WorldWideScience

Sample records for acoustic emission simulation

  1. Acoustic emission from fuel pellets in a simulated reactor environment

    International Nuclear Information System (INIS)

    Kupperman, D.S.; Kennedy, C.R.; Reimann, K.J.

    1977-01-01

    Thermal-shock damage of nuclear reactor fuel pellets in a simulated reactor environment has been correlated with acoustic-emission data obtained from sensors placed on extensions of the electrical feedthroughs. Ringdown counts, rms output data, and event-location data has been acquired for experiments carried out with single pellets as well as multiple pellet stacks. These tests have shown that acoustic-emission monitoring can provide information indicating the onset and the extent of cracking

  2. Acoustic emission

    International Nuclear Information System (INIS)

    Nichols, R.W.

    1976-01-01

    The volume contains six papers which together provide an overall review of the inspection technique known as acoustic emission or stress wave emission. The titles are: a welder's introduction to acoustic emission technology; use of acoustic emission for detection of defects as they arise during fabrication; examples of laboratory application and assessment of acoustic emission in the United Kingdom; (Part I: acoustic emission behaviour of low alloy steels; Part II: fatigue crack assessment from proof testing and continuous monitoring); inspection of selected areas of engineering structures by acoustic emission; Japanese experience in laboratory and practical applications of acoustic emission to welded structures; and ASME acoustic emission code status. (U.K.)

  3. Proton beam characterization by proton-induced acoustic emission: simulation studies

    International Nuclear Information System (INIS)

    Jones, K C; Witztum, A; Avery, S; Sehgal, C M

    2014-01-01

    Due to their Bragg peak, proton beams are capable of delivering a targeted dose of radiation to a narrow volume, but range uncertainties currently limit their accuracy. One promising beam characterization technique, protoacoustic range verification, measures the acoustic emission generated by the proton beam. We simulated the pressure waves generated by proton radiation passing through water. We observed that the proton-induced acoustic signal consists of two peaks, labeled α and γ, with two originating sources. The α acoustic peak is generated by the pre-Bragg peak heated region whereas the source of the γ acoustic peak is the proton Bragg peak. The arrival time of the α and γ peaks at a transducer reveals the distance from the beam propagation axis and Bragg peak center, respectively. The maximum pressure is not observed directly above the Bragg peak due to interference of the acoustic signals. Range verification based on the arrival times is shown to be more effective than determining the Bragg peak position based on pressure amplitudes. The temporal width of the α and γ peaks are linearly proportional to the beam diameter and Bragg peak width, respectively. The temporal separation between compression and rarefaction peaks is proportional to the spill time width. The pressure wave expected from a spread out Bragg peak dose is characterized. The simulations also show that acoustic monitoring can verify the proton beam dose distribution and range by characterizing the Bragg peak position to within ∼1 mm. (paper)

  4. Probe beam deflection technique as acoustic emission directionality sensor with photoacoustic emission source.

    Science.gov (United States)

    Barnes, Ronald A; Maswadi, Saher; Glickman, Randolph; Shadaram, Mehdi

    2014-01-20

    The goal of this paper is to demonstrate the unique capability of measuring the vector or angular information of propagating acoustic waves using an optical sensor. Acoustic waves were generated using photoacoustic interaction and detected by the probe beam deflection technique. Experiments and simulations were performed to study the interaction of acoustic emissions with an optical sensor in a coupling medium. The simulated results predict the probe beam and wavefront interaction and produced simulated signals that are verified by experiment.

  5. Calibration of acoustic emission transducers

    International Nuclear Information System (INIS)

    Leschek, W.C.

    1976-01-01

    A method is described for calibrating an acoustic emission transducer to be used in a pre-set frequency range. The absolute reception sensitivity of a reference transducer is determined at frequencies selected within the frequency range. The reference transducer and the acoustic emission transducer are put into acoustic communication with the surface of a limited acoustic medium representing an equivalent acoustic load appreciably identical to that of the medium in which the use of the acoustic emission transducer is intended. A blank random acoustic noise is emitted in the acoustic medium in order to establish a diffuse and reverberating sound field, after which the output responses of the reference transducer and of the acoustic emission transducer are obtained with respect to the diffuse and reverberating field, for selected frequencies. The output response of the acoustic emission transducer is compared with that of the reference transducer for the selected frequencies, so as to determine the reception sensitivity of the acoustic emission transducer [fr

  6. Acoustic Emission Technology and Application

    International Nuclear Information System (INIS)

    Joo, Y. S.; Lim, S. H.; Eom, H. S.; Kim, J. H.; Jung, H. K.

    2003-10-01

    Acoustic emission is the elastic wave that is generated by the rapid release of energy from the localized sources within a material. After the observation of acoustic emission phenomenon in 1950, the research and further investigation had been performed. Acoustic emission examination becomes a rapidly matured nondestructive testing method with demonstrated capabilities for characterizing material behavior and for detecting the defect. It is of interest as a possible passive monitoring technique for detecting, locating and characterizing the defects in component and structure. Acoustic emission technology has recently strengthened the on-line monitoring application for the detection of incipient failures and the assurance of structural integrity. The field of acoustic emission testing is still growing vigorously and presents many challenges. Especially, acoustic emission has been successfully applied in the leak detection of primary pressure boundary of nuclear power plants. In this state-of-art report, the principle, measurement and field applications of acoustic emission technique is reviewed and summarized. Acoustic emission technology will contribute to the assurance of nuclear safety as the on-line monitoring technique of structural integrity of NSSS components and structures

  7. Simulation of non-destructive inspections and acoustic emission measurements involving guided waves

    International Nuclear Information System (INIS)

    Baronian, V; Lhemery, A; Bonnet-BenDhia, A-S

    2009-01-01

    In a structure that guides elastic waves, a discontinuity (defect, shape variation) causes scattering (reflection, partial extinction or mode conversion). Two modal formulations have been developed to link separate models dealing with the calculation of the modal decomposition, with the generation and reception of guided waves (GW), with their scattering. The first concerns pulse-echo configurations (involving a single transducer), the other concerns pitch-catch configurations (two transducers involved). A new finite element (FE) method has been developed to compute the scattering by an arbitrary discontinuity, based on the modal decomposition of the field. Perfectly transparent boundary conditions (Dirichlet-to-Neuman boundaries) are developed, allowing the FE computation zone to be reduced to a minimum. A specific variational problem including these boundary conditions was obtained and solved using FE tools. By combining the modal formulations, the new FE scheme and tools for GW radiation, propagation and reception based on the Semi-Analytical Finite Element (SAFE) method, a new simulation tool has been developed. It can address almost arbitrary configurations of GW nondestructive testing. Moreover, a source inside the FE computation zone can be defined so that configurations of testing by acoustic emission can also be simulated. Examples of use of this tool are shown, some dealing with junctions of complex geometry between two guides, other with surface or bulk sources of acoustic emission.

  8. Signal Simulation and Experimental Research on Acoustic Emission using LS-DYNA

    Directory of Open Access Journals (Sweden)

    Zhang Jianchao

    2015-09-01

    Full Text Available To calculate sound wave velocity, we performed the Hsu-Nielsen lead break experiment using the ANSYS/LS-DYNA finite element software. First, we identified the key problems in the finite element analysis, such as selecting the exciting force, dividing the grid density, and setting the calculation steps. Second, we established the finite element model of the sound wave transmission in a plate under the lead break simulation. Results revealed not only the transmission characteristics of the sound wave but also the simulation and calculation of the transmission velocity of the longitudinal and transverse waves through the time travel curve of the vibration velocity of the sound wave at various nodes. Finally, the Hsu-Nielsen lead break experiment was implemented. The results of the theoretical calculation and simulation analysis were consistent with the experimental results, thus demonstrating that the research method using the ANSYS/LS-DYNA software to simulate sound wave transmissions in acoustic emission experiments is feasible and effective.

  9. Acoustic emission linear pulse holography

    International Nuclear Information System (INIS)

    Collins, H.D.; Busse, L.J.; Lemon, D.K.

    1983-01-01

    This paper describes the emission linear pulse holography which produces a chronological linear holographic image of a flaw by utilizing the acoustic energy emitted during crack growth. A thirty two point sampling array is used to construct phase-only linear holograms of simulated acoustic emission sources on large metal plates. The concept behind the AE linear pulse holography is illustrated, and a block diagram of a data acquisition system to implement the concept is given. Array element spacing, synthetic frequency criteria, and lateral depth resolution are specified. A reference timing transducer positioned between the array and the inspection zone and which inititates the time-of-flight measurements is described. The results graphically illustrate the technique using a one-dimensional FFT computer algorithm (ie. linear backward wave) for an AE image reconstruction

  10. Novel Fiber-Optic Ring Acoustic Emission Sensor.

    Science.gov (United States)

    Wei, Peng; Han, Xiaole; Xia, Dong; Liu, Taolin; Lang, Hao

    2018-01-13

    Acoustic emission technology has been applied to many fields for many years. However, the conventional piezoelectric acoustic emission sensors cannot be used in extreme environments, such as those with heavy electromagnetic interference, high pressure, or strong corrosion. In this paper, a novel fiber-optic ring acoustic emission sensor is proposed. The sensor exhibits high sensitivity, anti-electromagnetic interference, and corrosion resistance. First, the principle of a novel fiber-optic ring sensor is introduced. Different from piezoelectric and other fiber acoustic emission sensors, this novel sensor includes both a sensing skeleton and a sensing fiber. Second, a heterodyne interferometric demodulating method is presented. In addition, a fiber-optic ring sensor acoustic emission system is built based on this method. Finally, fiber-optic ring acoustic emission experiments are performed. The novel fiber-optic ring sensor is glued onto the surface of an aluminum plate. The 150 kHz standard continuous sinusoidal signals and broken lead signals are successfully detected by the novel fiber-optic ring acoustic emission sensor. In addition, comparison to the piezoelectric acoustic emission sensor is performed, which shows the availability and reliability of the novel fiber-optic ring acoustic emission sensor. In the future, this novel fiber-optic ring acoustic emission sensor will provide a new route to acoustic emission detection in harsh environments.

  11. Acoustic emission

    International Nuclear Information System (INIS)

    Straus, A.; Lopez Pumarega, M.I.; Di Gaetano, J.O.; D'Atellis, C.E.; Ruzzante, J.E.

    1990-01-01

    This paper is related to our activities on acoustic emission (A.E.). The work is made with different materials: metals and fibre reinforced plastics. At present, acoustic emission transducers are being developed for low and high temperature. A test to detect electrical discharges in electrical transformers was performed. Our experience in industrial tests to detect cracks or failures in tanks or tubes is also described. The use of A.E. for leak detection is considered. Works on pattern recognition of A.E. signals are also being performed. (Author)

  12. Acoustic emission linear pulse holography

    Science.gov (United States)

    Collins, H.D.; Busse, L.J.; Lemon, D.K.

    1983-10-25

    This device relates to the concept of and means for performing Acoustic Emission Linear Pulse Holography, which combines the advantages of linear holographic imaging and Acoustic Emission into a single non-destructive inspection system. This unique system produces a chronological, linear holographic image of a flaw by utilizing the acoustic energy emitted during crack growth. The innovation is the concept of utilizing the crack-generated acoustic emission energy to generate a chronological series of images of a growing crack by applying linear, pulse holographic processing to the acoustic emission data. The process is implemented by placing on a structure an array of piezoelectric sensors (typically 16 or 32 of them) near the defect location. A reference sensor is placed between the defect and the array.

  13. Novel Fiber-Optic Ring Acoustic Emission Sensor

    Directory of Open Access Journals (Sweden)

    Peng Wei

    2018-01-01

    Full Text Available Acoustic emission technology has been applied to many fields for many years. However, the conventional piezoelectric acoustic emission sensors cannot be used in extreme environments, such as those with heavy electromagnetic interference, high pressure, or strong corrosion. In this paper, a novel fiber-optic ring acoustic emission sensor is proposed. The sensor exhibits high sensitivity, anti-electromagnetic interference, and corrosion resistance. First, the principle of a novel fiber-optic ring sensor is introduced. Different from piezoelectric and other fiber acoustic emission sensors, this novel sensor includes both a sensing skeleton and a sensing fiber. Second, a heterodyne interferometric demodulating method is presented. In addition, a fiber-optic ring sensor acoustic emission system is built based on this method. Finally, fiber-optic ring acoustic emission experiments are performed. The novel fiber-optic ring sensor is glued onto the surface of an aluminum plate. The 150 kHz standard continuous sinusoidal signals and broken lead signals are successfully detected by the novel fiber-optic ring acoustic emission sensor. In addition, comparison to the piezoelectric acoustic emission sensor is performed, which shows the availability and reliability of the novel fiber-optic ring acoustic emission sensor. In the future, this novel fiber-optic ring acoustic emission sensor will provide a new route to acoustic emission detection in harsh environments.

  14. Acoustic Purcell Effect for Enhanced Emission

    KAUST Repository

    Landi, Maryam

    2018-03-13

    We observe that our experimentally measured emission power enhancement of a speaker inside a previously proposed metacavity agrees with our numerically calculated enhancement of the density of states (DOS) of the source-cavity system. We interpret the agreement by formulating a relation between the emitted sound power and the acoustic DOS. The formulation is an analog to Fermi’s golden rule in quantum emission. The formulation complements the radiation impedance theory in traditional acoustics for describing sound emission. Our study bridges the gap between acoustic DOS and the acoustic Purcell effect for sound emission enhancement.

  15. Acoustic Purcell Effect for Enhanced Emission

    KAUST Repository

    Landi, Maryam; Zhao, Jiajun; Prather, Wayne E.; Wu, Ying; Zhang, Likun

    2018-01-01

    We observe that our experimentally measured emission power enhancement of a speaker inside a previously proposed metacavity agrees with our numerically calculated enhancement of the density of states (DOS) of the source-cavity system. We interpret the agreement by formulating a relation between the emitted sound power and the acoustic DOS. The formulation is an analog to Fermi’s golden rule in quantum emission. The formulation complements the radiation impedance theory in traditional acoustics for describing sound emission. Our study bridges the gap between acoustic DOS and the acoustic Purcell effect for sound emission enhancement.

  16. Acoustic emission technique and its applications

    International Nuclear Information System (INIS)

    Sato, Ichiya; Sasaki, Soji

    1976-01-01

    Acoustic emission technique is described. The characteristics of acoustic emission signal, measurement techniques, and its application are explained. The acoustic signals are grouped into continuous and burst types. The continuous signal is due to plastic deformation, and the burst type is due to the generation and growth of cracks. The latter can be used for the identification of the position of cracks. The frequency of the acoustic emission is in the range from several tens of KHz to two MHz. Piezoelectric ceramics are used as the oscillators of sensors. The dynamic behavior of acoustic emission can be observed with a two-channel acoustic emission measuring apparatus. Multi-channel method was developed at Hitachi, Ltd., and is used for large structures. General computer identification method and simple zone identification method are explained. Noise elimination is important for the measurement, and the methods were studied. Examples of application are the observation of acoustic emission in the plastic deformation of steel, the tensile test of large welded material with natural defects, and others. The method will be used for the diagnosis and observation of large structures, the test and quality control of products. (Kato, T.)

  17. Practical acoustic emission testing

    CERN Document Server

    2016-01-01

    This book is intended for non-destructive testing (NDT) technicians who want to learn practical acoustic emission testing based on level 1 of ISO 9712 (Non-destructive testing – Qualification and certification of personnel) criteria. The essential aspects of ISO/DIS 18436-6 (Condition monitoring and diagnostics of machines – Requirements for training and certification of personnel, Part 6: Acoustic Emission) are explained, and readers can deepen their understanding with the help of practice exercises. This work presents the guiding principles of acoustic emission measurement, signal processing, algorithms for source location, measurement devices, applicability of testing methods, and measurement cases to support not only researchers in this field but also and especially NDT technicians.

  18. Flaw identification using acoustic emission

    International Nuclear Information System (INIS)

    Woodward, B.; McDonald, N.R.

    1975-01-01

    Acoustic emission 'signatures' contain information about the fine structure of metallurgical source events and their interpretation may provide a means of assessing the severity of internal flaws as well as surface flaws. The ultimate aim of this research on signature analysis is to develop a real time non-destructive testing technique having the capability of flaw recognition as well as flaw location in nuclear reactor components and structures under stress. Thus the requisite, unlike that in most acoustic emission work to date, is for a technique which affords discrimination between acoustic emission from different types of flaws propagating simultaneously. The approach described here requires detailed analysis of the emission signatures in terms of a specific statistical parameter, energy spectral density. In order to realise the full inspection potential of acoustic emission monitoring data obtained from zirconium and steel testpieces have been correlated with metallurgical condition and mechanical behaviour, since the nature of emission signatures is strongly affected by the physical characteristics and internal structure of the material. (Auth.)

  19. Pattern recognition methods for acoustic emission analysis

    International Nuclear Information System (INIS)

    Doctor, P.G.; Harrington, T.P.; Hutton, P.H.

    1979-07-01

    Models have been developed that relate the rate of acoustic emissions to structural integrity. The implementation of these techniques in the field has been hindered by the noisy environment in which the data must be taken. Acoustic emissions from noncritical sources are recorded in addition to those produced by critical sources, such as flaws. A technique is discussed for prescreening acoustic events and filtering out those that are produced by noncritical sources. The methodology that was investigated is pattern recognition. Three different pattern recognition techniques were applied to a data set that consisted of acoustic emissions caused by crack growth and acoustic signals caused by extraneous noise sources. Examination of the acoustic emission data presented has uncovered several features of the data that can provide a reasonable filter. Two of the most valuable features are the frequency of maximum response and the autocorrelation coefficient at Lag 13. When these two features and several others were combined with a least squares decision algorithm, 90% of the acoustic emissions in the data set were correctly classified. It appears possible to design filters that eliminate extraneous noise sources from flaw-growth acoustic emissions using pattern recognition techniques

  20. Relationships between acoustic emissions and microstructures

    International Nuclear Information System (INIS)

    Rao, G.V.; Gopal, R.

    1979-01-01

    Results of a systematic study of 'microstructure-deformation-acoustic emission' relationships on two widely used pressure retaining component materials, namely A533-B nuclear pressure vessel steel and a 7075 aluminum alloy, are presented. The study consists of conducting acoustic monitored tensile tests on a variety of quenched and aged microstructures in the two alloy systems and extensive microstructural characterization of test specimens by light optic and electron microscopy techniques. The results suggest a consistent relationship between acoustic emissions and microdeformation mechanisms. The role of specific microstructural constituents in generating acoustic emissions in the two alloys is discussed. (author)

  1. A study on the evaluation of internal leak in valve using acoustic emission method(3)

    International Nuclear Information System (INIS)

    Lee, Sang Guk; Lee, Wook Ryun; Park, Jong Hyuck; Kim, Kwang Hong

    2005-01-01

    The objective of this study is to estimate the feasibility of acoustic emission method for the internal leak from the valves. In this study, valve leak tests using various types of specimen simulated seat damage were performed in order to analyzer acoustic emission properties when leaks arise in valve seat. As a result of leak test for specimens simulated valve seat, we conformed that leak sound level increased in proportion to the increase of hole diameter and leak velocity, and decreased in proportion to the increase of leak depth. And also, leak sound level has hysteresis for leak velocity. From the experimental results, it was suggested that the acoustic emission method for monitoring of leak was feasible.

  2. Acoustic emission from polycrystalline graphites

    International Nuclear Information System (INIS)

    Ioka, I.; Yoda, S.; Oku, T.; Miyamoto, Y.

    1987-01-01

    Acoustic emission was monitored from polycrystalline graphites with different microstructure (pore size and pore volume) subjected to compressive loading. The graphites used in this study comprised five brands, that is, PGX, ISEM-1, IG-11, IG-15, and ISO-88. A root mean square (RMS) voltage and event counts of acoustic emission for graphites were measured during compressive loading. The acoustic emission was measured using a computed-based data acquisition and analysis system. The graphites were first deformed up to 80 % of the average fracture stress, then unloaded and reloaded again until the fracture occured. During the first loading, the change in RMS voltage for acoustic emission was detected from the initial stage. During the unloading, the RMS voltage became zero level as soon as the applied stress was released and then gradually rose to a peak and declined. The behavior indicated that the reversed plastic deformation occured in graphites. During the second loading, the RMS voltage gently increased until the applied stress exceeded the maximum stress of the first loading; there is no Kaiser effect in the graphites. A bicrystal model could give a reasonable explanation of this results. The empirical equation between the ratio of σ AE to σ f and σ f was obtained. It is considered that the detection of microfracture by the acoustic emission technique is effective in macrofracture prediction of polycrystalline graphites. (author)

  3. Numerical Investigation of Acoustic Emission Events of Argillaceous Sandstones under Confining Pressure

    Directory of Open Access Journals (Sweden)

    Zhaohui Chong

    2017-01-01

    Full Text Available At the laboratory scale, locating acoustic emission (AE events is a comparatively mature method for evaluating cracks in rock materials, and the method plays an important role in numerical simulations. This study is aimed at developing a quantitative method for the measurement of acoustic emission (AE events in numerical simulations. Furthermore, this method was applied to estimate the crack initiation, propagation, and coalescence in rock materials. The discrete element method-acoustic emission model (DEM-AE model was developed using an independent subprogram. This model was designed to calculate the scalar seismic tensor of particles in the process of movement and further to determine the magnitude of AE events. An algorithm for identifying the same spatiotemporal AE event is being presented. To validate the model, a systematic physical experiment and numerical simulation for argillaceous sandstones were performed to present a quantitative comparison of the results with confining pressure. The results showed good agreement in terms of magnitude and spatiotemporal evolution between the simulation and the physical experiment. Finally, the magnitude of AE events was analyzed, and the relationship between AE events and microcracks was discussed. This model can provide the research basis for preventing seismic hazards caused by underground coal mining.

