The use of numerical and phased array techniques to focus guided waves and perform inspection of plates and pipes has not been widely used; it represents an interesting solution for defect detection and localization. In addition, imaging of ultrasonic guided wave results using color coded B-Scans is also considered a highly valuable tool for data interpretation. While commercial ultrasonic phas...

The propagation of the fundamental quasi-symmetric Lamb mode S(0) travelling along 3C-SiC/c-AlN composite plates is theoretically studied with respect to the AlN and SiC film thickness, the acoustic wave propagation direction and the electrical boundary conditions. The temperature effects on the phase velocity have been considered for four AlN/SiC-based electroacoustic coupling configurations, ...

Considerable efforts have been made in recent years to develop quantitative nondestructive evaluation (NDE) techniques for composite materials, which are being used increasingly in primary structures. The leaky Lamb wave phenomenon has shown considerable potential as an NDE method [1]. Most results reported in this area to date have been concerned with unidirectional laminates [2-4]. This is at...

Using Brillouin scattering we have succeeded in observing the normal modes of vibration of unsupported films in a region where the dispersion relationship is quadratic. Extremely low-lying excitations were observed in thin films with thicknesses as small as 200 A. Contrary to what has been found in work on supported films, we are able to extract information on a number of the elastic moduli bec...

1 Institute of Mathematics and Computing Science, University of Groningen, 9700 AV Groningen, The Netherlands 2 Institute of Applied and Experimental Mechanics, University of Stuttgart, Pfaffenwaldring 9, 70569 Stuttgart, Germany 3Computer Science Department, University of North Carolina, Chapel Hill, NC 27599-3175, USA 4School of Civil and Environmental Engineering and G.W.Woodruff School of M...

This study develops an automated method capable of detecting notches in isotropic plates. Laser ultrasonic techniques are used to generate and detect Lamb waves in perfect and notched plates. These signals are first transformed into the time-frequency domain using a short time Fourier transform (STFT) and subsequently into the group velocity-frequency domain. Finally, the notch is located with ...

This paper considers the bonded joint as a multilayer structure that is analysed using the Transfer Matrix method. In this particular case three layers (two adherents and the adhesive) are considered. The study of this propagation problem may be developed from matrix formulations which describe elastic waves in layered media. This technique combines the theory of the dynamics of the continuum w...

It is well known that acoustic emission (AE) signals, generated by external impacts or damages such as crack initiation, mainly propagate in the form of Lamb waves plate-like structures. In this work, MEMS-based resonant capacitive micro-machined ultrasonic transducers (CMUTs), which are designed for sensing out-of-plane displacements, have been verified finite element method (FEM) modeling and...

The object of this research is to characterize the porous bones by an ultrasonic method using Lamb waves. In recent years, the characterization of such materials has attracted many authors and takes a perfect place in the field of medicine. It requires the development of more efficient technology for getting the necessary quality and security. This paper aims to exploits the dispersion curves o...