Showing papers by "Ajit Mal published in 1981"

Diffraction of Elastic Waves by a Surface Crack on a Plate

Abstract: The interaction of time harmonic elastic waves with an edge crack in a plate is studied. The crack is assumed to be normal to the plate surface and its depth small compared to plate thickness. Only plane strain deformations are considered. The incident waves are assumed to be either plane body waves (compressional (P) or inplane shear (SV) ) of arbitrary angle of propagation or surface Rayleigh waves propagating at right angles to the crack. For each incident wave type the complete high frequency diffracted field on the plate surface is calculated. Solution is obtained by the application of an asymptotic theory of diffraction. Application to ultrasonic inspection techniques is indicated.

Scattering of elastic waves

Abstract: The problem of the scattering of time harmonic plane elastic waves by an inclusion is considered. It is shown that the scattered field can be expressed either as a surface integral or a volume integral over the scatterer. The integrand contains a certain combination of the unknown displacements and stresses within or on the surface of the scatterer. Three different schemes for the determination of these unknowns are discussed. These are (1) low‐ and high‐frequency estimates via an approximate analysis, (2) numerical determination via an integral equation formulation, and (3) numerical calculations via a finite element approach. Once these estimates are known, the scattered waves are determined from the integral representation. Results are presented for the scattering of body waves by obstacles in infinite space or of body and surface waves by obstacles embedded in a half‐space.