  4. Acoustic emission monitoring from a lab scale high shear granulator--a novel approach.

    Science.gov (United States)

    Watson, N J; Povey, M J W; Reynolds, G K; Xu, B H; Ding, Y

    2014-04-25

    A new approach to the monitoring of granulation processes using passive acoustics together with precise control over the granulation process has highlighted the importance of particle-particle and particle-bowl collisions in acoustic emission. The results have shown that repeatable acoustic results could be obtained but only when a spray nozzle water addition system was used. Acoustic emissions were recorded from a transducer attached to the bowl and an airborne transducer. It was found that the airborne transducer detected very little from the granulation and only experienced small changes throughout the process. The results from the bowl transducer showed that during granulation the frequency content of the acoustic emission shifted towards the lower frequencies. Results from the discrete element model indicate that when larger particles are used the number of collisions the particles experience reduces. This is a result of the volume conservation methodology used in this study, therefore larger particles results in less particles. These simulation results coupled with previous theoretical work on the frequency content of an impacting sphere explain why the frequency content of the acoustic emissions reduces during granule growth. The acoustic system used was also clearly able to identify when large over-wetted granules were present in the system, highlighting its benefit for detecting undesirable operational conditions. High-speed photography was used to study if visual changes in the granule properties could be linked with the changing acoustic emissions. The high speed photography was only possible towards the latter stages of the granulation process and it was found that larger granules produced a higher magnitude of acoustic emission across a broader frequency range. Copyright © 2014 Elsevier B.V. All rights reserved.

  5. Acoustic emission generated by fluid leakage

    International Nuclear Information System (INIS)

    Kim, H.C.

    1987-01-01

    The noise generated by the leaking saturated steam and subcooled water form various sizes of hole has been measured as function of leak rate and stagnation pressure. Acoustic emission (proportinal to root mean sguare voltage) is shown to be proportional to the leak rate and stagnation pressure. A transition of acoustic emission power is observed at the stagnation pressure 0.185 MPa associated with the transition to the critical flow state. Substantially higher acoustic emission power generated by the subcooled water leakage is attributed to the flashing source involving the phase transformation and volume expansion. The relative amplitude of noise spectrum becomes more spiky as the leak rate and stagnation pressure increased. (Author)

  6. Application of acoustic emission to hydride cracking

    International Nuclear Information System (INIS)

    Sagat, S.; Ambler, J.F.R.; Coleman, C.E.

    1986-07-01

    Acoustic emission has been used for over a decade to study delayed hydride cracking (DHC) in zirconium alloys. At first acoustic emission was used primarily to detect the onset of DHC. This was possible because DHC was accompanied by very little plastic deformation of the material and furthermore the amplitudes of the acoustic pulses produced during cracking of the brittle hydride phase were much larger than those from dislocation motion and twinning. Acoustic emission was also used for measuring crack growth when it was found that for a suitable amplitude threshold, the total number of acoustic emission counts was linearly related to the cracked area. Once the proportionality constant was established, the acoustic counts could be converted to the crack length. Now the proportionality between the count rate and the crack growth rate is used to provide feedback between the crack length and the applied load, using computer technology. In such a system, the stress at the crack tip can be maintained constant during the test by adjusting the applied load as the crack progresses, or it can be changed in a predetermined manner, for example, to measure the threshold stress for cracking

  7. Acoustic emission from thermal-gradient cracks in UO2

    International Nuclear Information System (INIS)

    Kennedy, C.R.; Kupperman, D.S.; Wrona, B.J.

    1975-01-01

    A feasibility study has been conducted to evaluate the potential use of acoustic emission to monitor thermal-shock damage in direct electrical heating of UO 2 pellets. In the apparatus used for the present tests, two acoustic-emission sensors were placed on extensions of the upper and lower electrical feedthroughs. Commercially available equipment was used to accumulate acoustic-emission data. The accumulation of events displayed on a cathode-ray-tube screen indicates the total number of acoustic-emission events at a particular location within the pellet stack. These tests have indicated that acoustic emission can be used to monitor thermal-shock damage in UO 2 pellets subjected to direct-electrical heating. 8 references

  8. Parametric Room Acoustic workflows with real-time acoustic simulation

    DEFF Research Database (Denmark)

    Parigi, Dario

    2017-01-01

    The paper investigates and assesses the opportunities that real-time acoustic simulation offer to engage in parametric acoustics workflow and to influence architectural designs from early design stages......The paper investigates and assesses the opportunities that real-time acoustic simulation offer to engage in parametric acoustics workflow and to influence architectural designs from early design stages...

  9. Acoustic emission pickup essentially for waveguide

    International Nuclear Information System (INIS)

    Asty, Michel; Saglio, Robert.

    1979-01-01

    Lambda wave length acoustic emission pickup comprising two juxtaposed piezoelectric capsules of equal lambda/2 thickness and with opposite polarization, separated by an electrically insulating foil, the two opposite sides of the capsules being earthed. The electric signal resulting from the acoustic emission is picked up on the two sides facing both sides of the insulating foil and the assembly of the two piezoelectric capsules is mounted on a base insulating it from the structure on which the acoustic emission is being listened to. Application of this pickup to the surveillance of defects in the steel vessels of nuclear reactors, characterized in that it is placed at the end of a metal ultrasonic wave guide the other end of which is welded directly to the vessel [fr

  10. Time reversal signal processing in acoustic emission testing

    Czech Academy of Sciences Publication Activity Database

    Převorovský, Zdeněk; Krofta, Josef; Kober, Jan; Dvořáková, Zuzana; Chlada, Milan; Dos Santos, S.

    2014-01-01

    Roč. 19, č. 12 (2014) ISSN 1435-4934. [European Conference on Non-Destructive Testing (ECNDT 2014) /11./. Praha, 06.10.2014-10.10.2014] Institutional support: RVO:61388998 Keywords : acoustic emission (AE) * ultrasonic testing (UT) * signal processing * source location * time reversal acoustic s * acoustic emission * signal processing and transfer Subject RIV: BI - Acoustic s http://www.ndt.net/events/ECNDT2014/app/content/Slides/637_Prevorovsky.pdf

  11. Detection of simulated pitting corrosion and noises in crude oil storage tank by acoustic emission

    International Nuclear Information System (INIS)

    Shukri Mohd; Latif, N.A.; Azhar Mohd Sinin; Mohamad Daud; Abd Nasir Ibrahim

    2008-01-01

    The damage mechanisms associated with crude oil storage tanks can be complex and varied and include pitting corrosion due to presence of species such as sulphate reducing bacteria. Acoustic Emission (AE) could be used to characterise the pitting corrosion signal in crude oil storage tanks but it is extremely difficult to simulate the pitting corrosion in the laboratory using crude oil as electrolyte because crude oil is considered as non corrosive medium. In this study, induced current have been introduced onto a surface ASTM 516 steel as an electrical source to simulate the electrical noise produced during pitting corrosion process and AE sensor have been used to detect this current. It is found that AE system could detect AE signal release during current induction this current and is expected that if the exact simulation of the current magnitude produced during pitting corrosion process is made available, AE characterisation of pitting corrosion in such tank could be made possible. (Author)

  12. World Conference on Acoustic Emission 2013

    CERN Document Server

    Wu, Zhanwen; Zhang, Junjiao

    2015-01-01

    This volume collects the papers from the 2013 World Conference on Acoustic Emission in Shanghai. The latest research and applications of Acoustic Emission (AE) are explored, with particular emphasis on detecting and processing of AE signals, development of AE instrument and testing standards, AE of materials, engineering structures and systems, including the processing of collected data and analytical techniques as well as experimental case studies.

  13. World Conference on Acoustic Emission 2015

    CERN Document Server

    Wu, Zhanwen; Zhang, Junjiao

    2017-01-01

    This volume collects the papers from the World Conference on Acoustic Emission 2015 (WCAE-2015) in Hawaii. The latest research and applications of Acoustic Emission (AE) are explored, with particular emphasis on detecting and processing of AE signals, development of AE instrument and testing standards, AE of materials, engineering structures and systems, including the processing of collected data and analytical techniques as well as experimental case studies.

  14. Validation and Simulation of Ares I Scale Model Acoustic Test - 2 - Simulations at 5 Foot Elevation for Evaluation of Launch Mount Effects

    Science.gov (United States)

    Strutzenberg, Louise L.; Putman, Gabriel C.

    2011-01-01

    The Ares I Scale Model Acoustics Test (ASMAT) is a series of live-fire tests of scaled rocket motors meant to simulate the conditions of the Ares I launch configuration. These tests have provided a well documented set of high fidelity measurements useful for validation including data taken over a range of test conditions and containing phenomena like Ignition Over-Pressure and water suppression of acoustics. Expanding from initial simulations of the ASMAT setup in a held down configuration, simulations have been performed using the Loci/CHEM computational fluid dynamics software for ASMAT tests of the vehicle at 5 ft. elevation (100 ft. real vehicle elevation) with worst case drift in the direction of the launch tower. These tests have been performed without water suppression and have compared the acoustic emissions for launch structures with and without launch mounts. In addition, simulation results have also been compared to acoustic and imagery data collected from similar live-fire tests to assess the accuracy of the simulations. Simulations have shown a marked change in the pattern of emissions after removal of the launch mount with a reduction in the overall acoustic environment experienced by the vehicle and the formation of highly directed acoustic waves moving across the platform deck. Comparisons of simulation results to live-fire test data showed good amplitude and temporal correlation and imagery comparisons over the visible and infrared wavelengths showed qualitative capture of all plume and pressure wave evolution features.

  15. Acoustic emission during low temperature phase transformations in plutonium

    International Nuclear Information System (INIS)

    Khejpl, K.; Karpenter, S.

    1988-01-01

    To study the nature of phase transformations in plutonium and plutonium-gallium alloys (0.3 and 0.57% Ga) the measurement of acoustic emission is conducted. The presence of acoustic emission testifies to martensitic character of transformation, related to sharp local changes in the volume, which cause elastic waves. It is detected that during α reversible β transformations in non-alloyed plutonium acoustic emission is absent, and that testifies to nonmartensitic nature of the transformations. σ reversible α transformation in plutonium-gallium alloys is accompanied by the appearance of acoustic emission, i.e. it is of martensitic origin

  16. Acoustic emission leak monitoring system LMS-96

    International Nuclear Information System (INIS)

    Liska, J.; Cvrcek, M.; Mueller, L.

    1997-01-01

    On-line acoustic emission leak monitoring under industrial conditions of nuclear power plants is a problem with specific features setting specific demands on the leak monitoring system. The paper briefly reviews those problems (attenuation pattern of a real structure, acoustic background, alarm system, etc.) and the solution of some of them is discussed. Information is presented on the Acoustic Emission Leak Monitoring System LMS-96 by SKODA NUCLEAR MACHINERY and the system's function is briefly described. (author)

  17. Utilisation of acoustic emission technique to monitor lubrication condition in a low speed bearing

    International Nuclear Information System (INIS)

    Nordin Jamaludin; Mohd Jailani Mohd Nor

    2003-01-01

    Monitoring of lubrication condition in rolling element bearings through the use of vibration analysis is an established technique. However, this success has not mirrored at low rotational speeds. At low speeds the energy generated from the poor lubricated bearing lubrication might not show as an obvious change in signature and thus become undetectable using conventional vibration measuring equipment. This paper presents an investigation into the applicability of acoustic emission technique and analysis for detecting poorly lubricated bearing rotating at a speed of 1.12 rpm. Investigations were centered on a test-rig designed to simulate the real bearing used in the field. The variation of lubricant amount in the low-speed bearing was successfully monitored using a new developed method known as pulse injection technique (PIT). The PIT technique was based on acoustic emission method. The technique involved transmitting a Dirac pulse to the test bearing via a transmitting acoustic emission sensor while the bearing was in operation. Analysing the captured acoustic emission signatures using established statistical method could differentiate between properly and poorly lubricated bearing. (Author)

  18. Research on Acoustic Emission and Electromagnetic Emission Characteristics of Rock Fragmentation at Different Loading Rates

    Directory of Open Access Journals (Sweden)

    Fujun Zhao

    2018-01-01

    Full Text Available The relationships among the generation of acoustic emission, electromagnetic emission, and the fracture stress of rock grain are investigated, which are based on the mechanism of acoustic emission and electromagnetic emission produced in the process of indenting rock. Based on the relationships, the influence of loading rate on the characteristics of acoustic emission and electromagnetic emission of rock fragmentation is further discussed. Experiment on rock braking was carried out with three loading rates of 0.001 mm/s, 0.01 mm/s, and 0.1 mm/s. The results show that the phenomenon of acoustic emission and electromagnetic emission is produced during the process of loading and breaking rock. The wave forms of the two signals and the curve of the cutter indenting load show jumping characteristics. Both curves have good agreement with each other. With the increase of loading rate, the acoustic emission and electromagnetic emission signals are enhanced. Through analysis, it is found that the peak count rate, the energy rate of acoustic emission, the peak intensity, the number of pulses of the electromagnetic emission, and the loading rate have a positive correlation with each other. The experimental results agree with the theoretical analysis. The proposed studies can lead to an in-depth understanding of the rock fragmentation mechanism and help to prevent rock dynamic disasters.

  19. Acoustic emission measurement on large scale coils at JAERI

    International Nuclear Information System (INIS)

    Yoshida, K.; Hattori, Y.; Nishi, M.F.; Shimamoto, S.; Tsuji, H.

    1986-01-01

    The objective of acoustic emission measurement at Japan Atomic Energy Research Institute (JAERI) is an establishment of a general diagnostic method for superconducting magnet systems. Output of strain and displacement gages can not cover a whole system in monitoring premonitory phenomena of a magnet system s failure, because these sensors are mounted on points and therefore localized. Acoustic emissions can be transmitted to sensors through structural materials without electrical noise. Monitoring of acoustic emission will be one of the methods to predict a serious failure of magnet systems in a vacuum vessel. For this purpose, several sensors were installed on the Japanese LCT coil and the Test Module Coil (TMC). Some of acoustic activity was similar as seen in these coils. The correlation between voltage spikes and acoustic events is excellent during single coil charging mode, but poorer during out of plane force mode. There are no indicative acoustical phenomena before a magnet quench or during normal zone generation. The conditioning of acoustic events and voltage spikes can be seen after any cooling down. The localization of electrical insulation damage with the acoustic emission technique is one of its most useful applications

  20. Pre-service Acoustic Emission Testing for Metal Pressure Vessel

    International Nuclear Information System (INIS)

    Lee, Jong O; Yoon, Woon Ha; Lee, Tae Hee; Lee, Jong Kyu

    2003-01-01

    The field application of acoustic emission(AE) testing for brand-new metal pressure vessel were performed. We will introduce the test procedure for acoustic emission test such as instrument check distance between sensors, sensor location, whole system calibration, pressurization sequence, noise reduction and evaluation. The data of acoustic emission test contain many noise signal, these noise can be reduced by time filtering which based on the description of observation during AE test

  1. Evoked acoustic emission

    DEFF Research Database (Denmark)

    Elberling, C; Parbo, J; Johnsen, N J

    1985-01-01

    Stimulated acoustic emissions were recorded in response to tonal stimuli at 60 dB p.e. SPL in a small group of normal-hearing adults. Power spectral analysis reveals that the evoked activity from each ear contains energy in preferential frequency bands and the change of stimulus frequency has only...

  2. Acoustic emission during hydrogen absorption and desorption in palladium

    International Nuclear Information System (INIS)

    Ramesh, R.; Mukhopadhyay, C.K.; Jayakumar, T.; Baldev Raj

    1996-01-01

    Acoustic emission technique has been used to study charging and discharging of hydrogen in palladium. During charging, breaking of oxide film due to surface activation and saturation of hydrogen absorption have been identified by acoustic emission. In the discharging cycle, the desorption of hydrogen from the specimen leads to high AE activity immediately after initiation of discharging, followed by gradual decrease in the acoustic activity, which reaches a minimum upon completion of the desorption. The potential of the acoustic emission technique for studying the kinetics of hydrogen absorption and desorption in metals has been shown. (author)

  3. Experimental Study on Mechanical and Acoustic Emission Characteristics of Rock-Like Material Under Non-uniformly Distributed Loads

    Science.gov (United States)

    Wang, Xiao; Wen, Zhijie; Jiang, Yujing; Huang, Hao

    2018-03-01

    The mechanical and acoustic emission characteristics of rock-like materials under non-uniform loads were investigated by means of a self-developed mining-induced stress testing system and acoustic emission monitoring system. In the experiments, the specimens were divided into three regions and different initial vertical stresses and stress loading rates were used to simulate different mining conditions. The mechanical and acoustic emission characteristics between regions were compared, and the effects of different initial vertical stresses and different stress loading rates were analysed. The results showed that the mechanical properties and acoustic emission characteristics of rock-like materials can be notably localized. When the initial vertical stress and stress loading rate are fixed, the peak strength of region B is approximately two times that of region A, and the maximum acoustic emission hit value of region A is approximately 1-2 times that of region B. The effects of the initial vertical stress and stress loading rate on the peck strain, maximum hit value, and occurrence time of the maximum hit are similar in that when either of the former increase, the latter all decrease. However, peck strength will increase with the increase in loading rate and decrease with the increase in initial vertical stress. The acoustic emission hits can be used to analyse the damage in rock material, but the number of acoustic emission hits cannot be used alone to determine the degree of rock damage directly.

  4. Acoustic and photon emissions during mechanical deformation of coloured alkali halide crystals

    International Nuclear Information System (INIS)

    Chandra, B.P.

    1984-01-01

    Acoustic and photon emissions take place in the elastic and plastic as well as the fracture region of x-irradiated KBr, KCl and NaCl crystals. The rate of photon emission is linear with the strain rate: however, the RMS value of the acoustic emission is proportional to the square root of the strain rate. The acoustic emission is maximum for x-irradiated NaCl crystals; however, the photon emission is maximum for x-irradiated KBr crystals. From the similarity between the acoustic emission and the photon emission, it seems that mobile dislocations are responsible for the acoustic emission in coloured alkali halide crystals. (author)

  5. An acoustic emission study of plastic deformation in polycrystalline aluminium

    Science.gov (United States)

    Bill, R. C.; Frederick, J. R.; Felbeck, D. K.

    1979-01-01

    Acoustic emission experiments were performed on polycrystalline and single crystal 99.99% aluminum while undergoing tensile deformation. It was found that acoustic emission counts as a function of grain size showed a maximum value at a particular grain size. Furthermore, the slip area associated with this particular grain size corresponded to the threshold level of detectability of single dislocation slip events. The rate of decline in acoustic emission activity as grain size is increased beyond the peak value suggests that grain boundary associated dislocation sources are giving rise to the bulk of the detected acoustic emissions.

  6. Developments in acoustic emission for application to nuclear reactor systems

    International Nuclear Information System (INIS)

    Bentley, P.G.

    1982-01-01

    Developments in acoustic emission are summarised as they relate to the principal applications to nuclear reactors, and light water reactor pressure vessels in particular. Improvement in the understanding of acoustic emission has come from materials tests and these confirm the problems in applying the technique for in-service or periodic proof test monitoring of growing fatique cracks. Applications in LMFBR have confirmed that acoustic emission can be applied in the nuclear environment and the detection of stress corrosion cracking in both BWR and LMFBR seems possible. Some information is included on the developing interest in applying the techniques of acoustic emission for leak detection during shop hydro and in-service monitoring. Acoustic emission is also being developed for weld fabrication monitoring and recently introduced pattern recognition techniques are having a significant impact in this application. (author)

  7. Acoustic Emission Stethoscope - Measurements with Acoustic Emission on Wind Turbines

    Energy Technology Data Exchange (ETDEWEB)

    Krystof Kryniski [AaF Infrastructure, Stockholm (Sweden)

    2013-02-15

    A remote ultrasonic stethoscope, designed on mobile devices to help a maintenance team in diagnosing drive train problems, has been demonstrated. By implementing an acoustic emission technology, the operating conditions of wind turbines have been assessed by trending techniques and ultrasonic acoustic emission converted into audible sound. The new approach has been developed and tested and compared to other monitoring techniques. Acoustic emission has generally been shown to provide a number of advantages over vibration and shock pulse methods because the system is operating in a substantially higher frequency range (100 kHz) and therefore it is more immune to operation of surrounding machines and components. Quick attenuation of ultrasonic propagation waves in the drive-train structure helps to pin-point the origin of any fault as the signals are sharper and more pronounced. Further, with the intensity measurements a direction of the source of ultrasonic energy can be identified. Using a high frequency thus makes the method suitable for measuring local effects and to determine local defects since the disturbing signals from other parts are damped. Recently developed programmable sensors capable of processing signals onboard, producing quality outputs with extremely low noise-to-signal ratio, have been used. It is discussed how the new approach can lower the cost of a wind-turbine monitoring system, while at the same time making it simple and more reliable, see Appendix A. The method has been tested on rotating parts of wind-turbines, including traditionally difficult areas such as low speed main bearings and planetary gearboxes. The method developed in the project was designed to see physical processes such as friction, impacts and metal removal, occurring when machinery degrades, can be detected and notified with the developed notification system. Apart from reporting the status and displaying the changes of the pre-defined parameters or symptoms, the system has

  8. Mechanical Seal Opening Condition Monitoring Based on Acoustic Emission Technology

    Directory of Open Access Journals (Sweden)

    Erqing Zhang

    2014-06-01

    Full Text Available Since the measurement of mechanical sealing film thickness and just-lift-off time is very difficult, the sealing film condition monitoring method based on acoustic emission signal is proposed. The mechanical seal acoustic emission signal present obvious characteristics of time-varying nonlinear and pulsating. In this paper, the acoustic emission signal is used to monitor the seal end faces just-lift-off time and friction condition. The acoustic emission signal is decomposed by empirical mode decomposition into a series of intrinsic mode function with independent characteristics of different time scales and different frequency band. The acoustic emission signal only generated by end faces friction is obtained by eliminating the false intrinsic mode function components. The correlation coefficient of acoustic emission signal and Multi-scale Laplace Wavelet is calculated. It is proved that the maximum frequency (8000 Hz of the correlation coefficient is appeared at the spindle speed of 300 rpm. And at this time (300 rpm the end faces have just lifted off. By a set of mechanical oil seal running test, it is demonstrated that this method could accurately identify mechanical seal end faces just-lift-off time and friction condition.

