An optimized rational fraction polynomial approach for modal parameters estimation from FRF measurements

2010 ◽  
Vol 24 (3) ◽  
pp. 831-842 ◽  
Author(s):  
Omar Omar ◽  
Nejah Tounsi ◽  
Eu-Gene Ng ◽  
M. A. Elbestawi
Keyword(s):  
Parameters Estimation ◽  
Modal Parameters ◽  
Rational Fraction ◽  
Rational Fraction Polynomial

scholarly journals Modal control based on direct modal parameters estimation

2017 ◽  
Vol 24 (12) ◽  
pp. 2389-2399 ◽  
Author(s):  
Baptiste Chomette ◽  
Adrien Mamou-Mani
Keyword(s):  
Frequency Domain ◽  
Controller Design ◽  
State Space Model ◽  
Parameters Estimation ◽  
Modal Parameters ◽  
Rational Fraction ◽  
Modal Control ◽  
Identification Algorithm ◽  
Human Intervention ◽  
Rational Fraction Polynomial

Modal active control is based on a state model that requires the identification of modal parameters. This identification can typically be done through a rational fraction polynomial algorithm applied in the frequency domain. This method generates numerical problems when estimating high-order models, particularly when moving from the basis of orthogonal polynomials for the modal basis. This algorithm must therefore be applied independently on multiple frequency ranges with a low order for each range. In this case, the controller design cannot be automated and requires a lot of human intervention, especially to build the state space model. To address this issue, this paper presents the application of the direct modal parameters estimation (DMPE) algorithm for active modal control design. The identification algorithm is presented in a simplified version with only positive frequencies. Unlike other classical identification methods in the frequency domain, the DMPE algorithm provides a solution with a great numerical stability and allows estimating models with a higher order. Using this method, the design of the controller can be largely automated and requires a minimum of human intervention. After a theoretical presentation, the proposed method is experimentally validated by controlling the vibration modes of a suspended plate.

Comparison of Different Estimation Algorithms Used in the Experimental Determination of Modal Parameters

2015 ◽  
Vol 816 ◽  
pp. 412-415
Author(s):  
Róbert Huňady ◽  
Martin Hagara ◽  
Peter Pavelka
Keyword(s):  
Circular Cross Section ◽  
Extraction Methods ◽  
Modal Parameters ◽  
Rational Fraction ◽  
Polynomial Method ◽  
Laser Vibrometer ◽  
Estimation Algorithms ◽  
Freely Suspended ◽  
Rational Fraction Polynomial

The paper deals with the estimation of modal parameters and its main purpose is to compare differences in the values of natural frequencies and damping ratios, which were estimated using three different extraction methods: Rational Fraction Polynomial method, Complex Mode Indicator Function and Polyreference Time Domain Technique. These methods are well suited to the more general application to multi-FRF data, both of the SIMO and the MIMO types. The object of measurement was a freely suspended steel rod of circular cross section. The responses of the analyzed structure were measured by accelerometer and laser vibrometer. The results of these measurements are also discussed in the paper.

Improving the accuracy of SOD for modal parameters estimation of damped systems

2014 ◽  
Vol 226 (6) ◽  
pp. 1673-1687 ◽  
Author(s):  
Mousa Rezaee ◽  
Gholamreza Fattahi Yam
Keyword(s):  
Parameters Estimation ◽  
Modal Parameters ◽  
Damped Systems

Real-time vision-based modal parameters estimation at 10000 fps

2012 ◽  
Author(s):  
Hua Yang ◽  
Idaku Ishii ◽  
Takeshi Takaki
Keyword(s):  
Real Time ◽  
Parameters Estimation ◽  
Modal Parameters

Output-Only Analysis for Modal Parameters Estimation of an Elastically Scaled Ship

2008 ◽  
Vol 52 (01) ◽  
pp. 45-56
Author(s):  
Giuliano Coppotelli ◽  
Daniele Dessi ◽  
Riccardo Mariani ◽  
Marcello Rimondi
Keyword(s):  
Life Prediction ◽  
Structural Response ◽  
Random Excitation ◽  
Parameters Estimation ◽  
Elastic Response ◽  
Modal Parameters ◽  
Practical Application ◽  
Scaled Model ◽  
Output Only ◽  
Ship Speed

