Laser induced Zero-Group Velocity resonances in Transversely Isotropic cylinder

TL;DR

This study investigates laser-induced resonances in transversely isotropic elastic cylinders, revealing the importance of elastic anisotropy in accurately predicting resonance spectra and matching experimental results.

Contribution

The paper introduces a transverse isotropic model to accurately predict laser-induced resonances in elastic cylinders, improving upon isotropic assumptions.

Findings

Resonances are mainly Zero-Group Velocity guided modes.

Transverse isotropic modeling aligns well with experimental data.

Elastic anisotropy is crucial for precise resonance prediction.

Abstract

The transient response of an elastic cylinder to a laser impact is studied. When the laser source is a line perpendicular to the cylinder axis, modes guided along the cylinder are generated. For a millimetric steel cylinder up to ten narrow resonances can be locally detected by laser interferometry below 8 MHz. Most of these resonances correspond to Zero-Group Velocity guided modes while a few others can be ascribed to thickness modes. We observe that the theory describing the propagation of elastic waves in an isotropic cylinder is not sufficient to precisely predict the resonance spectrum. In fact, the texture of such elongated structure manifest as elastic anisotropy. Thus, a transverse isotropic (TI) model is used to calculate the dispersion curves and compare them with the measured one, obtained by moving the source along the cylinder. The five elastic constants of a TI cylinder are adjusted leading to a good agreement between measured and theoretical dispersion curves. Then, all the resonance frequencies are satisfactorily identified.