title: Application of orthogonality-relation for the separation of Lamb modes at a plate edge: numerical and experimental predictions.
abstract: In this study the orthogonality relation-based method for post-processing finite element (FE) predictions and experimental measurements is applied in order to separate Lamb modes at a plate edge at normal incidence. The scattered wave field from the free edge is assumed to be a superposition of all the eigenmodes of an infinite plate. The eigenmode amplitudes of the reflected wave field are determined by implementing the orthogonality-based method on the measured plate edge displacements. Overlapping wavepackets of Lamb modes at a plate edge are simulated by using the FE model and the experiment in the case of an incident S0 mode in a plate with a notch. In the experiment a 3D Scanning Laser Doppler Vibrometer (3D SLDV) (Johansmann and Sauer, 2005) is used to measure 3 dimensional vibrations and thus the edge two-dimensional displacement components simultaneously. It is demonstrated that it is possible to extract signals of various propagating and non-propagating modes in time-domain. The influences of the errors in practical measurements on the extraction procedure have also been studied.
authors.affiliation: Department of Mechanics, Tallinn University of Technology, Ehitajate tee 5, Tallinn 19086, Estonia. Electronic address: madis.ratassepp@ttu.ee.
authors.forename: M
authors.initials: M
authors.lastname: Ratassepp
authors.affiliation: Department of Mechanics, Tallinn University of Technology, Ehitajate tee 5, Tallinn 19086, Estonia.
authors.forename: A
authors.initials: A
authors.lastname: Klauson
authors.affiliation: Laboratoire Ondes et Milieux Complexes UMR CNRS 6294, Université Le Havre, 75 rue Bellot CS 50540, Le Havre, France.
authors.forename: F
authors.initials: F
authors.lastname: Chati
authors.affiliation: Laboratoire Ondes et Milieux Complexes UMR CNRS 6294, Université Le Havre, 75 rue Bellot CS 50540, Le Havre, France.
authors.forename: F
authors.initials: F
authors.lastname: Léon
authors.affiliation: Laboratoire Ondes et Milieux Complexes UMR CNRS 6294, Université Le Havre, 75 rue Bellot CS 50540, Le Havre, France.
authors.forename: D
authors.initials: D
authors.lastname: Décultot
authors.affiliation: Laboratoire Ondes et Milieux Complexes UMR CNRS 6294, Université Le Havre, 75 rue Bellot CS 50540, Le Havre, France.
authors.forename: G
authors.initials: G
authors.lastname: Maze
authors.affiliation: Polytec GmbH, Sales International, Waldbronn, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Fritzsche
keywords: 3D Scanning Laser Doppler Vibrometer; Lamb modes; Mode separation; Orthogonality