Host: The Japan Society of Mechanical Engineers
Name : [in Japanese]
Date : December 15, 2016 - December 16, 2016
Bolted joints are widely used in mechanical and architectural structures. However, many serious accidents occur because of loosening of bolted joints. Conventionally, the inspection method of the loosening bolted joint is generally the measurement of axial tension of a bolted joint by using ultrasonic waves. These methods require the use of special measurement equipment and the human operation. In this study, a smart washer was proposed to detect the loosening without human involvement. The smart washer is in cantilever type with piezoelectric material, which adds the washer of the self-sensing and actuating function. Previous research had indicated that a correlation was confirmed between the natural frequency of the smart washer and the tightening axial tension with the theoretical and experimental results. The subject of this method is to identify the natural frequency of the smart washer by changing the bolt tightening axial tension, which is using the self-sensing and actuating by applying the piezoelectric material. This paper describes the natural frequency identification method for smart washer with the adaptive observer by fixed and variable adaptive law. The influences of initial parameter vector were considered computationally and experimentally when applying the adaptive observer.
