Elastic plates or cylinders can support guided modes with zero group velocity (ZGV) at a nonzero value of the wave number. Using laser-based ultrasonic techniques, we experimentally investigate some fascinating properties of these ZGV modes: resonance and ringing effects, backward wave propagation, interference between backward and forward modes. Then, the conditions required for the existence ...

Matching pursuit (MP) is an adaptive signal decomposition technique and can be applied to process Lamb waves, such as denoising, wave parameter estimation, and feature extraction, for health monitoring applications. This paper explored matching pursuit decomposition using Gaussian and chirplet dictionaries to decompose/approximate Lamb waves and extract wave parameters. While Gaussian dictionar...

This paper deals with the study of the spectral components of Lamb waves generated in thin aluminium plate using pulsed Nd-YAG laser and detected using a He-Ne Laser Heterodyne interferometer. Laser generation of Lamb waves leads to simultaneous generation of various frequency component as well as multiple Lamb wave modes. The Lamb wave signals are successfully and comprehensively analyzed usin...

This paper investigates the characteristics of the second harmonic generation of Lamb waves in a plate with quadratic nonlinearity. Analytical asymptotic solutions to Lamb waves are first obtained through the use of a perturbation method. Then, based on a careful analysis of these asymptotic solutions, it is shown that the cross-modal generation of a symmetric second harmonic mode by an antisym...

In recent years, ultrasonic methods have been developed that can be used to measure the mechanical stiffness of materials.1-5 In one such method, the velocity of a flexural plate wave, the lowest order antisymmetric Lamb mode, is measured as a function of frequency. Lamb waves arise from a coupling at the free boundaries between the shear waves and compressional waves in a plate structure.6 The...

Acoustic techniques are used to monitor the temperature of silicon wafers in rapid thermal processing environments from room temperature to 1000" C with f 5 " C accuracy. Acoustic transducers are mounted at the bases of the quartz pins that support the silicon wafer during processing. An electrical pulse applied across the transducer generates an extensional mode acoustic wave which is guided b...

Normal regional pulse wave velocity predicts absence of aortic luminal growth in patients with Marfan syndrome: a comprehensive MRI-study Eleanore Kroner, Arthur Scholte, Patrick Koning, Pieter J van den Boogaard, Rob J van der Geest, Lucia J M Kroft, Hildo J Lamb, Yvonne Hilhorst-Hofstee, Maarten Groenink, Teodora Radonic, Barbara J Mulder, Ernst E van der Wall, Jeroen J Bax, Albert de Roos, J...

Time reversal active sensing using Lamb waves is investigated for health monitoring of a composite structure. In the present work experiments were conducted on a glass/epoxy composite plates to study the time reversal behavior of A0 and S0 Lamb wave modes. PZT wafer sensors were surface bonded to the structure for generation and reception of the Lamb wave modes. Time reversal experiments were f...

This article investigates the scattering characteristics of Lamb waves from a debonding at a structural feature in a composite laminate. This study specifically focuses on the use of the low frequency fundamental antisymmetric (A(0)) Lamb wave as the incident wave for debonding detection. Three-dimensional finite element (FE) simulations and experimental measurements are used to investigate the...

Peridynamic based elastodynamic computation tool named Peri-elastodynamics is proposed herein to simulate the three-dimensional (3D) Lamb wave modes in materials for the first time. Peri-elastodynamics is a nonlocal meshless approach which is a scale-independent generalized technique to visualize the acoustic and ultrasonic waves in plate-like structure, micro-electro-mechanical systems (MEMS) ...