35 Years with Structural Measurements at Brüel &amp; Kjær

Gade, Svend; Herlufsen, H.

doi:10.1007/978-3-319-29859-7_4

Cited by 6 publications

(7 citation statements)

References 2 publications

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“…The peaks in

, shown as black circles in the figure, indicate the natural frequencies of the structure. These frequencies were obtained for each measurement point in the structure, and the experimental mode shapes were calculated using the quadrature picking method [ 24 ]. It can be seen in the figure that the value of the coherence function is close to one at all frequencies, indicating that individual measurements are very consistent with each other.…”

Section: Methodology Overviewmentioning

confidence: 99%

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Experimental Detection and Measurement of Crack-Type Damage Features in Composite Thin-Wall Beams Using Modal Analysis

Pacheco-Chérrez

Cárdenas

Probst

2021

Sensors

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An experimental proof-of-concept for damage detection in composite beams using modal analysis has been conducted. The purpose was to demonstrate that damage features can be detected, located, and measured on the surface of a relatively complex thin-wall beam made from composite material. (1) Background: previous work has been limited to the study of simple geometries and materials. (2) Methods: damage detection in the work is based on the accurate measurement of mode shapes and an appropriate design of the detection mesh. Both a method requiring information about the healthy structure and a baseline-free method have been implemented. (3) Results: short crack-type damage features, both longitudinal and transverse, were detected reliably, and the true length of the crack can be estimated from the damage signal. Simultaneous detection of two cracks on the same sample is also possible. (4) This work demonstrates the feasibility of automated damage detection in composite beams using sensor arrays.

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“…The peaks in

Section: Methodology Overviewmentioning

confidence: 99%

“…Reflective tape was placed at all locations to ensure a strong signal at the vibrometer. The quadrature picking method [ 24 ] was used to construct the mode shapes.…”

Section: Laboratory Experimentsmentioning

confidence: 99%

Experimental Detection and Measurement of Crack-Type Damage Features in Composite Thin-Wall Beams Using Modal Analysis

Pacheco-Chérrez

Cárdenas

Probst

2021

Sensors

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“…To minimize the noise (<40 μV and 127 μV, respectively) in the experiment, we selected sampling frequencies exhibiting the maximum decimation rate of 256. Moreover, the noise and possible scalloping loss were further reduced by extracting the effective value from the signal spectrum via an FFT with a flat top window [ 24 ].…”

Section: Methodsmentioning

confidence: 99%

A New Method to Perform Direct Efficiency Measurement and Power Flow Analysis in Vibration Energy Harvesters

Kunz

Fialka

Pikula

et al. 2021

Sensors

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Measuring the efficiency of piezo energy harvesters (PEHs) according to the definition constitutes a challenging task. The power consumption is often established in a simplified manner, by ignoring the mechanical losses and focusing exclusively on the mechanical power of the PEH. Generally, the input power is calculated from the PEH’s parameters. To improve the procedure, we have designed a method exploiting a measurement system that can directly establish the definition-based efficiency for different vibration amplitudes, frequencies, and resistance loads. Importantly, the parameters of the PEH need not be known. The input power is determined from the vibration source; therefore, the method is suitable for comparing different types of PEHs. The novel system exhibits a combined absolute uncertainty of less than 0.5% and allows quantifying the losses. The approach was tested with two commercially available PEHs, namely, a lead zirconate titanate (PZT) MIDE PPA-1011 and a polyvinylidene fluoride (PVDF) TE LDTM-028K. To facilitate comparison with the proposed efficiency, we calculated and measured the quantity also by using one of the standard options (simplified efficiency). The standard concept yields higher values, especially in PVDFs. The difference arises from the device’s low stiffness, which produces high displacement that is proportional to the losses. Simultaneously, the insufficient stiffness markedly reduces the PEH’s mechanical power. This effect cannot be detected via the standard techniques. We identified the main sources of loss in the damping of the movement by the surrounding air and thermal losses. The latter source is caused by internal and interlayer friction.

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“…One of the approaches used for extracting the mode shapes, where a little effort is needed, is the approach known as the (Quadrature Picking). In this approach a light pairing between the modes is assumed [14]. The observed mode shapes of the three beams and for all loading steps were generated all through in this work.…”

Section: Effect Of Damage On Mode Shapementioning

confidence: 99%

The use of modal parameters in structural health monitoring

Al-Ghalib

Mohammad

2018

MATEC Web Conf.

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The concrete is liable to damage due to various stresses which compensate its adequacy and safety. The estimation of remaining strength in reinforced concrete beams when subjected to increased loading action utilizing vibration parameters is investigated. For this reason, three beams are loaded statically close to failure in various increasing load steps and then repaired. The beams are all of same dimensions, but are different in strength and range of defects introduced to each sample. Following each loading step, the experimental modal testing is utilized to collect the vibration parameters (natural frequency, damping ratio and mode shapes) of each beam when tested under free support boundary conditions. The use of vibration parameters for the purpose of damage identification are known to be an elaborate and lengthy process. On the other hand, they are successful for the structural health monitoring given that they are able to provide global on-site automated continuous monitoring. The paper features post analysis procedures for experimental modal measurements of three concrete samples to obtain and correlate the basic modal parameters (natural frequency, modal damping and mode shapes). The results of the extracted modal parameters and their combination are exploited in this research as quantified identification parameters. This paper concludes that modal parameters are successful in determining the location and quantity of structural degradation, when holistic approach considered through a system.

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35 Years with Structural Measurements at Brüel & Kjær

Cited by 6 publications

References 2 publications

Experimental Detection and Measurement of Crack-Type Damage Features in Composite Thin-Wall Beams Using Modal Analysis

Experimental Detection and Measurement of Crack-Type Damage Features in Composite Thin-Wall Beams Using Modal Analysis

A New Method to Perform Direct Efficiency Measurement and Power Flow Analysis in Vibration Energy Harvesters

The use of modal parameters in structural health monitoring

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