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Modal testing

About: Modal testing is a research topic. Over the lifetime, 4047 publications have been published within this topic receiving 64772 citations.


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Journal ArticleDOI
TL;DR: In this article, a Bayesian approach for identifying the modal parameters (i.e., frequency, damping ratio, and modal excitation) of electromechanical modes is presented.
Abstract: This paper presents a Bayesian approach for identifying the modal parameters (i.e., frequency, damping ratio, and modal excitation) of electromechanical modes. The proposed approach identifies the modal parameters and calculates their uncertainty using ambient phasor measurement unit (PMU) measurements from a power system. The method is applied in the frequency domain on a selected frequency band, which significantly simplifies the identification. The performance of the method is studied with simulated data from the IEEE New England test system and the Nordic power system simulation model. In addition, measured PMU data from the Nordic power system are used. The results indicate that the modal parameters of electromechanical modes can be identified reliably and their identification uncertainty can be fundamentally calculated using the proposed method. Thus, the Bayesian approach is a promising identification method for wide-area monitoring of electromechanical oscillations.

14 citations

Journal ArticleDOI
TL;DR: It is shown in the paper that the non-Gaussian phase selection in the IFFT generation can reduce kurtosis to 1.7 and bring the crest factor of drive signals from 4.5 to 2.5 without any loss of the controller's dynamic range.
Abstract: The non-Gaussian random shaker testing with kurtosis control has been known as a way of increasing the excitation crest factor in order to realistically simulate ground vehicle vibrations and other situations when the time history includes extreme peaks higher than those appearing in Gaussian random signals. However, an opposite action is also useful in other applications, particularly in modal testing. If the PSD is the only test specification, more power can be extracted from the same shaker if the crest factor is decreased and an extra space is created between the peaks of reduced height and the system abort limit. To achieve this, a technique of sigma clipping is commonly used but it generates harmonic distortions reducing dynamic range of shaker system. It is shown in the paper that the non-Gaussian phase selection in the IFFT generation can reduce kurtosis to 1.7 and bring the crest factor of drive signals from 4.5 to 2. The phase selection method does this without any loss of the controller's dynamic range that inevitably occurs after sigma clipping or polynomial transformation of time histories.

14 citations

Proceedings ArticleDOI
01 Jan 2003
TL;DR: In this article, the authors applied the matrix formulation and postprocessing techniques to an inflated torus with bonded membrane mirror to extract modal parameters, such as the damped natural frequencies, associated damping, and mode shapes within the frequency bandwidth of interest for these structures (5 − 200 Hz).
Abstract: The future of space satellite technology lies in the development of ultra-large, ultra-lightweight space structures orders of magnitude greater in size than current satellite technology. Such large craft will increase current communication and imaging capabilities from orbit. To get ultra-large structures in space, they will have to be stored within the Space Shuttle cargo bay and then inflated on-orbit. However, the highly flexible and pressurized nature of these ultra-large spacecraft poses several daunting vibration and control problems. Disturbances (i.e. on-orbit maneuvering, guidance and attitude control, and the harsh environment of space) wreck havoc with the on-orbit stability, pointing accuracy, and surface resolution capability of the inflated satellite. However, recent advances in integrated smart material systems promise to provide solutions to these problems. Recent research into the use of Macro-Fiber Composite (MFC®) devices integrated into the dynamic measurement and vibration control of inflated structures has had promising results. These piezoelectric-based devices possess a superior electromechanical coupling coefficient making them superb sensors and actuators in dynamic analysis applications. Initially, research was performed on an inflated torus using single-input, single-output (SISO) testing techniques. Since then, steps have been taken to outline a new, multiple-input, multiple-output (MIMO) testing technique for these ultralarge structures. Based on the matrix formulation and postprocessing techniques recently developed, the current work applies these results to an inflated torus with bonded membrane mirror to extract modal parameters, such as the damped natural frequencies, associated damping, and mode shapes within the frequency bandwidth of interest for these structures (5 – 200 Hz). MIMO modal testing techniques are ideal for large, inflated structure applications. The nature of the structure requires the use of multiple sensors and actuators for worthwhile dynamic analysis and control. Therefore, in the future, the results of this work will form the premise for an autonomous, self-contained system that can both identify the vibratory characteristics of an ultra-large, inflated space craft and apply an appropriate control algorithm to suppress any unwanted vibration—all while on-orbit.Copyright © 2003 by ASME

14 citations

Journal ArticleDOI
TL;DR: In this article, a modification to the approach of Liu et al. is proposed, in that, it uses eigenvalue shift approach to enhance convergence when the frequency of the harmonic excitation is larger than the frequencies of the truncated modes.

14 citations

Journal ArticleDOI
TL;DR: In this paper, the authors investigated the least square complex exponential (LSCE) and modified least-square complex exponential methods in the case of a string instrument to identify modal parameters of the instrument when it is played.

14 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202367
2022164
202141
202059
201967
201878