Analysis for the generalized thermoelastic Lamb waves, which propagates in anisotropic thin plates in generalized thermoelasticity, is presented employing normal mode expansion method. The displacement and temperature fields are expressed by a summation of the symmetric and antisymmetric thermoelastic modes in the surface thermal stresses and thermal gradient free orthotropic plate, therefore t...

A pulsed Nd:YAG laser with an approximately Gaussian beam shape is directed onto the surface of an aluminium sheet at an energy density below which damage by laser ablation occurs, generating Lamb waves in the sheet. The laser beam is raster scanned across the surface of the sample. The Lamb waves travel radially outwards from the generation point and are detected some distance away by an elect...

Many structural health monitoring (SHM) applications in use monitor the progress of Lamb waves across a test object in order to detect structural problems, such as cracks and material losses. This study proposes the use of S-transformation techniques to identify the frequency–time domain characteristics and to reduce the noise of the signals at the receiver. Two time domain models, time delay–a...

ABSTRACT. Many structural health monitoring (SHM) applications in use monitor the progress of Lamb waves across a test object in order to detect structural problems such as cracks and material losses. This paper proposes the use of Stransformation techniques to identify the frequency-time domain characteristics and to reduce the noise of the signals at the receiver. Two time domain models, time...

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...

Our previous papers reported dispersion curves for leaky Lamb waves in a water-loaded plate and wave structures for several typical modes including quasi-Scholte waves [1,2]. The calculations were carried out with a semianalytical finite element (SAFE) method developed for leaky Lamb waves. This study presents SAFE calculations for transient guided waves including time-domain waveforms and anim...

Leaky-Rayleigh waves have been studied extensively at liquid-solid interface in the last 30 years [1-4]. Both leaky-Rayleigh and leaky-Lamb waves have found many application in Nondestructive Evaluation, e.g. surface defect characterization, etc [5,6]. Because of the difficulties associated with ultrasonic wave generation and detection in air in the megaHerz region air coupled non destructive e...

The characteristics of confined magnetoelastic waves in nanoscale ferromagnetic magnetostrictive waveguides have been investigated by a combination analytical and numerical calculations. presence both magnetostriction inverse leads to the coupling between spin elastic Lamb waves. Numerical simulations coupled system used extract dispersion relations as well their mode profiles.

Non-contact ultrasonic, enables rapid testing of structures using ultrasonic tests that are not possible via conventional contact transducers. This paper reports on laser ultrasonic and air/gas coupled ultrasonic measurements that are performed remotely, do not require direct access to test area, do not need traditional ultrasonic coupling and do not have traditional C-scan fixture requirements...

Due to the problems of dispersion and multi-modes overlap for ultrasonic Lamb wave propagation, it is difficult to use it in many fields, such as long-range inspection. After ultrasonic Lamb waves are generated by a broadband ultrasonic pulse, these problems make the wave packets to spread out and various modes overlap in both time and space domain as they propagate through a plate or pipe. It ...