2014/04/30 by Jérôme Laurent, Daniel Royer, Claire Prada · 1 citation
Physics and Astronomy · #physics.class-ph #physics.flu-dyn #physics.optics
paper · pdf · doi:10.1016/j.wavemoti.2014.04.001
8 pages, 7 figures. Wave Motion 2014
crossref created 2014/04/15 · arxiv created 2014/08/04 · arxiv updated 2014/08/05 · crossref issued 2014/09/01 · crossref published 2014/09/01 · crossref published-print 2014/09/01 · crossref deposited 2019/08/09 · crossref indexed 2026/08/06
This paper investigates the dependence on Poisson's ratio of local plate resonances in low attenuating materials. In our experiments, these resonances are generated by a pulse laser source and detected with a heterodyne interferometer measuring surface displacement normal to the plate. The laser impact induces a set of resonances that are dominated by Zero Group Velocity (ZGV) Lamb modes. For some Poisson's ratio, thickness-shear resonances are also detected. These experiments confirm that the temporal decay of ZGV modes follows a t-0.5 law and show that the temporal decay of the thickness resonances is much faster. Similar decays are obtained by numerical simulations achieved with a finite difference code. A simple model is proposed to describe the thickness resonances. It predicts that a thickness mode decays as t-1.5 for large times and that the resonance amplitude is proportional to D-1.5 where D is the curvature of the dispersion curve ω(k) at k=0. This curvature depends on the order of the mode and on the Poisson's ratio, and it explains why some thickness resonances are well detected while others are not.