• Title, Summary, Keyword: Ultrasonic velocity

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Applicability of Coda Wave Interferometry Technique for Measurement of Acoustoelastic Effect of Concrete

  • Shin, Sung Woo
    • Journal of the Korean Society for Nondestructive Testing
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    • v.34 no.6
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    • pp.428-434
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    • 2014
  • In this study, we examined the applicability of coda wave interferometry (CWI) technique, which was developed to characterize seismic waves, to detect and evaluate change in the velocity of ultrasonic waves in concrete due to acoustoelastic effect. Ultrasonic wave measurements and compressive loading tests were conducted on a concrete specimen. The measured wave signals were processed with CWI to detect and evaluate the relative velocity change with respect to the stress state of the specimen. A phase change due to the acoustoelastic effect of concrete was clearly detected in the late-arriving coda wave. This shows that the relative velocity change of ultrasonic waves in concrete due to the acoustoelastic effect can be evaluated successfully and precisely using CWI.

A Basic Research on Estimation of Material Condition by Using Nonlinear Elastic Modulus (비선형 탄성계수를 이용한 재료변질 상태평가에대한 기초적 연구)

  • 김경조;장경영
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.348-352
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    • 1995
  • In the conventional linear elasticity, ultrasonic velocity is determined by elastic modulus and density of te medium which ultrasonic wave propagates through. But, practical ultrsonic wave depends on the stress acting in the medium, and as the stress increases such dependency becomes nonlinear. This nonlinear dependencyof ultrasonic velocity on stress can be identified by using nonlinear elastic modulus up to 4th order. In thid paper, with the above background relationships between nonlinear elastic modulus and the internalstatus of materials, normal, plastic deformed or heat stressed, are discussed. For this purpose, a new type of measuring system extended from the general nondestructive UT(ultrasonic test) equipment is constructed.

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Evaluation of Mechanical Properties of Structural Ceramics ($Al_{2}O_{3}$) Using the High Frequency Ultrasonic C - Scan (초음파 C-Scan을 이용한 구조용 세라믹스의 기계적 특성평가)

  • Chang, Y.K.
    • Journal of the Korean Society for Nondestructive Testing
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    • v.9 no.2
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    • pp.18-24
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    • 1989
  • Computer-aided high frequency ultrasonic is applied to aluminum oxide(85w%, 94w%, 96w%, and 99w%) MOR(modulus of rupture) samples to evaluate mechanical properties such as density variation, pore content, elastic modulus, shear modulus, and poisson's ratio. Ultrasonic wave velocity and attenuation measurement techniques were used as an evaluator of such properties. Pulse-echo C-Scan images with different fate setting method using 50MHz center frequency 1 inch focal length transducer allows evaluation of density variation and pore content. Elastic modulus calculated with the relation of density and ultrasonic velocity. It shows good reliability as compared with resonance method. Sintered density variation of $0.025g/cm^{3}$, that is 0.6% of theoretical density in $Al_{2}O_{3}$ samples can be observed by ultrasonic velocity measurement. Attenuation measurement method qualitatively agree with 4-point fracture testing result concerning of porosity content.

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Characteristics of Ultrasonic Propagation of the fruit and Vegetables

  • Lee, Y.H.;Kim, M.S.;Cho, Y.K.;Cho, D.S.l
    • Proceedings of the Korean Society for Agricultural Machinery Conference
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    • pp.344-353
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    • 1996
  • A fundamental study was conducted to obtain the basic data involved in nondestructive quality evaluation of the fruit and vegetables. An experimental equipment for ultrasonic propagation characteristics of the fruit and vegetables such as radish , carrot , potato, and apple was set up and also power spectrum analysis system of an ultrasonic wave through the fruit and vegetables was set up. The velocity and attenuation of ultrasonic wave through the tissue specimens from the fruit and vegetables were measured and analyzed. The elastic modulus and density by the mechanical method currently used were compared with those using by ultrasonic method. The ultrasonic tranit time was almost linearly increased with the length of the specimens and attenuation of ultrasonic was mainly affected by the internal flbrous structure of the products. The regression equation was derived from the highly correlated experimental variables.

