ABOUT HEAD WAVES AND UNDER-SURFACE LONGITUDINAL WAVES, RADIATED BY THE NORMAL PROBE WHICH IS TAKING PLACE ON A FREE FLAT SURFACE OF THE ELASTIC ENVIRONMENT

Abstract

On the basis of integrated representations Fourier–Bessel a component of displacement of elastic waves, radiating by the normal converter which is taking place on a free flat surface of the elastic environment, receives analytical estimations of displacement a under-surface longitudinal and head (it is surface-longitudinal) waves. Components of displacement a under-surface longitudinal wave are the sum a component in approximation of geometrical acoustics (GA), the diffraction amendments to this approximation and the amendments which are taking into account influence of feature when the parameter of integrated representation is equal to wave number of a longitudinal wave. Components of displacement of a head wave are defined as the sum appropriate diffraction amendments for a component of displacement of a volumetric longitudinal wave in approximation GA and a component of displacement of a lateral wave. The maximum of amplitude of displacement a under-surface longitudinal wave in angular area of a direction of distribution near to a free surface of environment is caused by one of local maxima of the directivity characteristic of the normal probe. Thus dependence of change of amplitude of this wave of distance wave from the centre of the probe practically corresponds to similar dependence for displacement of a volumetric longitudinal wave in GA approximation. Quantitative estimations of maxima of amplitude of displacement under-surface longitudinal and head waves concerning the greatest amplitude, radiated by the normal probe of a volumetric longitudinal wave.