Análise do comportamento dinâmico de rotores embarcados quando da ocorrência de contato mecânico

Abstract

This work presents a numerical and experimental investigation of the dynamic behavior of an onboard rotating machine in the case of rotor-stator contact. Onboard rotor is the one that is characterized by excitations at its base that are included in the mathematical model of the system. In this case, the system studied is composed by a single disk mounted on a flexible shaft supported by ball bearings. To perform the analysis, a finite element model of the rotor was built. The mathematical model of the rotor is obtained from the Lagrange's equations and the finite element method, considering the deformation and kinetic energies of the shaft and the kinetic energies of the disk and the unbalanced mass. The base of the rotating system is considered rigid. The equations of motion of the system are used to determine vibration responses from excitations due to unbalance and base motion. The contact phenomenon was included in the onboard rotor model. Two formulations of the contact effect were evaluated: the first model is widely used in scientific works and the second is the result of a partnership with Laboratoire de Mécanique des Contacts et des Structures (LaMCos) of INSA-Lyon. Numerical analyses investigated the occurrence of contact due to a base excitation. Contact models, sinusoidal and impulse-type excitations with different amplitudes and frequencies were evaluated. Numerical results were compared with experimental ones as obtained from the test bench. Different experimental tests were carried out both in time and frequency domains, so that frequency response functions, orbits, and unbalance responses were obtained. The experimental analyses for comparison purposes are also presented in this work. Simulation results exhibit good agreement with experimental ones.