Narrow Results

The effect of surface/interface stress on mechanical behaviors may become remarkable when the characteristic size of a structure decreases to nanoscale. Various problems have been analyzed to reveal the size-dependent mechanical behaviors of nano structures with curved surfaces/interfaces. In this work, the problem of planar surfaces/interfaces is addressed. The generalized Young–Laplace equation is presented for a planar interface and the propagation behavior of Love wave in a nanocoating is discussed. Parametric studies indicate that if the surface effect of the nanocoating is considered the phase velocity of Love wave shows notable size-dependency on both the nanocoating thickness and the wavelength. When these two sizes are both in nanoscale, the phase velocity further depends on the relative size between them. In addition, increasing the residual surface stress may reduce the phase velocity of Love wave.

The present paper is devoted to study the Love wave propagation in a fiber-reinforced medium laying over a nonhomogeneous half-space. The upper layer is assumed as reinforced medium and we have taken exponential variation in both rigidity and density of lower half-space. As Mathematical tools the techniques of separation of variables and Whittaker function are applied to obtain the dispersion equation of Love wave in the assumed media. The dispersion equation has been investigated for three different cases. In a special case when both the media are homogeneous our computed equation coincides with the classical equation of Love wave. For graphical representation, we used MATLAB software to study the effects of reinforced parameters and inhomogeneity parameters. It has been observed that the phase velocity increases with the decreases of nondimensional wave number. We have also seen that the phase velocity decreases with the increase of reinforced parameters and inhomogeneity parameters. The results may be useful to understand the nature of seismic wave propagation in fiber reinforced medium.

In this paper, the effect of initial stress on the propagation of Love waves in a layered structure with a thin piezoelectric film bonded perfectly to an elastic substrate has been investigated. General dispersion equations, describing the properties of Love waves in both cases, electrically open case and electrically shorted case of the piezoelectric layer, have been obtained. The effects of inhomogeneity parameters in the substrate and the initial stress in both, the layer and the substrate on the phase velocity of Love waves, are analyzed and presented graphically. The analytical method and obtained results may find applications for designing the resonators and sensors.

Investigations are carried out to predict the characteristic behavior of Love-wave fields propagating in a non-local elastic model under the effects of irregular boundary surfaces, reinforcement, and porosity distributions. The model includes an anisotropic fiber-reinforced medium lying over an anisotropic porous half-space. Two different porosity distributions are investigated within the porous half-space, namely uniform porosity and asymmetrical porosity. Analytical solutions to the displacement fields for both the upper layer and the lower porous half-space are calculated. Solutions to the latter porosity distribution are obtained by using the asymptotic expansions of the Kummer hypergeometric functions of the second kind. Both the interface and the upper surface of the two-layered media are subjected to irregular boundary conditions, which leads to a complex form of the dispersion relation. We analyze the phase velocity and damped velocity behavior of the traveling Love-wave fields separately by using the real and imaginary components of the velocity dispersion relation. The calculated phase velocity curves obtained at the same parameters have been compared to demonstrate the accuracy of the established model. The effects of corrugation parameters, porosity distributions, non-local elasticity, and reinforcement on the phase velocity and the damped velocity curves are analyzed in detail using MATLAB software.

The problem of the propagation of Love waves in multilayers of generalized magneto-thermoelastic materials has been investigated using Haskell matrix method. The dispersion relations for the Love waves are derived for the topmost layer with the help of appropriate conditions. We have observed that there are two wavefronts of Love-type surface waves: the first wavefront is due to the electro-magnetic parameters and the second wavefront appears due to the thermal parameters. The dispersion curves of both these fronts are computed for two and three layers and results are represented graphically. The phase velocity corresponding to first wavefront is non-attenuating, while that of second wavefront is attenuating. The 3D pictures of displacement, conductive temperature and heat flux have shown that transverse displacement, conductive temperature and heat flux are sinusoidal natures.

Love waves have great potential in geological inspection and ultrasonic nondestructive testing for near-surface underground characteristics. A thorough and effective utilization of the Love wave requires a better understanding of its scattering phenomenon. The paper studies the problem of Love wave scattering by cavity-like flaws on the interface between the upper layer and the lower half-plane. For the forward analysis, we suggest a modified boundary element method (BEM) incorporating the far-field displacement patterns, which can effectively eliminate fictitious reflections introduced by model truncation. For inverse analysis, we propose a quantitative reconstruction procedure for the flaw shape using reflection coefficients of the first-order Love wave. By theoretical deduction, it can be proved that the cavity’s geometric shape is approximately expressed as an inverse spatial Fourier transform of far-field reflection coefficients in the wavenumber domain. Numerical examples are given by substituting the reflection coefficients obtained from the forward analysis into the inversion algorithm, and high consistency is shown between the reconstructed flaw images and the geometric characteristics of the actual flaws.