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COB95 ANÁLISE DAS CAUSAS DO APARECIMENTO DE TRINCAS NA CARROCERIA DE UM TREM METROPOLITANO / CAUSES OF STRUCTURAL CRACKS IN A METROPOLITAN TRAIN

Francisco Gastal, Dario Klein e João Campagnolo

Laboratório de Ensaios e Modelos Estruturais (LEME) do Curso de Pós Graduação em Engenharia Civil (CPGEC) da Universidade Federal do Rio Grande do Sul (UFRGS) - Porto Alegre - RS - Brasil - E-mail: LEME10@VORTEX.UFRGS.BR

This work presents the results of a numerical and experimental study on the fixing region of the anchor of the traction system for the metropolitan trains of Porto Alegre. The study is part of an investigation to elucidate the causes of structural cracks detected in the mentioned region. The methodology used in the complete study, statical and dynamic numerical analysis and tests and a fracture analysis of the cracked region, are described. The experimental tests, obtained with the instrumentation of the component parts of the traction system, allow the evaluation of the behaviour of the structure when submitted to loads representing passengers and vehicle traction forces. The results of the static and dynamic tests were used as information for the numerical analyses.

Keywords: Train anchor system, Numerical analysis, Experimental Tests, Structural Cracks. / Sistema de Tração, Análise Numérica, Análise Experimental, Trincas Estruturais, Trem Metropolitano.

COB465 ANÁLISE DE SENSIBILIDADE E OTIMIZAÇÃOAO ESTRUTURAL EM PROBLEMAS ELASTOSTÁTICOS LINEARES / SENSITIVITY ANALYSIS AND STRUCTURAL OPTIMIZATION OF LINEAR ELASTIC PROBLEMS

Cláudio A. de Carvalho Silva & Marco Lúcio Bittencourt

Departamento de Projeto Mecânico, Faculdade de Engenharia Mecânica - UNICAMP

CEP: 13083-970 Campinas/SP - Brasil -- E-mail: mlb@fem.unicamp.br

Structural optimization has features, such as high structural analysis and gradient evaluation costs besides the intense flux of data between analysis and optimization codes, that make it more complex than common mathematical programming problems. This work shows an interior point optimization algorithm and the continuous formulation of the sensitivity analysis taking into account those features, implemented using object-oriented programming tecniques.

Keywords: Optimization, sensitivity analysis, finite elements, object-oriented programming, C++, otimização, análise

de sensibilidade, elementos finitos, programação orientada por objetos.

COB483 On the Modeling and Dynamics of Flexible Slewing Structures. II: Some Comparisons Between Small and Large Deflections ( Contributions )

André Fenili ⁽¹⁾ , José M. Balthazar ⁽²⁾ , Dean T. Mook ⁽³⁾ & João M. Rosário ⁽¹⁾

( 1 ) Department of Mechanical Design of the Faculty of Mechanical Engineering - UNICAMP

POBOX 6122 - 13800-970 - Campinas - SP - Brazil

( 2 ) Department of Applied Mathematics of the State University of São Paulo - UNESP

POBOX 178 - 13500-200 - Rio Claro - SP - Brazil

( 3 ) Department of Engineering and Sciences and Mechanics - VPI&SU - Blacksburg , VA, 24060, USA

In this work is studied the dynamical behavior of flexible structures in slewing motion. Nondimensional equations of motion are obtained for large deflections. A small parameter appears multiplying the nonlinear terms in the equations of motion, so the influence of the nonlinerities in the system behavior can be verified. We also analysed the differences between the contributions of small and large deflections nonlinearities on the dynamics of slewing flexible structures. The known Crespo da Silva and Glynn theory for flexible beams is obtained from the one discussed here making some particularizations.

Keywords: Slewing Flexible Structures, Assumed Modes Method, Large Deflections, Small Parameter, Nonlinear Oscillations.

COB624 A DOMAIN DECOMPOSITION METHOD FORSTRUCTURAL DYNAMIC PROBLEMS

Alexandre Santos Hansen & Fernando Alves Rochinha

Mechanical Engineering Department, EE-COPPE-UFRJ, Cx. Postal 68503, CEP 21945-970, RIO DE JANEIRO-BRAZIL

We present , for structural dynamic problems, a Domain Decomposition method based on an augmented Lagrangian formulation. This method uses the Inexact Uzawa algorithm to solve the linear system required at any time increment. A three dimensional elasticity dynamic problem is solved by the method and the number of iterations is compared witli the unpreconditioned FETI method.

Keywords: domain decomposition; dynamics; inexact uzawa; parallel processing.

COB1153 OTIMIZAÇÃO ESTRUTURAL DE PRENSAS EXCÊNTRICAS EM "C" / STRUCTURAL OPTIMISATION OF "C" SHAPED EXCENTRICAL PRESSES

Paulo Carlos Kaminski

Departamento de Engenharia Mecânica, Escola Politécnica da USP - São Paulo - Av. Prof. Mello Moraes, 2231 - CEP 05508-900 - São Paulo - Brasil - e-mail: pckamins@usp.br

This paper reports the structural optimisation made on C-Shaped Excentrical Presses done together with a private enterprise. Its focus is practical and not theoretical and the criterion used on the optimisation was the minimisation of structure building costs of the press, including the reduction of the material (steel) and the elimination, as far as possible, of the components which were difficult to build. The first step was the development of a simplified model in order to define the main stresses the press is exposed to. Then, a global model of finite elements was made. This model was "validated" by experimental data of displacement, press opening. From the global analysis, regions with the highest levels of stress/deformation were identified and local models of finite elements were created for them. From these models, several alternatives of changes were analysed searching an standardisation of the stress levels and the elimination of the components that were hard and costly to be built. The result achieved was satisfactory, mainly in terms of rationalisation of the components, which will be built without losses in the efficiency of the press, offering a world level competitive advantage to the enterprise involved with the project.

Keywords: mechanical press, structural optimisation, finite elements / prensa mecânica - otimização estrutural - elementos finitos - solicitações

COB1508 VIRTUAL MEASUREMENTS IN EXPERIMENTAL STRUCTURAL ANALYSIS

Randall J. Allemang, PhD

Structural Dynamics Research Laboratory (UC-SDRL), University of Cincinnati

Cincinnati, Ohio 45221-0072, U.S.A. E-Mail: Randall.Allemang@UC.EDU

One of the most interesting advances in experimental structural analysis over the past twenty years is the extensive use of linear transformations to formulate virtual measurements. Simply stated, virtual measurements are linear transformations of physical measurements where certain characteristics of the data are preserved or enhanced. In experimental structural analysis, virtual measurements result from linear transformations that are based upon theoretical estimates of the modal vectors, experimental estimates of the modal vectors and/or vectors derived from singular value decomposition (SVD) or eigenvalue decomposition (ED) of analytical or experimental information. Principal force analysis, the enhanced frequency response function (eFRF) and Kalman filtered order tracking are discussed as examples of the use of virtual measurements in experimental structural analysis.

Keywords: Virtual, Measurements, Experimental, Structural, Analysis