Abstract

This work shows the wave propagation in fluid-solid interfaces due to dynamic excitations, such interface waves are known as Scholtes waves. We studied a wide range of elastic solid materials used in engineering. The interface connects an acoustic medium (fluid) and another solid. It has been shown that by means of an analysis of diffracted waves in a fluid, it is possible to deduce the mechanical characteristics of the solid medium, specifically, its propagation velocities. For this purpose, the diffracted field of pressures and displacements, due to an initial pressure in the fluid, are expressed using boundary integral representations, which satisfy the equation of motion. The initial pressure in the fluid is represented by a Hankels function of second kind and zero order. The solution to this problem of wave propagation is obtained by means of the Indirect Boundary Element Method, which is equivalent to the well-known Somiglianas representation theorem. The validation of the results was performed by means of the Discrete Wave Number Method. Firstly, spectra of pressures to illustrate the behavior of the fluid for each solid material considered are included, then, the Fast Fourier Transform algorithm to display the results in the time domain is applied, where the emergence of Scholtes waves and the amount of energy that they carry are highlighted.

Abstract

This work is focused on the finding of numerical results for detection and characterization of sub-surface cracks in solids under the incidence of Rayleighs elastic waves. The results are obtained from boundary integral equations, which belong to the field of dynamics of elasticity. Once applied the boundary conditions, a system of Fredholms integral equations of second kind and zero order is obtained, which is solved using Gaussian elimination. The method that is used for the solution of such integral equations is known as the Indirect Boundary Element Method, which can be seen as a derivation of the Somiglianas classic theorem. On the basis of the analysis made in the frequency domain, resonance peaks emerge and allow us to infer the presence of cracks through the spectral ratios. Several models of cracked media were analyzed, where analyses reveal the great utility that displays the use of spectral ratios to identify cracks. We studied the effects of orientation and location of cracks. The results show good agreement with the previously published.