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COB21 MODELAGEM E SIMULAÇÃO DO FENÔMENO DE ENDURECIMENTO POR PRECIPITAÇÃO EM BARRAS DE ALUMÍNIO/MODELING AND SIMULATION OF PRECIPITATION HARDENING PHENOMENON IN ALUMINIUM BARS

Cláudia Maria Imbroizi Ajús & Heraldo S. Costa Mattos

Laboratório de Mecânica Teórica e Aplicada, Departamento de Engenharia Mecânica, Universidade Federal Fluminense - UFF, CEP 24.210-24 Niterói / RJ, Brasil - E-mail:heraldo@caa.uff.br

The present work is concerned with the modeling of the coupling between the aging hardening phenomenon and the elasto-plastic behavior in aluminium bars. Such a microstructural process, caused by the diffusion of precipitates in the solid matrix, has a very strong influence on the yield stress, affecting the hardening behavior. The plastic deformation, on the other side, affects the velocity of precipitation (aging). The coupling between these phenomena is described through a constitutive theory in which an additional variable, related with the parcel of the isotropic hardening caused by aging, is introduced. To check the potentiality of the proposed theory, examples concerning 2024 aluminium bars are presented and analyzed, showing a good agreement between experiments and model prevision.

Keywords: Elasto-plasticity, aluminium-copper alloys, age hardening, precipitation hardening / elastoplasticidade, ligas de alumíno - cobre, envelhecimento, endurecimento por precipitação.

COB98 SELEÇÃO DE ESTADOS EM REDUÇÃO DE MODELOS COM REALIZAÇÃO BALANCEADA / STATES SELECTION IN MODEL REDUCTION VIA BALANCED REALIZATION

Edvaldo Assunção¹, Pedro L. D. Peres², Paulo A. V. Ferreira² & Elder M. Hemerly³

¹Departamento de Engenharia Elétrica, Faculdade de Engenharia - UNESP - Ilha Solteira

CEP 15.385-000 Ilha Solteira, SP, Brasil - E-mail: edvaldo@dee.feis.unesp.br

²Departamento de Telemática, Faculdade de Engenharia Elétrica e de Computação - UNICAMP

CP 6101, CEP 13.081-970 Campinas, SP, Brasil - E-mail: {peres,valente}@dt.fee.unicamp.br

³Instituto Tecnológico de Aeronáutica - CTA - ITA - IEEE

CEP 12228-900, São José dos Campos, SP, Brasil - E-mail: hemerly@ele.ita.cta.br

This work evaluates the performance of two different techniques for selecting the states to be maintained in the reduced model obtained through balanced realization. The model reduction method via balanced realization is presented, and a criterion that takes into account the reduced model impulse response is proposed. The main advantage of this criterion is that it considers not only the singular values, but also the coefficients of the dynamic system output matrix. An example is presented, indicanting the better performance of proposed criterion when compared with the classsical one adopted in the balanced realization.

Keywords: sistemas dinâmicos, redução de modelos, realização balanceada, resposta ao impulso / dynamic systems, model reduction, balanced realization, impulse response.

COB160 HEAT TRANSFER COEFFICIENT AT THE METAL-MOULD INTERFACE IN THE SOLIDIFICATION OF Cu-8%Sn ALLOYS

Marcelo de Aquino Martorano & José Deodoro Trani Capocchi

Departamento de Engenharia Metalúrgica e de Materiais - Escola Politécnica - USP - São Paulo - CEP 05508-900 Cidade Universitária, São Paulo, Brasil - E-mail: martoran@usp.br , jdtcapoc@usp.br

The heat transfer coefficient at the metal-mould interface during the directional solidification of a Cu-8%Sn alloy was calculated using the whole domain method for the inverse solution of the heat conduction differential equation. The finite control volume method was employed in the numerical procedure to solve the two dimensional differential equation and a least squares procedure was used for the whole domain method. The estimated heat transfer coefficient values are in good agreement with published ones and a sensitivity analysis is carried out to assess the coefficient accuracy. The present method has proved to be satisfactory as regards stability and accuracy.

Keywords: Heat transfer coefficient; Inverse heat conduction; Mathematical modelling; Metal-mould interface; Solidification.

