Technical Center by using a machine composed by a tower and a drop carriage. The specimen has been attached to the carriage and dropped from different heights to the ground, allowing the assessment of landings of variable severity. The gear attachment has observed the same conditions verified on the actual aircraft assembling. The dynamic characteristics obtained during the tests have been correlated with theoretical drop test curves previously simulated on computer. The results have verified the requirements defined in the Brazilian Airworthiness Certification Regulations and used by the Industrial Fostering and Coordination Institute, the official airworthiness authority.

Keywords: Landing gear, drop test, certification.

 

COB649 SOME COMMENTS ON DISPLACEMENT MEASUREMENTS USING ACCELEROMETERS

Ribeiro, J.G.T.

Materials and Mechanical Engineering Department , IME, CEP 22.290-270 Praça General Tibúrcio 80, Rio de Janeiro, R.J., Brazil

E-.mail: d4jose@epq.ime.eb.br

Castro, J.T.P. & Freire, J.L.F.

Mechanical Engineering Department, PUC-Rio, CEP 22.453-900 R. Marquês de São Vicente 225, Rio de Janeiro, Brazil

E-mail: jtcastro@mec.puc-rio.br & jlfreire@mec.puc-rio.br

Some problems in measuring displacements using analog double integration of acceleration data are discussed in this paper. The main problem in using analog double integration is due to the nonlinear phase response of the double integrator and its transient response that can induce great errors. These errors are unacceptable when the purpose of the measurement is to verify structural integrity, since damage is dependent on the peak and valleys of the waveform. In order to quantify some of these errors, several displacement measurements were made using simultaneously double integration of acceleration data and a LVDT. These results indicate that accelerometers should not be used to measure displacements unless the double integration errors are considered and appropriately corrected.

Keywords: Measurements, accelerometers, displacements, integration/ Medições, acelerômetros, deslocamentos, integração

 

COB662 TRANSDUTOR CAPACITIVO PARA MEDIDAS DE FRAÇÃO DE VAZIO EM ESCOAMENTOS BIFÁSICOS. PARTE I: MODELAGEM E SIMULAÇÃO / CAPACITIVE TRANSDUCER FOR VOLUME FRACTION DETERMINATION IN TWO PHASE FLOW. PART I: MODELING AND SIMULATION.

Mauro Speranza Neto

Departamento de Engenharia Mecânica - PUC-Rio - E-mail: msn@mec.puc-rio.br

This paper shows the dynamic modeling and simulation of a two phase flow capacitive transducer. This device, coupled to AC bridge, is used to flow measurements in petroleum industry and it has good characteristics of electrical sensitivity and low cost. A mathematical model for the capacitive transducer and the complementary electrical circuit was developed and simulated with a commercial simulation program aiming the specification of its components and the analysis of the system behavior under several solicitations.

Keywords: Sistemas Dinâmicos, Instrumentação, Medidores de Vazão, Transdutores Capacitovos, Medidas em Escoamentos Bifásicos. Dynamic Systems, Instrumentation, Flow Meters, Capacitive Transducers, Two Phase Flow Measurements

 

COB663 TRANSDUTOR CAPACITIVO PARA MEDIDAS DE FRAÇÃO DE VAZIO EM ESCOAMENTOS BIFÁSICOS. PARTE II: CONSTRUÇÃO DO PROTÓTIPO E TESTES EXPERIMENTAIS / CAPACITIVE TRANSDUCER FOR VOLUME FRACTION DETERMINATION IN TWO PHASE FLOW. PART II: PROTOTYPE CONSTRUCTION AND EXPERIMENTAL TESTS.

Mauro Speranza Neto1, Jorge Dias Lage2, Marcelo de Albuquerque Lima Gonçalves3 e Cláudio Barreiros da Costa e Silva4

1Departamento de Engenharia Mecânica - PUC-Rio - E-mail: msn@mec.puc-rio.br

2Instituto Tecnológico - PUC-Rio - E-mail: jlage@venus.rdc.puc-rio.br

3 e 4 PETROBRÁS/CENPES - DIPLOTE/SEPROTE - tel: (021) 5986548 - fax: (021) 5986798

This paper shows the construction and calibration procedures of a two phase flow capacitive transducer. This device, coupled to AC bridge, is used to flow measurements in petroleum industry and it has good characteristics of electrical sensitivity and low cost, but it is very sensitive to the ambient pressure and temperature fluctuations and to magnetic fields too. We show how to insulated this transducer and keep it stable under these adverse conditions.

