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Publication | Date |
Frequency Dependence of Receiving Sensitivity of Ultrasonic Transducers and Acoustic Emission Sensors K. Ono 35 University of California 34, Los Angeles, CA [USA] ultrasonic transducers, acoustic emission sensors, receiving sensitivity, low frequency characteristics, sinewave excitation, impulse method, open-circuit sensitivity, input impedance, frequency independent sensitivity, damped harmonic oscillator, minimum pulse duration
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Receiving displacement sensitivities (Rx) of ultrasonic transducers and acoustic emission
(AE) sensors are evaluated using sinewave packet excitation method and compared to the
corresponding data from pulse excitation method with a particular emphasis on low frequency
behavior below 20 kHz, down to 10 Hz. Both methods rely on the determination of transmitter
displacement characteristics using a laser interferometric method. Results obtained by two calibration
methods are in good agreement, with average spectral differences below 1 dB, indicating that the
two calibration methods yield identical receiving sensitivities. At low test frequencies, effects of
attenuation increase substantially due to increasing sensor impedance and Rx requires correction
in order to evaluate the inherent sensitivity of a sensor, or open-circuit sensitivity. This can differ
by more than 20 dB from results that used common preamplifiers with ~10 kΩ input impedance,
leading to apparent velocity response below 100 kHz for typical AE sensors. Damped broadband
sensors and ultrasonic transducers exhibit inherent velocity response (Type 1) below their main
resonance frequency. In sensors with under-damped resonance, a steep sensitivity decrease occurs
showing frequency dependence of f2~f5
(Type 2), while mass-loaded sensors exhibit flat displacement
response (Type 0). Such behaviors originate from sensor characteristics that can best be described by
the damped harmonic oscillator model. This model accounts for the three typical behaviors. At low
frequencies, typically below 1 kHz, receiving sensitivity exhibits another Type 0 behavior of frequency
independent Rx. Seven of 12 sensors showed this flat region, while three more appear to approach
the Type 0 region. This appears to originate from the quasi-static piezoelectric response of a sensing
element. In using impulse method, a minimum pulse duration is necessary to obtain spectral fidelity
at low frequencies and an approximate rule is given. Various factors for sensitivity improvement are
also discussed.
| NDT.net Review Session: Sensors (MDPI) | 2018-12 |
Review on Structural Health Evaluation with Acoustic Emission K. Ono 35 Department of Materials Science and Engineering; University of California 34, Los Angeles, CA [USA] acoustic emission, structural diagnosis, attenuation, source location, sensing, signal processing
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This review introduces several areas of importance in acoustic emission (AE) technology,
starting from signal attenuation. Signal loss is a critical issue in any large-scale AE monitoring, but few
systematic studies have appeared. Information on damping and attenuation has been gathered from
metal, polymer, and composite fields to provide a useful method for AE monitoring. This is followed
by discussion on source location, bridge monitoring, sensing and signal processing, and pressure
vessels and tanks, then special applications are briefly covered. Here, useful information and valuable
sources are identified with short comments indicating their significance. It is hoped that readers note
developments in areas outside of their own specialty for possible cross-fertilization.
| NDT.net Review Session: Applied Sciences (MDPI) | 2018-07 |
On the Piezoelectric Detection of Guided Ultrasonic Waves K. Ono 35 Department of Materials Science and Engineering; University of California 34, Los Angeles, CA [USA] guided ultrasonic waves, detector calibration, receiving sensitivity, Lamb waves, acoustic emission
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In order to quantify the wave motion of guided ultrasonic waves, the characteristics of piezoelectric detectors, or ultrasonic transducers and acoustic emission sensors, have been evaluated systematically. Such guided waves are widely used in structural health monitoring and nondestructive evaluation, but methods of calibrating piezoelectric detectors have been inadequate. This study relied on laser interferometry for the base displacement measurement of bar waves, from which eight different guided wave test set-ups are developed with known wave motion using piezoelectric transmitters. Both plates and bars of 12.7 and 6.4 mm thickness were used as wave propagation media. The upper frequency limit was 2 MHz. Output of guided wave detectors were obtained on the test set-ups and their receiving sensitivities were characterized and averaged. While each sensitivity spectrum was noisy for a detector, the averaged spectrum showed a good convergence to a unique receiving sensitivity. Twelve detectors were evaluated and their sensitivity spectra determined in absolute units. Generally, these showed rapidly dropping sensitivity with increasing frequency due to waveform cancellation on their sensing areas. This effect contributed to vastly different sensitivities to guided wave and to normally incident wave for each one of the 12 detectors tested. Various other effects are discussed and recommendations on methods of implementing the approach developed are provided.