COB189 UTILIZAÇÃO DA DECOMPOSIÇÃO DE VALOR SINGULAR NA REDUÇÃO DO NÍVEL DE RUÍDO EM SÉRIES TEMPORAIS / NOISE REDUCTION IN TIME SERIES BY USING SINGULAR VALUE DECOMPOSITION

Heraldo Nélio Cambraia

Departamento de Mecânica - Centro Politécnico - UFPR, CEP 81531-990 - Curitiba - PR - E-mail: heraldo@demec.ufpr.br

This work shows how Singular Value Decomposition (SVD) can help to reduce the level of Gaussian white noise in time series. The procedure here employed consists of using a dynamic to the data by means of an embedding in an Euclidian space, and information about this dynamic are organized in the so called trajectory matrix. The questions about the dimension and noise reduction can be discussed by studying the rank of the trajectory matrix, and the question about the rank of the trajectory matrix by SVD.

Keywords: Noise reduction, dimension, singular value decomposition.

COB200 VIBRAÇÕES INDUZIDAS PELO DESBALANCEAMENTO DE UM VENTILADOR CENTRÍFUGO, SOB INFLUÊNCIAS DE UMA FUNDAÇÃO EMBUTIDA E DOS MANCAIS COM FILME DE ÓLEO / FOUNDATION AND JOURNAL BEARINGS CONSIDERATIONS IN THE VIBRATION INDUCED BY UNBALANCED CENTRIFUGAL FAN.

Luciana Raquel C. da Silva, Alexandre Augusto Simões

Departamento de Engenharia Mecânica, Escola Federal de Engenharia de Itajubá - EFEI - Itajubá CEP 37.500.000, Brasil - E-mail: simoes@iem.efei.rmg.br

This paper presents a simplified dynamic interaction analysis of a fan supported by journal bearings and its foundation. The interaction changes the rotor-bearing critical speed and so the fan manufacturer may specify the foundations requirements or an improper foundation would result. The same will occur to the predicted resonance frequencies to the foundation-soil interaction. So this procedure can help the understanding between the fan manufacturer and the designer of the foundation. The simplified model is of minimal time consuming and is convenient during the early project. The bearing data, obtained from computerized solutions of the lubrication equations, and the soil dynamics data are used as input to the model. The unbalance response of the entire system is consider as measured at the bearings.

Keywords: ventilador, mancal, fundação, foundation, fan.

COB208 CÁLCULO DE FORÇAS EM MANCAIS MAGNÉTICOS COMPARAÇÃO DE RESULTADOS / FORCE CALCULATION IN MAGNETIC BEARINGS - COMPARISON OF RESULTS

Márcio Feres Bessa & Roberto Firmento de Noronha

Universidade Federal Fluminense - Departamento de Engenharia Mecânica

Rua Passo da Pátria, 156 - C.E.P. 24.210-240 - Niterói - RJ - BRASIL - E-mail: rnoronha@rionet.com.br

Magnetic bearings have been regarded as a very good alternative for the support of rotors in various industrial branches, where some of their special characteristics have helped to solve problems in pre-existent tecnologies and arising new ones. The modeling of magnetic field in these bearings furnishes the correlation between the rotor support forces and the winding current and allows for an improved simulation and design of the device and its control system. Comparisons between finite element analysis, analytical and experimental results are presented.

Keywords: Mancais Magnéticos, Mapeamento de Campo, Forças de Sustentação do Rotor, Elementos Finitos /

Magnetic Bearings, Field Modeling, Rotor Support Forces, Finite Elements

COB360 UM MODELO PARA A PREVISÃO DAS TENSÕES RESIDUAIS iNTRODUZIDAS PELO Processo de Têmpera em Aços A MODEL To PREDICT RESIDUAL STRESSES INTRODUCED BY THE QUENCHING PROCESS IN STEELS

Pedro Manuel Calas Lopes Pacheco, Sérgio De Almeida Oliveira

Departamento de Engenharia Mecânica - COCPG, CEFET/RJ, 20.271.110, Rio de Janeiro, RJ - E-Mail: calas@cefet-rj.br

Arnaldo Freitas Camarão

Rockwell Automotive - Braseixos - Engenharia de Desenvolvimento, Av. João Batista 824 - 06.097-900, Osasco, SP

E-Mail: AFCAMARA@auto.rockwell.com

Marcelo Amorim Savi

Departamento de Engenharia Mecânica e de Materiais, Instituto Militar de Engenharia, 22.290.270, Rio de Janeiro, RJ