The study of the ship structural response assumes an increasing importance as soon as the structures, characterized by much more lightness, are designed and built for faster vessels. This requisite implies a greater flexibility of the structures themselves, the elastic response of which has to be evaluated with accuracy in order to predict the dynamic behavior. In the present paper, a methodology for the identification of the modal parameters from the measurement of only the responses of a vibrating structure has been developed and applied to an elastically scaled model. This output-only technique is successfully applied to the segmented model of a real ship towed in the INSEAN linear basin. The broadband random excitation, provided by the loads exerted by an irregular sea pattern, induces a stochastic response of the model, which is monitored with accelerometers. The obtained results not only outline the parametric dependence of the modal properties on the ship speed, but also suggest a possible practical application of this technique for on-board structural monitoring and fatigue-life prediction.

scholarly journals Real Time Estimation of Modal Parameters and Their Quality Assessment

2008 ◽  
Vol 15 (3-4) ◽  
pp. 299-306 ◽  
Author(s):  
Tadeusz Uhl ◽  
Maciej Petko ◽  
Grzegorz Karpiel ◽  
Andrzej Klepka
Keyword(s):  
Laboratory Test ◽  
Quality Assessment ◽  
Real Time ◽  
Time Estimation ◽  
Parameters Estimation ◽  
Modal Parameters ◽  
Recursive Method ◽  
Test Rig ◽  
Confidence Bounds ◽  
Real Time Estimation

In this paper the recursive method for modal parameters estimation is formulated and verified. Formulated algorithms are implemented in the FPGA electronic chip. As a result, the modal parameters and confidence bounds for the modal parameters are obtained in real time. The algorithms and their implementations are tested on laboratory test rig data and applied to – flight modal analysis of an airframe structure.

scholarly journals Automated Harmonic Signal Removal Technique Using Stochastic Subspace-Based Image Feature Extraction

2020 ◽  
Vol 6 (3) ◽  
pp. 10
Author(s):  
Muhammad Danial Bin Abu Hasan ◽  
Zair Asrar Bin Ahmad ◽  
Mohd Salman Leong ◽  
Lim Meng Hee
Keyword(s):  
Feature Extraction ◽  
System Identification ◽  
Output Signal ◽  
Parameters Estimation ◽  
Human Interaction ◽  
Image Feature ◽  
Modal Parameters ◽  
Start Up ◽  
Stabilization Diagram ◽  
Harmonic Components

This paper presents automated harmonic removal as a desirable solution to effectively identify and discard the harmonic influence over the output signal by neglecting any user-defined parameter at start-up and automatically reconstruct back to become a useful output signal prior to system identification. Stochastic subspace-based algorithms (SSI) methods are the most practical tool due to the consistency in modal parameters estimation. However, it will be problematic when applied to structures with rotating machines and the presence of harmonic excitations. Difficulties arise when automating this procedure without any human interaction and the problem is still unresolved because stochastic subspace-based algorithms (SSI) methods still require parameters (the maximum within-cluster distance) that are compulsory to be defined at start-up for each analysis of the dataset. Thus, the use of image-based feature extraction for clustering and classification of harmonic components and structural poles directly from a stabilization diagram and for modal system identification is the focus of the present paper. As a fundamental necessary condition, the algorithm has been assessed first from computed numerical responses and then applied to the experimental dataset with the presence of harmonic excitation. Results of the proposed approach for estimating modal parameters demonstrated very high accuracy and exhibited consistent results before and after removing harmonic components from the response signal.

Operational Modal Test of an Arch Bridge

2012 ◽  
Vol 446-449 ◽  
pp. 3233-3238
Author(s):  
Xin Zhang ◽  
Xiu Li Du
Keyword(s):  
Frequency Response Function ◽  
Traffic Load ◽  
Modal Parameters ◽  
Rational Fraction ◽  
Frequency Domain Method ◽  
Arch Bridge ◽  
Operational Conditions ◽  
The Road ◽  
Modal Test ◽  
White Noises

A modal test was carried out on a 120m span concrete filled steel tubular arch bridge under operational conditions. The moving traffic load is considered as uncorrelated white noises at various points of the road surface and the test is of the type of multi-input multi-output (MIMO). The modal parameters are identified by Global Rational Fraction Polynomials (GRFP) method, a frequency domain method. In order to taking the mobile nature of the traffic load into consideration, a multi-input NExT method is utilized to retrieve the frequency response function needed by GRFP. A proof of the NExT method in the case of multi-input case is also provided in this paper.

A robust methodology for modal parameters estimation applied to SHM

2017 ◽  
Vol 95 ◽  
pp. 24-41 ◽  
Author(s):  
Rharã Cardoso ◽  
Alexandre Cury ◽  
Flávio Barbosa
Keyword(s):  
Parameters Estimation ◽  
Modal Parameters
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