| NDT.net Review Session: Materials (MDPI) | 2018-02 |
Through-Transmission Characteristics of AE Sensor Couplants K. Ono 35 Department of Materials Science and Engineering; University of California 34, Los Angeles, CA [USA] Sensors, Couplants, Through-transmission, Attenuation, Frequency effects
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This study examined the behavior of AE sensor couplants for through-transmission of acoustic
signals or out-of-plane motion. In order to provide controlled conditions, face-to-face transmitterreceiver
arrangement was utilized. All liquid and gel couplants are found to give satisfactory
service with careful installation, producing the minimum couplant thickness of 5 to 8 μm. Their
performance is nearly identical to 1.2 MHz. With normal installation procedures, however, the loss
can be 3 to 5 dB with viscous resins and gels, as couplant thickness can become 10 to 15 μm and
high frequency components are lost more than the peak amplitude reduction. Honey turns out to
be an excellent couplant because of its higher acoustic impedance, while commonly used silicone
grease can be a poor choice at higher frequencies. Higher frequency transmission loss increases
with thickness as predicted by theory of through-gap transmission with approximately linear
dependence on frequency.
| Journal-AE Session: Volume 34, 2016 | 2017-10 |
An Experimental Study of Acoustic Emission Waveguides K. Ono 35 Department of Materials Science and Engineering; University of California 34, Los Angeles, CA [USA] Waveguides, Rod waves, Tube waves, Threaded rods, Dispersion, Reverberation
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This study reports the characteristics of acoustic emission (AE) waveguides using displacement
pulse of about 1-μs duration from an ultrasonic transducer, driven by a short impulse. By
using one of broadband sensors as a receiver, improved characterization of waveguides is possible
over 50 to 2000 kHz. Here, we obtained responses of circular rod waveguides of different
diameters from 1.6 to 12.7 mm with lengths varying from 60 to 900 mm. It is found that the lowfrequency
part of L(0,1)-mode rod waves is dominant in thin rod waveguides. This mode is increasingly
suppressed above 6-mm diameter. This mode is also responsible for stretching a shortduration
(~1 μs) source into a long pulse of more than 100 μs as its velocity is reduced at higher
frequencies. At larger diameters, slower L(0,3)-mode becomes the dominant one, and its peak is
found at its highest velocity over a narrow range of frequency. To keep the pulse duration short,
it is necessary to keep the waveguide diameter below 3 mm, preferably at 1.6 mm or less so that
the relatively non-dispersive L(0,1)-mode prevails over the frequency range of interest. Diameter
reduction, however, leads to reduced sensitivity unless small aperture sensors are used. Tube
waveguides are found to offer a significant advantage of spectral smoothness. In tubes, L(0,2)
mode plays an important role of providing nearly constant velocity and spectral flatness. Effects
of threading are also evaluated. Three practical waveguide designs are suggested. More extensive
exploration of tubular waveguides is highly recommended.
| Journal-AE Session: Volume 34, 2016 | 2017-10 |
On Acoustic Emission Sensor Characterization K. Ono 35 Department of Materials Science and Engineering; University of California 34, Los Angeles, CA [USA]
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We examined calibration methods for acoustic emission (AE) sensors. In spite of the self-evident
needs of reliable calibration, the current state is deplorable globally. The only primary standard at NIST (US) is
non-operational, yet no other standard has emerged. Widely practiced face-to-face calibration methods have no
validated foundation. Reciprocity calibration methods are invalid for the lack of reciprocity and sensor dependent
reciprocity parameters. This work provides three workable solutions based on laser-based displacement
measurement, which leads to “direct” method using the face-to-face arrangement. This leads to the second “indirect”
method of mutually consistent determination of transmitting and receiving sensitivities of sensors/transducers. For
all ultrasonic and AE sensors examined, their receiving and transmitting sensitivities are found to be always
different and non-reciprocal. Displacement vs. velocity calibration terminology is clarified, correlating the “V/bar”
reference to laser-based calibration. We demonstrate the validity of the direct and indirect methods and the third
one based on Hill-Adams equation, called Tri-Transducer method. This uses three transducers as in reciprocity
method, but incorporates experimentally determined reference sensor sensitivities ratio without a transfer block and
can get both transmitting and receiving sensitivities. These three methods provide consistent calibration results for
over 30 AE sensors.