E-Mail: d4savi@epq.ime.eb.br

Quenching is a process associated with phase transformation. It generates internal stresses, which can produce warping and even cracking the body. Hence, it is very important to develop an analysis that permits predictions of internal stresses in steel during quenching. Two types of modification occur when phase transformation takes place under an applied stress. The first type is a kinetic modification and sometimes leads to a different morphology in the phase produced. The second is a mechanical modification related to the progress of transformation, and takes place when plastic deformation occurs under stresses lower than material yield stress. For mechanical modeling, metallurgical and mechanical upsetting of the metal must be incorporated into the model along with the effect on the stresses appearing during cooling. Current work discusses the quenching modeling in uniaxial context. Thermomechanical coupling is considered. A numerical procedure is developed and some numerical results are presented.

Keywords: Quenching, Residual Stresses, Elastoplasticity, Modeling. / Têmpera, Tensões Residuais, Elastoplasticidade, Modelagem.

COB371 A NON-EXPLOSIVE RELEASE DEVICE FOR AEROSPACE APPLICATIONS USING SHAPE MEMORY ALLOYS

Pedro Manuel Calas Lopes Pacheco

Departamento de Engenharia Mecânica, CEFET/RJ, 20.271.110, Rio de Janeiro, RJ - E-Mail: calas@cefet-rj.br

Marcelo Amorim Savi

Departamento de Engenharia Mecânica e de Materiais, Instituto Militar de Engenharia, 22.290.270, Rio de Janeiro, RJ

E-Mail: d4savi@epq.ime.eb.br

Aerospace applications use pyrotechnic devices with many different functions. Functional shock, safety, overall system cost issues, and availability of new technologies, however, question the continued use of these mechanisms on aerospace applications. Release device is an important example of a task usually executed by pyrotechnic mechanisms. Many aerospace applications like satellite solar panels deployment or weather balloon separation need a release device. Several incidents, where pyrotechnic mechanisms could be responsible for spacecraft failure, have been encouraging new designs for these devices. The Frangibolt is a non-explosive device which comprises a commercially available bolt and a small collar made of shape memory alloy (SMA) that replace conventional explosive bolt systems. This paper presents the modeling and simulation of Frangibolt. This analysis may contribute to improve the Frangibolt design.

Keywords: Shape Memory Alloys, Aerospace Applications, Release Device, Frangibolt.

COB654 MODELAGEM PARALELA E DISTRIBUIDA DE SÉRIES TEMPORAIS EM SUBESPAÇOS DO ESPAÇO DE ESTADO / PARALLEL AND DISTRIBUTED MODELING OF TIME SERIES IN SUBSPACES OF THE STATE SPACE

Celso Pascoli Bottura Y, Gilmar Barreto Y, Maurício José E. Bordon1& José E. Tarcisio Costa Filho²

¹ Faculdade de Engenharia Elétrica e Computação, Universidade Estadual de Campinas

UNICAMP, Campinas, Brasil, gbarreto@fee.unicamp.br.

² Departamento Engenharia Elétrica - Universidade Federal do Maranhão, São Luís , Brasil., tarcisio@ufma.br

In this paper a procedure using a subspace method developed by Aoki (1990) for multivariate time series state space modeling high performance computing is proposed. The resulting algorithm allows the obtention of the triple of matrices (A; B and C), for the state space model for multivariable time series, using singular value decomposition of the Hankel matrix, obtained from data of the time series we intend to model. This contribution aims the viabilization of applications to large scale systems needing real time multivariate time series modeling.

Keywords: State space, time series, identification, modeling, state estimation. Espaço de estado, séries temporais,

identificação, modelagem, estimação de estado.

COB701 Modeling of pig motion under transient fluid flow

Eijiro Vianes Campo & Felipe Bastos De Freitas Rachid

Departamento de Engenharia Mecânica, Universidade Federal Fluminense

24210-240 - Niterói - RJ - Brazil - E-mail: rachid@caa.uff.br

This paper presents a very simple, from the mechanical and mathematical viewpoints, model to predict pig motion driven by transient incompressible fluid flows. Mechanical and hydrodynamical friction forces, inertia effects of both pig and fluid, operational characteristics of equipment installed in the line as well as other features are properly taken into account. Numerical simulations carried out for a representative problem illustrate the model capability of describing some non-trivial peculiar behaviors related to pig motion.

Keywords: Pig Motion Modeling; Transient Regime; Incompressible Flow.