  9. A New Fault Location Approach for Acoustic Emission Techniques in Wind Turbines

    Directory of Open Access Journals (Sweden)

    Carlos Quiterio Gómez Muñoz

    2016-01-01

    Full Text Available The renewable energy industry is undergoing continuous improvement and development worldwide, wind energy being one of the most relevant renewable energies. This industry requires high levels of reliability, availability, maintainability and safety (RAMS for wind turbines. The blades are critical components in wind turbines. The objective of this research work is focused on the fault detection and diagnosis (FDD of the wind turbine blades. The FDD approach is composed of a robust condition monitoring system (CMS and a novel signal processing method. CMS collects and analyses the data from different non-destructive tests based on acoustic emission. The acoustic emission signals are collected applying macro-fiber composite (MFC sensors to detect and locate cracks on the surface of the blades. Three MFC sensors are set in a section of a wind turbine blade. The acoustic emission signals are generated by breaking a pencil lead in the blade surface. This method is used to simulate the acoustic emission due to a breakdown of the composite fibers. The breakdown generates a set of mechanical waves that are collected by the MFC sensors. A graphical method is employed to obtain a system of non-linear equations that will be used for locating the emission source. This work demonstrates that a fiber breakage in the wind turbine blade can be detected and located by using only three low cost sensors. It allows the detection of potential failures at an early stages, and it can also reduce corrective maintenance tasks and downtimes and increase the RAMS of the wind turbine.

  10. Acoustic emission intrusion detector

    International Nuclear Information System (INIS)

    Carver, D.W.

    1978-01-01

    In order to improve the security of handling special nuclear materials at the Oak Ridge Y-12 Plant, a sensitive acoustic emission detector has been developed that will detect forcible entry through block or tile walls, concrete floors, or concrete/steel vault walls. A small, low-powered processor was designed to convert the output from a sensitive, crystal-type acoustic transducer to an alarm relay signal for use with a supervised alarm loop. The unit may be used to detect forcible entry through concrete, steel, block, tile, and/or glass

  11. Microcracking in ceramics and acoustic emission

    International Nuclear Information System (INIS)

    Subbarao, E.C.

    1991-01-01

    One of the limitations in the use of ceramics in critical applications is due to the presence of microcracks, which may arise from differential thermal expansion and phase changes, among others. Acoustic emission signals occur when there are abrupt microdeformations in a material and thus offer a convenient means of non-destructive detection of microcracking. Examples of a study of acoustic emission from microcracking due to anisotropic thermal expansion in low thermal expansion single phase ceramics such as niobia and sodium zirconium phosphate ceramics and due to phase changes in zirconia and superconducting YBa 2 Cu 3 Osub(7-x) ceramics are presented, together with the case of lead titanate ceramics, which exhibits both a phase change (paraelectric to ferroelectric) and an anisotropic thermal expansion. The role of grain size on the extent of microcracking is illustrated in the case of niobia ceramics. Some indirect evidence of healing of microcracks on heating niobia and lead titanate ceramics is presented from the acoustic emission results. (author). 69 refs., 9 figs

  12. Size Effect on Acoustic Emission Characteristics of Coal-Rock Damage Evolution

    Directory of Open Access Journals (Sweden)

    Zhijie Wen

    2017-01-01

    Full Text Available Coal-gas outburst, rock burst, and other mine dynamic disasters are closely related to the instability and failure of coal-rock. Coal-rock is the assemblies of mineral particles of varying sizes and shapes bonded together by cementing materials. The damage and rupture process of coal-rock is accompanied by acoustic emission (AE, which can be used as an effective means to monitor and predict the instability of coal-rock body. In this manuscript, considering the size effect of coal-rock, the influence of different height to diameter ratio on the acoustic emission characteristics of coal-rock damage evolution was discussed by microparticle flow PFC2D software platform. The results show that coal-rock size influences the uniaxial compressive strength, peak strain, and elastic modulus of itself; the size effect has little effect on the acoustic emission law of coal-rock damage and the effects of the size of coal-rock samples on acoustic emission characteristics are mainly reflected in three aspects: the triggering time of acoustic emission, the strain range of strong acoustic emission, and the intensity of acoustic emission; the damage evolution of coal-rock specimen can be divided into 4 stages: initial damage, stable development, accelerated development, and damage.

  13. Acoustic emission signal measurements in pressure vessel testing

    International Nuclear Information System (INIS)

    Peter, A.

    1984-01-01

    The number of acoustic emission events per plastically deformed unit of volume caused by artificial notches in real pressure vessels has been calculated taking into account reference voltage, distance between acoustic emission source and sensor as well as the effect of noise background. A test performed at a 100 m 3 gasholder verifies the theoretical considerations. (author)

  14. The Influence of Sensor Size on Acoustic Emission Waveforms—A Numerical Study

    Directory of Open Access Journals (Sweden)

    Eleni Tsangouri

    2018-01-01

    Full Text Available The performance of Acoustic Emission technique is governed by the measuring efficiency of the piezoelectric sensors usually mounted on the structure surface. In the case of damage of bulk materials or plates, the sensors receive the acoustic waveforms of which the frequency and shape are correlated to the damage mode. This numerical study measures the waveforms received by point, medium and large size sensors and evaluates the effect of sensor size on the acoustic emission signals. Simulations are the only way to quantify the effect of sensor size ensuring that the frequency response of the different sensors is uniform. The cases of horizontal (on the same surface, vertical and diagonal excitation are numerically simulated, and the corresponding elastic wave displacement is measured for different sizes of sensors. It is shown that large size sensors significantly affect the wave magnitude and content in both time and frequency domains and especially in the case of surface wave excitation. The coherence between the original and received waveform is quantified and the numerical findings are experimentally supported. It is concluded that sensors with a size larger than half the size of the excitation wavelength start to seriously influence the accuracy of the AE waveform.

  15. Acoustic emission evolution during sliding friction of Hadfield steel single crystal

    Science.gov (United States)

    Lychagin, D. V.; Novitskaya, O. S.; Kolubaev, A. V.; Sizova, O. V.

    2017-12-01

    Friction is a complex dynamic process. Direct observation of processes occurring in the friction zone is impossible due to a small size of a real contact area and, as a consequence, requires various additional methods applicable to monitor a tribological contact state. One of such methods consists in the analysis of acoustic emission data of a tribological contact. The use of acoustic emission entails the problem of interpreting physical sources of signals. In this paper, we analyze the evolution of acoustic emission signal frames in friction of Hadfield steel single crystals. The chosen crystallographic orientation of single crystals enables to identify four stages related to friction development as well as acoustic emission signals inherent in these stages. Acoustic emission signal parameters are studied in more detail by the short-time Fourier transform used to determine the time variation of the median frequency and its power spectrum. The results obtained will facilitate the development of a more precise method to monitor the tribological contact based on the acoustic emission method.

  16. Acoustic emission sensor radiation damage threshold experiment

    International Nuclear Information System (INIS)

    Beeson, K.M.; Pepper, C.E.

    1994-01-01

    Determination of the threshold for damage to acoustic emission sensors exposed to radiation is important in their application to leak detection in radioactive waste transport and storage. Proper response to system leaks is necessary to ensure the safe operation of these systems. A radiation impaired sensor could provide ''false negative or false positive'' indication of acoustic signals from leaks within the system. Research was carried out in the Radiochemical Technology Division at Oak Ridge National Laboratory to determine the beta/gamma radiation damage threshold for acoustic emission sensor systems. The individual system consisted of an acoustic sensor mounted with a two part epoxy onto a stainless steel waveguide. The systems were placed in an irradiation fixture and exposed to a Cobalt-60 source. After each irradiation, the sensors were recalibrated by Physical Acoustics Corporation. The results were compared to the initial calibrations performed prior to irradiation and a control group, not exposed to radiation, was used to validate the results. This experiment determines the radiation damage threshold of each acoustic sensor system and verifies its life expectancy, usefulness and reliability for many applications in radioactive environments

  17. Acoustic emission characterization of the tetragonal-monoclinic phase transformation in zirconia

    International Nuclear Information System (INIS)

    Clarke, D.R.; Arora, A.

    1983-01-01

    The processes accompanying the tetragonal-monoclinic phase transformation in zirconia (ZrO 2 ) have been studied using acoustic emission and electron microscopy in an attempt to characterize the different mechanisms by which the transformation can be accommodated in bulk materials. Experiments in which the acoustic emission is detected as specimens are cooled through the transformation, following densification by sintering, are described. For comparison, the acoustic emission from free, nominally unconstrained powders similarly cooled through the transformation is reported. The existence of distinct processes accompanying the phase transformation is established on the basis of postexperiment multiparametric correlation analysis of the acoustic emission

  18. Monitoring of lubrication conditions in journal bearing by acoustic emission

    International Nuclear Information System (INIS)

    Yoon, Dong Jin; Kwon, Oh Yang; Jung, Min Hwa

    1993-01-01

    Systems with journal bearings generally operate in large scale and under severe loading conditions such as steam generator turbines and internal combustion engines, in contrast to the machinery using rolling element bearings. Failure of the bearings in these machinery can result in the system breakdown. To avoid the time consuming repair and considerable economic loss, the detection of incipient failure in journal bearings becomes very important. In this experimental approach, acoustic emission monitoring is employed to the detection of incipient failure caused by intervention of foreign particles most probable in the journal bearing systems. It has been known that the intervention of foreign materials, insufficient lubrication and misassembly etc. are principal factors to cause bearing failure and distress. The experiment was conducted under such designed conditions as inserting alumina particles to the lubrication layer in the simulated journal bearing system. The results showed that acoustic emission could be an effective tool to detect the incipient failure in journal bearings.

  19. Flaw identification using acoustic emission

    International Nuclear Information System (INIS)

    Woodward, B.; McDonald, N.R.

    1975-01-01

    In order to realise the full inspection potential of acoustic emission monitoring, data obtained from zirconium and steel testpieces have been correlated with metallurgical condition and mechanical behaviour, since the nature of emission signatures is strongly affected by the physical characteristics and internal structure of the material. During experiments, signals were tape recorded and the surface of each testpiece was recorded on movie film or videotape so that acoustic and visual information could be correlated. Large numbers of tape-recorded bursts have been analysed with a real time spectrum analyser, and statistical parameters (such as mean energy density, mean frequency and variance) derived from the spectra were calculated by an IBM 360/50 computer and selectively displayed on a line plotter. In the case of zirconium, observed differences in these parameters were an indication that the emission signals were generated by three different metallurgical mechanisms. A movie film of testpiece surface deformation revealed the occurrence of twin initiation, twin broadening and slip. Fracture events either in the zirconium matrix or in second phase particles are also possible although not observed directly. A direct correlation was confirmed between twin initiations and emission signals. Work is proceeding on establishing a different correlation between emission signals and stress corrosion cracks

  20. Acoustic emission from zirconium alloys during mechanical and fracture testing

    International Nuclear Information System (INIS)

    Coleman, C.E.

    1986-10-01

    The application of acoustic emission during the mechanical and fracture testing of zirconium alloys is reviewed. Acoustic emission is successful in following delayed hydride cracking quantitatively. It is especially useful when great sensitivity is required. Application to fatigue, tensile deformation and stress corrosion cracking appears promising but requires more work to separate phenomena before it can be used quantitatively. This report is based on an invited review for the American Society of Non-Destructive Testing Handbook: Volume 5, Acoustic Emission Testing

  1. Holographic and acoustic emission evaluation of pressure vessels

    International Nuclear Information System (INIS)

    Boyd, D.M.

    1980-01-01

    Optical holographic interfereometry and acoustic emission monitoring were simultaneously used to evaluate two small, high pressure vessels during pressurization. The techniques provide pressure vessel designers with both quantitative information such as displacement/strain measurements and qualitative information such as flaw detection. The data from the holographic interferograms were analyzed for strain profiles. The acoustic emission signals were monitored for crack growth and vessel quality

  2. Acoustic emission from fiber reinforced plastic damaged hoop wrapped cylinders

    Energy Technology Data Exchange (ETDEWEB)

    Akhtar, A.; Kung, D.; Westbrook, D.R.

    2000-03-01

    Metal lined continuous fiber reinforced plastic (FRP) hoop wrapped cylinders with axial cuts to the FRP were modeled mathematically and tested experimentally. Steel lined and aluminum alloy lined glass FRP vessels were subjected to acoustic emission tests (AE) and hydraulic burst tests. The burst pressure decreased monotonically with the length of the axial cut. Acoustic emission increased initially with a decrease in burst pressure, and attained a maximum at an intermediate level of damage to the FRP. However, acoustic emission decreased when the level of damage was higher and the burst pressure was lower. Implications of the findings are discussed in the context of the search for an acoustic emission test method to inspect periodically the vessels used for the storage of compressed gaseous fuels on natural gas vehicles (NGV) and hydrogen vehicles.

  3. Acoustic emission monitoring of the bending under tension test

    DEFF Research Database (Denmark)

    Moghadam, Marcel; Sulaiman, Mohd Hafis Bin; Christiansen, Peter

    2017-01-01

    Preliminary investigations have shown that acoustic emission has promising aspects as an online monitoring technique for assessment of tribological conditions during metal forming as regards to determination of the onset of galling. In the present study the acoustic emission measuring technique h...... in BUT testing has been found to describe the frictional conditions during forming well and to allow for accurate assessment of the limits of lubrication....... been applied for online monitoring of the frictional conditions experienced during Bending Under Tension (BUT) testing. The BUT test emulates the forming conditions experienced when drawing sheet material over a die curvature as in deep drawing processes. Monitoring of the developed acoustic emission...

  4. Nondestructive online testing method for friction stir welding using acoustic emission

    Science.gov (United States)

    Levikhina, Anastasiya

    2017-12-01

    The paper reviews the possibility of applying the method of acoustic emission for online monitoring of the friction stir welding process. It is shown that acoustic emission allows the detection of weld defects and their location in real time. The energy of an acoustic signal and the median frequency are suggested to be used as informative parameters. The method of calculating the median frequency with the use of a short time Fourier transform is applied for the identification of correlations between the defective weld structure and properties of the acoustic emission signals received during welding.

  5. Continuous acoustic emission from aluminium

    International Nuclear Information System (INIS)

    Fenici, P.; Kiesewetter, N.; Schiller, P.

    1976-01-01

    Continuous acoustic emission of aluminum single crystals and polycrystals during tensile tests at constant cross-head speed and at room temperature is measured with a Root Mean Square Level recorder. By means of the Kaiser effect it is shown that the continuous emission is related to the plastic deformation. The plot of continuous emission against strain takes different shapes for pure single crystals, pure polycrystals and impure polycrystals. The measured voltages have about the same value for pure single and polycrystals and are considerably greater than that for impure polycrystals. A method is developed to distinguish between continuous emission and burst

  6. Acoustic emission intrusion detector

    International Nuclear Information System (INIS)

    Carver, D.W.; Whittaker, J.W.

    1980-01-01

    An intrusion detector is provided for detecting a forcible entry into a secured structure while minimizing false alarms. The detector uses a piezoelectric crystal transducer to sense acoustic emissions. The transducer output is amplified by a selectable gain amplifier to control the sensitivity. The rectified output of the amplifier is applied to a Schmitt trigger circuit having a preselected threshold level to provide amplitude discrimination. Timing circuitry is provided which is activated by successive pulses from the Schmitt trigger which lie within a selected time frame for frequency discrimination. Detected signals having proper amplitude and frequency trigger an alarm within the first complete cycle time of a detected acoustical disturbance signal

  7. Classification Identification of Acoustic Emission Signals from Underground Metal Mine Rock by ICIMF Classifier

    Directory of Open Access Journals (Sweden)

    Hongyan Zuo

    2014-01-01

    Full Text Available To overcome the drawback that fuzzy classifier was sensitive to noises and outliers, Mamdani fuzzy classifier based on improved chaos immune algorithm was developed, in which bilateral Gaussian membership function parameters were set as constraint conditions and the indexes of fuzzy classification effectiveness and number of correct samples of fuzzy classification as the subgoal of fitness function. Moreover, Iris database was used for simulation experiment, classification, and recognition of acoustic emission signals and interference signals from stope wall rock of underground metal mines. The results showed that Mamdani fuzzy classifier based on improved chaos immune algorithm could effectively improve the prediction accuracy of classification of data sets with noises and outliers and the classification accuracy of acoustic emission signal and interference signal from stope wall rock of underground metal mines was 90.00%. It was obvious that the improved chaos immune Mamdani fuzzy (ICIMF classifier was useful for accurate diagnosis of acoustic emission signal and interference signal from stope wall rock of underground metal mines.

  8. Ellipsoidal reflector for measuring oto-acoustic emissions

    DEFF Research Database (Denmark)

    Epp, Bastian; Pulkki, Ville; Heiskanen, Vesa

    2014-01-01

    A truncated prolate ellipsoidal reflector having the ear canal of a listener at one focal point and large- diaphragm low-noise microphone at the other focal point is proposed for free-field recordings of oto-acoustic emissions. A prototype reflector consisting of three pieces is presented, which...... enables measuring the response of the system with different truncations. The response of the system is measured with a miniature loud- speaker, and proof-of-concept measurements of oto-acoustic emissions are presented. The effect of truncation and other physical parameters to the performance of the system...

  9. Study of green state ceramics damage by acoustic emission

    International Nuclear Information System (INIS)

    Kerboul, Genevieve

    1992-01-01

    Dry pressing is a delicate operation of the conventional process of elaboration of ceramic materials as most of the detected defects in sintered products are appearing during it, this research thesis reports the study of ceramic powder forming by using the non destructive technique of acoustic emission to detect defects in pressed samples as soon as they initiate. An original signal processing system has also been designed to analyse the effective value of acoustic signals emitted during pressing on industrial hydraulic presses, but comprising a single tooling. Three powders have been tested: UO_2, Al_2O_3 and a UO_2-PuO_2 mixture. In a first part, the author recalls some elements regarding the fabrication of nuclear fuel, knowledge on powder pressing, and general principles of acoustic emission. She reports a feasibility study and then defines experimental conditions. In the second part, she presents acoustic emission periods during a pressing cycle, and reports the study of the response of flawless and flawed pressed samples. She reports the examination of their evolution with respect to powder nature and to fabrication process parameters. She reports a detailed analysis of acoustic emission parameters as a basis to define the principle of operation of an in situ and real time detection of flawed pressed samples [fr

  10. Acoustic emission monitoring during hydrotest of a thin wall pressure vessel

    International Nuclear Information System (INIS)

    Fontana, E.; Grugni, G.; Panzani, C.; Pirovano, B.; Possa, G.; Tonolini, F.

    1976-01-01

    Results are presented of the acoustic emission monitoring during hydrotests of a thin wall steel pressure vessel. Location of acoustic sources was based on longitudinal wave front detection. The careful calibration of the three sensors used for acoustic source location was found to be very useful, and allowed an accurate location error analysis. Acoustic emission in the hydrotests was found to be due mainly to stress release in weld seams

  11. Acoustic emission monitoring of HFIR vessel during hydrostatic testing

    International Nuclear Information System (INIS)

    Friesel, M.A.; Dawson, J.F.

    1992-08-01

    This report discusses the results and conclusions reached from applying acoustic emission monitoring to surveillance of the High Flux Isotope Reactor vessel during pressure testing. The objective of the monitoring was to detect crack growth and/or fluid leakage should it occur during the pressure test. The report addresses the approach, acoustic emission instrumentation, installation, calibration, and test results

  12. Changes in oto-acoustic emissions after exposure to live music

    DEFF Research Database (Denmark)

    Ordoñez, Rodrigo Pizarro; Hammershøi, Dorte; Voetmann, Jan

    2012-01-01

    Distortion Product Oto-acoustic Emissions (DPOAE) and Transient Evoked Oto-acoustic Emissions (TEOAE) were measured in subjects before and after attendance to live music. The changes measured were compared to the exposure levels measured at the position of the subject. The main objectives...

  13. Statistics of the acoustic emission signals parameters from Zircaloy-4 fuel cladding

    International Nuclear Information System (INIS)

    Oliveto, Maria E.; Lopez Pumarega, Maria I.; Ruzzante, Jose E.

    2000-01-01

    Statistic analysis of acoustic emission signals parameters: amplitude, duration and risetime was carried out. CANDU type Zircaloy-4 fuel claddings were pressurized up to rupture, one set of five normal pieces and six with defects included, acoustic emission was used on-line. Amplitude and duration frequency distributions were fitted with lognormal distribution functions, and risetime with an exponential one. Using analysis of variance, acoustic emission was appropriated to distinguish between defective and non-defective subsets. Clusters analysis applied on mean values of acoustic emission signal parameters were not effective to distinguish two sets of fuel claddings studied. (author)

  14. Diesel Engine Valve Clearance Detection Using Acoustic Emission

    Directory of Open Access Journals (Sweden)

    Fathi Elamin

    2010-01-01

    Full Text Available This paper investigated, using experimental method, the suitability of acoustic emission (AE technique for the condition monitoring of diesel engine valve faults. The clearance fault was adjusted experimentally in an exhaust valve and successfully detected and diagnosed in a Ford FSD 425 four-cylinder, four-stroke, in-line OHV, direct injection diesel engine. The effect of faulty exhaust valve clearance on engine performance was monitored and the difference between the healthy and faulty engine was observed from the recorded AE signals. The measured results from this technique show that using only time domain and frequency domain analysis of acoustic emission signals can give a superior measure of engine condition. This concludes that acoustic emission is a powerful and reliable method of detection and diagnosis of the faults in diesel engines and this is considered to be a unique approach to condition monitoring of valve performance.

  15. Detection of ductile crack initiation by acoustic emission testing

    International Nuclear Information System (INIS)

    Richter, H.; Boehmert, J.; Viehrig, H.W.

    1998-08-01

    A Charpy impact test equipment is described permitting simultaneous measurement of impact force, crack tip opening, acoustic emissions and magnetic emissions. The core of the equipment is an inverted pendulum ram impact testing machine and the tests have been performed with laterally notched, pre-fatigue ISO-V specimens made of steels of various strength and toughness properties. The tests are intended to ascertain whether the acoustic emission method is suitable for detecting steady crack initiation in highly ductile steels. (orig./CB) [de

  16. Acoustic emission from hydrogen saturated Type 304L stainless steel

    International Nuclear Information System (INIS)

    Caskey, G.R. Jr.

