&lt;title&gt;Holographic modal analysis for the separation of narrow-spaced eigenmodes&lt;/title&gt;

Klingele, H.; Steinbichler, H.; Freymann, Raymond; Honsberg, Wolfram; Haberstok, C.

doi:10.1117/12.248664

Cited by 10 publications

(5 citation statements)

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“…The upper frequency limit of a modal test depends on the spacing between the response sensors. Holographic modal tests allow the analysis of high frequency and narrow spaced modes (Klingele et al, 1996).…”

Section: Limitations and Trendsmentioning

confidence: 99%

Theory and application of modal analysis in vehicle noise and vibration refinement

Kronast

2010

Vehicle Noise and Vibration Refinement

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Section: Limitations and Trendsmentioning

confidence: 99%

Theory and application of modal analysis in vehicle noise and vibration refinement

Kronast

2010

Vehicle Noise and Vibration Refinement

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“…every 0.5 Hz between 150 and 500 Hz). For this stepped-sine procedure, software has been developed, to control hardware equipment like function generator, laser trigger system and force measurement [6,8,9]. As a result the discrete FRF H(w) = XRe (wH lXim () (4)…”

Section: Double-pulsed Lasermentioning

confidence: 99%

<title>Holographic modal analysis for the investigation of vibro-acoustic systems</title>

Haberstok¹,

Freymann

Steinbichler³

et al. 1999

SPIE Proceedings

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In order to optimise the vibro-acoustic behaviour of panel-like structures in a more systematic way, accurate structural models are needed. However, at the frequencies of relevance to the vibro-acoustic problem, the mode shapes are very complex, requiring a high spatial resolution in the measurement procedure.The large number of required transducers and their mass loading effects limit the applicability of accelerometer testing.In recent years, optical measurement methods have been proposed. Direct electronic (ESPI) imaging, using strobed laser illumination, or more recently, pulsed laser illumination, have lately created the possibility to bring the holographic testing approach to the level of industrial applicability for modal analysis procedures. Therefore an automated ESPI system has been developed for the measurement of frequency response functions using stepped sine testing. A conventional numerical modal analysis procedure is used to obtain the modal information.The present paper discusses the various critical elements of a holographic ESPI modal testing system. Next to the optical parts, the integration with the modal analysis procedures, including the integration of geometry and response measurement, are discussed. The paper furthermore discusses test results optained on a car panel in a vibro-acoustic setup. The results show, that the quality of the frequency response functions is very good, when compared with accelearation sensor measurements. The measurement data are used to predict interior noise.

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“…The vibration responses are then used as estimates of the mode shapes [6,7j• In the present project, the goal of the measurements was to obtain complex-valued vibration amplitudes (in principle at pixel resolution) that, in reference to the excitation force, yield an "image" of frequency response functions (FRFs). These FRF images are accumulated over a range of frequencies [8,9] The stepped-sine excitation technique is used hereto. To determine the unknown value of the complex amplitude, at least two measurements per frequency need to be made at (at least) two different time points [6]• When more than two time points are used, the complex amplitude is calculated by a least squares procedure, which not only reduces the effects ofnoise in the measurement data, but also has a filtering effect of harmonic disturbances in the excitation and/or response signals.…”

Section: Espi-holograndphy Based Frf Measurementsmentioning

confidence: 99%

<title>Integration of pulsed-laser ESPI with spatial domain modal analysis: results from the SALOME project</title>

Auweraer

Steinbichler²,

Haberstok

et al. 2000

Fourth International Conference on Vibration Measurements by Laser Techniques: Advances and Applications

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The present paper discusses the various critical elements of a modal testing system based on pulsed-laser holographic ESPI measurements. Such system allows making very high spatial resolution measurements on panel-like structures at frequencies which are of relevance for the vibro-acoustic behavior.Next to the optical parts, the integration with the modal analysis procedures, including the integration of geometry and response information, is reviewed. The ESPI based Image-domain frequency response functions are accumulated frequency by frequency. Special attention is paid to the modal parameter extraction of the large DOF number data, for which a special data reduction scheme was developed. The approach has been applied to several case studies related to car panels. The research was conducted in the context ofthe Brite/Euram project SALOME and the EUREKA project HOLOMODAL.

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<title>Holographic modal analysis for the separation of narrow-spaced eigenmodes</title>

Cited by 10 publications

References 0 publications

Theory and application of modal analysis in vehicle noise and vibration refinement

Theory and application of modal analysis in vehicle noise and vibration refinement

<title>Holographic modal analysis for the investigation of vibro-acoustic systems</title>

<title>Integration of pulsed-laser ESPI with spatial domain modal analysis: results from the SALOME project</title>

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