COB851 REPRESENTAÇÃO DA INTERAÇÃO ENTRE ELEMENTOS FLEXÍVEIS E RÍGIDOS NO PROBLEMA DA DINÂMICA DE ROTORES / REPRESENTATION OF THE INTERACTION BETWEEN FLEXIBLE AND RIGID ELEMENTS IN THE ROTOR DYNAMIC PROBLEM

Fernando Ribeiro da Silva & Carlos Frederico Pacheco Furtado

Departamento de Engenharia Mecânica e de Materiais - Instituto Militar de Engenharia

CEP 22290-270 Rio de Janeiro, Brasil - E-Mail: d4fernan@epq.ime.eb.br

The rotor dynamics problems have been developed using the classical methodologies of the structural analysis (the Finite Element Method) with the procedures of the rigid body dynamic. In this work we use an alternative procedure with the generalized technique of Bond Graphs, presenting advantages like modularity and facility to obtain the mathematical model of the global system. We present some results for a typical problem of the rotor dynamics.

Keywords: Rotor dynamics, Dynamic Systems, Bond Graphs / Dinâmica de Rotor, Sistemas Dinâmicos, Grafos de Ligação

COB864 A LOOP-BASED DATA STRUCTURE FOR B-REP SOLID AND WIREFRAME MODELS

Angelo Roncalli O. Guerra, *S.Hinduja & *P T Ling

Departamento de Engenharia Mecânica, Universidade Federal do Rio Grande do Norte - UFRN- PPGEM

CEP 59072-970, Campus Universitário, CT-DEM, Natal-Rn, Brazil - E-mail: ang@ct.ufrn.br

(*) Co-authors from the Department of Mechanical Engineering, UMIST, Manchester, UK.

This paper describes a data structure for representing objects in the B-rep form. The data structure is loop centred, rather then edge centred. Its highlight is the achieved reduction in storage cost when compared with current enhanced edge-based implementations and yet being able to represent non-polyhedral objects efficiently. Since the edges in a loop are explicitly stored, face traversals are relatively straight-forward. The loop based data structure can also represent 2D wireframe based objects. This data structure has been used as the heart of TTM (Techturn Techmill Modeller) which is an academic solid modeller developed for two very large technologically oriented CAPP systems already published in the literature.

Keywords: Data Structure , Solid Modelling, CAD/CAM.

COB871 DINÂMICA DE VEÍCULOS COMERCIAIS COM SUSPENSÃO DO TIPO PIVOTAMENTO OSCILANTE E TRAÇÃO 6X4 / DYMAMIC OF COMMERCIAL VEHICLES WITH WALKING-BEAM SUSPENSION AND 6X4 TRACTION SYSTEM

Antônio Carlos Canale

USP - EESC, São Carlos - SP, Brasil - E.mail: canale@sc.usp.br

Hélio Aparecido Navarro

UNESP - IGCE - DEMAC, Rio Claro - SP - E.mail.:helio@demac.igce.unesp.br

Nicolas Basile Valtas, José Roberto Saraiva & José Eduardo D’Elboux

Mercedes-Benz do Brasil S.A., São Bernardo do Campo-SP, Brasil

The aim of this paper is to analyse the response of the commercial vehicle to the forces produced by the transmission system. The calculation model for the ideal distribution of the driving force is presented for bus, truck and tractor-trailer combinations. For the tractor, the forces acting on an accelerating vehicle in case of three-axle with walking beam suspension are considered. The proposed model considers the resistance forces (drag, rolling resistance, translation and rotation acceleration, climbing resistance) and traction system 6x4. The center of gravity of the vehicle, the dynamic driving forces, the dynamic axle load and the resistance forces are determined. This work analyses one of the Mercedes-Benz do Brasil trucks with traction system 6x4. The comparison of ideal and real distribution of driving forces and tire-road friction utilization are presented.

Keywords: Veículos rodoviários comerciais, modelagem, métodos numéricos em engenharia, suspensão do tipo pivotamento oscilante./ Road commercial vehicles, modeling, numercial methods in engineering, walking-beam suspension.

