円筒による狭ビーム音波の反射

概要

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When examining materials by using sound waves, it is common practice to utilize sound waves of narrow beam in order to obtain higher resolution. In this research, a study was made on the acoustic receiver outputs for the reflected waves in the direction of the sound source when sound waves narrow in the beam width compared with the dimension of the cylinder were projected against a cylinder from an acoustic transmitter/receiver traveling along the axis of the cylinder. Two approximate calculations were worked out. The first one was a simple approximation of geometrical optics in which the strength of the reflected wave was assumed to be dependent upon the effective area on the cylinder surface where differences in the pathes of the sound waves were within λ/(12) (λ:wave length). Theoretical values by this method and actual values were in close agreement with each other only when the cylinder was located in parallel with the scanning surface. Then a fairly strict approximate calculation was performed in which cylindrical scatter was integrated to obtain the sound pressure in the direction of the sound source. This method yielded theoretical values which agreed well with the actual values even when the cylinder was inclined, thus being considered applicable to general cases. Through this research, general properties were obtained on the narrow beam sound waves reflected from a cylinder.
社団法人日本音響学会の論文
1979-12-01