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Numerical modeling of thermoelastic generation of ultrasound by laser irradiation in the coupled thermoelasticity.

Veres IA, Berer T, Burgholzer P - Ultrasonics (2012)

Bottom Line: Moreover, the coupling leads to dispersion influencing the wave velocities at low frequencies.The numerical simulations are compared to theoretical results available in the literature.Wave fields generated by a line focused laser source are presented by the numerical model for isotropic and for transversely isotropic materials.

View Article: PubMed Central - PubMed

Affiliation: Research Center for Non-Destructive Testing GmbH (RECENDT), Altenberger Str. 69, 4040 Linz, Austria. istvan.veres@recendt.at

No MeSH data available.


Related in: MedlinePlus

(a) Time domain signals on the epicentral axis with the quasi longitudinal wave (precursor) for zinc (solid line) and longitudinal bulk wave for aluminum (dotted line), generated by a 20 ps laser pulse. (b) Fourier-transform of the signals, with frequency contents up to 100 GHz. (c) Waveforms on the epicentral axis for both materials. (d) Comparison of three discretisations for aluminum to test the convergence of the technique.
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f0015: (a) Time domain signals on the epicentral axis with the quasi longitudinal wave (precursor) for zinc (solid line) and longitudinal bulk wave for aluminum (dotted line), generated by a 20 ps laser pulse. (b) Fourier-transform of the signals, with frequency contents up to 100 GHz. (c) Waveforms on the epicentral axis for both materials. (d) Comparison of three discretisations for aluminum to test the convergence of the technique.

Mentions: To evaluate the frequency content of the generated bulk longitudinal wave, time domain signals on the epicentral axis are captured, shown in Fig. 3a. The sharp, positive peaks in the signals are the generated bulk waves (or quasi longitudinal wave in zinc), often described as the precursor. The generated wave in zinc has a larger amplitude as the result of the higher linear thermal expansion coefficient of zinc along the c axis of the crystal. The frequency contents of these pulses are evaluated by a temporal Fourier transform (Fig. 3b) after multiplication with a Hanning window. The excited frequency spectrum in Fig. 3b reaches above 100 GHz in both cases, whereby the corresponding wavelengths are Λ ∼ 50–60 nm. The full width at half maximum is, however, much higher for aluminum (∼35 GHz vs. ∼20 GHz in zinc). Spatial counterparts of the time domain signals are shown in Fig. 3c as epicentral wave forms (displacements on the epicentral axis) for both materials.


Numerical modeling of thermoelastic generation of ultrasound by laser irradiation in the coupled thermoelasticity.

Veres IA, Berer T, Burgholzer P - Ultrasonics (2012)

(a) Time domain signals on the epicentral axis with the quasi longitudinal wave (precursor) for zinc (solid line) and longitudinal bulk wave for aluminum (dotted line), generated by a 20 ps laser pulse. (b) Fourier-transform of the signals, with frequency contents up to 100 GHz. (c) Waveforms on the epicentral axis for both materials. (d) Comparison of three discretisations for aluminum to test the convergence of the technique.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4067043&req=5

f0015: (a) Time domain signals on the epicentral axis with the quasi longitudinal wave (precursor) for zinc (solid line) and longitudinal bulk wave for aluminum (dotted line), generated by a 20 ps laser pulse. (b) Fourier-transform of the signals, with frequency contents up to 100 GHz. (c) Waveforms on the epicentral axis for both materials. (d) Comparison of three discretisations for aluminum to test the convergence of the technique.
Mentions: To evaluate the frequency content of the generated bulk longitudinal wave, time domain signals on the epicentral axis are captured, shown in Fig. 3a. The sharp, positive peaks in the signals are the generated bulk waves (or quasi longitudinal wave in zinc), often described as the precursor. The generated wave in zinc has a larger amplitude as the result of the higher linear thermal expansion coefficient of zinc along the c axis of the crystal. The frequency contents of these pulses are evaluated by a temporal Fourier transform (Fig. 3b) after multiplication with a Hanning window. The excited frequency spectrum in Fig. 3b reaches above 100 GHz in both cases, whereby the corresponding wavelengths are Λ ∼ 50–60 nm. The full width at half maximum is, however, much higher for aluminum (∼35 GHz vs. ∼20 GHz in zinc). Spatial counterparts of the time domain signals are shown in Fig. 3c as epicentral wave forms (displacements on the epicentral axis) for both materials.

Bottom Line: Moreover, the coupling leads to dispersion influencing the wave velocities at low frequencies.The numerical simulations are compared to theoretical results available in the literature.Wave fields generated by a line focused laser source are presented by the numerical model for isotropic and for transversely isotropic materials.

View Article: PubMed Central - PubMed

Affiliation: Research Center for Non-Destructive Testing GmbH (RECENDT), Altenberger Str. 69, 4040 Linz, Austria. istvan.veres@recendt.at

No MeSH data available.


Related in: MedlinePlus