ZHANG X M, LI Z R, LI Z,et al.Theoretical calculation and experimental study on the characteristics of longitudinal ultrasonic guided wave propagation in a free bolt[J].Journal of Henan Polytechnic University(Natural Science) ,2023,42(2):27-33.

doi:10.16186/j.cnki.1673-9787.2021070094

Received:2021/07/24

Revised:2021/09/09

Published:2023/03/25

Theoretical calculation and experimental study on the characteristics of longitudinal ultrasonic guided wave propagation in a free bolt

ZHANG Xiaoming, LI Zhuoran, LI Zhi, YU Jiangong

School of Mechanical and Power Engineering，Henan Polytechnic University，Jiaozuo 454000，Henan，China

Abstract:The bolt nondestructive testing based on ultrasonic guided wave technology is of great significance to ensure the engineering safety.The propagation and attenuation characteristics of longitudinal ultrasonic guided wave in a free bolt were studied in this paper，and the group velocity and attenuation of longitudinal guided wave were solved by the presented analytical Legendre polynomial method.The presented method could overcome the deficiency that the traditional Legendre method was time-consuming caused by a large number of numerical integral calculations，and the computational efficiency was greatly improved.The group velocity and attenuation of longitudinal guided wave in a steel bolt were calculated and compared with the literature’s ones to validate the presented method.Compared with the traditional polynomial method，the efficiency of the presented method was revealed.The guided wave propagation in a free bolt was also studied experimentally.The group velocity was measured and compared with the obtained theoretical results.The results showed that for L（0，3）-L（0，10） modes of the free bolt，the minimum attenuation value and the maximum group velocity value appeared at the same frequency，and they increased with increasing the mode order.There was a relationship between the attenuation value and the echo amplitude.The smaller the attenuation value was，the larger the echo amplitude was.

Key words:free bolt;longitudinal ultrasonic guided wave;Legendre polynomial method;group velocity;attenuation

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