Keywords: Sistemas Dinâmicos, Instrumentação, Medidas de Escoamento, Transdutores Capacitivos, Medidas em Escoamentos Bifásicos. Dynamic Systems, Instrumentation, Flow Meters, Capacitive Transducers, Two Phase Flow Measurements

 

COB890 A LOW-COST PROBE TO MEASURE THREE MEAN VELOCITY COMPONENTS

Marco S. A. Veludo Gouveia, Jorge A. C. Chaves and André L. Amarante Mesquita

Departamento de Engenharia Mecânica, Centro Tecnológico, Universidade Federal do Pará - CEP 66.075-900 Belém - PA, Brasil

E-mail: gtdem@amazon.com.br

This paper presents the development of a low cost multihole probe to measure three dimensional flow-fields. Details of the construction of this probe are presented as well as the material used to construct the probe. The calibration method avoids the difficulties of nulling or pressure balancing, as the flow quantities are related to the hole pressures by calibration. Experimental procedures and results are demonstrated.

Keywords: Flow Measurement / Four-Hole Probe / Five-Hole Probe

 

COB972 SISTEMATIZAÇÃO DA ANÁLISE DE ERROS NA MULTIPLEXAÇÃO AUTOMATIZADA COM TRANSDUTORES PIEZOELÉTRICOS CONVENCIONAIS / SYSTEMATIZATION OF THE ERROR ANALYSIS IN THE AUTOMATED MULTIPLEXATION EMPLOYING CONVENTIONALS PIEZOELECTRIC TRANSDUCERS

Martim Blank1 & Carlos Alberto Flesch2

1 - Departamento de Tecnologia, Universidade Regional do Noroeste do Estado do Rio Grande do Sul, Campus Panambi - UNIJUÍ

Cx. Postal: 14 - CEP 98280-000 - Panambi/RS, Brasil - E-mail: blank@detec.unijui.tche.br

2 - Departamento de Engenharia Mecânica, Universidade Federal de Santa Catarina -UFSC

Cx. Postal: 5053 - CEP 88040-970 - Florianópolis/SC, Brasil - E-mail: flesch@emc.ufsc.br

In this work is presented a systematization of the error analysis due to the multiplexation in conventional piezoelectric transducers. The multiplexation can minimize instrumentation costs, but it is not common in these transducers. In the use of the multiplexation, measurement errors are increased. The analysis of these errors is more complicate because the conventional piezoelectric transducers quantify the output sign in electric charge. In this works is realized an error analysis employing equivalent electrical circuit models and parameters provided by manufacturers. The results demonstrate that the multiplexation can be advantageous but recommendations must be followed.

Keywords: Automed Measurement, Measurement Error, Piezoelectric Transducers, Acceleration Measurement, Multiplexion, Automação da Medição, Erro de Medição, Transdutores Piezoelétricos, Medição de Aceleração, Multiplexação.

 

COB973 ANÁLISE COMPARATIVA ENTRE ERROS METROLÓGICOS DECORRENTES DA MULTIPLEXAÇÃO AUTOMATIZADA OBTIDOS EM ANÁLISES TEÓRICA E EXPERIMENTAL / COMPARISON BETWEEN MEASUREMENT ERRORS FROM THE AUTOMATED MULTIPLEXION OBTAINED IN EXPERIMENTAL AND THEORETICAL ANALYSIS

Martim Blank1 & Carlos Alberto Flesch2

1 - Departamento de Tecnologia, Universidade Regional do Noroeste do Estado do Rio Grande do Sul, Campus Panambi - UNIJUÍ

Cx. Postal: 14 - CEP 98280-000 - Panambi/RS, Brasil - E-mail: blank@detec.unijui.tche.br

2 - Departamento de Engenharia Mecânica, Universidade Federal de Santa Catarina -UFSC

Cx. Postal: 5053 - CEP 88040-970 - Florianópolis/SC, Brasil - E-mail: flesch@emc.ufsc.br

In this work is realized a comparison between results from experimental and theoretical analysis, in the automated multiplexation. In some applications, simultaneous measurements of several mechanical magnitudes is necessary. The multiplexation can reduce instrumentation costs, allowing the use of only one conditioning unit for several transducers. But multiplexers have not ideal behaviour, so measurements errors are introduced in measurement chain. Analysis of these errors is critical due to lack of informations found in bibliography and provided by manufacturers. In this works is realized a theoretical analysis in multiplexers with relay and semiconductor switches. This analysis employed electrical equivalent models and parameters provided by manufacturers. The experimental analysis aimed to measure parameters of instruments and compare them with values supplied by manufacturers. By this way, it is evaluated the suitability of the electrical equivalent models. This works presents the modeling in the usual form and the results of experimental analysis.

