Frequency-domain generalized total least-squares identification for modal analysis

Verboven, Peter; Guillaume, Patrick; Cauberghe, Bart; Parloo, Eli; Vanlanduit, Steve

doi:10.1016/j.jsv.2003.09.058

Cited by 70 publications

(22 citation statements)

References 9 publications

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“…The system poles are passed on to the residue estimator also called the Least Squares Frequency Domain (LSFD) method [18]. From the obtained residues the mode shapes can be estimated.…”

Section: Modal Estimation Methodsmentioning

confidence: 99%

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Modal Measurements and Model Corrections of A Large Stroke Compliant Mechanism

Wijma¹,

Boer²,

Aarts³

et al. 2014

Archive of Mechanical Engineering

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In modelling flexure based mechanisms, generally flexures are modelled perfectly aligned and nominal values are assumed for the dimensions. To test the validity of these assumptions for a two Degrees Of Freedom (DOF) large stroke compliant mechanism, eigenfrequency and mode shape measurements are compared to results obtained with a flexible multibody model. The mechanism consists of eleven cross flexures and seven interconnecting bodies. From the measurements 30% lower eigenfrequencies are observed than those obtained with the model. With a simplified model, it is demonstrated that these differences can be attributed to wrongly assumed leaf spring thickness and misalignment of the leaf springs in the cross flexures. These manufacturing tolerances thus significantly affect the behaviour of the two DOF mechanism, even though it was designed using the exact constraint design principle. This design principle avoids overconstraints to limit internal stresses due to manufacturing tolerances, yet this paper shows clearly that manufacturing imperfections can still result in significantly different dynamic behaviour.

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“…The system poles are passed on to the residue estimator also called the Least Squares Frequency Domain (LSFD) method [18]. From the obtained residues the mode shapes can be estimated.…”

Section: Modal Estimation Methodsmentioning

confidence: 99%

“…Using a proper frequency dependent weighting function w j (ω f ) ensures that multiple nearby poles are estimated properly [18]. The weighing function is given as…”

Section: Modal Estimation Methodsmentioning

confidence: 99%

Modal Measurements and Model Corrections of A Large Stroke Compliant Mechanism

Wijma¹,

Boer²,

Aarts³

et al. 2014

Archive of Mechanical Engineering

View full text Add to dashboard Cite

show abstract

“…Close modes can be identified with high accuracy even in the case of strong noise contamination of the signals. The same OMA/FDD techniques are well documented in the theses of Verboven (2002), Cauberghe (2004) and Borges (2006). Peeters et al (2006) presented modern frequency-domain modal parameter estimation methods applied to in-flight aeroelastic response data measurements of a large aircraft.…”

Section: Operational Modal Analysismentioning

confidence: 79%

Comparison of in-Flight Measured and Computed Aeroelastic Damping: Modal Identification Procedures and Modeling Approaches

Follador¹,

Souza²,

Marto³

et al. 2016

J.Aerosp. Technol. Manag.

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AbstrAct:The Operational Modal Analysis technique is a methodology very often applied for the identification of dynamic systems when the input signal is unknown. The applied methodology is based on a technique to estimate the Frequency Response Functions and extract the modal parameters using only the structural dynamic response data, without assuming the knowledge of the excitation forces. Such approach is an adequate way for measuring the aircraft aeroelastic response due to random input, like atmospheric turbulence. The in-flight structural response has been measured by accelerometers distributed along the aircraft wings, fuselage and empennages. The Enhanced Frequency Domain Decomposition technique was chosen to identify the airframe dynamic parameters. This technique is based on the hypothesis that the system is randomly excited with a broadband spectrum with almost constant power spectral density. The system identification procedure is based on the Single Value Decomposition of the power spectral densities of system output signals, estimated by the usual Fast Fourier Transform method. This procedure has been applied to different flight conditions to evaluate the modal parameters and the aeroelastic stability trends of the airframe under investigation. The experimental results obtained by this methodology were compared with the predicted results supplied by aeroelastic numerical models in order to check the consistency of the proposed output-only methodology. The objective of this paper is to compare in-flight measured aeroelastic damping against the corresponding parameters computed from numerical aeroelastic models. Different aerodynamic modeling approaches should be investigated such as the use of source panel body models, cruciform and flat plate projection. As a result of this investigation it is expected the choice of the better aeroelastic modeling and Operational Modal Analysis techniques to be included in a standard aeroelastic certification process.

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“…The accuracy of parameter fitting depends on many factors, such as the fitting algorithm, the number of degrees of freedom used in the model, and measurement precision. Some of the most widely used fitting algorithms are the Rational Fraction Polynomial method (RFP) [25], Least Squares Frequency-Domain algorithm (LSFD), Poly-reference Least Squares Complex Frequency-domain estimator, Frequency-domain Direct Parameter Identification (FDPI) method or Frequency-domain Maximum Likelihood Estimator (MLE) (see [34] and the references therein). Stability lobe diagrams can be constructed using the fitted modal parameters.…”

Section: Robust Stability Analysis In Time Domainmentioning

confidence: 99%

Robust stability analysis of machining operations

Hajdu

Insperger

Stépàn

2016

Int J Adv Manuf Technol

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Prediction of machine tool chatter requires the characterization of dynamic of the machine-toolworkpiece system by means of frequency response functions (FRFs). Uncertainties of the measured FRFs result in uncertainties of the calculated stability diagrams, therefore robustness of stability prediction against parameter perturbations is of high importance. Although there exist methods to determine robust stability in terms of stability radii, these methods either give a conservative estimate of the real uncertainties or are limited to perturbations of a few modal parameters, only. In this paper, a frequency-domain approach is presented to determine robust stability boundaries using the measured FRFs directly without any modal parameter identification. The method is based on an envelope fitting around the measured FRFs combined with some considerations of the single-frequency method. The application of the method is demonstrated in case of a turning operation, where the machine tool structure is characterized by a series of FRF measurements.

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Frequency-domain generalized total least-squares identification for modal analysis

Cited by 70 publications

References 9 publications

Modal Measurements and Model Corrections of A Large Stroke Compliant Mechanism

Modal Measurements and Model Corrections of A Large Stroke Compliant Mechanism

Comparison of in-Flight Measured and Computed Aeroelastic Damping: Modal Identification Procedures and Modeling Approaches

Robust stability analysis of machining operations

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