| Journal-AE Session: Volume 34, 2016 | 2017-10 |
Attenuation of Lamb Waves in CFRP Plates K. Ono1 35, A. Gallego2 30 1Department of Materials Science and Engineering; University of California 34, Los Angeles, CA [USA] 2School of Technical Architecture; University of Granada 34, Granada [Spain]
| Journal-AE Session: Volume 30, 2012 | 2014-03 |
Lamb-wave source location of impact on anisotropic plates H. Yamada1 4, Y. Mizutani2 30, H. Nishino3 13, M. Takemoto4 32, K. Ono5 35 1Environment & Process Technology Center; Nippon Steel Corporation 3, [Japan] 2Aoyama Gakuin University 38, Sagamihara, Kanagawa [Japan] 3Department of Mechanical Engineering; University of Tokushima 20, Tokushima [Japan] 4Kanmeta Engineering Co. Ltd. 7, Osaka [Japan] 5Department of Materials Science and Engineering; University of California 34, Los Angeles, CA [USA]
| Journal-AE Session: Volume 18, 2000 | 2014-03 |
A new method of acoustic emission source location in Pipes using cylindrical guided waves H. Nishino1 13, F. Uchida1, S. Takashina1, M. Takemoto1 32, K. Ono2 35 1Faculty of Science and Engineering; Aoyama Gakuin University, Tokyo [Japan] 2Department of Materials Science and Engineering; University of California 34, Los Angeles, CA [USA]
| Journal-AE Session: Volume 18, 2000 | 2014-03 |
Dynamics and damage assessment in impacted cross-ply CFRP plate utilizing the wavaform simulation of Lamb wave acoustic emission Y. Mizutani1 30, H. Nishino2 13, M. Takemoto3 32, K. Ono4,2 35 1Aoyama Gakuin University 38, Sagamihara, Kanagawa [Japan] 2Department of Mechanical Engineering; University of Tokushima 20, Tokushima [Japan] 3Kanmeta Engineering Co. Ltd. 7, Osaka [Japan] 4Department of Materials Science and Engineering; University of California 34, Los Angeles, CA [USA]
| Journal-AE Session: Volume 18, 2000 | 2014-03 |
Acoustic Emission in Materials Research – A Review K. Ono 35 Department of Materials Science and Engineering; University of California 34, Los Angeles, CA [USA] Acoustic Emission (AE), Signal analysis, sensors, simulation analysis, source function, transfer function, plastic deformation, fracture, phase transformation, coating, film, corrosion, SCC
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This paper reviews progress in methods of signal analysis used in acoustic emission (AE) as applied to materials research field. The achievement and inadequacy in understanding of AE from materials during the deformation, fracture and other processes are examined systematically. New goals for the future are also discussed in view of new analytical tools and vastly advanced instrumentation.
| Journal-AE Session: Volume 29, 2011 | 2013-07 |
Experimental transfer functions of practical acoustic emission sensors K. Ono1 35, H. Cho2 24 1Department of Materials Science and Engineering; University of California 34, Los Angeles, CA [USA] 2Aoyama Gakuin University 38, Sagamihara, Kanagawa [Japan] Acoustic Emission (AE), deconvolution, Sensor Calibration, transfer functions, pulse-laser excitation, waveforms, displacement detection
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We have obtained the transfer functions of a wide range of AE sensors commonly available and utilized. These were determined by a pulse-laser excitation in conjunction with a laser interferometer and a deconvolution procedure typically in the frequency domain. Using typical source waveforms and a convolution procedure, one can then visualize waveforms expected out of these AE sensors. In turn, one can also deduce approximate source waveforms from AE signal waveforms, which a similar sensor has detected. Some sensors showed displacement response, while another gave velocity response. Some unexpected results are found, including a mixed response of a small sensor and location sensitivity of otherwise a well-behaved sensor.
