Using computational time reversal method for localization of forming and propagating crack

Kód výsledku v IS VaVaI

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Výsledek na webu

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DOI - Digital Object Identifier

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Jazyk výsledku

angličtina

Název v původním jazyce

Using computational time reversal method for localization of forming and propagating crack

Popis výsledku v původním jazyce

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, thisnmethod 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 andnreconstruction 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 isnrecorded 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 callednscatterers (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 elementn(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 ofnprescription 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).

Název v anglickém jazyce

Using computational time reversal method for localization of forming and propagating crack

Popis výsledku anglicky

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, thisnmethod 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 andnreconstruction 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 isnrecorded 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 callednscatterers (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 elementn(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 ofnprescription 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).

Druh

O - Ostatní výsledky

CEP obor

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OECD FORD obor

20501 - Materials engineering

Projekt

Výsledek vznikl pri realizaci vícero projektů. Více informací v záložce Projekty.

Návaznosti

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Rok uplatnění

2019

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů