scholarly journals Нелинейный фотоакустический отклик на механические напряжения вблизи отверстия в пластине из алюминиевого сплава Д16

2020 ◽  
Vol 46 (4) ◽  
pp. 22
Author(s):  
А.Л. Глазов ◽  
Н.Ф. Морозов ◽  
К.Л. Муратиков
Keyword(s):  
Aluminum Alloy ◽  
Laser Radiation ◽  
Thermal Effect ◽  
Modulation Frequency ◽  
Photoacoustic Signal ◽  
Theoretical Description ◽  
Mechanical Stresses ◽  
Electronic Subsystem ◽  
Sound Generation ◽  
Photoacoustic Effect

The features of the behavior of the photoacoustic signal depending on mechanical stresses near the hole in the plate made of aluminum alloy D16 are investigated. A new nonlinear photoacoustic effect was discovered, which consists in the appearance of a nonlinear component of the photoacoustic signal depending on mechanical stresses near the hole. This dependence is recorded in the signal at the modulation frequency of the laser radiation. A theoretical description of the discovered effect of sound generation by the thermoelastic mechanism in stressed metals is proposed basing on the consideration of the thermal effect of laser radiation on their electronic subsystem.

scholarly journals Влияние механических напряжений в пластине из алюминиевого сплава Д16 на генерацию акустических колебаний лазерным излучением

2019 ◽  
Vol 45 (17) ◽  
pp. 51
Author(s):  
А.Л. Глазов ◽  
К.Л. Муратиков
Keyword(s):  
Thermal Expansion ◽  
Thermodynamic Model ◽  
Coefficient Of Thermal Expansion ◽  
Photoacoustic Signal ◽  
Mechanical Stresses ◽  
Experimental Results ◽  
Laser Generation ◽  
Acoustic Vibrations ◽  
Electronic Subsystem ◽  
Alloy Plate

The process of laser generation of ultrasound in metals with internal mechanical stresses is analyzed. The features of the photoacoustic signal behavior near the hole in the D16 alloy plate when subjected to mechanical stresses are investigated. The discrepancy between the experimental results and the predictions of the thermodynamic model of the dependence of the coefficient of thermal expansion on mechanical stresses has been revealed. To correctly describe the features of the signal behavior in real metals, it was proposed to take into account the effect of the electronic subsystem on the laser generation of acoustic vibrations.

scholarly journals Photoacoustic trace detection of gases at the parts-per-quadrillion level with a moving optical grating

2017 ◽  
Vol 114 (28) ◽  
pp. 7246-7249 ◽  
Author(s):  
Lian Xiong ◽  
Wenyu Bai ◽  
Feifei Chen ◽  
Xian Zhao ◽  
Fapeng Yu ◽  
...  
Keyword(s):  
Sound Speed ◽  
Photoacoustic Signal ◽  
Laser Resonator ◽  
Trace Detection ◽  
Photoacoustic Cell ◽  
Optical Source ◽  
Photoacoustic Effect ◽  
One Dimensional ◽  
Optical Grating ◽  
Detector Crystal

The amplitude of the photoacoustic effect for an optical source moving at the sound speed in a one-dimensional geometry increases linearly in time without bound in the linear acoustic regime. Here, use of this principle is described for trace detection of gases, using two frequency-shifted beams from a CO2 laser directed at an angle to each other to give optical fringes that move at the sound speed in a cavity with a longitudinal resonance. The photoacoustic signal is detected with a high-Q, piezoelectric crystal with a resonance on the order of 443 kHz. The photoacoustic cell has a design analogous to a hemispherical laser resonator and can be adjusted to have a longitudinal resonance to match that of the detector crystal. The grating frequency, the length of the resonator, and the crystal must all have matched frequencies; thus, three resonances are used to advantage to produce sensitivity that extends to the parts-per-quadrillion level.

STUDY OF THERMAL TRANSPORT PARAMETERS IN PbI2 SINGLE CRYSTAL USING A PHOTOACOUSTIC TECHNIQUE

2006 ◽  
Vol 20 (20) ◽  
pp. 1253-1260 ◽  
Author(s):  
D. S. AHLAWAT ◽  
D. MOHAN ◽  
S. K. GHOSHAL ◽  
R. D. SINGH ◽  
MEENAKSHI SHARMA
Keyword(s):  
Thermal Conductivity ◽  
Thermal Diffusivity ◽  
Single Crystal ◽  
Characteristic Frequency ◽  
Modulation Frequency ◽  
Thermal Effusivity ◽  
Photoacoustic Signal ◽  
Photoacoustic Technique ◽  
Front Side ◽  
Transport Parameters

The present work discusses the study of the transport properties of the PbI 2 single crystal using an indigenously developed photoacoutistic spectrometer. The amplitude photoacoustic signal, being a function of the modulation frequency of the incident optical beam, has been measured by using the front-side detection configuration. The characteristic frequency (fc) of the single crystal has been found to be 55 Hz. The values of thermal diffusivity, thermal conductivity and thermal effusivity in the case of PbI 2 have been derived experimentally. Their values have been compared with the values reported in a case which studied other materials in the literature. Thermal diffusion lengths have also been calculated at different chopping frequencies from 15 Hz to 90 Hz.

Numerical analysis of thermal effect in aluminum alloy by monopulse laser

2014 ◽  
Author(s):  
Xiuying Gu ◽  
Guibo Chen ◽  
Guangyong Jin ◽  
Wei Zhang ◽  
Mingxin Li
Keyword(s):  
Aluminum Alloy ◽  
Numerical Analysis ◽  
Thermal Effect

scholarly journals Electro-acustic influence of the measuring system on the photoacoustic signal amplitude and phase in frequency domain

2016 ◽  
Vol 14 (1) ◽  
pp. 9-20 ◽  
Author(s):  
Sanja Aleksic ◽  
Dragana Markushev ◽  
Dragan Pantic ◽  
Mihajlo Rabasovic ◽  
Dragan Markushev ◽  
...  
Keyword(s):  
Frequency Domain ◽  
Flicker Noise ◽  
Modulation Frequency ◽  
Signal Amplitude ◽  
Photoacoustic Signal ◽  
Measuring System ◽  
Coherent Noise ◽  
Characteristic Frequencies ◽  
Signal Distortions ◽  
Set Up

The paper discusses the most common impacts of the measuring system on the amplitude and phase of the photoacoustic signals in the frequency domain using the open-cell experimental set-up. The highest signal distortions are detected at the ends of the observed modulation frequency range from 20 Hz to 20 kHz. The attenuation of the signal is observed at lower frequencies, caused by the electronic filtering of the microphone and sound card, with characteristic frequencies of 15 Hz and 25 Hz. At higher frequencies, the dominant signal distortions are caused by the microphone acoustic filtering, having characteristic frequencies around 9 kHz and 15 kHz. It has been found that the microphone incoherent noise, the so called flicker noise, is negligibly small in comparison to the signal and does not affect the signal shape. However, a coherent noise originating from the power modulation system of the light source significantly affects the shape of the signal in the range greater than 10 kHz. The effects of the coherent noise and measuring system influence are eliminated completely using the relevant signal correction procedure targeting the photoacoustic signal generated by the sample.

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