Acoustic Field Excited by Single Force with Arbitrary Direction in Semi-Infinite Elastic Space

Abstract

In this paper, the acoustic field excited by a single force with arbitrary direction in a semi-infinite elastic space is studied and its mathematical expressions are obtained. It shows that there are many complex behaviors when the elastic wave reaches the free boundary. The numerical simulation shows that there are several kinds of waves in the semi-infinite elastic space: direct P wave, direct SV wave, SP wave propagating along the free surface which can generate Head wave and Rayleigh wave. The forming mechanism of the SP wave and Rayleigh wave is specially studied. The waveforms at the observation point on the free surface of the semi-infinite space contain only direct P wave and direct SV wave when the SV wave incident angle is within the critical reflection angle. However, if the incident angle from the source to the observation point is exceeding to the critical reflection angle, not only direct P and direct SV wave but also the SP wave and Rayleigh wave are all be generated. It is focused on the relationships of the direction of single force to the excitation intensity of each wave. The relationship of each wave packet to the single force and observation direction is obtained and analyzed.