Large Modal Survey Testing Using the Ibrahim Time Domain Identification Technique

1982 ◽  
Vol 19 (5) ◽  
pp. 459-465 ◽  
Author(s):  
Samir R. Ibrahim ◽  
Richard S. Pappa
Keyword(s):  
Time Domain ◽  
Domain Identification ◽  
Identification Technique

A Frequency Domain Versus a Time Domain Identification Technique for Nonlinear Parameters Applied to Wire Rope Isolators

2000 ◽  
Vol 123 (4) ◽  
pp. 645-650 ◽  
Author(s):  
Gaetan Kerschen ◽  
Vincent Lenaerts ◽  
Stefano Marchesiello ◽  
Alessandro Fasana
Keyword(s):  
Frequency Domain ◽  
Time Domain ◽  
Nonlinear Dynamical Systems ◽  
Wire Rope ◽  
Restoring Force ◽  
Nonlinear Parameters ◽  
Nonlinear Dynamical ◽  
Domain Identification ◽  
Identification Technique ◽  
Reverse Path Method

The present paper aims to compare two techniques for identification of nonlinear dynamical systems. The Conditioned Reverse Path method, which is a frequency domain technique, is considered together with the Restoring Force Surface method, a time domain technique. Both methods are applied for experimental identification of wire rope isolators and the results are compared. Finally, drawbacks and advantages of each technique are underlined.

New time-domain identification technique

1987 ◽  
Vol 10 (3) ◽  
pp. 313-316 ◽  
Author(s):  
Fang-Bo Yeh ◽  
Ciann-Dong Yang
Keyword(s):  
Time Domain ◽  
Domain Identification ◽  
Identification Technique ◽  
New Time

Modal participation in multiple input Ibrahim time domain identification

2017 ◽  
Vol 24 (1) ◽  
pp. 168-180 ◽  
Author(s):  
Rune Brincker ◽  
Peter Olsen ◽  
Sandro Amador ◽  
Martin Juul ◽  
Abdollah Malekjafarian ◽  
...  
Keyword(s):  
Simulation Study ◽  
Time Domain ◽  
Toeplitz Matrices ◽  
Full Rank ◽  
Impulse Response Functions ◽  
System Matrix ◽  
Estimation Errors ◽  
Domain Identification ◽  
Multiple Input ◽  
Identification Technique

The Ibrahim time domain (ITD) identification technique was one of the first techniques formulated for multiple output modal analysis based on impulse response functions or general free decays. However, the technique has not been used much in recent decades due to the fact that the technique was originally formulated for single input systems that suffer from well-known problems in case of closely spaced modes. In this paper, a known, but more modern formulation of the ITD technique is discussed. In this formulation the technique becomes multiple input by adding some Toeplitz matrices over a set of free decays. It is shown that a special participation matrix can be defined that cancels out whenever the system matrix is estimated. The participation matrix becomes rank deficient if a mode is missing in the responses, but if any mode is present in one of the considered free decays, the participation matrix has full rank. This secures that all modes will be contained in the estimated system matrix. Finally, it is discussed how correlation functions estimated from the operational responses of structures can be used as free decays for the multiple-input ITD formulation, and the estimation errors of the identification technique are investigated in a simulation study with closely spaced modes. The simulation study shows that the multiple-input formulation provides estimates with significantly smaller errors on both mode shape and natural frequency estimates.

A Time Domain Identification Technique: The Oversized Eigenmatrix (OEM) Method

1985 ◽  
Vol 107 (1) ◽  
pp. 53-59 ◽  
Author(s):  
Yongxin Yang
Keyword(s):  
Cantilever Beam ◽  
Time Domain ◽  
High Efficiency ◽  
Natural Frequencies ◽  
Math Model ◽  
Noise Effect ◽  
Domain Identification ◽  
Free Decay ◽  
Identification Technique ◽  
Noisy Conditions

A method of identifying natural frequencies and associated damping ratios of a structure from its free decay response is presented. The method is based on the Prony’s algorithm with which the idea of using an oversized math model as in ITD to reduce the noise effect is incorporated. Two approaches are proposed for use in distinguishing the true poles from the extraneous poles introduced by oversizing the eigenmatrix. The simulated experiments on a cantilever beam show high efficiency of the method in reducing the noise effect on the identification results under extremely noisy conditions.

Experimental Identification Technique of Nonlinear Beams in Time Domain

1997 ◽  
Author(s):  
Kimihio Yasuda ◽  
Keisuke Kamiya
Keyword(s):  
Time Domain ◽  
Harmonic Balance ◽  
Least Square Method ◽  
Least Square ◽  
Governing Equations ◽  
Experimental Identification ◽  
Initial Values ◽  
Nonlinear Beams ◽  
Identification Technique ◽  
The Time Domain

Abstract In previous papers the authors proposed a new experimental identification technique applicable to elastic structures. The proposed technique is based on the principle of harmonic balance, and can be classified as the frequency domain technique. The technique requires the excitation force to be periodic. This is in some cases a restriction. So another technique free from this restriction is of use. In this paper, as a first step for developing such techniques, a technique applicable to beams is proposed. The proposed technique can be classified as the time domain one. Two variations of the technique are proposed, depending on what methods are used for estimating the parameters of the governing equations. The first method is based on the usual least square method. The second is based on solving a minimization problem with constraints. The latter usually yields better results. But in this method, an iteration procedure is used, which requires initial values for the parameters. To determine the initial values, the first method can be used. So both methods are useful. Finally the applicability of the proposed technique is confirmed by numerical simulation and experiments.

scholarly journals Synchronous machine parameter identification in frequency and time domain

2007 ◽  
Vol 4 (1) ◽  
pp. 51-69 ◽  
Author(s):  
M. Hasni ◽  
S. Djema ◽  
O. Touhami ◽  
R. Ibtiouen ◽  
M. Fadel ◽  
...  
Keyword(s):  
Time Domain ◽  
Synchronous Machine ◽  
Model Structure ◽  
Machine Parameter ◽  
Identification Procedure ◽  
Time Constants ◽  
Domain Identification ◽  
Salient Pole ◽  
Salient Pole Synchronous Machine ◽  
Input Signals

This paper presents the results of a frequency and time-domain identification procedure to estimate the linear parameters of a salient-pole synchronous machine at standstill. The objective of this study is to use several input signals to identify the model structure and parameters of a salient-pole synchronous machine from standstill test data. The procedure consists to define, to conduct the standstill tests and also to identify the model structure. The signals used for identification are the different excitation voltages at standstill and the flowing current in different windings. We estimate the parameters of operational impedances, or in other words the reactance and the time constants. The tests were carried out on synchronous machine of 1.5 kVA 380V 1500 rpm.

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