    1978-01-01

    Acoustic emission is attributed to energy release within a material body by localized plastic deformation or failure processes. The elastic stress waves may come from slip band formation, mechanical twinning, martensite transformation, or crack propagation. Each of these processes has slightly different acoustic characteristics allowing for easy identification. Acoustic emission was monitored during tensile tests of Type 304L austenitic stainless steel to explore the applicability of the technique to hydrogen-assisted fracture

  17. Analysis of the conical piezoelectric acoustic emission transducer

    Czech Academy of Sciences Publication Activity Database

    Červená, Olga; Hora, Petr

    2008-01-01

    Roč. 2, č. 1 (2008), s. 13-24 ISSN 1802-680X R&D Projects: GA ČR GA101/06/1689 Institutional research plan: CEZ:AV0Z20760514 Keywords : acoustic emission * conical transducer * FEM Subject RIV: BI - Acoustics

  18. Experimental Investigations into the Effects of Lithology on Acoustic Emission

    Directory of Open Access Journals (Sweden)

    Baozhu Tian

    2015-11-01

    Full Text Available In order to study how lithology affects acoustic emissions (AE, a series of tunnel rock burst simulation experiments, monitored by acoustic emission instruments, were conducted on granite, marble and basalt. By analyzing the characteristic parameters, this study found that AE events occur more frequently during the rock burst process on granite and basalt. Marble remains dormant until 75% of the loading time before the peak, at which point, cracks develop rapidly and AE events dramatically increase. During the rock burst process, the AE energy release demonstrates that low energy is released in the incubation phase and robust energy is released during the later phase. Before the rock burst occurs, increased in the heterogeneity index Cv values of the AE event are subject to lithology. The Cv values of granite and basalt have an increase of about 0.2-0.4, while marble shows an increase of 1.0-1.2. The heterogeneity index Cv value of an AE event is in line with the rock burst process.

  19. Considerations for acoustic emission monitoring of spherical Kevlar/epoxy composite pressure vessels

    Science.gov (United States)

    Hamstad, M. A.; Patterson, R. G.

    1977-01-01

    We are continuing to research the applications of acoustic emission testing for predicting burst pressure of filament-wound Kevlar 49/epoxy pressure vessels. This study has focused on three specific areas. The first area involves development of an experimental technique and the proper instrumentation to measure the energy given off by the acoustic emission transducer per acoustic emission burst. The second area concerns the design of a test fixture in which to mount the composite vessel so that the acoustic emission transducers are held against the outer surface of the composite. Included in this study area is the calibration of the entire test setup including couplant, transducer, electronics, and the instrument measuring the energy per burst. In the third and final area of this study, we consider the number, location, and sensitivity of the acoustic emission transducers used for proof testing composite pressure vessels.

  20. Status reports on developments and applications of acoustic emission analysis. Lectures

    International Nuclear Information System (INIS)

    1994-01-01

    The 25 lectures give a survey of the field of acoustic emission analysis. After a state-of-the-art report, the 4 new SE regulations of the DGZfP are presented which will standardize the applications of acoustic emission analysis. Acoustic emission sources and signal processing, including 3D detection, are discussed in 5 papers. After this, the practical applications of acoustic emission analysis are discussed in detail: Testing of gas tanks, inspection of storage container bottoms, reinforced concrete (3D analysis during extension testing), polymer-impregnated concrete, glass (testing up to 90 MHz), ceramics (thermoshock behaviour), fibre-reinforced plastics (4 contributions), PVD films, rock (analysis of workability and structure), glued joints between metals, monitoring of laser beam welding, metal cutting, and drying of cut wood. (orig.) [de

  1. Theory, simulation and experimental results of the acoustic detection of magnetization changes in superparamagnetic iron oxide

    Directory of Open Access Journals (Sweden)

    Borgert Jörn

    2011-06-01

    Full Text Available Abstract Background Magnetic Particle Imaging is a novel method for medical imaging. It can be used to measure the local concentration of a tracer material based on iron oxide nanoparticles. While the resulting images show the distribution of the tracer material in phantoms or anatomic structures of subjects under examination, no information about the tissue is being acquired. To expand Magnetic Particle Imaging into the detection of soft tissue properties, a new method is proposed, which detects acoustic emissions caused by magnetization changes in superparamagnetic iron oxide. Methods Starting from an introduction to the theory of acoustically detected Magnetic Particle Imaging, a comparison to magnetically detected Magnetic Particle Imaging is presented. Furthermore, an experimental setup for the detection of acoustic emissions is described, which consists of the necessary field generating components, i.e. coils and permanent magnets, as well as a calibrated microphone to perform the detection. Results The estimated detection limit of acoustic Magnetic Particle Imaging is comparable to the detection limit of magnetic resonance imaging for iron oxide nanoparticles, whereas both are inferior to the theoretical detection limit for magnetically detected Magnetic Particle Imaging. Sufficient data was acquired to perform a comparison to the simulated data. The experimental results are in agreement with the simulations. The remaining differences can be well explained. Conclusions It was possible to demonstrate the detection of acoustic emissions of magnetic tracer materials in Magnetic Particle Imaging. The processing of acoustic emission in addition to the tracer distribution acquired by magnetic detection might allow for the extraction of mechanical tissue parameters. Such parameters, like for example the velocity of sound and the attenuation caused by the tissue, might also be used to support and improve ultrasound imaging. However, the method

  2. Acoustic Emission Measurements for Tool Wear Evaluation in Drilling

    Science.gov (United States)

    Gómez, Martín P.; Migliori, Julio; Ruzzante, José E.; D'Attellis, Carlos E.

    2009-03-01

    In this work, the tool condition in a drilling process of SAE 1040 steel samples was studied by means of acoustic emission. The studied drill bits were modified with artificial and real failures, such as different degrees of wear in the cutting edge and in the outer corner. Some correlation between mean power of the acoustic emission parameters and the drill bit wear condition was found.

  3. Acoustic emission by self-organising effects of micro-hollow cathode discharges

    Science.gov (United States)

    Kotschate, Daniel; Gaal, Mate; Kersten, Holger

    2018-04-01

    We designed micro-hollow cathode discharge prototypes under atmospheric pressure and investigated their acoustic characteristics. For the acoustic model of the discharge, we correlated the self-organisation effect of the current density distribution with the ideal model of an acoustic membrane. For validation of the obtained model, sound particle velocity spectroscopy was used to detect and analyse the acoustic emission experimentally. The results have shown a behaviour similar to the ideal acoustic membrane. Therefore, the acoustic excitation is decomposable into its eigenfrequencies and predictable. The model was unified utilising the gas exhaust velocity caused by the electrohydrodynamic force. The results may allow a contactless prediction of the current density distribution by measuring the acoustic emission or using the micro-discharge as a tunable acoustic source for specific applications as well.

  4. Acoustic emission measurement during instrumented impact tests

    International Nuclear Information System (INIS)

    Crostack, H.A.; Engelhardt, A.H.

    1983-01-01

    Results of instrumented impact tests are discussed. On the one hand the development of the loading process at the hammer tup was recorded by means of a piezoelectric transducer. This instrumentation supplied a better representation of the load versus time than the conventional strain gauges. On the other hand the different types of acoustic emission occurring during a test could be separated. The acoustic emission released at the impact of the hammer onto the specimen is of lower frequency and its spectrum is strongly decreasing with increasing frequency. Plastic deformation also emits signals of lower frequency that are of quasi-continuous character. Both signal types can be discriminated by filtering. As a consequence typical burst signal were received afterwards that can be correlated with crack propagation. Their spectra exhibit considerable portions up to about 1.9 MHz. The development in time of the burst signals points to the kind of crack propagation resp. its sequence of appearance. However, definitive comparison between load and acoustic emission should become possible, only when the disadvantages of the common load measurement can be reduced, e.g. by determining the load directly at the specimen instead of the hammer tup

  5. Acoustic emission generated by dislocation mechanisms during the deformation of metals

    International Nuclear Information System (INIS)

    Heiple, C.R.

    1978-01-01

    Acoustic emission is a transient elastic wave generated by the rapid release of energy within a material. A wide variety of mechanisms have been proposed as possible sources of acoustic emission. Proposed mechanisms have included crack propagation, precipitate fracture, twin formation, martensite formation, dislocation motion and/or multiplication. This paper is concerned with acoustic emission generated by dislocation mechanisms operating during plastic deformation. Twinning and martensitic phase transformations are excluded even though dislocation motion is involved in the nucleation and growth of twins and the growth of martensite

  6. Acoustic emission generated by dislocation mechanisms during the deformation of metals

    Energy Technology Data Exchange (ETDEWEB)

    Heiple, C.R.

    1978-01-01

    Acoustic emission is a transient elastic wave generated by the rapid release of energy within a material. A wide variety of mechanisms have been proposed as possible sources of acoustic emission. Proposed mechanisms have included crack propagation, precipitate fracture, twin formation, martensite formation, dislocation motion and/or multiplication. This paper is concerned with acoustic emission generated by dislocation mechanisms operating during plastic deformation. Twinning and martensitic phase transformations are excluded even though dislocation motion is involved in the nucleation and growth of twins and the growth of martensite.

  7. Acoustic and electromagnetic emission as a tool for crack localization

    International Nuclear Information System (INIS)

    Sedlak, P; Sikula, J; Lokajicek, T; Mori, Y

    2008-01-01

    The creation of cracks is accompanied by electric charge redistribution due to loosened chemical bounds. Electric charge on a crack wall creates dipole moments. Vibrations of crack walls produce time-dependent dipole moments and, consequently, electric and magnetic fields are generated. An electric signal is induced on metal electrodes. Simultaneously with the electromagnetic emission (EME) signal, an acoustic emission (AE) signal is generated, but due to the different velocities of propagation of both waves, the detection of the AE signal is delayed. This time delay presents the time of the wave propagation from the individual acoustic emission sensor to the crack. The defect can be located by means of these time intervals. This paper describes the localization using acoustic and electromagnetic emission signals for the two-dimensional case

  8. Acoustic emission experiments for PHWR technology development

    International Nuclear Information System (INIS)

    Pellionisz, P.; Jha, S.K.; Goswami, G.L.

    1992-06-01

    An Indian-Hungarian joint research project has been started with the aim of applying acoustic emission testing to solve specific problems of nuclear power plants. Acoustic emission measurement and analyzing instrumentation and software have been provided by the Hungarian side, while the measurements have been performed at the Bhabha Atomic Research Centre (BARC), India. The first task of the project was to check the capability of the method for leakage detection and shuttle movement monitoring of Pressurized Heavy Water Reactors (PHWR), and for monitoring manufacturing processes as laser welding. The preliminary measurements and results are presented. (R.P.) 15 refs.; 11 figs.; 3 tabs

  9. Acoustic emission monitoring during hydrotests of a thin wall pressure vessel

    International Nuclear Information System (INIS)

    Fontana, E.; Grugni, G.; Panzani, C.; Pirovano, B.; Possa, G.; Tonolini, F.

    1975-01-01

    The results are presented of an acoustic emission monitoring performed during hydrotests of a thin wall steel pressure vessel. The location of acoustic sources was based on longitudinal wave front detection. The careful calibration of the three sensors instrumentation system used for acoustic source location was found to be useful, and alllowed an accurate location error analysis. Acoustic emission in the hydrotests was found to be mainly due to stress release in weld seams. (Fontana, E.; Grugni, G.; Panzani, C.; Pirovano, B.; Possa, G.; Tonolini, F.)

  10. Correlation between acoustic emission and microstructure. Final technical report

    International Nuclear Information System (INIS)

    Mukherjee, A.K.; Bunch, R.

    1977-01-01

    Acoustic emission from pure metals undergoing deformation is caused by dislocation unpinning and can be described by a theory which was a modified version of Gilman's mobile dislocation density theory. Acoustic emission from alloys can be dislocation related, but is primarily due to inclusion fracture. Factors affecting this include inclusion size, inclusion density, and the stress state. Inclusions crack more frequently during tensile testing than during fracture toughness testing

  11. Development of an incipient rotor crack detection method by acoustic emission techniques

    International Nuclear Information System (INIS)

    Le Reverend, D.; Massouri, M.H.

    1988-01-01

    The objective of the program presented is to develop a method of detection and monitoring of crack growth in machine rotor by application of acoustic emission techniques. This program is performed by R and D Division of Electricite de France, jointly with INSA de Lyon. The first task of the program is relative to the characterization of acoustic emission during a progressive tensile test performed on a NCT specimen. The second task of the program deals with the experimentation of acoustic emission techniques for the monitoring of a specimen during cycling bending tests. The last task of the program is relative to evaluation of application of acoustic emission techniques for a small rotor integrity monitoring during fatigue rotation tests [fr

  12. Dislocation unpinning model of acoustic emission from alkali halide ...

    Indian Academy of Sciences (India)

    The present paper reports the dislocation unpinning model of acoustic emis- sion (AE) from ... Acoustic emission; dislocation; alkali halide crystals; plastic deformation. ..... [5] T Nishimura, A Tahara and T Kolama, Jpn. Metal Inst. 64, 339 (2000).

  13. Acoustic emission on stressed concrete

    International Nuclear Information System (INIS)

    Jamet, P.; Birac, C.; Prunelle, D. de; Contre, M.; Astruc, M.; Kavyrchine, M.

    1983-08-01

    In a first part of this study, a comparison is made between the mechanical behaviour and the acoustic emission measurements on laboratory specimen during four points bending tests. The specimen were made of plain or/and reinforced concrete. The second part confirms, on real reinforced beams, the laboratory study results

  14. Continuous and recurrent testing of acoustic emission sensors

    International Nuclear Information System (INIS)

    Sause, Markus G.R.; Schmitt, Stefan; Potstada, Philipp

    2017-01-01

    In many fields of application of acoustic emission, the testing can lead to a lasting change in the sensor characteristics. This can be caused by mechanical damage, thermal stress or use under aggressive environmental conditions. Irrespective of visually testable damages of the sensors, a shift in the spectral sensitivity, a reduction in the absolute sensitivity or a reduction in the signal-to-noise ratio can occur. During the test, this requires a possibility to periodically check the sensors, including the coupling aids used. For recurring testing, recommendations are given in Directive SE 02 ''Verification of acoustic emission sensors and their coupling in the laboratory''. This paper discusses possibilities for continuous monitoring of the sensors during the test and presents an application example for the partly automated recurring testing of acoustic emission sensors using Directive SE 02. For this purpose, a test stand for the supply of the sensors to be tested was constructed and the signal recording and data reduction implemented in freely available software programs. The operating principle is demonstrated using selected case studies. [de

  15. On architectural acoustic design using computer simulation

    DEFF Research Database (Denmark)

    Schmidt, Anne Marie Due; Kirkegaard, Poul Henning

    2004-01-01

    properties prior to the actual construction of a building. With the right tools applied, acoustic design can become an integral part of the architectural design process. The aim of this paper is to investigate the field of application that an acoustic simulation programme can have during an architectural...... acoustic design process. The emphasis is put on the first three out of five phases in the working process of the architect and a case study is carried out in which each phase is represented by typical results ? as exemplified with reference to the design of Bagsværd Church by Jørn Utzon. The paper...... discusses the advantages and disadvantages of the programme in each phase compared to the works of architects not using acoustic simulation programmes. The conclusion of the paper is that the application of acoustic simulation programs is most beneficial in the last of three phases but an application...

  16. Standard practice for examination of fiberglass reinforced plastic fan blades using acoustic emission

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2010-01-01

    1.1 This practice provides guidelines for acoustic emission (AE) examinations of fiberglass reinforced plastic (FRP) fan blades of the type used in industrial cooling towers and heat exchangers. 1.2 This practice uses simulated service loading to determine structural integrity. 1.3 This practice will detect sources of acoustic emission in areas of sensor coverage that are stressed during the course of the examination. 1.4 This practice applies to examinations of new and in-service fan blades. 1.5 This practice is limited to fan blades of FRP construction, with length (hub centerline to tip) of less than 3 m [10 ft], and with fiberglass content greater than 15 % by weight. 1.6 AE measurements are used to detect emission sources. Other nondestructive examination (NDE) methods may be used to evaluate the significance of AE sources. Procedures for other NDE methods are beyond the scope of this practice. 1.7 Units—The values stated in either SI units or inch-pound units are to be regarded separately as sta...

  17. On Architectural Acoustics Design using Computer Simulation

    DEFF Research Database (Denmark)

    Schmidt, Anne Marie Due; Kirkegaard, Poul Henning

    2004-01-01

    The acoustical quality of a given building, or space within the building, is highly dependent on the architectural design. Architectural acoustics design has in the past been based on simple design rules. However, with a growing complexity in the architectural acoustic and the emergence of potent...... room acoustic simulation programs it is now possible to subjectively analyze and evaluate acoustic properties prior to the actual construction of a facility. With the right tools applied, the acoustic design can become an integrated part of the architectural design process. The aim of the present paper...... this information is discussed. The conclusion of the paper is that the application of acoustical simulation programs is most beneficial in the last of three phases but that an application of the program to the two first phases would be preferable and possible with an improvement of the interface of the program....

  18. Matrix method for acoustic levitation simulation.

    Science.gov (United States)

    Andrade, Marco A B; Perez, Nicolas; Buiochi, Flavio; Adamowski, Julio C

    2011-08-01

    A matrix method is presented for simulating acoustic levitators. A typical acoustic levitator consists of an ultrasonic transducer and a reflector. The matrix method is used to determine the potential for acoustic radiation force that acts on a small sphere in the standing wave field produced by the levitator. The method is based on the Rayleigh integral and it takes into account the multiple reflections that occur between the transducer and the reflector. The potential for acoustic radiation force obtained by the matrix method is validated by comparing the matrix method results with those obtained by the finite element method when using an axisymmetric model of a single-axis acoustic levitator. After validation, the method is applied in the simulation of a noncontact manipulation system consisting of two 37.9-kHz Langevin-type transducers and a plane reflector. The manipulation system allows control of the horizontal position of a small levitated sphere from -6 mm to 6 mm, which is done by changing the phase difference between the two transducers. The horizontal position of the sphere predicted by the matrix method agrees with the horizontal positions measured experimentally with a charge-coupled device camera. The main advantage of the matrix method is that it allows simulation of non-symmetric acoustic levitators without requiring much computational effort.

  19. Acoustic Emission Sensing for Maritime Diesel Engine Performance and Health

    Science.gov (United States)

    2016-05-01

    system does not provide direct current power to the preamplifier, equivalent pre-amplifiers with external power inputs were purchased , but the... behaviour of piston ring/cylinder liner interaction in diesel engines using acoustic emission. Tribology International 39 (12) 12 / 01 / 1634-1642...diesel engine using in-cylinder pressure and acoustic emission techniques. Dyanmics for Sustainable Engineering 1 454-463 26. Lowe, D. P., et al

  20. Modeling the complexity of acoustic emission during intermittent plastic deformation: Power laws and multifractal spectra.

    Science.gov (United States)

    Kumar, Jagadish; Ananthakrishna, G

    2018-01-01

    Scale-invariant power-law distributions for acoustic emission signals are ubiquitous in several plastically deforming materials. However, power-law distributions for acoustic emission energies are reported in distinctly different plastically deforming situations such as hcp and fcc single and polycrystalline samples exhibiting smooth stress-strain curves and in dilute metallic alloys exhibiting discontinuous flow. This is surprising since the underlying dislocation mechanisms in these two types of deformations are very different. So far, there have been no models that predict the power-law statistics for discontinuous flow. Furthermore, the statistics of the acoustic emission signals in jerky flow is even more complex, requiring multifractal measures for a proper characterization. There has been no model that explains the complex statistics either. Here we address the problem of statistical characterization of the acoustic emission signals associated with the three types of the Portevin-Le Chatelier bands. Following our recently proposed general framework for calculating acoustic emission, we set up a wave equation for the elastic degrees of freedom with a plastic strain rate as a source term. The energy dissipated during acoustic emission is represented by the Rayleigh-dissipation function. Using the plastic strain rate obtained from the Ananthakrishna model for the Portevin-Le Chatelier effect, we compute the acoustic emission signals associated with the three Portevin-Le Chatelier bands and the Lüders-like band. The so-calculated acoustic emission signals are used for further statistical characterization. Our results show that the model predicts power-law statistics for all the acoustic emission signals associated with the three types of Portevin-Le Chatelier bands with the exponent values increasing with increasing strain rate. The calculated multifractal spectra corresponding to the acoustic emission signals associated with the three band types have a maximum

  1. Design of acoustic emission monitoring system based on VC++

    Science.gov (United States)

    Yu, Yang; He, Wei

    2015-12-01

    At present, a lot of companies at home and abroad have researched and produced a batch of specialized monitoring instruments for acoustic emission (AE). Most of them cost highly and the system function exists in less stable and less portability for the testing environment and transmission distance and other aspects. Depending on the research background and the status quo, a dual channel intelligent acoustic emission monitoring system was designed based on Microsoft Foundation Classes in Visual Studio C++ to solve some of the problems in the acoustic emission research and meet the needs of actual monitoring task. It contains several modules such as main module, acquisition module, signal parameters setting module and so on. It could give out corrosion AE waveform and signal parameters results according to the main menu selected parameters. So the needed information could be extracted from the experiments datum to solve the problem deeply. This soft system is the important part of AE detection g system.

  2. Coating adherence in galvanized steel assessed by acoustic emission wavelet analysis

    International Nuclear Information System (INIS)

    Gallego, Antolino; Gil, Jose F.; Vico, Juan M.; Ruzzante, Jose E.; Piotrkowski, Rosa

    2005-01-01

    Coating-substrate adherence in galvanized steel is evaluated by acoustic emission wavelet analysis in scratch tests on hot-dip galvanized samples. The acoustic emission results are compared with optical and electron microscopy observations in order to understand coating features related to adherence and to establish criteria aimed at improving the manufacture process

  3. An introduction to acoustic emission technology for in-process inspection of welds

    International Nuclear Information System (INIS)

    Goswami, G.L.

    1983-01-01

    Weld quality monitoring, as it stands today, is primarily done by X-ray radiography and ultrasonic testing which is applied after welding is complete. Acoustic Emission Technique (AET) also presents a possible substitute for weld quality monitoring which can be used during welding. Acoustic signals are generated during welding and the sound waves of weld defects are picked up by using AE sensors. With the introduction of sophisticated instrumentation in AET, it is possible to carry out the test even in noisy shop floor environments. Large number of reports on the subject of acoustic emission in recent years is a clear indication that it is gaining importance in welding industry. The present day status of the acoustic emission technology as an on-line weld quality monitoring technique has been reviewed. This report discusses the technique and system along with the acoustic emission parameters important for weld quality analysis. This also deals with the application of this technique in different welding processes like TIG, resistance, electro slag and submerged arc. It has been reported that monitoring of emission during welding can detect crack formation, crack growth and lack of fusion precisely. Static defects like porosity and inclusion do not generate very strong acoustic signals and are therefore difficult to intercept, but, however, lately they have detected successfully. (author)

  4. Investigation into some regularities in acoustic emission during deformation of the 16 GNMA steel

    International Nuclear Information System (INIS)

    Chelyshev, N.A.; Chervov, G.A.; Petrov, V.I.; Yakovenko, V.S.; Kazakov, V.V.

