Quantitative analysis of laser-generated ultrasonic wave characteristics and their correlation with grain size in poly crystalline materials

徐兆文 ¹白雪 ¹马健 ¹万壮壮 ¹王超群¹

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作者信息

1. Laser Institute,Qilu University of Technology(Shandong Academy of Sciences),Jinan 250104,China
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Abstract

Quantitative relationship between nanosecond pulsed laser parameters and the characteristics of laser-generated ul-trasonic waves in polycrystalline materials was evaluated.The high energy of the pulsed laser with a large irradiation spot simultaneously generated ultrasonic longitudinal and shear waves at the epicenter under the slight ablation regime.An optimized denoising technique based on wavelet thresholding and variational mode decomposition was applied to reduce noise in shear waves with a low signal-to-noise ratio.An approach for characterizing grain size was proposed using spectral central frequency ratio(SCFR)based on time-frequency analysis.The results demonstrate that the generation regime of ultrasonic waves is not solely determined by the laser power density;even at high power densities,a high energy with a large spot can generate an ultrasonic waveform dominated by the thermoelastic effect.This is ascribed to the intensification of the thermoelastic effect with the proportional increase in laser irradiation spot area for a given laser power density.Fur-thermore,both longitudinal and shear wave SCFRs are linearly related to grain size in polycrystalline materials;however,the shear wave SCFR is more sensitive to finer-grained materials.This study holds great significance for evaluating metal material properties using laser ultrasound.

Key words

laser-ultrasonics/polycrystalline materials/ultrasonic time-frequency characteristics/grain size

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基金项目

Natural science Foundation of Shandong Province,China(ZR2023ME073)

National Natural Science Foundation of China(51805304)

Education Department of Shandong Province,China(2022KJ130)

Qilu University of Technology(Shandong Academy of Sciences),China(2023PY009)

Qilu University of Technology(Shandong Academy of Sciences),China(2021JC02008)

Qilu University of Technology(Shandong Academy of Sciences),China(2022GH005)

出版年

2024

中国物理B(英文版)

中国物理学会和中国科学院物理研究所

中国物理B(英文版)

CSTPCDEI

影响因子：0.995

ISSN：1674-1056

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