カドワキ　レン   Ren Kadowaki   門脇　廉    所属   追手門学院大学  理工学部 機械工学科    職種   准教授
発表年月日	2019/08
発表テーマ	超音波の瞬時振動数を用いた隙間寸法の測定
会議名	Dynamics and Design Conference 2019
学会区分	全国学会
発表形式	その他
国名	日本
開催地名	九州大学伊都キャンパス（福岡県福岡市）
開催期間	2019/08/27～2019/08/30
発表者・共同発表者	大久保 知輝,井上 卓見,門脇 廉,大村 和久
概要	There are many contact interfaces including a thin liquid layer, which almost is machine oil, between two solids within machines. The purpose of this study is to evaluate contact pressure acting a thin liquid layer between two solids through measuring the liquid layer thickness. Changing the contact pressure, thickness of the liquid layer also changes. In this paper, we propose a thickness measurement method for the liquid layer using an ultrasonic pulse. In the proposed method, an ultrasonic pulse is sent from outside of one solid to the liquid layer. And we observe a reflected pulse from the liquid layer. The sent ultrasonic pulse is reflected at two boundary interfaces between the liquid and the solids several times. The reflected pulses interfere with each other, and received as an interfered pulse. When the liquid layer thickness changes, transmission paths of some of the reflected pulses expand or contract. It means that time delays of the reflected pulses also change. The interfered pulse is affected by the change of the time delay. The change of the interfered pulse is small. So we observe its instantaneous frequency to evaluate the change of the liquid layer thickness which causes the small interference change. In this study, we demonstrated the proposed method by applying it to some sample liquid layers whose thicknesses are known. To compare with the experimental results, we estimated the interfered reflected pulse by means of a numerical simulation. We discussed the mechanism of the proposed method and its effectiveness using these results. Additionally, we give a more accurate calculation method of the instantaneous frequency than existing one.