We use finite element simulations and experiments to examine the excitation of waves in a plate by normal forces applied to an edge. At low values of the frequency-plate thickness product, f·d, multiple Lamb wave modes are excited with different group velocities, but increasing f·d leads to the formation of a train of well-defined nearly-longitudinal pulses. We investigate the transition betwee...

The piezoelectric wafer active sensors (PWAS) are low-power non-resonant devices with broadband capabilities. They interrogate the structure through guided Lamb waves. PWAS capabilities for Lamb-wave damage detection have been validated experimentally, but the modeling of the in-situ PWAS behavior is still incomplete. This paper addresses fundamental aspects of the Lamb-wave interaction between...

Hollow cylinders used in the industry must be regularly inspected. Elastic guided waves, similar to Lamb modes in a plate, can propagate in the axial direction or around the circumference. They are sensitive to geometrical and mechanical parameters of the cylindrical shell. The objective of this paper is to show that zero group velocity (ZGV) Lamb modes can be used to bring out anisotropy and t...

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...

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...

The inspection of a storage tank floor is a time consuming and expensive procedure, mainly due to necessity to empty and to clean the tank before an inspection. For this purpose a long range ultrasonic technique based on Lamb waves may be applied. Such an approach is used for inspection of pipes and can cover the distances up 100m. However the storage tanks are much more complicated structures ...

The guided wave has been widely employed to characterize thin plates and layered media. The dispersion curves of phase and group velocities are essential for the quantitative application of guided waves. The technique using leaky Lamb wave (LLW) is one of the excellent methods to obtain dispersion curves. In the present work, a fully automated system for the measurement of LLW has been develope...

The present study is concerned with the propagation of Lamb waves in a homogeneous isotropic thermoelastic micropolar solid with two temperatures bordered with layers or half spaces of inviscid liquid subjected to stress free boundary conditions. The generalized theory of thermoelasticity developed by Lord and Shulman has been used to investigate the problem. The secular equations for symmetric...