Influence of material viscoelasticity on the scattering of guided waves by defects

Department of Mechanics, University Politehnica Bucharest, Splaiul Independentei 313, Sector 6,

Bucharest 060042, Romania

Michel Castaings, Ludovic Moreau

Laboratoire de Mécanique Physique, UMR CNRS 5469, Université Bordeaux 1, 351 cours de la Libération,

33400 Talence, France

.

Guided waves are potential candidates for the nondestructive evaluation of viscoelastic structures

due to their relatively long range of propagation. The major drawback is the difficulty in interpreting

the scattered waves especially at high frequency-thickness values since many modes then exist.

Moreover, in damping material waveguides, each mode of the scattered field has its own attenuation.

Viscoelastic material characterization has been widely investigated by many authors in the past, but

very few are treating multimodal scattering by discontinuities in viscoelastic guide. The scattering

of a pure fundamental mode incident on a trough in a viscoelastic plate is investigated in this paper,

over a relatively large frequency range, with up to five scattered modes. A hybrid two-dimensional

finite element and modal projection method is used, based on modal orthogonality, to obtain the

relative energy fluxes of each mode. Experiments are also made to validate the numerical

predictions.

©

2008 Acoustical Society of America. DOI: 10.1121/1.2977604

PACS number

.s: 43.35.Mr, 43.20.Mv, 43.35.Cg RLW Pages: 2883–2894