Effect on detection sensitivity for smart washer configuration and ambient temperature characteristics on bolted joint

Abstract

The objective of this study is to apply the concept of structural health monitoring to the detection of bolted joints loosening without human involvement. This paper proposes a method of bolt loosening detection by adopting a smart washer with sub-space state space identification (4SID) algorithm. The smart washer is the cantilevered plate type washer bonded piezoelectric material. The feature is the self-sensing and actuation function. The principle of how to detect the loosening of a bolt is the basis that the natural frequency of a smart washer system vary depending on a bolt tightening axial tension. The natural frequency of the smart washer was identified by using the sub-space state space identification method. For practical use of the smart washer, it is necessary to investigate the problem of repeatability and data quality depending on the influence of the ambient temperature characteristics, and to improve the sensitivity at the initial state of the bolt tightening axial tension decreasing. This paper describes the results of experimental and analytical about the effect on the sensitivity for the smart washer configuration, and the ambient temperature characteristics on the bolted joint. The experimental results indicate the influence of the temperature variation to the bolt tightening axial tension. In order to the sensitivity of the improve bolt loosening detection, vibration-modal analysis of the smart washer system is performed for the configuration of the smart washer. The design parameters of the smart washer was discussed on the results of the numerical simulation.

Embedded nonlinear ultrasonics for structural health monitoring of satellite joints

“…In contrast, Verijenko (2006) monitored a bolt's martensitic phase transition under tension. Okugawa and Tanaka (2007) reported an approach that explores the changes in the washer's natural frequency after alternating bolt tension. Although technologies focusing on monitoring a single bolt are quite promising, their application to the assessment of a satellite's condition would require significant hardware resources and considerable additional weight as a satellite can contain more than 1000 bolts.…”

Detection of Anomaly in a Pretensioned Bolted Beam-to-Column Connection Node Using Digital Image Correlation and Neural Networks

“…Although this approach "can be easily applied for real-time structural health monitoring of any engineering structure" [11], the size of detected loosenings was greater (loosenings were visible with the naked eye) than that considered in this paper. Another approach to detect changes in bolt tightening relies on the application of intelligent washers, see, e.g., [13]. Changing the bolt tightening affects the frequency of free vibrations of a cantilever pad with piezoelectric sensors (PZT) mounted on it.…”