COB1016 CÁLCULO DE SISTEMAS DE AQUECIMENTO POR INDUÇÃO PELO MÉTODO DOS CIRCUITOS MUTUAMENTE ACOPLADOS / MUTUALLY COUPLED METHOD FOR THE CALCULATION OF INDUCTION HEATING SYSTEMS

Maysa Nunes Alves

Departamento de Engenharia Elétrica, Faculdade de Engenharia , UNESP, Guaratinguetá CEP 12500-000 Guaratinguetá–SP, Brasil - E-mail: maysa@feg.unesp.br

This paper deals with a numerical method based on the couples equivalent circuit for the calculation of axially symmetric induction heating systems. Using a procedure for the calculation of the self and mutual inductances, it is possible to calculate the currents, even in the case of complex configurations and with no limits on the choice of the subdivision elements.

Keywords: Tratamento térmico; Indução; Método de Cálculo / Heat Treatment, Induction, Calculation Method

COB1214 SIMULAÇÃO NUMÉRICA DO COMPORTAMENTO DE "PUFFS" PARA REPRESENTAR A DISPERSÃO DE GASES PESADOS NA ATMOSFERA / NUMERICAL SIMULATION OF BEHAVIOUR OF PUFFS FOR REPRESENT THE ATMOSPHERIC DISPERSION OF DENSE GASES

Edson Abel dos S. Chiaramonte e César Antônio Leal

Programa de Pós-Graduação em Engenharia Mecânica, UFRGS

CEP: 90410-001, Porto Alegre / RS, Brasil, AV.Protásio Alves, 1187/ Apt. 02

E-mail:edsonchi@ufrgs.vortex.br

The releases of the heavy gases at ground level into the atmosphere can have all kinds of behaviour, that is a release can be instantaneous, continuos or intermitent. In this paper is showing a simple model, that can describe these all kinds of releases.The releases continuos or intermitent are represented in the model as sucession of instantaneous releases (the puff model). This puffs are sumed up and combined to form continuous or intermitent releases. The heavy gas puff is represented by a bulk mathematics model as a cylinder of heavy gas with homogenous properties profiles of the speed, temperature and density (the composition of puff) in his interior (box model). The puffs sum and combination process is showing for representation of a heavy gas continuos release with constant rate. In the later of the paper the numerical results obtain with the model are compared with the field experimental data available in the literature for continuos releases of the liquefied natural gas (LNG) and the liquefied petroleum gas (LPG).

Keywords: Gases pesados, dispersão atmosférica, excesso de densidade, modelo de "puff"

COB1250 SIMULAÇÃO NUMÉRICA DE PROCESSOS EM FORNALHAS PARA SECAGEM DE GRÃOS / NUMERICAL SIMULATION OF THE PROCESS OF FURNACE DRYING CEREALS

Viktor Krioukov, Sérgio Dalepiane, Lecir Dalabrida

Departamento de Física, Estatística e Matemática - UNIJUI - Ijuí, RS, CP 560 CEP 98.700-000 Ijuí,RS

E-mail: kriukov@super.unijui.tche.br

The mathematical model, developed by the autors in previous works, aplly to prevent the furnace main features of drying cereals, depending on the functioning regime parameters. The comparison was done with experimental data and the process features behavior were explained. The possibility to prevent the abnormal regime is showed and also its explanation.

Keywords: Furnace, Modelling, Combustion, Heat Transfer, Hydraulic loss / Fornalha, Modelagem, Combustão, Transferência de Calor, Perdas Hidráulicas

COB1504 CONSTRUCTAL THEORY: FROM ENGINEERING TO SHAPE AND STRUCTURE IN NATURE

Adrian Bejan

J.A. Jones Professor of Mechanical Engineering, Duke University, NC 27708-0300, USA, no e-mail

This is a review of two new and important developments in thermal science. First, there exist fundamental optima in the constitution and operation of flow (non-equilibrium) systems, man-made and natural. These optima can be identified based on the simplest models that still retain the essential features of the real system. Examples are the spatial allocation of heat transfer area in a power plant, and the temporal optimization of on & off processes. The second development is that the engineering method of modeling and optimization has been extended to natural systems, animate and inanimate (e.g. tree networks). This step has been named constructal theory for reasons given in Section 3. The objective of such work is to predict the macroscopic spatial and temporal structure (organization) that is everywhere. It is to inject a dose of determinism (theory) in a field that until recently considered natural structures to be non-deterministic: results of chance and necessity. These developments bring to mind the advice left to us by J. W. Gibbss more than one hundred years ago:

"One of the principal objects of theoretical research in any department of knowledge is to find the point of view from which the subject appears in its greatest simplicity".

Keywords: Constructal, Fractal, Self-organizing, Non-equilibrium thermodynamics.