We have calculated the phonon frequencies of KC1 along symmetry directions using an approach which is a combination of the frozen phonon and force constants methods. We also calculated Griineisen parameters for all modes at X and L points in the Brillouin zone. Finally, the slope of acoustic dispersion curves around zone center were used to calculate the three independent elastic coefficien...

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...

Abstract In this work a procedure to compute the dispersion curves for one dimensional viscoelastic waveguides exploiting the finite element based global mass matrix and complex stiffness matrix is proposed. The global matrices of a finite length portion of the waveguide, the unit cell, are post-processed by enforcing Bloch-type boundary conditions along the wave propagation direction and next ...

Most ultrasonic systems employing guided waves for flaw detection require information such as dispersion curves, transducer locations, and expected propagation loss. Degraded system performance may result if assumed parameter values do not accurately reflect the actual environment. By characterizing the propagating environment in situ at the time of test, potentially erroneous a priori estimate...

A general model is introduced which describes a system with cubic nonlinearities, in a situation when the linear dispersion relation has three branches which nearly intersect. The system consists of two waves with a strong linear coupling between them, to which a third wave is coupled. This model has are two gaps in its linear spectrum. A nonlinear analysis is performed for zero-velocity solito...

A general model is introduced to describe a wave-envelope system for the situation when the linear dispersion relation has three branches, which in the absence of any coupling terms between these branches, would intersect pairwise in three nearly coincident points. The system contains two waves with a strong linear coupling between them, to which a third wave is then coupled. This model has two...

The transient response of an elastic cylinder to a laser impact is studied. When the laser source is a line perpendicular to the cylinder axis, modes guided along the cylinder are generated. For a millimetric steel cylinder up to ten narrow resonances can be locally detected by a laser interferometer below 8 MHz. These resonances correspond to Zero-Group Velocity guided modes or to circumferent...

for the lattice constants i.e. 11 C , 12 C , 44 C , 44 12 C C − , 44 12 C C and bulk modulus B obtained using the Hartree (H) local field correction function has higher values in comparison with the results obtained for the same properties using Ichimaru-Utsumi (IU) local field correction function. The results for the Shear modulus ( C ′ ), deviation from Cauchy’s relation, Poisson’s ratio σ , ...

In the present work, liquid flow pattern in a Tubular Electrochemical Reactor (TC-ECR) with concentric cylindrical expanded meshes as electrodes and inlet/outlet distributors of shower‑sprinkler type was evaluated. It found that CFD theoretical results describe experimental F(t)-curves obtained methodology “step-signal input”. Later, estimated for each reactor zone were adequately approximated ...