title: Ultrasonic Lateral Displacement Sensor for Health Monitoring in Seismically Isolated Buildings.
abstract: An ultrasonic lateral displacement sensor utilizing air-coupled ultrasound transducers is proposed. The normally-distributed far field of an ultrasound transducer in a lateral direction is taken advantage of for measuring lateral displacement. The measurement system is composed of several air-coupled ultrasound transducers as a receiver and several transmitters. The transmitters are immobilized at a fixed point, whereas the receiver set-up is separately arranged on the opposite side. In order to improve measurement accuracy, a correction method that utilizes polynomial approximation is introduced. The difference between the corrected lateral displacement and the reference displacement is estimated to be 0.2 mm at maximum for the two transmitters system. A good responsiveness is demonstrated by conducting a dynamic response experiment. When five transmitters are arranged, their measurement range is easily extended up to ±60 mm with an accuracy of 0.7 mm. In both cases, the fluctuations to the measurement ranges show less than 1%. These results indicate that the developed sensor system is useful for measuring relative lateral displacement of a seismically isolated building in the field of structural health monitoring.
authors.affiliation: Department of Mechanical Engineering, Nagaoka University of Technology, Kamitomioka 1603-1, Nagaoka 940-2188, Niigata, Japan. matsuya@mech.nagaokaut.ac.jp.
authors.forename: Iwao
authors.initials: I
authors.lastname: Matsuya
authors.affiliation: Department of Mechanical Engineering, Nagaoka University of Technology, Kamitomioka 1603-1, Nagaoka 940-2188, Niigata, Japan. fumy1991@gmail.com.
authors.forename: Fumiya
authors.initials: F
authors.lastname: Matsumoto
authors.affiliation: Department of Mechanical Engineering, Nagaoka University of Technology, Kamitomioka 1603-1, Nagaoka 940-2188, Niigata, Japan. ihara@mech.nagaokaut.ac.jp.
authors.forename: Ikuo
authors.initials: I
authors.lastname: Ihara
keywords: air-coupled ultrasound; earthquake; lateral displacement; normal distribution; polynomial approximation; seismically isolated building; sound field; structural health monitoring