Assessment of Plastic Deformation in Al6061 Alloy using Acoustic Nonlinearity of Laser-Generated Surface Wave

Kim, Chung-Seok; Nam, Tae Woon; Choi, Sungho; Jhang, Kyung-Young

doi:10.7779/jksnt.2012.32.1.020

Cited by 4 publications

(3 citation statements)

References 14 publications

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“…A surface wave generated by a pulsed laser beam results from thermal expansion and contraction of the surface of the specimen, which is caused by interaction between the laser and the surface within thermo-elastic regime [9].…”

Section: Principle Of Surface Wave Generationmentioning

confidence: 99%

Frequency Characteristics of Surface Wave Generated by Single-Line Pulsed Laser Beam with Two Kinds of Spatial Energy Profile Models: Gaussian and Square-Like

Seo¹,

Kim²,

Choi³

et al. 2012

Journal of the Korean Society for Nondestructive Testing

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Using a single-line pulsed laser beam is well known as a useful noncontact method to generate a directional surface acoustic wave. In this method, different laser beam energy profiles produce different waveforms and frequency characteristics. In this paper, we considered two typical kinds of laser beam energy profiles, Gaussian and square-like, to find out a difference in the frequency characteristics. To achieve this, mathematical models were proposed first for Gaussian laser beam profile and square-like respectively, both of which depended on the laser beam width. To verify the theoretical models, experimental setups with a cylindrical lens and a line-slit mask were respectively designed to produce a line laser beam with Gaussian spatial energy profile and square-like. The frequency responses of the theoretical models showed good agreement with experimental results in terms of the existence of harmonic frequency components and the shift of the first peak frequencies to low.

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Section: Principle Of Surface Wave Generationmentioning

confidence: 99%

Frequency Characteristics of Surface Wave Generated by Single-Line Pulsed Laser Beam with Two Kinds of Spatial Energy Profile Models: Gaussian and Square-Like

Seo¹,

Kim²,

Choi³

et al. 2012

Journal of the Korean Society for Nondestructive Testing

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“…Using a line laser beam, the directivity of the SAW becomes improved [6]. A single-line laser-generated SAWs can be excited by several methods such as the use of a cylindrical lens and a line-slit mask [3,5,8,12]. Using a line-arrayed slit mask, a single-point laser beam can be modulated to line-arrayed laser beam able to generate tone-burst SAWs.…”

Section: Introductionmentioning

confidence: 98%

“…Especially, for measuring acoustic nonlinearity, using SAWs generated by a line-arrayed pulsed laser beam is one of the effective NDE methods [3,8,9]. The line-arrayed laser-generated SAWs exhibit a narrow bandwidth that facilitates the frequency decomposition between the fundamental and harmonic components, which is essential to measure acoustic nonlinearity from the frequency analysis of SAWs.…”

Section: Introductionmentioning

confidence: 99%

Influence of laser beam profiles on the frequency bandwidth of laser-generated surface acoustic waves

Seo

Choi

Jhang

2014

2014 IEEE Far East Forum on Nondestructive Evaluation/Testing

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The frequency characteristics of laser-generated surface acoustic waves (SAWs) were investigated depending on laser beam profiles. The laser-generated SAWs were analytically and experimentally compared when using the single-line laser beams of Gaussian and square-like energy profiles. Also, the line-arrayed laser beam in the square-like energy distribution was introduced to generate the SAW that had a narrow frequency bandwidth. The results from both the experiments and the simulations showed the similar distinction of the frequency characteristics in between using Gaussian and square-like laser energy profiles. The SAW by the Gaussian laser beam showed only single peak in the frequency spectrum, whereas the odd harmonic frequency components appeared in the case of using the square-like laser beams. Moreover, the SAW by the line-arrayed laser beam had narrower frequency bandwidth than the SAW by the single-line laser beam. These results were in good agreement with the theoretical predictions, which supports that laser-generated SAWs have the advantage of frequency modulation by modifying the spatial energy profile of a laser beam.

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Fully Non-Contact Assessment of Acoustic Nonlinearity According to Plastic Deformation in Al6061 Alloy

Lee¹,

Chen²,

Kim³

et al. 2012

Journal of the Korean Society for Nondestructive Testing

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This study proposes a fully non-contact measurement method to assess acoustic nonlinearity of narrowband surface waves generated by a line-arrayed laser beam by using a laser-ultrasonic detector in the way of two-wave mixing (TWM) method. This method was applied to figure out a relationship between plastic deformation and nonlinearity characteristics of a plastically deformed aluminum specimens. The experimental results showed that the acoustic nonlinearity of the laser-generated surface wave increased proportionally to the level of tensile deformation. This tendency is in good agreement with the result of measurement by contact method with PZT-transducer.Keywords: Acoustic Nonlinearity, Laser-generated Surface Wave, Laser Ultrasound Detector, Two-wave Mixing

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Assessment of Plastic Deformation in Al6061 Alloy using Acoustic Nonlinearity of Laser-Generated Surface Wave

Cited by 4 publications

References 14 publications

Frequency Characteristics of Surface Wave Generated by Single-Line Pulsed Laser Beam with Two Kinds of Spatial Energy Profile Models: Gaussian and Square-Like

Frequency Characteristics of Surface Wave Generated by Single-Line Pulsed Laser Beam with Two Kinds of Spatial Energy Profile Models: Gaussian and Square-Like

Influence of laser beam profiles on the frequency bandwidth of laser-generated surface acoustic waves

Fully Non-Contact Assessment of Acoustic Nonlinearity According to Plastic Deformation in Al6061 Alloy

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