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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 paper, the modal method is applied to analyze coupled vibration of belt drive systems, which is a hybrid system consisting of continuous belts modeled as strings as well as discrete pulleys and a tensioner arm.
Abstract: The modal method is applied to analyze coupled vibration of belt drive systems. A belt drive system is a hybrid system consisting of continuous belts modeled as strings as well as discrete pulleys and a tensioner arm. The characteristic equation of the system is derived from the governing equation. Numerical results demenstrate the effects of the transport speed and the initial tension on natural frequencies.

15 citations

Journal Article
TL;DR: The development of experimental modal analysis techniques is reviewed and the current trend toward multiple input utilization in the estimation of system parameters is noted.
Abstract: The development of experimental modal analysis techniques is reviewed. System and excitation assumptions are discussed. The methods examined include the forced normal mode excitation method, the frequency response function method, the damped complex exponential response method, the Ibrahim time domain approach, the polyreference approach, and mathematical input-output model methods. The current trend toward multiple input utilization in the estimation of system parameters is noted.

15 citations

Journal ArticleDOI
TL;DR: In this paper, the modal damping of flexural oscillation of suspended cable models was measured and the modality of each normal mode is found to be the primary cause of damping and the damping in the first in-plane symmetric mode is much larger than that of other modes around the crossover point of the first and second natural frequencies.
Abstract: The modal damping of flexural oscillation of suspended cable models was measured and is reported in this paper. Numerical analyses of free oscillation of the cables were also made to calculate natural frequencies, normal modes and additional dynamic strains. It is found that the additional dynamic strain of each normal mode is the primary cause of modal damping and that the damping of the first in-plane symmetric mode is much larger than that of other modes around the ‘crossover’ point of the first and second natural frequencies. The effects of the span length, the tensile rigidity and the chord inclination are also investigated.

15 citations

Journal ArticleDOI
TL;DR: In this article, a noncontact method for modal testing, of suspensions in air, that utilizes the radiation force at the difference frequency generated by two intersecting ultrasound beams was discussed. But, since the ultrasound radiation force is noncontact, a specialized test fixture was not needed; the technique was relatively insensitive to distracting resonances of fixtures and support structures.
Abstract: The head‐gimbal assembly suspension is a cantilever‐like structure that holds the heads on a hard drive. We will discuss a noncontact method for modal testing, of suspensions in air, that utilizes the radiation force at the difference frequency generated by two intersecting ultrasound beams. The resulting low‐frequency excitations were measured using a scanning vibrometer. This excitation technique has been demonstrated for MEMS and other small devices. There are several unique advantages of the ultrasound radiation force relative to mechanical shakers. Since the ultrasound radiation force is noncontact, a specialized test fixture was not needed; the technique was relatively insensitive to distracting resonances of fixtures and support structures. Another advantage is broadband excitation; a 550‐kHz confocal ultrasound transducer excited suspension resonance frequencies from under 1 kHz to over 50 kHz. Other advantages include the ability to selectively excite different modes. For example, the amplitude of the suspension’s 2.28‐kHz transverse mode was suppressed by an order of magnitude by shifting the modulation phase between the two ultrasound beams by 90. In another test, the amplitude of the 6.01‐kHz torsional mode was doubled by moving the ultrasound focus point from near the center to near the edge of the suspension.

15 citations

Journal ArticleDOI
TL;DR: In this article, the effects of high-amplitude initial conditions on the accuracy of modal parameters, identified from output-only vibration data, are investigated, and the influence on the sample output correlation function, which is the basis of most time-domain operational modal analysis techniques, is analyzed first.
Abstract: SUMMARY In this study, the effects of high-amplitude initial conditions on the accuracy of modal parameters, identified from output-only vibration data, are investigated. The influence on the sample output correlation function, which is the basis of most time-domain operational modal analysis techniques, is analyzed first. Then, a numerical simulation is performed to quantify the effect of nonzero initial conditions on the relative accuracy of natural frequencies, damping ratios, and mode shapes. It is shown that, when all identification assumptions are satisfied, high-amplitude initial conditions can significantly reduce the estimation errors, especially for short data records. Finally, a full-scale application is presented where the modal parameters of a six-span high-speed railway bridge are determined from output-only data. The results obtained with two different data sets are compared: The first one consists of the bridge's response to ambient data only, whereas the second one also contains the free vibration recorded immediately after a train passage. Although for most modes the results are similar, it is possible to identify some additional bending and torsion modes from the free vibration data with good accuracy. Copyright © 2013 John Wiley & Sons, Ltd.

15 citations


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