On finite element modelling in time reversal problems

0483320 - ÚT 2018 RIV CZ eng C - Conference Paper (international conference)
Mračko, Michal - Kober, Jan - Kolman, Radek - Převorovský, Zdeněk - Plešek, Jiří - Masák, Jan - Kruisová, Alena
On finite element modelling in time reversal problems.
NDT in PROGRESS. Praha: Institute of Thermomechanics AS CR, v .v. i., 2017 - (Převorovský, Z.), s. 46-50. ISBN 978-80-87012-63-5.
[International Workshop of NDT Experts /9./. Praha (CZ), 09.10.2017-11.10.2017]
R&D Projects: GA MŠMT(CZ) EF15_003/0000493; GA ČR GA17-22615S
Institutional support: RVO:61388998
Keywords : time reversal * explicit finite element analysis * elastic wave propagation * non-destructive testing * source reconstruction * refocusing
OECD category: Acoustics

In this paper we analyse suitability and accuracy of computational techniques in time reversal applications based on finite element method (FEM) for detection and localization of defects, cracks or other acoustic emission sources in bodies and structures. As it is known, a classical explicit integration scheme - central difference is reversible. The central difference scheme as a time integrator is widely used for linear and nonlinear finite element analyses and it is also implemented in commercial and open-source finite element software. In the paper properties of the explicit FEM in time reversal problems are studied and analysed. We use the standard Galerkin FEM formulation with linear shape functions, one-point Gauss integration and lumped mass matrix. Loading by the Ricker pulse was applied for modelling of the acoustic source in an elastic square domain. A special attention is paid to the choice of boundary conditions in reverse problem which keep the reversibility of problems of interest. Finally, we show the quality of refocusing of the original acoustic source.
Permanent Link: http://hdl.handle.net/11104/0279215