    1981-01-01

    A device with variable band of transmission and regulated width of emission band (3-20 kHz) is the most optimal variant of acoustic emission recorder. Change of signal registration frequency of acoustic emission results in change of both qualitative and quantitative peculiarities of summary emission during deformation. A zone of elastic deformation transition to elastic-plastic for the given steel is well marked out according to the data of summary acoustic emission and intensity of signals. Application of devices with variable registration frequency requires usage of wide-band transformers [ru

  5. Acoustic emissions of a boiling liquid - an experimental survey in water and extrapolation to SFRs

    International Nuclear Information System (INIS)

    Vanderhaegen, M.; Paumel, K.; Tourin, A.

    2013-06-01

    The acoustic detection of sodium boiling is seen as a promising and innovative surveillance technique for sodium-cooled fast reactors (SFRs). It could be especially useful to detect in-core boiling that are the consequence of initiating accidents or whilst the mean subassembly temperature is very close to the nominal value. This latter is a consequence of the fuel assembly design of SFRs. Furthermore, it is a technique that has been proven to be successful in the past to follow the boiling behavior during SFR experiments that were aimed at simulating accidental conditions. However its effectiveness as in-core instrumentation still has to be demonstrated. In that aim, the acoustic emissions of sodium boiling in subassemblies are studied. Experimental studies are however limited to the boiling of common coolants due to the complications that arise when boiling liquid metals. As such, simple water experiments are performed. And although the results of these experiments are not completely representative for sodium boiling due to the incomplete thermo-hydraulic similarities between sodium and water, they can provide an interesting knowledge of the many influences that control the acoustic pressure field. In this article we'll specifically show how the condensation of vapor in subcooled liquid, the principal contribution to the acoustic emissions during boiling and hence the acoustic spectrum, is influenced by a pin-bundle geometry. We study this influence by comparing pool boiling experimental acoustic recordings with those of a simple pin-bundle geometry boiling experiment. The qualitative link, between this relatively simple pin-bundle experiment and the condensation phenomena that take place during sodium boiling inside SFR subassemblies, is used as a basis for this analysis. This simple experimental evidence, together with other theoretical arguments based on a thorough analysis of the sodium material properties, enables us to deduce that simple sodium

  6. System for detecting acoustic emissions in multianvil experiments: Application to deep seismicity in the Earth

    International Nuclear Information System (INIS)

    Jung, Haemyeong; Fei Yingwei; Silver, Paul G.; Green, Harry W.

    2006-01-01

    One of the major goals in the experimental study of deep earthquakes is to identify slip instabilities at high pressure and high temperature (HPHT) that might be responsible for the occurrence of earthquakes. Detecting acoustic emissions from a specimen during faulting provides unique constraints on the instability process. There are few experimental studies reporting acoustic emissions under HPHT conditions, due to technical challenges. And those studies have used only one or at most two acoustic sensors during the experiments. Such techniques preclude the accurate location of the acoustic emission source region and thus the ability to distinguish real signal from noise that may be coming from outside the sample. We have developed a system for detecting acoustic emissions at HPHT. Here we present a four-channel acoustic emission detecting system working in the HPHT octahedral multianvil apparatus. Each channel has high resolution (12 bits) and a sampling rate of 30 MHz. In experiments at the pressures up to 6 GPa and temperatures up to 770 deg. C, we have observed acoustic emissions under various conditions. Analyzing these signals, we are able to show that this system permits us to distinguish between signal and noise, locate the source of the acoustic emission, and obtain reliable data on the radiation pattern. This system has greatly improved our ability to study faulting instabilities under high pressure and high temperature

  7. Uncertainty of input data for room acoustic simulations

    DEFF Research Database (Denmark)

    Jeong, Cheol-Ho; Marbjerg, Gerd; Brunskog, Jonas

    2016-01-01

    Although many room acoustic simulation models have been well established, simulation results will never be accurate with inaccurate and uncertain input data. This study addresses inappropriateness and uncertainty of input data for room acoustic simulations. Firstly, the random incidence absorption...... and scattering coefficients are insufficient when simulating highly non-diffuse rooms. More detailed information, such as the phase and angle dependence, can greatly improve the simulation results of pressure-based geometrical and wave-based models at frequencies well below the Schroeder frequency. Phase...... summarizes potential advanced absorption measurement techniques that can improve the quality of input data for room acoustic simulations. Lastly, plenty of uncertain input data are copied from unreliable sources. Software developers and users should be careful when spreading such uncertain input data. More...

  8. Acoustic emission events from sodium vapour bubble collapsing: a stochastic model

    Energy Technology Data Exchange (ETDEWEB)

    Colombino, A; Dentico, G; Pacilio, N; Papalia, B; Taglienti, S; Tosi, V; Vigo, A [Comitato Nazionale per l' Energia Nucleare, Casaccia (Italy). Centro di Studi Nucleari; Galli, C [Rome Univ. (Italy). Ist. di Matematica

    1981-01-01

    The forward Kolomogorov equation method has been applied to a zero-dimensional model which describes the time distribution of acoustic emissions from sodium vapour bubble collapsing. Processes taken into account as components for outlining the upstated phenomenon are: energy generation, energy dissipation, bubble creation, acoustic emission and energy release from bubble collapsing. Processes involve affect or are induced by a population of particles (bubbles, acoustic pulses) and pseudoparticles (energetic units). A formulation is obtained for the expected values of some stochastic indicators, i.e., factorial moments and cumulants, autocorrelation functions, waiting time distribution between contiguous events, of the time series consisting of acoustic emission pulses as detected by a suitable sensor. Preliminary, but promising, validation of the model and a sound prelude to effective boiling regime diagnosing is obtained by processing data from the out-of-pile CFNa loop in Grenoble, France. Data are collected from a piezoelectric accelerometer located nearby the circuit.

  9. Evaluation of forced-convection nucleate boiling detection by acoustic emission

    International Nuclear Information System (INIS)

    Wells, R.P.; Paterson, J.A.

    1981-10-01

    Acoustic Emission techniques are being investigated for use as protection systems in neutral beam accelerators and water cooled beam dumps. For this purpose, the characteristics of the boiling curve for forced-convection surface boiling have been compared to the Acoustic Emission (AE) produced. Results indicate that AE, in the form of count-rate, is a sensitive indicator of nucleate boiling incipience and is relatively insensitive to flow velocity in the 0 to 12 m/s range

  10. Acoustic emission measurements during impacts tests for determining ductile fracture data

    International Nuclear Information System (INIS)

    Richter, H.

    2000-09-01

    The document reports work for further development of methods and tests to obtain better information on the crack initiation toughness (J id ) under impact loading conditions, by acoustic emission measurements. The applicability of the acoustic emission tests for the given purpose was proven by instrumented Charpy tests using modified ISO-V specimens. The physical crack initiation toughness served as the reference value for reliable evaluation of the characteristic data obtained. This reference value is derived from the crack resistance curve determined by the multi-specimen cleavage fracture method combined with data from measurements of the stretching zone width. Verification of the acoustic emission-defined initiation value included a variety of tests, as e.g. additional dynamic single-specimen methods (L-COD, magnetic emission), and supplementary tests (D3PB, pendulum impact testing machine). The test materials are various steels with different strength/toughness properties. (orig./CB) [de

  11. Acoustic Emission Analysis Applet (AEAA) Software

    Science.gov (United States)

    Nichols, Charles T.; Roth, Don J.

    2013-01-01

    NASA Glenn Research and NASA White Sands Test Facility have developed software supporting an automated pressure vessel structural health monitoring (SHM) system based on acoustic emissions (AE). The software, referred to as the Acoustic Emission Analysis Applet (AEAA), provides analysts with a tool that can interrogate data collected on Digital Wave Corp. and Physical Acoustics Corp. software using a wide spectrum of powerful filters and charts. This software can be made to work with any data once the data format is known. The applet will compute basic AE statistics, and statistics as a function of time and pressure (see figure). AEAA provides value added beyond the analysis provided by the respective vendors' analysis software. The software can handle data sets of unlimited size. A wide variety of government and commercial applications could benefit from this technology, notably requalification and usage tests for compressed gas and hydrogen-fueled vehicles. Future enhancements will add features similar to a "check engine" light on a vehicle. Once installed, the system will ultimately be used to alert International Space Station crewmembers to critical structural instabilities, but will have little impact to missions otherwise. Diagnostic information could then be transmitted to experienced technicians on the ground in a timely manner to determine whether pressure vessels have been impacted, are structurally unsound, or can be safely used to complete the mission.

  12. Acoustic emission generated during scratch test of various thin films

    Czech Academy of Sciences Publication Activity Database

    Boháč, Petr; Tomáštík, J.; Čtvrtlík, R.; Dráb, M.; Koula, V.; Cvrk, K.; Jastrabík, Lubomír

    2014-01-01

    Roč. 19, č. 12 (2014), s. 16635 ISSN 1435-4934 R&D Projects: GA TA ČR TA03010743 Institutional support: RVO:68378271 Keywords : acoustic emission * scratch test * thin films * AE data analysis * mechanical toughness Subject RIV: BI - Acoustics

  13. Preliminary study of acoustic emission (ae) noise signal identification for crude oil storage tank

    International Nuclear Information System (INIS)

    Nurul Ain Ahmad Latif; Shukri Mohd

    2008-08-01

    This preliminary work was carried out to simulate the Acoustic Emission (AE) signal contributed by pitting corrosion, and noise signal from environment during crude oil storage tanks monitoring. The purpose of this study is to prove that acoustic emission (AE) could be used to detect the formation of pitting corrosion in the crude oil storage tank and differentiated it from other sources of noise signal. In this study, the pitting corrosion was simulated by inducing low voltage and low amperage current onto the crude oil storage tank material (ASTM 516 G 70). Water drop, air blow and surface rubbing were applied onto the specimen surface. To simulate the noise signal produce by rain fall, wind blow and other sources of noise during AE crude oil storage tanks monitoring. AE sensor was attached onto the other surface of specimen to acquire all of these AE signals which then has send to AE DiSP 24 data acquisition system for signal conditioning. AE win software has been used to analyse this entire signal. It is found that, simulated pitting corrosion could be detected by AE system and differentiated from other sources of noise by using amplitude analysis. From the amplitude analysis is shown that 20-30 dB is the range amplitude for the blow test, 50-60 dB for surface rubbing test and over than 60 dB for water drop test. (Author)

  14. Analysis of acoustic emission during abrasive waterjet machining of sheet metals

    Science.gov (United States)

    Mokhtar, Nazrin; Gebremariam, MA; Zohari, H.; Azhari, Azmir

    2018-04-01

    The present paper reports on the analysis of acoustic emission (AE) produced during abrasive waterjet (AWJ) machining process. This paper focuses on the relationship of AE and surface quality of sheet metals. The changes in acoustic emission signals recorded by the mean of power spectral density (PSD) via covariance method in relation to the surface quality of the cut are discussed. The test was made using two materials for comparison namely aluminium 6061 and stainless steel 304 with five different feed rates. The acoustic emission data were captured by Labview and later processed using MATLAB software. The results show that the AE spectrums correlated with different feed rates and surface qualities. It can be concluded that the AE is capable of monitoring the changes of feed rate and surface quality.

  15. Study of static characteristics of acoustic-emission radiation

    Energy Technology Data Exchange (ETDEWEB)

    Vakar, K B; Rzhevkin, V R [Gosudarstvennyj Komitet po Ispol' zovaniyu Atomnoj Ehnergii SSSR, Moscow. Inst. Atomnoj Ehnergii

    1982-09-01

    Experimental installation for measuring statistical parameters of acoustic emission is described and results of measuring dimetric histograms-amplitude of emission pulses-interval between pulses - are given. The installation was constructed on the base of CAMAC ideology and anables to analyse emission signals both in real time scale and after the experiment reading out the data from outer carrier. The given results demonstrate the principle possibility to distinguish processes, proceeding in material on load.

  16. Acoustic Emission Monitoring of Compression-after-Impact Test of Nano-Particles-Coated CFRP Damaged by Simulated Lightning Strikes

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Je Ha; Kwon, Oh Yang; Seo, Seong Wook [Inha University, Incheon (Korea, Republic of)

    2011-02-15

    Nanoparticles-coated and impact-damaged carbon-fiber reinforced plastics(CFRP) laminates were tested under compression-after-impact(CAI) mode and the propagation of damage due to compressive loading has been monitored by acoustic emission(AE). The impact damage was induced not by mechanical loading but by a simulated lightning strike. CFRP laminates were made of carbon prepregs prepared by coating of conductive nano-particles directly on the fibers and the coupons were subjected to simulated lightning strikes with a high voltage/current impulse of 10{approx}40 kA within a few microseconds. The effects of nano-particles coating and the degree of damage induced by the simulated lightning strikes on the AE activities were examined, and the relationship between the compressive residual strength and AE behavior has been evaluated in terms of AE event counts and the onset of AE activity with the compressive loading. The degree of impact damage was also measured in terns of damage area by using ultrasonic C-scan images. From the results assessed during the CAI tests of damaged CFRP showed that AE monitoring appeared to be very useful to differentiate the degree of damage hence the mechanical integrity of composite structures damaged by lightning strikes

  17. Acoustic Emission Monitoring of Compression-after-Impact Test of Nano-Particles-Coated CFRP Damaged by Simulated Lightning Strikes

    International Nuclear Information System (INIS)

    Shin, Je Ha; Kwon, Oh Yang; Seo, Seong Wook

    2011-01-01

    Nanoparticles-coated and impact-damaged carbon-fiber reinforced plastics(CFRP) laminates were tested under compression-after-impact(CAI) mode and the propagation of damage due to compressive loading has been monitored by acoustic emission(AE). The impact damage was induced not by mechanical loading but by a simulated lightning strike. CFRP laminates were made of carbon prepregs prepared by coating of conductive nano-particles directly on the fibers and the coupons were subjected to simulated lightning strikes with a high voltage/current impulse of 10∼40 kA within a few microseconds. The effects of nano-particles coating and the degree of damage induced by the simulated lightning strikes on the AE activities were examined, and the relationship between the compressive residual strength and AE behavior has been evaluated in terms of AE event counts and the onset of AE activity with the compressive loading. The degree of impact damage was also measured in terns of damage area by using ultrasonic C-scan images. From the results assessed during the CAI tests of damaged CFRP showed that AE monitoring appeared to be very useful to differentiate the degree of damage hence the mechanical integrity of composite structures damaged by lightning strikes

  18. Testing of acoustic emission method during pressure tests of WWER-440 steam generators and pressurizers

    International Nuclear Information System (INIS)

    Wuerfl, K.; Crha, J.

    1987-01-01

    The results are discussed of measuring acoustic emission in output pressure testing of steam generators and pressurizers for WWER-440 reactors. The objective of the measurements was to test the reproducibility of measurements and to find the criterion which would be used in assessing the condition of the components during manufacture and in operation. The acoustic emission was measured using a single-channel Dunegan/Endevco apparatus and a 16-channel LOCAMAT system. The results showed that after the first assembly, during a repeat dismantle of the lids and during seal replacement, processes due to seal contacts and bolt and washer deformations were the main source of acoustic emission. A procedure was defined of how to exclude new acoustic emission sources in such cases. The acoustic emission method can be used for the diagnostics of plastic deformation processes or of crack production and propagation in components during service. (Z.M.)

  19. Acoustic emission analysis coupled with thermogravimetric experiments dedicated to high temperature corrosion studies on metallic alloys

    International Nuclear Information System (INIS)

    Serris, Eric; Al Haj, Omar; Peres, Veronique; Cournil, Michel; Kittel, Jean; Grosjean, Francois; Ropital, Francois

    2014-01-01

    High temperature corrosion of metallic alloys (like iron, nickel, zirconium alloys) can damage equipment of many industrial fields (refinery, petrochemical, nuclear..). Acoustic emission (AE) is an interesting method owing to its sensitivity and its non-destructive aspect to quantify the level of damage in use of these alloys under various environmental conditions. High temperature corrosive phenomena create stresses in the materials; the relaxation by cracks of these stresses can be recorded and analyzed using the AE system. The goal of our study is to establish an acoustic signals database which assigns the acoustic signals to the specific corrosion phenomena. For this purpose, thermogravimetric analysis (TGA) is coupled with acoustic emission (AE) devices. The oxidation of a zirconium alloy, zircaloy-4, is first studied using thermogravimetric experiment coupled to acoustic emission analysis at 900 C. An inward zirconium oxide scale, preliminary dense, then porous, grow during the isothermal isobaric step. The kinetic rate increases significantly after a kinetic transition (breakaway). This acceleration occurs with an increase of acoustic emission activity. Most of the acoustic emission bursts are recorded after the kinetic transition. Acoustic emission signals are also observed during the cooling of the sample. AE numerical treatments (using wavelet transform) completed by SEM microscopy characterizations allows us to distinguish the different populations of cracks. Metal dusting represents also a severe form of corrosive degradation of metal alloy. Iron metal dusting corrosion is studied by AE coupled with TGA at 650 C under C 4 H 10 + H 2 + He atmosphere. Acoustic emission signals are detected after a significant increase of the sample mass.

  20. Ambiguity of source location in acoustic emission technique

    International Nuclear Information System (INIS)

    Barat, P.; Mukherjee, P.; Kalyanasundaram, P.; Raj, B.

    1996-01-01

    Location of acoustic emission (AE) source in a plane is detected from the difference of the arrival times of the AE signal to at least three sensors placed on it. The detected location may not be unique in all cases. In this paper, the condition for the unambiguous solution for the location of the source has been deduced mathematically in terms of arrival times of the AE signal, the coordinate of the three sensors and the acoustic velocity. (author)

  1. Inspection of nuclear power plant piping welds by in-process acoustic emission monitoring

    International Nuclear Information System (INIS)

    Prine, D.W.

    1976-01-01

    The results of using in-process acoustic emission monitoring on nuclear power plant piping welds are discussed. The technique was applied to good and intentionally flawed test welds as well as production welds, and the acoustic emission results are compared to standard NDT methods and selected metallographic cross-sections

  2. Research Based on the Acoustic Emission of Wind Power Tower Drum Dynamic Monitoring Technology

    Science.gov (United States)

    Zhang, Penglin; Sang, Yuan; Xu, Yaxing; Zhao, Zhiqiang

    Wind power tower drum is one of the key components of the wind power equipment. Whether the wind tower drum performs safety directly affects the efficiency, life, and performance of wind power equipment. Wind power tower drum in the process of manufacture, installation, and operation may lead to injury, and the wind load and gravity load and long-term factors such as poor working environment under the action of crack initiation or distortion, which eventually result in the instability or crack of the wind power tower drum and cause huge economic losses. Thus detecting the wind power tower drum crack damage and instability is especially important. In this chapter, acoustic emission is used to monitor the whole process of wind power tower drum material Q345E steel tensile test at first, and processing and analysis tensile failure signal of the material. And then based on the acoustic emission testing technology to the dynamic monitoring of wind power tower drum, the overall detection and evaluation of the existence of active defects in the whole structure, and the acoustic emission signals collected for processing and analysis, we could preliminarily master the wind tower drum mechanism of acoustic emission source. The acoustic emission is a kind of online, efficient, and economic method, which has very broad prospects for work. The editorial committee of nondestructive testing qualification and certification of personnel teaching material of science and technology industry of national defense, "Acoustic emission testing" (China Machine Press, 2005.1).

  3. Sound field simulation and acoustic animation in urban squares

    Science.gov (United States)

    Kang, Jian; Meng, Yan

    2005-04-01

    Urban squares are important components of cities, and the acoustic environment is important for their usability. While models and formulae for predicting the sound field in urban squares are important for their soundscape design and improvement, acoustic animation tools would be of great importance for designers as well as for public participation process, given that below a certain sound level, the soundscape evaluation depends mainly on the type of sounds rather than the loudness. This paper first briefly introduces acoustic simulation models developed for urban squares, as well as empirical formulae derived from a series of simulation. It then presents an acoustic animation tool currently being developed. In urban squares there are multiple dynamic sound sources, so that the computation time becomes a main concern. Nevertheless, the requirements for acoustic animation in urban squares are relatively low compared to auditoria. As a result, it is important to simplify the simulation process and algorithms. Based on a series of subjective tests in a virtual reality environment with various simulation parameters, a fast simulation method with acceptable accuracy has been explored. [Work supported by the European Commission.

  4. Acoustic simulation in architecture with parallel algorithm

    Science.gov (United States)

    Li, Xiaohong; Zhang, Xinrong; Li, Dan

    2004-03-01

    In allusion to complexity of architecture environment and Real-time simulation of architecture acoustics, a parallel radiosity algorithm was developed. The distribution of sound energy in scene is solved with this method. And then the impulse response between sources and receivers at frequency segment, which are calculated with multi-process, are combined into whole frequency response. The numerical experiment shows that parallel arithmetic can improve the acoustic simulating efficiency of complex scene.

  5. Barkhausen Effect and Acoustic Emission in a Metallic Glass - Preliminary Results

    International Nuclear Information System (INIS)

    Lopez Sanchez, R.; Lopez Pumarega, M.I.; Armeite, M.; Piotrkowski, R.; Ruzzante, J.E.

