Banca de QUALIFICAÇÃO: Nicolas da Silva Dias

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : Nicolas da Silva Dias
DATE: 28/07/2023
TIME: 14:00
LOCAL: Sala da reuniões do ENM
TITLE:

ANALYSIS AND CONTROL OF TORSIONAL VIBRATIONS IN RECIPRO- CATING COMPRESSORS IN THE PRESENCE OF NONLINEARITIES

KEY WORDS:

torsional vibration, vibration attenuation, rainbow metastructures, recipro-cating compressor.

PAGES: 81
BIG AREA: Engenharias
AREA: Engenharia Mecânica
SUMMARY:

Torsional vibrations are inherent in the operation of rotating machines, which is one of the leading causes of mechanical failures. This work analyzes the torsional vibration of a crankshaft of a single-cylinder reciprocating compressor, with the objective is to investigate the coupling effects of identical and rainbow metastructures in the attenuation band formation. Moreover, evaluating the torsional vibration of the shaft considers the nonlinearity of the inertia of the cylinder without metamaterials. The shaft is modeled for a continuous nonlinear system, considering the variable inertia of the crank-slider mechanism. Initially, a linearization of the system is considered assuming that the inertia is constant, and two formulations are considered. The first inserts the concentrated inertias through boundary conditions, and the second introduces the inertias into the governing equation. The comparative analysis between the two modelings shows that they are equivalent to low inertia ratios. However, they present divergencies that stabilize with the increase of this ratio. The identical resonators effectively attenuated vibrations near the target frequency. On the other hand, rainbow metastructures produce an attenuation zone 600% wider than identical resonators with the same added inertia. The results of the nonlinear system show that the responses exhibit nonlinear effects only for higher nonlinearities of the non-constant inertia and excitation amplitudes

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