| EWGAE 2008
| 2013-07 |
Acoustic emission analysis of the over-straining of pipes in a polyethylene reactor I. Baran1 22, M. Nowak1 15, K. Ono2,4,2 35 1Laboratory of Applied Research; Cracow University of Technology 29, Krakow [Poland] 2Department of Materials Science and Engineering; University of California 34, Los Angeles, CA [USA] Over-straining, pattern recognition analysis, plastic deformation, residual stress
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Techniques of acoustic emission (AE) were used during the over-straining applied on 10-m length straight pipes and elbows of a polyethylene reactor in a factory. Over-straining is done before the pipes were put in operation and also periodically during service. AE enables us to monitor the stability of the deformation process and indicates the zones, which will require further detailed examinations by other NDT techniques; it should also improve safety during this process through early detection of critical damage. We examined several groups of pipes using a pattern recognition program to separate the signals due to cracking, confirmed by other NDT techniques. We will report on the attempt to establish new criterion.
| EWGAE 2008
| 2013-07 |
Diagnostics of Reinforced Concrete Bridges by Acoustic Emission L. Golaski1 2, P. Gebski1 3, K. Ono2,4,2 35 1Kielce University of Technology 8, Kielce [Poland] 2University of California 34, Los Angeles, CA [USA] Acoustic Emission (AE), concrete bridge, zone location, intensity analysis
| Journal-AE Session: Volume 20, 2003 | 2012-11 |
Micro-Cracking and Breakdown of Kaiser Effect in Ultra High Strength Steels H. Cho1 24, K. Fukaura2, K. Ono3,4,2 35 1Department of Materials Processing; Tohoku University 47, Sendai [Japan] 2University of Hyogo, Himeji [Japan] 3University of California 34, Los Angeles, CA [USA] Acoustic Emission (AE), Kaiser effect, microcracking, carbide cracking, high strength steel
| Journal-AE Session: Volume 21, 2003 | 2012-11 |
Acoustic Emission from The Fracture of Atmospheric Rust M. Takemoto1 32, T. Sogabe1, K. Matsuura1, K. Ono2,2 35 1Faculty of Science and Engineering; Aoyama Gakuin University 38, Sagamihara, Kanagawa [Japan] 2University of California 34, Los Angeles, CA [USA] Acoustic Emission (AE), wavelet transform, atmospheric rust, rust fracture, self-fracture, magnetite, hematite, crack opening volume, Lamb wave detection
| Journal-AE Session: Volume 21, 2003 | 2012-11 |
AE Monitoring from Cvd-Diamond Film Subjected to Micro-Indentation and Pulse Laser Spallation R. Ikeda1 3, H. Cho2 24, M. Takemoto2 32, K. Ono3,2 35 1Asahi Diamond Industrial Co. 3, Chiba [Japan] 2Aoyama Gakuin University 38, Sagamihara, Kanagawa [Japan] 3University of California 34, Los Angeles, CA [USA] Acoustic Emission (AE)
| Journal-AE Session: Volume 22, 2004 | 2012-11 |
Rods and Tubes as AE Waveguides K. Ono1 35, H. Cho2 24 1University of California 34, Los Angeles, CA [USA] 2Faculty of Science and Engineering; Aoyama Gakuin University 38, Sagamihara, Kanagawa [Japan] Acoustic Emission (AE)
| Journal-AE Session: Volume 22, 2004 | 2012-11 |
Acoustic Emission Behavior of Failure Processes of Glass-Fiber Laminates Under Complex State of Loading J. Schmidt1 8, I. Baran1 22, K. Ono2,3,2 35 1Laboratory of Applied Research; Cracow University of Technology 29, Krakow [Poland] 2MSE Department; University of California 34, Los Angeles, CA [USA] Acoustic Emission (AE)
| Journal-AE Session: Volume 23, 2005 | 2012-11 |
The Origin of Continuous Emissions K. Ono1 35, H. Cho2 24, M. Takuma3 3 1Department of Materials Science and Engineering; University of California 34, Los Angeles, CA [USA] 2Department of Mechanical Engineering; Aoyama Gakuin University 38, Sagamihara, Kanagawa [Japan] 3Department of Mechanical Engineering; Kansai University 3, Suita-shi, Osaka [Japan] Acoustic Emission (AE)
| Journal-AE Session: Volume 23, 2005 | 2012-11 |
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