An Algebraic Approach for Identification of Rotordynamic Parameters in Bearings with Linearized Force Coefficients

Abstract

In this work, a novel methodology for the identification of stiffness and damping rotordynamic coefficients in a rotor-bearing system is proposed. The mathematical model for the identification process is based on the algebraic identification technique applied to a finite element (FE) model of a rotor-bearing system with multiple degree-of-freedom (DOF). This model considers the effects of rotational inertia, gyroscopic moments, shear deformations, external damping and linear forces attributable to stiffness and damping parameters of the supports. The proposed identifier only requires the system’s vibration response as input data. The performance of the proposed identifier is evaluated and analyzed for both schemes, constant and variable rotational speed of the rotor-bearing system, and numerical results are obtained. In the presented results, it can be observed that the proposed identifier accurately determines the stiffness and damping parameters of the bearings in less than 0.06 s. Moreover, the identification procedure rapidly converges to the estimated values in both tested conditions, constant and variable rotational speed.

A Simplified Model for the On-Line Identification of Bearing Direct-Dynamic Parameters Based on Algebraic Identification (AI)

“…It is important to highlight that the proposed identifier only uses the lateral displacements of a single node to identify the coefficients; in this case, it was node 11. This is a great advantage since other identifiers based on a more complex model need the entire displacement vector, i.e., the lateral vibration and the slope nodes of the node which you want to identify and of two adjacent nodes [23,24]. This is complex to achieve in the experimental part: First, the nodal slopes cannot be measured directly; it is best to approximate them with the lateral displacements.…”

“…Later, Mendoza Larios G. et al [23], in a numerical approach, developed an estimator for the rotor dynamic coefficients by applying algebraic identification, in which the Finite Element Method was used to numerically obtain the response of the rotary system by using a multiple degrees-of-freedom (DOF) model. The proposed identifier requires the lateral displacements and the slope of the node located at the support to identify, as well as the slope of the adjacent node.…”