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COB466 ANÁLISE DE EFEITOS COMBINADOS DE ATRITO E RESTITUICÇÃO NÃO LINEAR EM ROTORES / COMBINED EFFECT ANALYSIS OF CUBIC STIFFNESS AND DRY FRICTION ON A NONLINEAR ROTOR

I. L. E. Santo & K. L. Cavalca & J. M. Balthazar

Dep. de Projeto Mecânico, Fac. de Engenharia Mecânica - UNICAMP

CEP 13083-970 Campinas, Brasil - E-mail: ivanlima@dpm.fem.unicamp.br

The nonlinear analysis of a simple Laval Rotor with a non ideal power source crossing its resonance under a Coulomb dry friction action and cubic restoring force of the shaft is done. Dynamical changes on the system response are observed through numerical integration in the case of strong nonlinearity and through average method in the case of weakly nonlinearity. Some important constitutive request appear from the studies of the behavior. One could verify that after critical speed the dry friction works as a damping force while the restoring force drives the oscillation to be unpredictable.

Keywords: rotor, perturbação, método da média, restituição cúbica, atrito seco, rotor, perturbation, average

method, cubic stiffness, dry friction.

COB745 MODELOS REDUZIDOS DA CONVECÇÃO DE RAYLEIGH-BÈNARD / LOW-ORDER MODELS FOR RAYLEIGH-BÈNARD CONVECTION

Miriam Maria de Resende & Paulo Ignácio Fonseca de Almeida

Departamento de Engenharia Química -UFSCar - São Carlos - CEP: 13565-905 São Carlos, SP, Brasil

E-mail: pignacio@power.ufscar.br

Since Lorenz’s model for two dimensional Rayleigh-Bènard flow in atmosphere, it has been proposed several low-order models for representing the fluid cellular motion. The present work is a revision of the main low-orders models published. A methodology for the strange attractors simulations in two of then is presented. The bifurcation diagrams based in Nusse & Yorke(1994) method for dynamics explorations is also developed and the evolution of the temperature and stream function fields are related by level curves obtained from the model. The good quality of the graphics results is a credit for going on the methodological numerical investigation.

Keywords: Modelos dinâmicos reduzidos, escoamento Rayleigh-Bènard/ Dynamics low order models, Rayleigh-Bènard flow