    2004-01-01

    Magneto Acoustic Emission, which is Barkhausen Noise (BN) and Acoustic Emission (AE), depends on microstructure and existing residual stresses in magnetic materials. Preliminary results obtained by magnetization along two perpendicular directions on a metal glass foil are presented. Signals were analyzed with Statistic, Fast Fourier and Wavelet methods. Results are part of a Joint Research Project of the Faculty of Science, Cantabria University, Spain, and the Elastic Waves Group of the National Atomic Energy Commission, Argentina

  6. Aero-Acoustic Modelling using Large Eddy Simulation

    International Nuclear Information System (INIS)

    Shen, W Z; Soerensen, J N

    2007-01-01

    The splitting technique for aero-acoustic computations is extended to simulate three-dimensional flow and acoustic waves from airfoils. The aero-acoustic model is coupled to a sub-grid-scale turbulence model for Large-Eddy Simulations. In the first test case, the model is applied to compute laminar flow past a NACA 0015 airfoil at a Reynolds number of 800, a Mach number of 0.2 and an angle of attack of 20 deg. The model is then applied to compute turbulent flow past a NACA 0015 airfoil at a Reynolds number of 100 000, a Mach number of 0.2 and an angle of attack of 20 deg. The predicted noise spectrum is compared to experimental data

  7. Early-age acoustic emission measurements in hydrating cement paste: Evidence for cavitation during solidification due to self-desiccation

    DEFF Research Database (Denmark)

    Lura, Pietro; Couch, J.; Jensen, Ole Mejlhede

    2009-01-01

    . According to these experimental results, the acoustic emission measured around setting time was attributed to cavitation events occurring in the pores of the cement paste due to self-desiccation. This paper shows how acoustic emission might be used to indicate the time when the fluid–solid transition occurs......In this study, the acoustic emission activity of cement pastes was investigated during the first day of hydration. Deaired, fresh cement pastes were cast in sealed sample holders designed to minimize friction and restraint. The majority of acoustic emission events occurred in lower water to cement...... ratio pastes, while cement pastes with higher water to cement ratios showed significantly less acoustic activity. These acoustic events occurred around the time of setting. A layer of water on the surface of the cement pastes substantially reduced acoustic emission activity at the time of setting...

  8. Detecting and identifying damage in sandwich polymer composite by using acoustic emission

    Energy Technology Data Exchange (ETDEWEB)

    McGugan, M.; Soerensen, Bent F.; Oestergaard, R.; Bech, T.

    2006-12-15

    Acoustic emission is a useful monitoring tool for extracting extra information during mechanical testing of polymer composite sandwich materials. The study of fracture mechanics within test specimens extracted from wind turbine blade material is presented. The contribution of the acoustic emission monitoring technique in defining different failure modes identified during the testing is discussed. The development of in-situ structural monitoring and control systems is considered. (au)

  9. Method and apparatus for generating acoustic waves

    International Nuclear Information System (INIS)

    Rao, G.V.; Gopal, R.

    1982-01-01

    A portable source of acoustic waves comprises a sample of iron-nickel alloy including an austenite phase cooled to become martensite, and a wave guide to transmit the acoustic waves. The source is applied to the pressure boundary region of a pressurized water reactor to simulate an actual metal flaw and test the calibration of the monitoring and surveillance system. With at most 29.7% nickel in the sample, the source provides acoustic emission due to ductile deformation, and with at least 30% nickel the acoustic emission is characteristic of a brittle deformation. Thus, the monitoring and surveillance system can be tested in either or both situations. In the prior art, synthetic waveform signals were used for such calibration but found not suitable for on-line simulation of the surveillance system. This invention provides an improved system in that it generates true acoustic signals. (author)

  10. Acoustic emission characterization of fracture toughness for fiber reinforced ceramic matrix composites

    International Nuclear Information System (INIS)

    Mei, Hui; Sun, Yuyao; Zhang, Lidong; Wang, Hongqin; Cheng, Laifei

    2013-01-01

    The fracture toughness of a carbon fiber reinforced silicon carbide composite was investigated relating to classical critical stress intensity factor K IC , work of fracture, and acoustic emission energy. The K IC was obtained by the single edge notch beam method and the work of fracture was calculated using the featured area under the load–displacement curves. The K IC , work of fracture, and acoustic emission energy were compared for the composites before and after heat treatment and then analyzed associated with toughening microstructures of fiber pullout. It indicates that the work of fracture and acoustic emission energy can be more suitable to reflect the toughness rather than the traditional K IC , which has certain limitation for the fracture toughness characterization of the crack tolerant fiber ceramic composites.

  11. Transcranial passive acoustic mapping with hemispherical sparse arrays using CT-based skull-specific aberration corrections: a simulation study

    International Nuclear Information System (INIS)

    Jones, Ryan M; O’Reilly, Meaghan A; Hynynen, Kullervo

    2013-01-01

    The feasibility of transcranial passive acoustic mapping with hemispherical sparse arrays (30 cm diameter, 16 to 1372 elements, 2.48 mm receiver diameter) using CT-based aberration corrections was investigated via numerical simulations. A multi-layered ray acoustic transcranial ultrasound propagation model based on CT-derived skull morphology was developed. By incorporating skull-specific aberration corrections into a conventional passive beamforming algorithm (Norton and Won 2000 IEEE Trans. Geosci. Remote Sens. 38 1337–43), simulated acoustic source fields representing the emissions from acoustically-stimulated microbubbles were spatially mapped through three digitized human skulls, with the transskull reconstructions closely matching the water-path control images. Image quality was quantified based on main lobe beamwidths, peak sidelobe ratio, and image signal-to-noise ratio. The effects on the resulting image quality of the source’s emission frequency and location within the skull cavity, the array sparsity and element configuration, the receiver element sensitivity, and the specific skull morphology were all investigated. The system’s resolution capabilities were also estimated for various degrees of array sparsity. Passive imaging of acoustic sources through an intact skull was shown possible with sparse hemispherical imaging arrays. This technique may be useful for the monitoring and control of transcranial focused ultrasound (FUS) treatments, particularly non-thermal, cavitation-mediated applications such as FUS-induced blood–brain barrier disruption or sonothrombolysis, for which no real-time monitoring techniques currently exist. (paper)

  12. Transcranial passive acoustic mapping with hemispherical sparse arrays using CT-based skull-specific aberration corrections: a simulation study

    Science.gov (United States)

    Jones, Ryan M.; O’Reilly, Meaghan A.; Hynynen, Kullervo

    2013-01-01

    The feasibility of transcranial passive acoustic mapping with hemispherical sparse arrays (30 cm diameter, 16 to 1372 elements, 2.48 mm receiver diameter) using CT-based aberration corrections was investigated via numerical simulations. A multi-layered ray acoustic transcranial ultrasound propagation model based on CT-derived skull morphology was developed. By incorporating skull-specific aberration corrections into a conventional passive beamforming algorithm (Norton and Won 2000 IEEE Trans. Geosci. Remote Sens. 38 1337–43), simulated acoustic source fields representing the emissions from acoustically-stimulated microbubbles were spatially mapped through three digitized human skulls, with the transskull reconstructions closely matching the water-path control images. Image quality was quantified based on main lobe beamwidths, peak sidelobe ratio, and image signal-to-noise ratio. The effects on the resulting image quality of the source’s emission frequency and location within the skull cavity, the array sparsity and element configuration, the receiver element sensitivity, and the specific skull morphology were all investigated. The system’s resolution capabilities were also estimated for various degrees of array sparsity. Passive imaging of acoustic sources through an intact skull was shown possible with sparse hemispherical imaging arrays. This technique may be useful for the monitoring and control of transcranial focused ultrasound (FUS) treatments, particularly non-thermal, cavitation-mediated applications such as FUS-induced blood-brain barrier disruption or sonothrombolysis, for which no real-time monitoring technique currently exists. PMID:23807573

  13. Variations in frequency content of acoustic emission during extension of HF-1 steel

    International Nuclear Information System (INIS)

    Hartman, W.F.; Kline, R.A.

    1977-01-01

    Acoustic emissions resulting from continuous, dead-weight, tensile loading of quenched and tempered HF-1 steel were analyzed for frequency content. Three distinct frequency spectra were observed. These correspond to microplasticity, plasticity and deformation after recovery. It is shown that frequency analysis of acoustic emission can be a sensitive evaluation technique for assessing structural integrity

  14. Decision-making for acoustic emission data set

    International Nuclear Information System (INIS)

    Pellionisz, P.

    1992-12-01

    Acoustic emission techniques are widely applied in proof tests of pressure vessels. Correct interpretation of experimental data is of primary importance. The AE DATA EXPERT system performs this task in three procedures: source separation, source purification and source classification. Basic production rules are discussed. (author) 19 refs.; 16 figs.; 2 tabs

  15. Flaw evolution monitoring by acoustic emission technique

    International Nuclear Information System (INIS)

    Ghia, S.; Sala, A.; Lucia, A.

    1986-01-01

    Flaw evolution monitoring during mechanical fatigue test has been performed by acoustic emission (AE) technique. Testing on 1:5 reduced scale vessel containing fabrication defects was carried out in the frame of an European program for pressure component residual life evaluation. Characteristics of AE signals associated to flaw evolution are discussed

  16. Acoustic simulations of Mudejar-Gothic churches.

    Science.gov (United States)

    Galindo, Miguel; Zamarreño, Teófilo; Girón, Sara

    2009-09-01

    In this paper, an iterative process is used in order to estimate the values of absorption coefficients of those materials of which little is known in the literature, so that an acoustic simulation can be carried out in Mudejar-Gothic churches. The estimation of the scattering coefficients, which is even less developed, is based on the size of the irregularities. This methodology implemented is applied to six Mudejar-Gothic churches of Seville (southern Spain). The simulated monophonic acoustic parameters, both in the frequency domain and as a function of source-receiver distance (spatial distribution), are analyzed and compared with the in situ measures. Good agreement has been found between these sets of values, whereby each parameter is discussed in terms of the just noticeable difference. This procedure for existing buildings, especially for those which are rich in heritage, enables a reliable evaluation of the effect on the maintenance, restoration, and conditioning for new uses, as well as the recreation of the acoustic environment of ancient times. Along these lines, the acoustic influence of the timber roof and the presence of the public in these churches have also been studied.

  17. Status reports on the development and application of acoustic emission analysis. Proceedings; Statusberichte zur Entwicklung und Anwendung der Schallemissionsanalyse. Beitraege

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2009-07-01

    This proceedings-CD comprises 20 papers presented at the 17. Kolloquium Schallemission (Acoustic Emission Colloquium) at Bad Schandau. The following subjects were discussed: 1. Acoustic emission analysis of tensile tests on standard test specimens of different wood materials; 2. Application of pattern recognition methods for damage analyses of fibre-reinforced plastics; 3. Acoustic emission analysis for measuring crack growth in finned armor steel under dynamic load; 4. Acoustic emission analysis with zonal sound location: Test objects, test results and evaluation of acoustic emission signals; 5. Acoustic emission analysis in overall fatigue testing of a wind rotor blade; 6. Laboratory methods for assessing the sensitivity of acoustic emission sensors; 7. Acoustic emission analysis in burst tests of cast aluminium casings; 8. Visualization of acoustic emission localizations; 9. Threshold-independent and complete recording of characteristics and wave forms of transient and continuous acoustic emission; 10. Characterization of wide-band acoustic emission sensors; 11. Handling of large data volumes in acoustic emission analysis, a contribution to the development of algorithms; 12. Acoustic emission analysis and ultrasonic analysis for the characterization of crack networks in saline rock. One of the papers is available as a separate record in this database. [German] Diese Tagungs-CD enthaelt 20 Vortraege, die auf dem 17. Kolloquium Schallemission in Bad Schandau gehalten wurden. Die Themen waren: 1. Schallemissionsanalyse von Zugversuchen an Standardpruefkoerpern aus unterschiedlichen Holzwerkstoffen; 2. Anwendung von Mustererkennungsverfahren zur Schadensanalyse in faserverstaerkten Kunststoffen; 3. Anwendung der Schallemissionsanalyse zur Ermittlung des Risswachstums bei schwingender Beanspruchung von geripptem Bewehrungsstahl; 4. Schallemissionspruefung mit zonaler Ortung Pruefobjekte, Pruefergebnisse und Nachbewertung von Schallemissionssignalen; 5

  18. Crack Propagation Analysis Using Acoustic Emission Sensors for Structural Health Monitoring Systems

    Science.gov (United States)

    Horn, Walter; Steck, James

    2013-01-01

    Aerospace systems are expected to remain in service well beyond their designed life. Consequently, maintenance is an important issue. A novel method of implementing artificial neural networks and acoustic emission sensors to form a structural health monitoring (SHM) system for aerospace inspection routines was the focus of this research. Simple structural elements, consisting of flat aluminum plates of AL 2024-T3, were subjected to increasing static tensile loading. As the loading increased, designed cracks extended in length, releasing strain waves in the process. Strain wave signals, measured by acoustic emission sensors, were further analyzed in post-processing by artificial neural networks (ANN). Several experiments were performed to determine the severity and location of the crack extensions in the structure. ANNs were trained on a portion of the data acquired by the sensors and the ANNs were then validated with the remaining data. The combination of a system of acoustic emission sensors, and an ANN could determine crack extension accurately. The difference between predicted and actual crack extensions was determined to be between 0.004 in. and 0.015 in. with 95% confidence. These ANNs, coupled with acoustic emission sensors, showed promise for the creation of an SHM system for aerospace systems. PMID:24023536

  19. Acoustic emission monitoring of leakage through seal-plug in PHWR systems

    Energy Technology Data Exchange (ETDEWEB)

    Jha, S K; Badgujar, B P; Goswami, G L [Bhabha Atomic Research Centre, Bombay (India). Atomic Fuels Div.; Patel, R J; Bhattacharya, S; Agrawal, R G [Bhabha Atomic Research Centre, Mumbai (India). Refuelling Technology Division

    1994-12-31

    Acoustic Emission (AE) technique is being developed as an in-service inspection tool for monitoring the leakage through seal-plugs in Pressurised Heavy Water Reactors (PHWRs). Time as well as frequency domain analysis have been utilised during the experiment carried out at Bhabha Atomic Research Centre (BARC) using test set up simulating the pressure and temperature conditions. The work involved were to determine the temperature profile on end-fitting, effect of pressure and temperature on leakage etc. This paper discusses various relationships like signal-level vs. pressure, frequency spectrum of signal, signal-level vs. leakage based on the above experimental work. (author). 4 refs., 6 figs.

  20. Identification of acoustic emission sources in early stages of fatigue process of Inconel 713LC

    Energy Technology Data Exchange (ETDEWEB)

    Bartkova, Denisa; Vlasic, Frantisek; Mazal, Pavel [Brno Univ. of Technology, Brno (Czech Republic). Faculty of Mechanical Engineering

    2014-11-01

    Inconel 713LC is low carbon variant of Inconel 713 nickel-based cast alloy. The biggest advantage of these alloys is their ability to resist a wide variety of operating conditions (corrosive environment, high temperature, high stresses). Main area of applications is aircraft, energetic, chemical and petrochemical industry etc. In many applications, components undergo cyclic stresses. This study presents results of acoustic emission response of Inconel 713LC during high-cycle fatigue testing. In comparison with low-cycle fatigue, stage of initiation of micro cracks is in high-cycle region much more significant and can take several tens of percent of whole fatigue life. This work is focused on comparison of selected parameters of acoustic emission signal in pre-initiation and initiation stage of fatigue crack creation. Signal data were specified by linear location technique, hence only signal from shallow notch was analysed. Acoustic emission signal was correlated with frequency of load reversals which is a function of specimen's rigidity (modulus). Acoustic emission hits with higher stress were detected in pre-initiation stage whereas initiation stage hits exhibited low stress. Acoustic emission signal measurements are supplemented by fractographic and metallographic analysis.

  1. Modified Acoustic Emission for Prognostic Health Monitoring, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Prime Photonics proposes to team with Dr. Duke of Virginia Tech to develop a multi-mode, enhanced piezoelectric acoustic emission sensing system to couple large...

  2. Time-resolved tomography using acoustic emissions in the laboratory, and application to sandstone compaction

    Science.gov (United States)

    Brantut, Nicolas

    2018-02-01

    Acoustic emission and active ultrasonic wave velocity monitoring are often performed during laboratory rock deformation experiments, but are typically processed separately to yield homogenised wave velocity measurements and approximate source locations. Here I present a numerical method and its implementation in a free software to perform a joint inversion of acoustic emission locations together with the three-dimensional, anisotropic P-wave structure of laboratory samples. The data used are the P-wave first arrivals obtained from acoustic emissions and active ultrasonic measurements. The model parameters are the source locations and the P-wave velocity and anisotropy parameter (assuming transverse isotropy) at discrete points in the material. The forward problem is solved using the fast marching method, and the inverse problem is solved by the quasi-Newton method. The algorithms are implemented within an integrated free software package called FaATSO (Fast Marching Acoustic Emission Tomography using Standard Optimisation). The code is employed to study the formation of compaction bands in a porous sandstone. During deformation, a front of acoustic emissions progresses from one end of the sample, associated with the formation of a sequence of horizontal compaction bands. Behind the active front, only sparse acoustic emissions are observed, but the tomography reveals that the P-wave velocity has dropped by up to 15%, with an increase in anisotropy of up to 20%. Compaction bands in sandstones are therefore shown to produce sharp changes in seismic properties. This result highlights the potential of the methodology to image temporal variations of elastic properties in complex geomaterials, including the dramatic, localised changes associated with microcracking and damage generation.

  3. Application of acoustic emission, as non destructive testing technique, to nuclear components inspection

    International Nuclear Information System (INIS)

    Sanchez Miro, J.J.

    1980-01-01

    A panorama of actual state of acoustic emission as non destructive testing technique, from stand point of its safety applications to nuclear reactor is offered. In first place the physic grounds of acoustic emission phenomenon is briefly exposed. After we speak about the experimental methods for detection, and overall is made an explanation of the problems which are found during the application of this technology to on-line inspection of nuclear oower plants. It is hoped that this repport makes a contribution in the sense of to create a favourable atmosphere toward the introduction in our country of this important technique, and concretely within the nuclear power industry. In this last field the employ of acoustic emission is overcoming the experimental stage. (author)

  4. Acoustic emission measurements on real reactor components with fracture mechanical interpretation

    Energy Technology Data Exchange (ETDEWEB)

    Deuster, G

    1988-12-31

    This document presents acoustic emission measurements carried out on a reactor pressure vessel during different loadings: thermal shocking, hydro-test, cyclic loading. The acoustic emission system is described and results are provided. It appears that signals from crack border friction and crack propagation can be separated by the analysis of the signal parameters. During thermal shock, crack propagation can be detected very sensitively, together with crack border friction. During hydro-test, it appears that defects which do not grow during the experiment are not indicated, and no border friction appears. (TEC). 6 refs.

  5. Acoustic emission measurements on real reactor components with fracture mechanical interpretation

    International Nuclear Information System (INIS)

    Deuster, G.

    1988-01-01

    This document presents acoustic emission measurements carried out on a reactor pressure vessel during different loadings: thermal shocking, hydro-test, cyclic loading. The acoustic emission system is described and results are provided. It appears that signals from crack border friction and crack propagation can be separated by the analysis of the signal parameters. During thermal shock, crack propagation can be detected very sensitively, together with crack border friction. During hydro-test, it appears that defects which do not grow during the experiment are not indicated, and no border friction appears. (TEC)

  6. Study on acoustic emission signals of active defect in pressure piping under hydraulic pressure

    International Nuclear Information System (INIS)

    Ai Qiong; Liu Caixue; Wang Yao; He Pan; Song Jian

    2009-01-01

    Experimental investigations of acoustic emission (AE) of active defect in pressure piping with a prefabricated crack under hydraulic pressure tester were conducted. AE signals of fatigue-crack-growth in pressure piping were monitored incessantly in all processes, and all signals recorded were analyzed and processed. The result of signal processing show that the amplitude and energy of acoustic emission signals from defect in pressure pipeline increase gradually with the load time, and thus the active defects in pipeline can be identified; the amplitude, energy and count of acoustic emission signals increase sharply before the defect runs through, and we can forecast the penetrated leakage of pipeline. (authors)

  7. Experimental observation of acoustic emissions generated by a pulsed proton beam from a hospital-based clinical cyclotron

    International Nuclear Information System (INIS)

    Jones, Kevin C.; Solberg, Timothy D.; Avery, Stephen; Vander Stappen, François; Janssens, Guillaume; Prieels, Damien; Bawiec, Christopher R.; Lewin, Peter A.; Sehgal, Chandra M.

    2015-01-01

    Purpose: To measure the acoustic signal generated by a pulsed proton spill from a hospital-based clinical cyclotron. Methods: An electronic function generator modulated the IBA C230 isochronous cyclotron to create a pulsed proton beam. The acoustic emissions generated by the proton beam were measured in water using a hydrophone. The acoustic measurements were repeated with increasing proton current and increasing distance between detector and beam. Results: The cyclotron generated proton spills with rise times of 18 μs and a maximum measured instantaneous proton current of 790 nA. Acoustic emissions generated by the proton energy deposition were measured to be on the order of mPa. The origin of the acoustic wave was identified as the proton beam based on the correlation between acoustic emission arrival time and distance between the hydrophone and proton beam. The acoustic frequency spectrum peaked at 10 kHz, and the acoustic pressure amplitude increased monotonically with increasing proton current. Conclusions: The authors report the first observation of acoustic emissions generated by a proton beam from a hospital-based clinical cyclotron. When modulated by an electronic function generator, the cyclotron is capable of creating proton spills with fast rise times (18 μs) and high instantaneous currents (790 nA). Measurements of the proton-generated acoustic emissions in a clinical setting may provide a method for in vivo proton range verification and patient monitoring

  8. Acoustic Emission Monitoring of Incipient in Journal Bearings - Part I : Detectability and measurement for bearing damages

    International Nuclear Information System (INIS)

    Yoon, Dong Jin; Kwon, Oh Yang; Chung, Min Hwa; Kim, Kyung Woong

    1994-01-01

    In contrast to the machinery using rolling element bearings, systems with journal bearings generally operate in large scale and under severe loading condition such as steam generator turbines and internal combustion engines. Failure of the bearings in these machinery can result in the system breakdown. To avoid the time consuming repair and considerable economic loss, the detection of incipient failure in journal bearings becomes very important. In this experimental approach, acoustic emission monitoring is applied to the detection of incipient failure caused by several types of abnormal operating condition most probable in the journal bearing systems. It has been known that the intervention of foreign materials, insufficient lubrication and misassembly etc. are principal factors to cause bearing failure and distress. The experiment was conducted under such designed conditions as hard particles in the lubrication layer, insufficient lubrication, and metallic contact in the simulated journal bearing system. The results showed that acoustic emission could be an effective tool to detect the incipient failure in journal bearings

  9. Acoustic emission during tensile deformation and fracture of nuclear grade AISI type 304 stainless steel specimens with notches

    International Nuclear Information System (INIS)

    Mukhopadhyay, C.K.; Jayakumar, T.; Baldev Raj

    1996-01-01

    Acoustic emission generated during tensile deformation and fracture of nuclear grade AISI type 304 stainless steel specimens with notches has been studied. The extent of acoustic activity generated depends on notch tip severity, notch tip blunting and tearing of the notches. The equation N=AK m applied to the acoustic emission data of the notched specimens has shown good correlation. Acoustic emission technique can be used to estimate the size of an unknown notch. (author)

  10. An FBG acoustic emission source locating system based on PHAT and GA

    Science.gov (United States)

    Shen, Jing-shi; Zeng, Xiao-dong; Li, Wei; Jiang, Ming-shun

    2017-09-01

    Using the acoustic emission locating technology to monitor the health of the structure is important for ensuring the continuous and healthy operation of the complex engineering structures and large mechanical equipment. In this paper, four fiber Bragg grating (FBG) sensors are used to establish the sensor array to locate the acoustic emission source. Firstly, the nonlinear locating equations are established based on the principle of acoustic emission, and the solution of these equations is transformed into an optimization problem. Secondly, time difference extraction algorithm based on the phase transform (PHAT) weighted generalized cross correlation provides the necessary conditions for the accurate localization. Finally, the genetic algorithm (GA) is used to solve the optimization model. In this paper, twenty points are tested in the marble plate surface, and the results show that the absolute locating error is within the range of 10 mm, which proves the accuracy of this locating method.

