Marble Ageing Characterization by Acoustic Waves

Boudani, Mohamed El; Wilkie-Chancellier, Nicolas; Martinez, L.; Hébert, Ronan; Rolland, Olivier; Forst, Sébastien; Vergès‐Belmin, Véronique; Serfaty, Sylvia

doi:10.1016/j.phpro.2015.08.140

Cited by 6 publications

(2 citation statements)

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“…[ 6 , 7 , 8 , 9 ]. In the preservation of cultural heritage, it is also used either as an in-situ testing method of the current state of structural elements or as a monitoring tool in the form of a sensor array [ 10 , 11 , 12 ]. Due to a simple testing principle, there are many variations of this method in the form of, for example, the low-frequency pulse-echo method [ 13 , 14 ] or modal analysis [ 15 , 16 , 17 ].…”

Section: Introductionmentioning

confidence: 99%

Effect of Hammer Type on Generated Mechanical Signals in Impact-Echo Testing

Dvořák

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2021

Materials

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The impact-echo diagnostic method is a well-known nondestructive pulse compression test method, which can be relatively easily used for the testing of concrete and reinforced concrete elements. The evaluation of the measurement with this method is based on the analysis of the signal itself in the time and frequency domains. This allows acquisition of information on the velocity of the mechanical wave, the resonant frequency of the specimen or on the presence of internal defects. The ability to interpret these measurements depends on the experience of the diagnostic technician. The advent of classification algorithms in the field of machine learning has brought an increasing number of applications where the entire interpretation phase can be considerably simplified with the help of classification models. However, this automated evaluation procedure must be provided with the information of whether the signal acquired by the test equipment has actually been measured under optimally set conditions. This paper proposes a procedure for the mutual comparison of different measuring setups with a variable tip type, hammer handle and impact force. These three variables were used for a series of measurements which were subsequently compared with each other using multi-criteria evaluation. This offers a tool for the evaluation of measured data and their filtering. As an output of the designed method, each measurement is marked by a score value, which represents how well the acquired signal fit the weight demands for each observed feature of the signal. The method allows the adjustment of selected demands for a specific application by means of set thresholds. This approach enables the understanding of characteristics of the signal in the automated pre-processing of measured data, where computing power is limited. Thus, this solution is potentially suitable for remote long-term observations with sensor arrays or for acoustic emission signals pre-processing.

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Section: Introductionmentioning

confidence: 99%

Effect of Hammer Type on Generated Mechanical Signals in Impact-Echo Testing

Dvořák

Topolář

2021

Materials

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“…These applications typically exploit a frequency range of 50-500 kHz (central frequency) in order to achieve penetrations around tens of centimeters or more. The use of frequencies higher than 1 MHz is limited by their strong attenuation in marble [35,37]. Thus, in direct transmission measurements it is desirable to find a compromise between spatial resolution and penetration, mainly due to the need of recording pulse-echo signals from the back surface.…”

Section: Introductionmentioning

confidence: 99%

A photoacoustic pulse-echo probe for monitoring surface stone mechanical properties: Validation tests in consolidation of Carrara marble

Mencaglia

Ciofini

2018

Construction and Building Materials

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The present work focuses on the development and validation of a laser-based photoacoustic sensor for non-destructive monitoring of surface stone mechanical properties. The sensor is constituted of a carbon black target excited by fiber-coupled Q-Switched Nd:YAG(1064 nm) laser with variable pulse duration between 10 and 50 ns, a superimposed PVDF film transducer, and gel coupler. The high optical absorption of the target and its relatively large lateral size allowed generating planar longitudinal pressure waves of amplitude around 1 MPa using a laser pulse fluence of about 8 mJ/cm 2. The probe provided an almost flat spectral response over a bandwidth of 7.5-30 MHz. Thanks to the high pulse-to-pulse laser power stability, the pressure transients were highly reproducible in amplitude and waveform. These features and the FFT analysis of the back reflected signal were exploited to characterize the surface mechanical properties of decayed Carrara marble upon consolidation. Treatment tests were carried out using three commercial products: acrylic-siloxane polymer, a fluoroelastomeracrylic polymer, and ethyl-silicate. The acoustic reflection and then surface sound speed spectra were measured and analyzed for the first time within a spectral window of 1-30 MHz. Surface speed spectra and dephasing derived from reflectance measurements resulted to be essential parameters for characterizing and monitoring stone consolidation. The results achieved provide evidence that the technique proposed offers significant advantages with respect to traditional approaches and can represent an effective tool in conservation-restoration of stone artifacts, wall paintings, and other.

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