Eventos Anais de eventos
DINAME 2017
XVII International Symposium on Dynamic Problems of Mechanics
Operational Modal Parameters Identification Using the ARMAV Model
Submission Author:
Heraldo Cambraia , PR
Co-Authors:
Heraldo Cambraia, Leonardo Contini, Paulo Roberto Gardel Kurka
Presenter: Heraldo Cambraia
doi://10.26678/ABCM.DINAME2017.DIN17-0218
Abstract
Applied system identification is an important issue in the science and engineering. Experimental modal analysis is used to describe the dynamical behavior of structures, in general, for a given set of input and output data. This article deals with multidimensional modal parameters identification valid for output-only data. This approach is interesting when the input is not known or difficult to be measured. A linear, time-invariant and finite dimensional mechanical system is considered, which is described mathematically by an autoregressive-moving-average-vector (ARMAV) model, excited by unknown operating forces assumed to be a white Gaussian process – a persistent excitation. The focus of the study is on, both, theoretical and practical aspects of the ARMAV model. Specifically, it is discussed the need of using an output-vector as reference for output-only parameters identification scheme. The model order is identified by inspection of more significant singular values of a block Hankel matrix derived directly from the formulation of the model. The AR parameters matrices of the ARMAV model, contained in a companion matrix, are determined via least-squares technique. Natural frequencies, damping factors and modal shapes are identified by means of eigenvalues and eigenvectors of that companion matrix. Examples using computational simulation are presented.
Keywords
Operational Modal Analysis, ARMAV Model, Least squares approach