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A Study on the Wet Type Ultrasonic Flow-meter System Development (습식방식의 초음파 유량계 시스템 개발에 관한 연구)

  • Lee Eung-Suk;Kwon Oh-Hoon;Rho Myung-Hwan;Lee Hyung-Suk
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.29 no.12
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    • pp.1638-1644
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    • 2005
  • This paper suggests fur the study on a fluid velocity measuring system using ultrasonic transducer. In general, the time difference method to measure the distance between transducers has been known. In this paper, the practical technology for manufacturing ultrasonic flow meter system is studied using the time difference method. The ultrasonic transducer was designed and manufactured. The transmission and receiving algorithm for ultrasonic signal was studied. The ultrasonic flow measuring system was experimented in laboratory using a water reservoir for verifying the distance measuring accuracy. Finally, it was tested in flow calibration laboratory for the velocity measuring performance. The system, designed in this study, showed 0.3 mm resolution in distance measurement. For precise flow measurement, a high speed triggering algorithm is required for ultrasonic signal receiving.

A Study on the Statistical Distribution of Rebound Number and Ultrasonic Pulse Velocity in RC and PSC Concrete Structures (RC 및 PSC 콘크리트에서 반발도 및 초음파 속도의 변화에 대한 연구)

  • Sa, Min-Hyung;Yoon, Young-Geun;Lee, In-Bok;Woo, In-Sung;Oh, Tae Keun
    • Journal of the Korean Society of Safety
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    • v.32 no.4
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    • pp.53-58
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    • 2017
  • The rebound hammer test and the measurement of ultrasonic pulse velocity(UPV) have been widely used for the physical properties & condition evaluation of reinforced & prestressed concrete structures for a long time, but the acoustoelastic effects by the prestressing in the prestressed concrete structures on the rebound number and ultrasonic pulse velocity have not been studied clearly. Therefore, this study investigated the data distribution of the rebound numbers and ultrasonic pulse velocities in reinforced and prestressed concrete slabs of $3000{\times}3000mm$ with a thickness of 250 mm. Also, the Kolmogorov-Smirnov goodness-of-fit test was done in order to identify statistical consistency and reliability. The statistical analysis results show that the rebound number and ultrasonic pulse velocities increased about 1.9% and 2.5%, respectively when prestressing was applied. As expected, the UPV shows better statistical reliability and potential for in situ evaluation than the RB because the RB are more sensitive to testing posture, surface condition, temperature and humidity so on. The experimental data in this study can be used for the condition assessment of reinforced and prestressed concrete structures by the rebound number and ultrasonic pulse velocity.

Influence to the Doppler Images by the Defects of SAE in the Probe of Medical Ultrasonic Scanners (초음파 프로브에서 인접 단위 소자군(SAE) 결함이 도플러 영상에 미치는 영향)

  • Lee, Kyung-Sung
    • Journal of radiological science and technology
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    • v.38 no.1
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    • pp.7-15
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    • 2015
  • A ultrasonic probe is very important in medical ultrasonic image, but the frequency of probe defects are often. Therefore practical tools for probe based ultrasonic QA should be developed. Advanced research on the effects of the probe defects on the quality of ultrasonic images is required. This study has investigated the effects of the defects in the probe elements influence Doppler images in the medical ultrasonic scanners. Especially the defects in a set of adjacent elements(SAE) electrically disconnected influence Doppler images were tested. The results show Doppler brightness and velocity became rapidly reduced as the defected elements is located centrally, as the defected elements is activated. The more the defected elements increased, the more Doppler brightness and velocity increased. As a set of the element disconnected moved, it appeared Doppler velocity starting to decrease and then was followed by brightness. The strength is not consistent with the velocity in the number and location of the defected elements. The defects in the probe elements influence Doppler velocity when the defected elements got out of the elements activated at Doppler mode.

Assessing the effects of mineral content and porosity on ultrasonic wave velocity