  11. Acoustic emission methodology and application

    CERN Document Server

    Nazarchuk, Zinoviy; Serhiyenko, Oleh

    2017-01-01

    This monograph analyses in detail the physical aspects of the elastic waves radiation during deformation or fracture of materials. I presents the  methodological bases for the practical use of acoustic emission device, and describes the results of theoretical and experimental researches of evaluation of the crack growth resistance of materials, selection of the useful AE signals. The efficiency of this methodology is shown through the diagnostics of various-purpose industrial objects. The authors obtain results of experimental researches with the help of the new methods and facilities.

  12. The Acoustic Emission in the Nest of the Honey Bee Depending on the Extreme Weather Conditions

    Directory of Open Access Journals (Sweden)

    Jaromír Tlačbaba

    2014-01-01

    Full Text Available The vibroacoustic signals are an important part of communication in the honey bees (Apis mellifera L.. The aim of this study was to observe the acoustic emission that varies in a bee colony during different weather phenomena (strong winds and hailstorms and to estimate the nature and the extent of the reactions of the colony by the analysis of the obtained data. Experiments were carried out in the volume-reduced hives. The specific weather phenomena were followed by significant (P < 0.0001 increasing of the intensity of the acoustic emission in the colony in comparison with acoustic emission before or after the phenomena. Close linear positive relationship was confirmed between the intensity of wind gusts and intensity of acoustic emission (r = 0.72; P < 0.001. With the increase in the maximum gust of 1 km·h−1, the intensity of acoustic emission increased by 0.1466 mV. The character and degree of reaction of the colony can be estimated with analysis of the measured data. Permeability of vibration signals directly induced weather phenomena through the construction of the experimental hive and the stress in the colony are discussed. Observation of the acoustic emission distributed within the colony is one of the methodical alternatives for research of the vibroacoustic communication in the colony.

  13. Acoustic emission and magnification of atomic lines resolution for laser breakdown of salt water in ultrasound field

    International Nuclear Information System (INIS)

    Bulanov, Alexey V.; Nagorny, Ivan G.

    2015-01-01

    Researches of the acoustic effects accompanying optical breakdown in a water, generated by the focused laser radiation with power ultrasound have been carried out. Experiments were performed by using 532 nm pulses from Brilliant B Nd:YAG laser. Acoustic radiation was produced by acoustic focusing systems in the form hemisphere and ring by various resonance frequencies of 10.7 kHz and 60 kHz. The experimental results are obtained, that show the sharply strengthens effects of acoustic emission from a breakdown zone by the joint influence of a laser and ultrasonic irradiation. Essentially various thresholds of breakdown and character of acoustic emission in fresh and sea water are found out. The experimental result is established, testifying that acoustic emission of optical breakdown of sea water at presence and at absence of ultrasound essentially exceeds acoustic emission in fresh water. Atomic lines of some chemical elements like a Sodium, Magnesium and so on were investigated for laser breakdown of water with ultrasound field. The effect of magnification of this lines resolution for salt water in ultrasound field was obtained

  14. Mechanical Properties and Acoustic Emission Properties of Rocks with Different Transverse Scales

    Directory of Open Access Journals (Sweden)

    Xi Yan

    2017-01-01

    Full Text Available Since the stability of engineering rock masses has important practical significance to projects like mining, tunneling, and petroleum engineering, it is necessary to study mechanical properties and stability prediction methods for rocks, cementing materials that are composed of minerals in all shapes and sizes. Rocks will generate acoustic emission during damage failure processes, which is deemed as an effective means of monitoring the stability of coal rocks. In the meantime, actual mining and roadway surrounding rocks tend to have transverse effects; namely, the transverse scale is larger than the length scale. Therefore, it is important to explore mechanical properties and acoustic emission properties of rocks under transverse size effects. Considering the transverse scale effects of rocks, this paper employs the microparticle flow software PFC2D to explore the influence of different aspect ratios on damage mechanics and acoustic emission properties of rocks. The results show that (1 the transverse scale affects uniaxial compression strength of rocks. As the aspect ratio increases, uniaxial compression strength of rocks decreases initially and later increases, showing a V-shape structure and (2 although it affects the maximum hit rate and the strain range of acoustic emission, it has little influence on the period of occurrence. As the transverse scale increases, both damage degree and damage rate of rocks decrease initially and later increase.

  15. Acoustic emission test on a 25mm thick mild steel pressure vessel with inserted defects

    International Nuclear Information System (INIS)

    Bentley, P.G.; Dawson, D.G.; Hanley, D.J.; Kirby, N.

    1976-12-01

    Acoustic emission measurements have been taken on an experimental mild steel vessel with 4 inserted defects ranging in severity up to 90% of through thickness. The vessel was subjected to a series of pressure excursions of increasing magnitude until failure occurred by extension of the largest inserted defect through the vessel wall. No acoustic emission was detected throughout any part of the tests which would indicate the presence of such serious defects or of impending failure. Measurements of acoustic emission from metallurgical specimens are included and the results of post test inspection using conventional NDT and metallographic techniques are reported. (author)

  16. Coherent changes of multifractal properties of continuous acoustic emission at failure of heterogeneous materials

    Science.gov (United States)

    Panteleev, Ivan; Bayandin, Yuriy; Naimark, Oleg

    2017-12-01

    This work performs a correlation analysis of the statistical properties of continuous acoustic emission recorded in different parts of marble and fiberglass laminate samples under quasi-static deformation. A spectral coherent measure of time series, which is a generalization of the squared coherence spectrum on a multidimensional series, was chosen. The spectral coherent measure was estimated in a sliding time window for two parameters of the acoustic emission multifractal singularity spectrum: the spectrum width and the generalized Hurst exponent realizing the maximum of the singularity spectrum. It is shown that the preparation of the macrofracture focus is accompanied by the synchronization (coherent behavior) of the statistical properties of acoustic emission in allocated frequency intervals.

  17. Acoustic Emission Monitoring of Cementitious Wasteforms

    International Nuclear Information System (INIS)

    Spasova, L.M.; Ojovan, M.I.

    2013-01-01

    A summary is presented of the potential of non-destructive acoustic emission (AE) method to be applied for structures immobilising nuclear wastes. The use and limitations of the method are discussed with given examples of experimental configurations and results obtained from AE monitoring and data analysis of two different processes addressing particular issues related to the nuclear waste immobilisation. These are (a) corrosion of aluminium, classified as intermediate level waste (ILW) in the UK, encapsulated in cementitious structures and (b) partial melting and solidification during cooling of granite at a pressure of 0.15 GPa which simulates the conditions in a deep borehole disposal of canisters of vitrified high level waste (HLW). Methodology for analysis of the collected data and characterisation of the potential AE sources is performed at different steps including simple signals count and more complex signal parameter-based approach and advanced signal processing. The AE method has been shown as a potential tool for monitoring and inspection of structures immobilising nuclear wastes in relation to the time progress of different interactions of the waste with the encapsulating matrix or the wasteform with the hosting environment for permanent disposal. (author)

  18. Acoustic emission non-destructive testing of structures using source location techniques.

    Energy Technology Data Exchange (ETDEWEB)

    Beattie, Alan G.

    2013-09-01

    The technology of acoustic emission (AE) testing has been advanced and used at Sandia for the past 40 years. AE has been used on structures including pressure vessels, fire bottles, wind turbines, gas wells, nuclear weapons, and solar collectors. This monograph begins with background topics in acoustics and instrumentation and then focuses on current acoustic emission technology. It covers the overall design and system setups for a test, with a wind turbine blade as the object. Test analysis is discussed with an emphasis on source location. Three test examples are presented, two on experimental wind turbine blades and one on aircraft fire extinguisher bottles. Finally, the code for a FORTRAN source location program is given as an example of a working analysis program. Throughout the document, the stress is on actual testing of real structures, not on laboratory experiments.

  19. In situ calibration of acoustic emission transducers by time reversal method

    Czech Academy of Sciences Publication Activity Database

    Kober, Jan; Převorovský, Zdeněk; Chlada, Milan

    2016-01-01

    Roč. 240, April (2016), s. 50-56 ISSN 0924-4247 Institutional support: RVO:61388998 Keywords : time reversed acoustic s * calibration * in situ * acoustic emission Subject RIV: BI - Acoustic s Impact factor: 2.499, year: 2016 http://ac.els-cdn.com/S0924424716300334/1-s2.0-S0924424716300334-main.pdf?_tid=0acf4736-ef6d-11e5-b826-00000aacb362&acdnat=1458568911_1c21eda9762b905a684ff939463ef3fe

  20. An experimental modeling and acoustic emission monitoring of abrasive wear in a steel/diabase pair

    Science.gov (United States)

    Korchuganov, M. A.; Filippov, A. V.; Tarasov, S. Yu.; Podgornyh, O. A.; Shamarin, N. N.; Filippova, E. O.

    2016-11-01

    The earthmoving of permafrost soil is a critical task for excavation of minerals and construction on new territories. Failure by abrasive wear is the main reason for excavation parts of earthmoving and soil cutting machines. Therefore investigation of this type of wear is a challenge for developing efficient and wear resistant working parts. This paper is focused on conducting tribological experiments with sliding the steel samples over the surface of diabase stone sample where abrasive wear conditions of soil cutting are modeled experimentally. The worn surfaces of all samples have been examined and transfer of metal and stone particles revealed. The acoustic emission (AE) signals have been recorded and related to the results of worn surface analysis. he acoustic emission (AE) signals have been recorded and related to the results of worn surface analysis. As shown the wear intensity correlates to that of acoustic emission. Both acoustic emission signal median frequency and energy are found to be sensitive to the wear mode.

  1. The characteristics of acoustic emission signal under composite destruction on GFRP gas cylinder

    International Nuclear Information System (INIS)

    Jee, Hyun Sup; Lee, Jong O; Ju, No Hoe; So, Cheal Ho; Lee, Jong Kyu

    2013-01-01

    This study is investigation of the characteristics for acoustic emission signal generated by destruction on glass fiber bundles and specimen that was machined composite materials surrounding the outside of GFRP cylinder. The Amplitude of acoustic emission signal gets bigger as the cutting angle of knife increases. Accordingly, the number of hits in destruction of composite materials specimen have more in longitudinal direction (longitudinal direction to the glass fiber) than in hoop direction (horizontal direction to the glass fiber) while the amplitude of signals were bigger in hoop direction than longitudinal direction. It was found out that the amplitude of the glass fiber breakage is more than 40 dB and that the amplitude of signal for matrix crack was less than 40 dB because matrix crack signal was not observed when threshold value is 40 dB and matrix crack signal suddenly appeared when threshold value is 32 dB. The slope of the amplitude is related to the acoustic emission source and the slope of the amplitude of the horizontal and vertical directions are 0.16 and 0.08. In particular, The slope of the amplitude of longitudinal direction breakage appear similar to the glass fiber breakage and therefore Acoustic emission source of longitudinal direction breakage is estimated the glass fiber breakage.

  2. Acoustic emission localization on ship hull structures using a deep learning approach

    DEFF Research Database (Denmark)

    Georgoulas, George; Kappatos, Vassilios; Nikolakopoulos, George

    2016-01-01

    In this paper, deep belief networks were used for localization of acoustic emission events on ship hull structures. In order to avoid complex and time consuming implementations, the proposed approach uses a simple feature extraction module, which significantly reduces the extremely high dimension......In this paper, deep belief networks were used for localization of acoustic emission events on ship hull structures. In order to avoid complex and time consuming implementations, the proposed approach uses a simple feature extraction module, which significantly reduces the extremely high...

  3. Magneto acoustical emission in nanocrystalline Mn–Zn ferrites

    International Nuclear Information System (INIS)

    Praveena, K.; Murthty, S.R.

    2013-01-01

    Graphical abstract: Mn 0.4 Zn 0.6 Fe 2 O 4 powders were prepared by microwave hydrothermal method. The powders were characterized by X-ray diffraction, transmission electron microscope. The powders were sintered at different temperatures 400, 500, 600, 700, 800 and 900 °C/30 min using microwave sintering method. The grain size was estimated by scanning electron microscope. The room temperature dielectric and magnetic properties were studied in the frequency range (100 kHz–1.8 GHz). The magnetization properties were measured upto 1.5 T. The acoustic emission has been measured along the hysteresis loops from 80 K to Curie temperature. It is found that the magneto-acoustic emission (MAE) activity along hysteresis loop is proportional to the hysteresis losses during the same loop. This law has been verified on series of polycrystalline ferrites and found that the law is valid whatever the composition, the grain size and temperature. It is also found that the domain wall creation/or annihilation processes are the origin of the MAE. - Highlights: • The AE been measured along the hysteresis loops from 80 K to Curie temperature. • The MAE activity along hysteresis loop is proportional to P h during the same loop. • It is found that the domain wall creation/or annihilation processes are the origin of the MAE. - Abstract: Mn 0.4 Zn 0.6 Fe 2 O 4 powders were prepared by microwave hydrothermal method. The powders were characterized by X-ray diffraction, transmission electron microscope. The powders were sintered at different temperatures 400, 500, 600, 700, 800 and 900 °C/30 min using microwave sintering method. The grain size was estimated by scanning electron microscope. The room temperature dielectric and magnetic properties were studied in the frequency range (100 kHz–1.8 GHz). The magnetization properties were measured upto 1.5 T. The acoustic emission has been measured along the hysteresis loops from 80 K to Curie temperature. It is found that the magneto-acoustic

  4. Study of the uniform corrosion of non alloy and stainless steels: combined utilization of acoustic emission and electrochemical techniques

    International Nuclear Information System (INIS)

    Jaubert, Lionel

    2004-01-01

    In chemical and petrochemical industry, uniform corrosion induces important economic and security disappointments. The mechanisms of this damaging corrosion mode are well understood, but methods for on-line detection are badly missing. Acoustic emission technique presents, to palliate this lack, potentialities that have been studied in an instrumented laboratory loop allowing the simulation of industrial uniform corrosion conditions. In acidic media, acoustic activity is related to the hydrogen evolution resulting from proton reduction; it is therefore well correlated to the damage severity. In neutral aerated media, the deposit formation of corrosion products is not very emissive. Yet, a specific study of frequency parameters allows detection of corrosion evolution, but in that case, the quantification of corrosion rate remains difficult. A subsidiary study confirms the technique applicability in the case of 'acidic' corrosion, even in very noisy conditions. (author) [fr

  5. Acoustic Emission Beamforming for Detection and Localization of Damage

    Science.gov (United States)

    Rivey, Joshua Callen

    The aerospace industry is a constantly evolving field with corporate manufacturers continually utilizing innovative processes and materials. These materials include advanced metallics and composite systems. The exploration and implementation of new materials and structures has prompted the development of numerous structural health monitoring and nondestructive evaluation techniques for quality assurance purposes and pre- and in-service damage detection. Exploitation of acoustic emission sensors coupled with a beamforming technique provides the potential for creating an effective non-contact and non-invasive monitoring capability for assessing structural integrity. This investigation used an acoustic emission detection device that employs helical arrays of MEMS-based microphones around a high-definition optical camera to provide real-time non-contact monitoring of inspection specimens during testing. The study assessed the feasibility of the sound camera for use in structural health monitoring of composite specimens during tensile testing for detecting onset of damage in addition to nondestructive evaluation of aluminum inspection plates for visualizing stress wave propagation in structures. During composite material monitoring, the sound camera was able to accurately identify the onset and location of damage resulting from large amplitude acoustic feedback mechanisms such as fiber breakage. Damage resulting from smaller acoustic feedback events such as matrix failure was detected but not localized to the degree of accuracy of larger feedback events. Findings suggest that beamforming technology can provide effective non-contact and non-invasive inspection of composite materials, characterizing the onset and the location of damage in an efficient manner. With regards to the nondestructive evaluation of metallic plates, this remote sensing system allows us to record wave propagation events in situ via a single-shot measurement. This is a significant improvement over

  6. Acoustic emission measurements on type 316 stainless steel

    International Nuclear Information System (INIS)

    Palmer, I.G.; Holt, J.; Goddard, D.J.

    1976-01-01

    Acoustic emission measurements have been made on Type 316 stainless steel in the solution treated condition, as part of a feasibility study for the monitoring of fast reactor components. The work involved testing both plain tensile specimens and precracked compact tension specimens in the temperature range 20-200 deg C. At 20 deg C plastic deformation was a quiet process but ductile crack growth was accompanied by high amplitude emissions capable of detection on plant. At 200 deg C both plastic deformation and ductile crack growth were quiet

  7. Contribution of in situ acoustic emission analysis coupled with thermogravimetry to study zirconium alloy oxidation

    International Nuclear Information System (INIS)

    Al Haj, O.; Peres, V.; Serris, E.; Cournil, M.; Grosjean, F.; Kittel, J.; Ropital, F.

    2015-01-01

    Zirconium alloy (zircaloy-4) corrosion behavior under oxidizing atmosphere at high temperature was studied using thermogravimetric experiment associated with acoustic emission analysis. Under a mixture of oxygen and air in helium, an acceleration of the corrosion is observed due to the detrimental effect of nitrogen which produces zirconium nitride. The kinetic rate increases significantly after a kinetic transition (breakaway). This acceleration is accompanied by an acoustic emission (AE) activity. Most of the acoustic emission bursts were recorded after the kinetic transition or during the cooling of the sample. Acoustic emission signals analysis allows us to distinguish different populations of cracks in the ZrO 2 layer. These cracks have also been observed by SEM on post mortem cross section of oxidized samples and by in-situ microscopy observations on the top surface of the sample during oxidation. The numerous small convoluted thin cracks observed deeper in the zirconia scale are not detected by the AE technique. From these studies we can conclude that mechanisms as irreversible mechanisms, as cracks initiation and propagation, generate AE signals

  8. Acoustic phonon emission by two dimensional plasmons

    International Nuclear Information System (INIS)

    Mishonov, T.M.

    1990-06-01

    Acoustic wave emission of the two dimensional plasmons in a semiconductor or superconductor microstructure is investigated by using the phenomenological deformation potential within the jellium model. The plasmons are excited by the external electromagnetic (e.m.) field. The power conversion coefficient of e.m. energy into acoustic wave energy is also estimated. It is shown, the coherent transformation has a sharp resonance at the plasmon frequency of the two dimensional electron gas (2DEG). The incoherent transformation of the e.m. energy is generated by ohmic dissipation of 2DEG. The method proposed for coherent phonon beam generation can be very effective for high mobility 2DEG and for thin superconducting layers if the plasmon frequency ω is smaller than the superconducting gap 2Δ. (author). 21 refs, 1 fig

  9. On the possibility of the soliton description of acoustic emission during plastic deformation of crystals

    International Nuclear Information System (INIS)

    Pawelek, A.

    1987-06-01

    Two basic sources of acoustic emission (AE) during plastic deformation of pure crystals are discussed. One is related to non-stationary dislocation motion (the bremsstrahlung type of acoustic radiation), and the other to dislocation annihilation processes (the main component of the transition type of acoustic radiation). The possible soliton description of the bremsstrahlung acoustic radiation by oscillating dislocation kink and by bound kink-antikink pair (dislocation breather) is cosidered on the basis of Eshelby's theory (Proc. Roy. Soc. London A266, 222 (1962)). The dislocation annihilation component of transition acoustic emission is considered only in relation to the Frank-Read source operation. A soliton model for this type of acoustic radiation is proposed and the simple quantum-mechanical hypothesis is advanced for the purpose. Both soliton descriptions are discussed on the basis of available experimental data on the AE intensity behaviour during tensile deformation of crystals. (author). 36 refs, 5 figs

  10. Proportional monitoring of the acoustic emission in crypto-conditions

    Directory of Open Access Journals (Sweden)

    Petr Dostál

    2011-01-01

    Full Text Available The work is aimed at studying corrosion and fatigue properties of aluminum alloys by means of acoustic emission (AE. During material degradation are acoustic events scanned and evaluated. The main objective of the article is a description of behavior of aluminum alloys degraded in specific conditions and critical degradation stages determination. The first part of the article describes controlled degradation of the material in the crypto–conditions. The acoustic emission method is used for process analyzing. This part contains the AE signals assessment and comparing aluminium alloy to steel. Then the specimens are loaded on high-cyclic loading apparatus for fatigue life monitoring. Also, the synergy of fatigue and corrosion processes is taken into account.The aim is the description of fatigue properties for aluminum alloys that have already been corrosion-degraded. Attention is also focused on the structure of fatigue cracks. The main part of the article is aimed at corrosion degradation of aluminium alloys researched in real time by means of AE. The most important benefit of AE detection/recording is that it provides information about the process in real time. Using this measurement system is possible to observe the current status of the machines/devices and to prevent serious accidents.

