セラミックス多孔体の超音波伝ぱメカニズム : 第1報,理論

概要

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In this paper, the authors present a new theory of propagation of ultrasonic waves in porous ceramics. The idea is based upon the arrival probability of ultrasonic rays. When incident rays impinge a pore, they creep around the pore surface and delay the propagation time. We studied this process from a probabilistic standpoint, and found that the propagated waveforms can be expressed as Gaussian functions. The Gaussian waveform is determined from the porosity, mean pore size and pore shape. This new finding revealed the following important laws. (1)The delay time of an ultrasonic wave passing through porous ceramics is proportional to the porosity ; (2)the pulse width of the wave becomes wider with the increase in mean pore size ; (3) the amplitude of the wave decreases with the mean pore size : and (4) the delay time and pulse width of the wave increase with the mean pore perimeter. Formulas for these relationships between ultrasonic and porous characteristics were derived, and an ultrasonic method to evaluate porosity and mean pore size was proposed.
一般社団法人日本機械学会の論文
1994-09-25