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Using computational time reversal method for localization of forming and propagating crack
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SYSNO ASEP 0519747 Document Type A - Abstract R&D Document Type O - Ostatní Title Using computational time reversal method for localization of forming and propagating crack Author(s) Mračko, Michal (UT-L)
Kolman, Radek (UT-L) RID
Kober, Jan (UT-L) RID, ORCID
Převorovský, Zdeněk (UT-L) RID
Plešek, Jiří (UT-L) RID, ORCID, SAINumber of authors 5 Source Title NDT in Progress 2019. - Praha : Ústav termomechaniky AV ČR, v. v. i., 2019 / Převorovský Z. - ISBN 978-80-87012-72-7
S. 124Number of pages 1 s. Publication form Print - P Action NDT in Progress 2019 /10./ Event date 07.10.2019 - 10.10.2019 VEvent location Praha Country CZ - Czech Republic Event type WRD Language eng - English Country CZ - Czech Republic Keywords time reversal ; explicit finite element analysis ; elastic wave propagation ; non-destructive testing ; crack localization Subject RIV BI - Acoustics OECD category Materials engineering R&D Projects EF15_003/0000493 GA MŠMT - Ministry of Education, Youth and Sports (MEYS) GA17-22615S GA ČR - Czech Science Foundation (CSF) Institutional support UT-L - RVO:61388998 Annotation The time reversal (TR) method has found its application in many fields concerning wave propagation. Our object of interest is the application in non-destructive testing (NDT). In NDT, this
method can be used for tracing the source of vibrations in solid bodies, the source being a crack or some other defect. The TR method uses a backward wave propagation for refocusing and
reconstruction of the original source. The TR process consists of two steps. In the first step – the Frontal task, a real body is loaded at the given place with the defined loading signal and an output is
recorded in a prescribed position of the body. In the second step – the Reverse task, this responding signal is reversed in time and loaded into the computational model so as to locate so called
scatterers (e.g. cracks). In computational TR method, both steps are performed numerically. Here we focus on localization of an initializing and a propagating crack in the prestressed finite element
(FE) model. We also study how the length of the computation (number of reflections of the elastic waves) influences the probability of localization of the crack. Special attention is paid to the way of
prescription of the loading signal. For numerical solution, we use the linear FE method, with the lumped mass matrix, a one-point Gauss integration rule and an hourglass control. For the direct integration in time the explicit central difference scheme is employed. This integration scheme is conditionally stable and reversible in time. We evaluate the quality of localization mainly by observing the total energy distribution at the end of the Reversal task. We compare results for several lengths of computation (between 1 000 and 50 000 time steps). The conclusions show that with increasing length of computation (more information loaded into the model) the probability of localization of the crack also increases (the energy refocuses in the location of the source of vibrations).Workplace Institute of Thermomechanics Contact Marie Kajprová, kajprova@it.cas.cz, Tel.: 266 053 154 ; Jana Lahovská, jaja@it.cas.cz, Tel.: 266 053 823 Year of Publishing 2020
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