  • Fereidooni, Davood
    • Geomechanics and Engineering
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    • v.14 no.4
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    • pp.399-406
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    • 2018
  • The influences of mineral content and porosity on ultrasonic wave velocity were assessed for ten hornfelsic rocks collected from southern and western parts of the city of Hamedan, western Iran. Selected rock samples were subjected to mineralogical, physical, and index laboratory tests. The tested rocks contain quartz, feldspar, biotite, muscovite, garnet, sillimanite, kyanite, staurolite, graphite and other fine grained cryptocrystalline matrix materials. The values of dry unit weight of the rocks were high, but the values of porosity and water absorption were low. In the rocks, the values of dry unit weight are related to the presence of dense minerals such as garnet so not affected by porosity. The statistical relationships between mineral content, porosity and ultrasonic wave velocity indicated that the porosity is the most important factor influencing ultrasonic wave velocity of the studied rocks. The values of P-wave velocity of the rocks range from moderate to very high. Empirical equations, relevant to different parameters of the rocks, were proposed to determine the rocks' essential characteristics such as primary and secondary wave velocities. Quality indexes (IQ) of the studied samples were determined based on P-wave velocities of them and their composing minerals and the samples were classified as non-fissured to moderately fissured rocks. Also, all tested samples are classified as slightly fissured rocks according to the ratio of S-wave to P-wave velocities.

Ultrasonic Velocity and Absorption Measurements for poly (sodium 4-styrenesulfonate) and Water Solutions (Poly (sodium 4-styrenesulfonate)/ 물 이성분용액의 초음파 음속 및 흡수계수측정)

  • 배종림
    • The Journal of the Acoustical Society of Korea
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    • v.23 no.7
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    • pp.497-502
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    • 2004
  • Both ultrasonic velocity at 3 MHz and absorption coefficient in the frequency range of 0.2-2 MHz were measured for poly (sodium 4-styrenesulfonate) aqueous solution over the concentration range of 5 to 25 % by weight. Pulse echo overlap method was employed to measure the ultrasonic velocity over the temperature range of 10-90 ℃ and the high-a ultrasonic resonator method was used for the absorption coefficient measurement at 20 ℃. The velocity exhibited a maximum value at approximately 55. 59, 63. 67, and 71 ℃ in 25, 20. 15, 10. and 5 wt% solutions, respectively. The velocity increased with poly (sodium 4-styrenesulfonate) concentration at a given temperature. The concentrations dependences of the relaxation frequency and amplitude showed that the relaxation around 200 kHz is related to the structural fluctuations of polymer molecules, such as the segmental motions of the polymer chains and that around 1 MHz resulted from the proton transfer reaction of the oxygen sites of SO₃. Both the absorption and the shear viscosity increase with the Polymer concentration. but decrease with temperature.

Flow Visualization of Acoustic Streaming Induced by Ultrasonic Vibration Using Particle Imaging Velocimetry (PIV를 이용한 초음파 진동에 의해 유도된 음향유동의 가시화)

  • 노병국;권기정;이장연;이동렬
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.14 no.6
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    • pp.528-535
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    • 2004
  • Ultrasonic Vibrator is designed to achieve the maximum vibration amplitude at 30 kHz by in-cluding a horn (diameter, 40 mm), mechanical vibration amplifier at the top of the ultrasonic vibrator in the system and making the complete system resonate. In addition, it is experimentally visualized by particle imaging velocimetry (PIV) that the acoustic streaming velocity in the gap is at maximum when the gap between the ultrasonic vibrator and stationary plate agrees with the multiples of half-wavelength of the ultrasonic wave. This fact results from the resonance of the sound wave and the theoretical analysis of that is also accomplished and verified by experiment. It is observed that the magnitude of the acoustic streaming dependent upon the gap between the ultrasonic vibrator and stationary plate possibly changes due to the measurement of the average velocity fields of the acoustic streaming induced by the ultrasonic vibration at resonance and non-resonance. There exists extremely small average velocity at non-resonant gaps while the relatively large average velocity exists at resonant gaps compared with non-resonant gaps. It also reveals that there should be larger axial turbulent intensity at the hub region of the vibrator and at the edge of it in the resonant gap where the air streaming velocity is maximized and the flow phenomena is conspicuous than that at the other region. Because the variation of the acoustic streaming velocity at resonant gap is more distinctive than that at non-resonant gap, shear stress increases more in the resonant gap and is also maximized at the center region of the vibrator except the local position of center (r〓0). At the non-resonant gap there should be low values of vorticity distribution, but in contrast to the non-resonant gap, high and negative values of it exist at the center region of the vibrator with respect to the radial direction and in the vicinity of the middle region with respect to the axial direction. Acoustic streaming is noise-free due to the ultrasonic vibration and maintenance-free because of the absence of moving parts. Moreover, the proposed method by acoustic streaming can be utilized to the nano and micro-electro mechanical systems as a driving mechanism in addition to the augmentation of the streaming velocity.