Engenharia Mecânica

URI permanente desta comunidadehttps://repositorio.fei.edu.br/handle/FEI/23

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Agora exibindo 1 - 10 de 432

Silício: Abundante, eclético, sofisticado
(2004-01-04) PAPALEO, R.
Incremental root locus and pid tuning
(2006-10-04) GOMES, S. C. P.; Fabrizio Leonardi; DA CRUZ, J. J.
This work discusses the Incremental Root Locus property and one application of it to PID controllers tuning. It is shown that using that property it is easy do determine the departure angle from the real axis, which is a not a trivial task using the classical root locus rules. As an application, a procedure for tuning PID controllers in two steps is shown. Firstly it is necessary to perform a step response test using a proportional controller in order to stabilize the system. In a second step the PID design is performed by a zero-pole canceling. The controller obtained is a two-degree-of-freedom PID controller. Simulations carried out indicate that the controller associated with the setpoint tracking exhibits an almost first-order response whereas the one associated with the disturbance rejection exhibits a more oscillatory response. As illustrations, a real application for a position servo control system and some design projects tested by simulation were done.
Another argument to consider the reliability of the uncertainty Type B similar to Type A
(2006-09-22) BULBA, E. A.; SVOLL, V. R.
The ISO-GUM express that the standard deviation of the experimental standard deviation of the mean q obtained for ratio σ[s(q)]/ σ (q) has a not negligible value for practical values of n, and therefore that Type A evaluations of the standard uncertainty are not necessarily more reliable than Type B evaluations. Although this correct comparison either, the assertion based on the value of the s(q) is the not best, in way that this work to consider other relation as argument for this comparison.
Charge-based continuous equations for the transconductance and output conductance of graded-channel SOl MOSFET's
(2007-01-05) Michelly De Souza; Marcelo Antonio Pavanello
This paper presents charge-based continuous equations for the transconductance and output conductance of submicrometer Graded-Channel (GC) Silicon-On-Insulator (SOI) nMOSFET. The effects of carrier velocity saturation, channel length modulation and drain-induced barrier lowering were taken into account in the proposed equations. Experimental results were used to test the validity of the equations by comparing not only the transconductance and the output conductance, but also the Early voltage and the open-loop voltage gain, showing a good agreement in a wide range of bias.
Exergy analysis of the human respiration under physical activity
(2009-08-30) Cyro Albuquerque; PELLEGRINI, L. F.; FERREIRA, M. S.; YANAGIHARA, J. I.; OLIVEIRA, S. DE.
© 2009 by ABCM.This paper presents an exergy analysis of the human body under physical activity. A model of the respiratory system and a model of the thermal system were used for this purpose. They consider heat and mass transfers in lungs, tissues and blood. Each component of those models is represented by an uniform compartment governed by equations for diffusion, convection, O2 consumption, CO2/heat generation and heat and mass transfer with the environment. The models allow the calculation of the exergy destruction in the lung and tissues, and the participation of each entropy generation mechanism in the total generation. Furthermore, a discussion is proposed regarding the efficiency of the human body under physical exercise.
Integrated manufacturing laboratory and software tools applied to an industrial engineering undergraduate course
(2009-03-23) Fabio Lima; PRADO, A. C.; Alexandre Augusto Massote; Fabrizio Leonardi
This paper describes the experience of using software tools associated with an integrated manufacturing laboratory in an industrial engineering undergraduate course at FEI (Fundacao Educacional Inaciana, Brazil). The integrated manufacturing laboratory has got three complete manufacturing cells integrated by computer. The aim of the laboratory is to provide to the industrial engineering student a powerful analysis capability of how to use these kinds of systems to improve product quality and production performance. To do that, computational models are implemented using software tools like Visual Object Net++, Promodel® and WEB support. Finally, the models are validated in laboratory experiments. It was observed that such strategy has been given excellent learning results.
Modeling heat transfer in human arm and forearm: Effect of countercurrent heat exchange and superficial veins
(2009-06-25) FERREIRA, M. S.; YANAGIHARA, J. I.
Residual compressive stresses applied due to shot peening process in the Ti 6al 4v alloy
(2010-07-26) LAVOR, P. R. U.; MOURA-NETO, C. DE; Sergio Delijaicov; DE CAMPOS, V. S.
The objective is to measure the residual stresses in the Ti 6Al 4V alloy due the shot peening process. The specimens were manufactured in the conditions: 1st machined without Shot Peening; 2nd machined and submitted to Shot Peening in the range: 0,13 N(mm) - 0,46 N(mm); 3rd Machined and submitted to Shot Peening in the range: 0,15 A(mm) - 0,25 A(mm). The residual stresses were measured through the incremental hole drilling technique and the data obtained in a graphic form and are important for stress analysis in order to verify the influence of the residual stresses in the fatigue life. The graphics show the curves of the compressive tensions through the thickness of the three conditions studied and herein follows an idea of the obtained measurements: 1st Machined test specimens without shot peening application: residual compressive stresses of 200 MPa. 2 ndMachined test specimens and submitted to Shot Peening application in the range: 0.13 N(mm) - 0.46 N(mm): Residual Compressive Stresses of 500 MPa. 3rd: Machined test specimens and submitted Shot Peening application in the range: 0.15 A(mm) - 0.25 A(mm): Residual Compressive Stresses of 1000 MPa.
Plastic eta factors to determine experimental J-integral and ctod using homogeneous and mismatched SE(T) specimens
(2010-07-26) MOREIRA, F. C.; OLIVEIRA, G. P. DE; Gustavo Donato
This work presents procedures for experimental estimation of J - integral and CTOD (d) using the eta (h) method and SE(T) specimens in clamped and pin-loaded conditions. Homogeneous materials and also specimens containing mismatched welded joints are considered. The conceptual background is presented, followed by the details of the various finite element models developed for the analyses. As results, are presented h factors for J and CTOD experimental estimation. The main objective is to allow fracture toughness experimental evaluation using SE(T) specimens to reduce the conservatism in integrity assessments of pipelines and pressure vessels, which present very similar fracture conditions. Consequently, the results contribute for a better understanding of SE(T) specimens and encourage further developments since they are not available in current standards.
Investigation of residual stress in laser welding dissimilar materials Investigação da tensão residual na soldagem laser de mate riais dissimilares
(2010-07-26) MIRIM, D. DE C.; BERRETTA, J. R.; ROSSI, W. DE; LIMA, N. B. DE; OLIVEIRA, R. R. DE; Sergio Delijaicov; GOMES, D. O.
One of the most critical problems found in the different materials welding is the residual stress formation, that happens mainly for the fact of those materials they possess coefficients of thermal expansion and different thermal conductivities. Like this in this work the residual tension was evaluated in the technique of welding laser among the steel low carbon, AISI 1010 and AISI 304. The materials were united for it welds autogenous of top with a laser of continuous Nd:YAG in that they were varied the potency, speed and the focus of the laser stayed constant in relation to surface of the sample. The main objective of the study went identification and to analysis of the residual stress in HAZ on both sides of seem. Um planning factorial of two factors at two levels each it was executed for optimization the combination of the factors potency and speed. The obtained answers were the residual stress in different depths in HAZ. In the surface of the sample measures of residual stress were accomplished by the technique of X-ray difraction. The hole drilling strain gage method it was applied to measure the residual stress on both sides of the union. The results were analyzed using the variance analysis and the statistical regression based on the different influences of the entrance and combination of the factors in the residual stress generated in that union. The results indicate that the development of models can foresee the answers satisfactorily.

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