ultrasonic testing (ut), a nondestructive testing (ndt) method, is under development for quality determination of agricultural products, although it has long been used in the food industry. determination and measurement of product quality are important in modern agricultural research. noninvasive/nondestructive quality determination is a novel aspect of the postharvest process in which paramete...

we usewe use ml shear wave velocity to derive a high resolution 2d ml shear wave velocity map for the iranian plateau. the ml amplitudes and arrival times are routinely measured for the calculation of local magnitude. ml shear wave velocity is very sensitive to the lateral change of crustal thickness and switches between the velocity of lg and sn waves. an lg wave will die out as soon as encoun...

Adhesively bonded joints between metallic and composite plates are gaining increasing acceptance in safety critical applications such as automotive and aerospace structures. Lamb wave methods have considerable potential for the inspection of adhesive joints and assemblies for two reasons: they do not require direct access to the bond region, and they are much more amenable to rapid scanning tha...

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, ...

Lamb waves are frequently used in nondestructive evaluation and are proposed for structural health monitoring applications. While many numerical methods to obtain dispersion curves for Lamb waves have been developed and implemented, in general they are time consuming and do not lend themselves to analyses involving the perturbation of parameters such as the small thickness and wave speed change...

Fundamental asymmetric lamb wave’s interactions with rectangular notches in a steel plate are investigated in this paper. Elastodynamic finite integration technique previously mainly used to study wave propagation in elastic media is adopted to study lamb wave interaction with defects. Simulation examples are presented to illustrate the reflection and transmission coefficients’ variations with ...

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...

This paper is focused on the problem of mode identification of Lamb waves in ultrasonic testing, and the principle and process of two time-frequency transform method, smooth pseudo Wigner–Ville distribution and two-dimensional Fourier transform, were discussed. The experimental work were carried out in aluminium plates, and the single and multimode Lamb waves were excited by 5MHz oblique incide...

shear and compressional wave velocities along with other petrophysical logs, are considered as upmost important data for hydrocarbon reservoirs characterization. shear wave velocity (vs) in well logging is commonly measured by some sort of dipole logging tools, which are able to acquire shear waves as well as compressional waves such as sonic scanner, dsi (dipole shear sonic imager) by schlumbe...

Measured Amplitude Ratio (MAR) is a form of modal analysis for the classification of Acoustic Emission (AE) signals. MAR uses a comparison of the amplitudes of the first two primary lamb wave modes, symmetric (S0) and asymmetric (A0), to determine the orientation of the damage mechanisms in relation to the sensor. Previous researchers have demonstrated that some damage mechanisms, such as delam...