accurate measurements of physical characteristics of bone are essential for diagnosis, assessment of change following treatment, and therefore, indirectly, for evaluation of new forms of therapy. this is particularly true of osteoporosis and aging skeleton, in which fractures occur easily. methods: in this study an ultrasonic system was set-up and calibrated on plexiglas tubes of variable thick...

Among the various techniques available, ultrasonic Lamb waves offer a convenient method of examining composite materials. Since the Lamb wave velocity depends on the elastic properties of a material, an effective tool exists to evaluate composites by measuring the velocity of these waves. Lamb waves can propagate over long distances and are sensitive to the desired in-plane elastic properties o...

Among the various techniques available, ultrasonic Lamb waves offer a convenient method of evaluating composite materials. Since the Lamb wave velocity depends on the elastic properties of a structure, an effective tool exists to monitor damage in composites by measuring the velocity of these waves. Lamb wave measurements can propagate over long distances and are sensitive to the desired in-pla...

Ultrasonic guided wave inspection is much more efficient than traditional point-bypoint examination. Guided waves can propagate over long distances from a single position, and therefore is a good method of evaluating thickness degradation, especially for large-area structures such as pipes and vessels. In this paper, guided wave thickness measurement potential is studied utilizing a peak freque...

This paper examines in detail the characteristics of a leaky Lamb wave propagating in a piezoelectric plate immersed in a dielectric or conductive fluid. The analysis is based on the partial wave analysis and its numerical calculations. Some corrections have been made so that both the changes in phase velocity and the wave attenuation of leaky Lamb waves caused by fluid’s mechanical, dielectric...

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...

Modeling and experiments are used to investigate Lamb wave propagation in the direction perpendicular to an applied stress. Sensitivity, in terms of changes in velocity, for both symmetrical and anti-symmetrical modes was determined. Codes were developed based on analytical expressions for waves in loaded plates and they were used to give wave dispersion curves. The experimental system used a p...

Lamb waves offer a promising method of evaluating damage in composite materials. The Lamb wave velocity is directly related to the material parameters, so an effective tool exists to monitor damage in composites by measuring the velocity of these waves. The Lamb Wave Imager (LWI) uses a pulse/receive technique that excites an antisymmetric Lamb mode and measures the time-of-flight over a wide f...

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...

Acoustoelasticity, or the change in elastic wave speeds with stress, is a well-studied phenomenon for bulk waves. The effect of stress on Lamb waves is not as well understood, although it is clear that anisotropic stresses will produce anisotropy in the Lamb wave dispersion curves. Here the theory of acoustoelastic Lamb wave propagation is developed for isotropic media subjected to a biaxial, h...