Abstract
In this paper, a novel parameter recognition method of mode-converted wave in single-source ultrasound is put forward and applied to the estimation of axial stresses in bolts. To overcome the distortion and aliasing of the mode-converted wave in single-source ultrasonic signal, a time-frequency parameter recognition method based on the Gabor transform is introduced to recognize the accurate time of flight (TOF) of the mode-converted wave. Based on the mode conversion of the single-source longitudinal ultrasound, a new nonlinear evaluation model based on acoustoelastic equation is derived to determine the axial stress of bolt. The performance of the proposed method is evaluated by comparing it with the commonly used TOF ratio method of longitudinal wave and shear wave (L-S). The experiment result shows that the proposed method is more effective in detecting the connection status of bolted joints than the traditional L-S method.
Highlights
Loosening is one kind of failure that can markedly impact the stiffness and reliability of bolted joints
Yasui et al [13] proposed the longitudinal wave and shear wave (L-S) method based on multisource ultrasound to solve this problem, in which the stress is measured according to the time of flight (TOF) ratio of longitudinal wave (L-wave) and shear wave (S-wave) by two separate transducers mounted on the two ends of the bolt with great care and precision
The parameter recognition method based on the Gabor transform and Gaussian empirical model to obtain the accurate TOF of the mode-converted signal is introduced and its effectiveness is proved by simulation
Summary
Loosening is one kind of failure that can markedly impact the stiffness and reliability of bolted joints. The coupling conditions (e.g., installation position, pressure, and coupling agent concentration) of the L-wave and S-wave transducers must be repeatable to ensure accuracy This method is difficult to achieve reliable measurement results under practical conditions. Compared with the multi-source method, owing to aliasing and distortion in the mode-converted wave signal used in Kim’s method, it’s difficult to obtain accurate TOF directly. They used a special designed probe with an acoustic lens to Journal of Sensors generate the mode-converted wave with high SNR (signalnoise ratio). A novel axial stress evaluation method using the mode-converted wave generated by single-source ultrasound based on the Gabor transform is proposed. The experiment result shows that the proposed method is more effective in detecting the connection status of bolted joints than the traditional L-S method
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