Internal Cylinder Identification Based on Different Transmission of Longitudinal and Shear Ultrasonic Waves.

Wen-Bei Liu,Wen-Bo Yan,Zhi-Yong Tao,Huan Liu,Ya-Xian Fan,Cheng-Guo Tong

doi:10.3390/s21030723

Wen-Bei Liu, Wen-Bo Yan + Show 4 more

Open Access

https://doi.org/10.3390/s21030723

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Abstract

We have built a Fizeau fiber interferometer to investigate the internal cylindrical defects in an aluminum plate based on laser ultrasonic techniques. The ultrasound is excited in the plate by a Q-switched Nd:YAG laser. When the ultrasonic waves interact with the internal defects, the transmitted amplitudes of longitudinal and shear waves are different. The experimental results show that the difference in transmission amplitudes can be attributed to the high frequency damping of internal cylinders. When the scanning point is close to the internal defect, the longitudinal waves attenuate significantly in the whole defect area, and their amplitude is always smaller than that of shear waves. By comparing the transmitted amplitudes of longitudinal and shear waves at different scanning points, we can achieve a C scan image of the sample to realize the visual inspection of internal defects. Our system exhibits outstanding performance in detecting internal cylinders, which could be used not only in evaluating structure cracks but also in exploring ultrasonic transmission characteristics.

Highlights

In the aeronautics and automotive industry, there is a high demand for the quality of mechanical structures and materials
We built a Fizeau fiber interferometer to detect the internal defects in aluminum plates
Through experimental and theoretical analysis, we studied the interaction between internal defects and ultrasonic waves

Summary

Introduction

In the aeronautics and automotive industry, there is a high demand for the quality of mechanical structures and materials. Campman et al imaged surface defects in aluminum plates with laser ultrasonic methods [10] and developed the related methods and theories of wave propagation in marine seismic waves for applications [11,12] In these works, researchers focused on surface defects and usually analyzed the reflected or transmitted ultrasound to obtain information about the cracks.

Fizeau Fiber Interferometer

Experimental Processes

Transmission of Longitudinal and Shear Waves

Visualization of Internal Cylinders

Findings

Conclusions