کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1900530 | 1045340 | 2014 | 10 صفحه PDF | دانلود رایگان |
• Local plate resonances are measured with pulsed laser ultrasonic techniques.
• Resonance amplitudes depend on the curvature DD of the Lamb mode dispersion law.
• Time decay of zero group velocity Lamb mode resonances scale with (Dt)−0.5(Dt)−0.5.
• Time decay of thickness-shear resonances scale with (Dt)−1.5(Dt)−1.5.
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−0.5t−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−1.5t−1.5 for large times and that the resonance amplitude is proportional to D−1.5D−1.5 where DD is the curvature of the dispersion curve ω(k)ω(k) at k=0k=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.
Journal: Wave Motion - Volume 51, Issue 6, September 2014, Pages 1011–1020