Keywords: Data Acquisition Systems, Automated Measurement, Measurement Error, Multiplexation, Experimental Research, Sistemas de Aquisição de Sinais, Automação da Medição, Erro de Medição, Multiplexação, Pesquisa Experimental.

 

COB1278 RESPOSTA DINÂMICA DE SENSORES DE TEMPERATURA ATRAVÉS DO DESMASCARAMENTO EM MEIO LÍQUIDO

João Nildo de S. Vianna, Alessandro Borges de S. Oliveira & Arthur Carneiro Neto

Departamento de Engenharia Mecânica, Universidade de Brasília - ENM-UnB

CEP 70910-900 Brasília - Brasil - E-mail: vianna@enm.unb.br

This work presents a comparative study between two methods for the generation of a step function temperature signal to be used in the dynamic calibration of temperature sensors in liquid. The classic method, in which the sensor is rapidly immersed in a fluid at different temperature, is compared with the unmasking method. In this method the sensor is placed in the fluid, but is isolated from it by a mask pressurized internally. An especially designed rotating tank was used in these tests. The results obtained have shown that, at least for a given type of sensor, the unmasking method presents better results than the immersion method.

Keywords: Calibração Dinâmica, Tempo de Resposta, Sensores de Temperatura, Medição Transiente de Temperatura.

 

COB1341 CONTROLE DE UM MULTIPROGRAMADOR VIA MATLAB / CONTROLING A MULTIPROGRAMMER USING MATLAB

Lourival Pereira de Lima Jr. e Paulo Giácomo Milani

Instituto Nacional de Pesquisas Espaciais, Divisão de Mecânica Espacial e Controle

12.201-970 São José dos Campos, SP. Caixa Postal 515 , fone:(012)325.6181, fax: (012)325.6226, e-mail: milani@dem.inpe.br

This work presents the software for the command of an interface between a Multiprogrammer STD-85MP (a data acquisition system) and the MATLAB software. The communication between the multiprogrammer and the host computer (in this case an IBM-PC) is done through a GPIB bus. Many different routines have been developed, at least one for each kind of multiprogrammer card available. The implemented routines in the form of MEX-files were developed in FORTRAN. The syntax of the commands follows the syntax used in MATLAB. The objective of this implementation is to simplify the development of software for the control of experiments in the Physical Simulation Laboratory of the Space Mechanics and Control Division - DMC of INPE. This tool facilitates the development of software at the same time that it brings the experiment data into the powerful analysis and graphical environment of MATLAB.

Keywords: Physical Simulation, Software, Device Driver, Hardware in the Loop/Simulação Física, Software, Acionador de Dispositivos, Hardware na Malha

 

COB1448 DESENVOLVIMENTO DE UM SENSOR POROSO CAPACITIVO PARA MEDIÇÃO DE UMIDADE NO SOLO / DEVELOPMENT OF A POROUS CAPACITIVE SENSOR FOR MEASURING OF GROUND HUMIDITY

Ramos Pinto, C. A. & Biage, M.

Departamento de Engenharia Mecânica - Universidade Federal de Uberlândia

Campus Santa Mônica - CEP 38400-903 - Uberlândia - MG - E-mail: carlosra@ufu.br

In this study was developed a capacitive sensor to measure the relative water mass present in the soil. The sensor is based in the ground water diffusion into dieletric material, where the capacitance of the sensor is representing the ground relative water mass variation. The low influence of the ground condutivity and temperature in de measurements using this method justify the use of this tecnics. Many geometrical dimensions were used in the preliminary measurement tests and the sensor with the best geometrical characteristics was built. Two sensors were used in the experiments. In the first, the dielectric was built with gypsum and the second with porous stone. These instrumens were experimented and calibrated with a balance to measure the ground relative water mass variation. Plots, for electric tension versus ground relative water mass and capacitance versus ground relative water mass were designed.

Keywords: Ground Humidity (Humidade de solo). Humidity Measurement (Medição de humidade). Capacitive Sensors (Sensor capacitivo). Irrigation (Irrigação). Instrumentation (Instrumentação).

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