  11. Computational simulation in architectural and environmental acoustics methods and applications of wave-based computation

    CERN Document Server

    Sakamoto, Shinichi; Otsuru, Toru

    2014-01-01

    This book reviews a variety of methods for wave-based acoustic simulation and recent applications to architectural and environmental acoustic problems. Following an introduction providing an overview of computational simulation of sound environment, the book is in two parts: four chapters on methods and four chapters on applications. The first part explains the fundamentals and advanced techniques for three popular methods, namely, the finite-difference time-domain method, the finite element method, and the boundary element method, as well as alternative time-domain methods. The second part demonstrates various applications to room acoustics simulation, noise propagation simulation, acoustic property simulation for building components, and auralization. This book is a valuable reference that covers the state of the art in computational simulation for architectural and environmental acoustics.  

  12. Controlled ultrasound-induced blood-brain barrier disruption using passive acoustic emissions monitoring.

    Directory of Open Access Journals (Sweden)

    Costas D Arvanitis

    Full Text Available The ability of ultrasonically-induced oscillations of circulating microbubbles to permeabilize vascular barriers such as the blood-brain barrier (BBB holds great promise for noninvasive targeted drug delivery. A major issue has been a lack of control over the procedure to ensure both safe and effective treatment. Here, we evaluated the use of passively-recorded acoustic emissions as a means to achieve this control. An acoustic emissions monitoring system was constructed and integrated into a clinical transcranial MRI-guided focused ultrasound system. Recordings were analyzed using a spectroscopic method that isolates the acoustic emissions caused by the microbubbles during sonication. This analysis characterized and quantified harmonic oscillations that occur when the BBB is disrupted, and broadband emissions that occur when tissue damage occurs. After validating the system's performance in pilot studies that explored a wide range of exposure levels, the measurements were used to control the ultrasound exposure level during transcranial sonications at 104 volumes over 22 weekly sessions in four macaques. We found that increasing the exposure level until a large harmonic emissions signal was observed was an effective means to ensure BBB disruption without broadband emissions. We had a success rate of 96% in inducing BBB disruption as measured by in contrast-enhanced MRI, and we detected broadband emissions in less than 0.2% of the applied bursts. The magnitude of the harmonic emissions signals was significantly (P<0.001 larger for sonications where BBB disruption was detected, and it correlated with BBB permeabilization as indicated by the magnitude of the MRI signal enhancement after MRI contrast administration (R(2 = 0.78. Overall, the results indicate that harmonic emissions can be a used to control focused ultrasound-induced BBB disruption. These results are promising for clinical translation of this technology.

  13. Influence of water-soaking time on the acoustic emission characteristics and spatial fractal dimensions of coal under uniaxial compression

    Directory of Open Access Journals (Sweden)

    Jia Zheqiang

    2017-01-01

    Full Text Available The water-soaking time affects the physical and mechanical properties of coals, and the temporal and spatial evolution of acoustic emissions reflects the fracture damage process of rock. This study conducted uniaxial compression acoustic emissions tests of coal samples with different water-soaking times to investigate the influence of water-soaking time on the acoustic emissions characteristics and spatial fractal dimensions during the deformation and failure process of coals. The results demonstrate that the acoustic emissions characteristics decrease with increases in the water-soaking time. The acoustic emissions spatial fractal dimension changes from a single dimensionality reduction model to a fluctuation dimensionality reduction model, and the stress level of the initial descending point of the fractal dimension increases. With increases in the water-soaking time, the destruction of coal transitions from continuous intense failure throughout the process to a lower release of energy concentrated near the peak strength.

  14. Using acoustic emission technique to monitor fractures on the analogous pressure pipes

    International Nuclear Information System (INIS)

    Zhang Lichen

    1989-01-01

    By using the acoustic emission technique to monitor the fractures on analogous pressure pipes of the primary circuit which has had cracks and loading with pressure was investigated. The dynamical process, from cracking to fracturing, was recorded by the acoustic emission technique. Comparing with the conventional method, this method gives more informations, such as pre-cracking, cracking growing, fast fracturing and the pressure values at different phases. During testing time a microcomputer was used for real-time data processing and locating the fracturing position. These data are useful for the mechanical analysis of the reactor components

  15. Using acoustic emissions to enhance fracture toughness calculations for CCNBD marble specimens

    Directory of Open Access Journals (Sweden)

    K. Kaklis

    2017-04-01

    Full Text Available Rock fracture mechanics has been widely applied to blasting, hydraulic fracturing, mechanical fragmentation, rock slope analysis, geophysics, earthquake mechanics and many other science and technology fields. Development of failure in brittle materials is associated with microcracks, which release energy in the form of elastic waves called acoustic emissions. In the present study, acoustic emission (AE measurements were carried out during cracked chevron notched Brazilian disc (CCNBD tests on Nestos marble specimens. The fracture toughness of different modes of loading (mode-I and –II is calculated and the results are discussed in conjunction with the AE parameters.

  16. Acoustic emission: who needs it - and why

    International Nuclear Information System (INIS)

    Spanner, J.C.

    1979-05-01

    Acoustic emission (AE) is an emerging NDT method that offers attractive capabilities for monitoring structural integrity and characterizing materials behavior. Although its limitations are such that it should not be regarded as a panacea, AE is proving to be a viable complement to the other NDT methods. The paper examines the extent and reasons for the growing industrial interest in AE. Some of the inherent limitations of conventional NDT methods are discussed, and several surveys of defects found during the manufacture and operation of pressure boundary components are reviewed. Although welds and weld-affected areas are the most likely locations for significant defects, very little experience is available to date to describe the AE response during impending pressure vessel failures due to weld associated defects. Acoustic emission offers potential for providing increased assurance of both initial, and continued, structural integrity. Furthermore, if AE is properly applied in conjunction with recently proposed fitness-for-purpose criteria, it may be possible to reduce present manufacturing costs without compromising actual structural adequacy. This technology is exhibiting definite signs of increasing industrial maturity, as evidenced by the recent availability of industrial standards, and the activities of various AE related technical groups throughout the world

  17. Low temperature tensile deformation and acoustic emission signal characteristics of AISI 304LN stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Barat, K.; Bar, H.N. [Material Science and Technology Division, CSIR-National Metallurgical Laboratory, Jamshedpur 831007 (India); Mandal, D. [Material Processing and Technology Division, CSIR-National Metallurgical Laboratory, Jamshedpur 831007 (India); Roy, H., E-mail: himadri9504@gmail.com [NDT and Metallurgy Group, CSIR-Central Mechanical Engineering Research Institute, Durgapur 713209 (India); Sivaprasad, S.; Tarafder, S. [Material Science and Technology Division, CSIR-National Metallurgical Laboratory, Jamshedpur 831007 (India)

    2014-03-01

    This investigation examines low temperature tensile deformation behavior of AISI 304LN stainless steel along with synergistic analysis of acoustic emission signals. The tensile tests are done at a range of temperatures starting from 283 K till 223 K. The fracture surfaces of the broken specimens are investigated using scanning electron microscope. The amount of deformation induced martensite is measured using a feritscope. The obtained results reveal that with decrease in test temperature, both strength and ductility increase. The increase in strength and ductility with decreasing temperature is explained in terms of void morphologies and formation of deformation induced martensite. The rapid increment in strength and ductility at 223 K is associated with the burst of martensitic transformation at that temperature; which has been clarified from acoustic emission signals. An additional initiative has been taken to model the evolution of martensite formation from the observed cumulative emission counts using a non linear logarithmic functional form. The fitted curves from the recorded acoustic emission cumulative count data are found to be better correlated compared to earlier obtained results. However, at 223 K normal non-linear logarithmic fit is not found suitable due to presence of burst type signals at intervals, therefore; piecewise logarithmic function to model acoustic emission bursts is proposed.

  18. In process acoustic emission in multirun submerged arc welding

    International Nuclear Information System (INIS)

    Asty, M.; Birac, C.

    1980-01-01

    In order to avoid the formation of deep grooves when repairing defects in welded joints in heavy plates, an investigation was made aiming to detect and locate the defects by in-process acoustic emission in multirun submerged arc welding. Twelve defects (lack of penetration, cracks, inclusions, lack of fusion together with inclusions, blowholes) were intentionally introduced when the first plate was welded. A space-time method for processing the acoustic activity during welding allowed the detection and the location of the intentional defects as well as of the most important accidental defects evidenced by ultrasonic testing [fr

  19. Lattice Boltzmann simulations of attenuation-driven acoustic streaming

    International Nuclear Information System (INIS)

    Haydock, David; Yeomans, J M

    2003-01-01

    We show that lattice Boltzmann simulations can be used to model the attenuation-driven acoustic streaming produced by a travelling wave. Comparisons are made to analytical results and to the streaming pattern produced by an imposed body force approximating the Reynolds stresses. We predict the streaming patterns around a porous material in an attenuating acoustic field

  20. Acoustic emission/flaw relationships for inservice monitoring of LWRs

    International Nuclear Information System (INIS)

    Hutton, P.H.; Kurtz, R.J.; Friesel, M.A.; Skorpik, J.R.; Dawson, J.F.

    1991-10-01

    The program concerning Acoustic Emission/Flaw Relationships for Inservice Monitoring of LWRs was initiated in FY76 with the objective of validating the application of acoustic emission (AE) to monitor nuclear reactor pressure-containing components during operation to detect cracking. The program has been supported by the US Nuclear Regulatory Commission, Office of Nuclear Regulatory Research. Research and development has been performed by Pacific Northwest Laboratory, operated for the Department of Energy by Battelle Memorial Institute. The program has shown the feasibility of continuous, on-line AE monitoring to detect crack growth and produced validated methods for applying the technology. Included are relationships for estimating flaw severity from AE data and field applications at Watts Bar Unit 1 Reactor, Limerick Unit 1 Reactor, and the High Flux Isotope Reactor. This report discusses the program scope and organization, the three program phases and the results obtained, standard and code activities, and instrumentation and software developed under this program

  1. Simulation of dust-acoustic waves

    International Nuclear Information System (INIS)

    Winske, D.; Murillo, M.S.; Rosenberg, M.

    1998-01-01

    The authors use molecular dynamics (MD) and particle-in-cell (PIC) simulation methods to investigate the dispersion relation of dust-acoustic waves in a one-dimensional, strongly coupled (Coulomb coupling parameter Λ = ratio of the Coulomb energy to the thermal energy = 120) dusty plasma. They study both cases where the dust is represented by a small number of simulation particles that form into a regular array structure (crystal limit) as well as where the dust is represented by a much larger number of particles (fluid limit)

  2. Acoustic emission during the compaction of brittle UO2 particles

    International Nuclear Information System (INIS)

    Hegron, Lise

    2014-01-01

    One of the options considered for recycling minor actinides is to incorporate about 10% to UO 2 matrix. The presence of open pores interconnected within this fuel should allow the evacuation of helium and fission gases to prevent swelling of the pellet and ultimately its interaction with the fuel clad surrounding it. Implementation of minor actinides requires working in shielded cell, reducing their retention and outlawing additions of organic products. The use of fragmentable particles of several hundred micrometers seems a good solution to control the microstructure of the green compacts and thus control the open porosity after sintering. The goal of this study is to monitor the compaction of brittle UO 2 particles by acoustic emission and to link the particle characteristics to the open porosity obtained after the compact sintering. The signals acquired during tensile strength tests on individual granules and compacts show that the acoustic emission allows the detection of the mechanism of fragmentation and enables identification of a characteristic waveform of this fragmentation. The influences of compaction stress, of the initial particle size distribution and of the internal cohesion of the granules, on the mechanical strength of the compact and on the microstructure and open porosity of the sintered pellets, are analyzed. By its ability to identify the range of fragmentation of the granules during compaction, acoustic emission appears as a promising technique for monitoring the compaction of brittle particles in the manufacture of a controlled porosity fuel. (author) [fr

  3. Estimation of the Tool Condition by Applying the Wavelet Transform to Acoustic Emission Signals

    International Nuclear Information System (INIS)

    Gomez, M. P.; Piotrkowski, R.; Ruzzante, J. E.; D'Attellis, C. E.

    2007-01-01

    This work follows the search of parameters to evaluate the tool condition in machining processes. The selected sensing technique is acoustic emission and it is applied to a turning process of steel samples. The obtained signals are studied using the wavelet transformation. The tool wear level is quantified as a percentage of the final wear specified by the Standard ISO 3685. The amplitude and relevant scale obtained of acoustic emission signals could be related with the wear level

  4. Progress for on-line acoustic emission monitoring of cracks in reactor systems

    International Nuclear Information System (INIS)

    Hutton, P.H.; Friesel, M.A.; Kurtz, R.J.

    1985-10-01

    This paper reviews FY1985 accomplishments and FY1986 plans for the NRC sponsored research program concerned with ''Acoustic Emission/Flaw Relationships for Inservice Monitoring of Nuclear Reactor Pressure Boundaries''. The objective of the acoustic emission (AE) monitoring program is to develop and validate the use of AE methods for continuous surveillance of reactor pressure boundaries to detect flaw growth. Topics discussed include testing AE monitoring on reactors, refinement of an AE signal identification relationship, study of slow crack growth rate effects on AE generation, and activity to produce an ASTM standard for AE monitoring and to gain ASME code acceptance of AE monitoring

  5. Quantitative evaluation of rejuvenators to restore embrittlement temperatures in oxidized asphalt mixtures using acoustic emission

    Science.gov (United States)

    Sun, Zhe; Farace, Nicholas; Arnold, Jacob; Behnia, Behzad; Buttlar, William G.; Reis, Henrique

    2015-03-01

    Towards developing a method capable to assess the efficiency of rejuvenators to restore embrittlement temperatures of oxidized asphalt binders towards their original, i.e., unaged values, three gyratory compacted specimens were manufactured with mixtures oven-aged for 36 hours at 135 °C. In addition, one gyratory compacted specimen manufactured using a short-term oven-aged mixture for two hours at 155 °C was used for control to simulate aging during plant production. Each of these four gyratory compacted specimens was then cut into two cylindrical specimen 5 cm thick for a total of six 36-hour oven-aged specimens and two short term aging specimens. Two specimens aged for 36 hours and the two short-term specimens were then tested using an acoustic emission approach to obtain base acoustic emission response of short-term and severely-aged specimens. The remaining four specimens oven-aged for 36 hours were then treated by spreading their top surface with rejuvenator in the amount of 10% of the binder by weight. These four specimens were then tested using the same acoustic emission approach after two, four, six, and eight weeks of dwell time. It was observed that the embrittlement temperatures of the short-term aged and severely oven-aged specimens were -25 °C and - 15 °C, respectively. It was also observed that after four weeks of dwell time, the rejuvenator-treated samples had recuperated the original embrittlement temperatures. In addition, it was also observed that the rejuvenator kept acting upon the binder after four weeks of dwell time; at eight weeks of dwell time, the specimens had an embrittlement temperature about one grade cooler than the embrittlement temperature corresponding to the short-term aged specimen.

  6. Study on the Measurement of Valve Leak Rate Using Acoustic Emission Technology

    International Nuclear Information System (INIS)

    Lee, Sang-Guk; Park, Jong-Hyuck; Yoo, Keun-Bae; Lee, Sun-Ki; Hong, Sung-Yull

    2006-01-01

    This study is to estimate the feasibility of acoustic emission(AE) method for the internal leak from the valves. In this study, 4 inch ball water valve leak tests using three different leak path and various leak rates were performed in order to analyze AE properties when leaks arise in valve seat. As a result of leak test for specimens simulated valve seat, we conformed that leak sound amplitude increased in proportion to the increase of leak rate, and leak rates were plotted versus peak acoustic amplitudes recorded within those two narrow frequency bands on each spectrum plot. The resulting plots of leak rate versus peak AE amplitude were the primary basis for determining the feasibility of quantifying leak acoustically. The large amount of data attained also allowed a favorable investigation of the effects of different leak paths, leak rates, pressure differentials and AE sensors on the AE amplitude spectrum. From the experimental results, it was suggested that the AE method for monitoring of leak was feasible. This paper describes quantitative measurements of fluid valve leak rates by the analysis of AE. Experimental apparatus were fabricated to accept a variety of leaking water valves in order to determine what characteristics of AE signal change with leak rate. The data for each valve were generated by varying the leak rate and recording the time averaged amplitude of AE versus frequency. Leak rates were varied by modifying the valve seating surfaces in ways designed to simulate actual defects observed in service. Most of the data analysis involved plotting the leak rate versus signal amplitude at a specific frequency to determine how well the two variables correlate in terms of accuracy, resolution, and repeatability

  7. Experimental study of advanced continuous acoustic emission monitoring of BWR components. Final report

    International Nuclear Information System (INIS)

    McElroy, J.W.; Hartman, W.F.

    1980-09-01

    The program consisted of installing, maintaining, and monitoring AE sensors located on primary piping, nozzles, and valves in the BWR system. Analysis of the AE data was correlated to the results of supplementary nondestructive testing techniques used during the in-service inspection, performed at refueling outages. Purpose of the program was to develop the on-line surveillance acoustic emission technique in order to identify areas of possible structural degradation. Result of reducing inspection time was to reduce accumulated radiation exposure to inspecting personnel and to reduce the amount of critical plant outage time by identifying the critical inspection areas during operation. The program demonstrated the capability of acoustic emission instrumentation to endure the nuclear reactor environment. The acoustic emission sensors withstood 12 months of reactor operation at temperatures of 400 0 F and greater in high radiation fields. The preamplifiers, also mounted in the reactor environment, operated for the 12-month period in 100% humidity, 250 0 F conditions. The remaining cable and AE instrumentation were operated in controlled environments

  8. Health monitoring of Ceramic Matrix Composites from waveform-based analysis of Acoustic Emission

    Directory of Open Access Journals (Sweden)

    Maillet Emmanuel

    2015-01-01

    Full Text Available Ceramic Matrix Composites (CMCs are anticipated for use in the hot section of aircraft engines. Their implementation requires the understanding of the various damage modes that are involved and their relation to life expectancy. Acoustic Emission (AE has been shown to be an efficient technique for monitoring damage evolution in CMCs. However, only a waveform-based analysis of AE can offer the possibility to validate and precisely examine the recorded AE data with a view to damage localization and identification. The present work fully integrates wave initiation, propagation and acquisition in the analysis of Acoustic Emission waveforms recorded at various sensors, therefore providing more reliable information to assess the relation between Acoustic Emission and damage modes. The procedure allows selecting AE events originating from damage, accurate determination of their location as well as the characterization of effects of propagation on the recorded waveforms. This approach was developed using AE data recorded during tensile tests on carbon/carbon composites. It was then applied to melt-infiltrated SiC/SiC composites.

  9. Numerical Simulation of Pressure Fluctuations in the Thermo-acoustic Transducer

    Directory of Open Access Journals (Sweden)

    D. A. Uglanov

    2015-01-01

    Full Text Available The article describes the features of numerical simulation of acoustic oscillation excitation in the resonators with a foam insert (regenerator to study the excitation of thermo-acoustic oscillations in the circuit of small-sized engine model on the pulse tube.The aim of this work is the numerical simulation of the emerging oscillations in thermoacoustic engine resonator at the standing wave. As a basis, the work takes a thermo-acoustic resonator model with the open end (without piston developed in DeltaEC software. The precalculated operation frequency of the given resonator model, as a quarter of the wave resonator, is ν = 560 Hz.The paper offers a simplified finite element resonator model and defines the harmonic law of the temperature distribution on regenerator. The time dependences of the speed and pressure amplitude for the open end of the resonator are given; the calculated value of the process operating frequency is approximately equal to the value of the frequency for a given length of the resonator. Key findings, as a result of study, are as follows:1. The paper shows a potential for using this ESI-CFD Advanced software to simulate the processes of thermal excitation of acoustic oscillations.2. Visualization of turbulent flow fluctuations in the regenerator zone extends the analysis capability of gas-dynamic processes.3. Difference between operating frequency of the process simulated by ESI-CFD Advanced and frequency value obtained by analytical methods is about 4%, which is evidence of the model applicability to study the acoustic parameters of thermo-acoustic transducers. Experimental results have proved these data.

  10. Computational simulation of acoustic fatigue for hot composite structures

    Science.gov (United States)

    Singhal, S. N.; Nagpal, V. K.; Murthy, P. L. N.; Chamis, C. C.

    1991-01-01

    This paper presents predictive methods/codes for computational simulation of acoustic fatigue resistance of hot composite structures subjected to acoustic excitation emanating from an adjacent vibrating component. Select codes developed over the past two decades at the NASA Lewis Research Center are used. The codes include computation of (1) acoustic noise generated from a vibrating component, (2) degradation in material properties of the composite laminate at use temperature, (3) dynamic response of acoustically excited hot multilayered composite structure, (4) degradation in the first-ply strength of the excited structure due to acoustic loading, and (5) acoustic fatigue resistance of the excited structure, including propulsion environment. Effects of the laminate lay-up and environment on the acoustic fatigue life are evaluated. The results show that, by keeping the angled plies on the outer surface of the laminate, a substantial increase in the acoustic fatigue life is obtained. The effect of environment (temperature and moisure) is to relieve the residual stresses leading to an increase in the acoustic fatigue life of the excited panel.

  11. Acoustic wave simulation using an overset grid for the global monitoring system

    Science.gov (United States)

    Kushida, N.; Le Bras, R.

    2017-12-01

    The International Monitoring System of the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) has been monitoring hydro-acoustic and infrasound waves over the globe. Because of the complex natures of the oceans and the atmosphere, computer simulation can play an important role in understanding the observed signals. In this regard, methods which depend on partial differential equations and require minimum modelling, are preferable. So far, to our best knowledge, acoustic wave propagation simulations based on partial differential equations on such a large scale have not been performed (pp 147 - 161 of ref [1], [2]). The main difficulties in building such simulation codes are: (1) considering the inhomogeneity of medium including background flows, (2) high aspect ratio of computational domain, (3) stability during long time integration. To overcome these difficulties, we employ a two-dimensional finite different (FDM) scheme on spherical coordinates with the Yin-Yang overset grid[3] solving the governing equation of acoustic waves introduces by Ostashev et. al.[4]. The comparison with real recording examples in hydro-acoustic will be presented at the conference. [1] Paul C. Etter: Underwater Acoustic Modeling and Simulation, Fourth Edition, CRC Press, 2013. [2] LIAN WANG et. al.: REVIEW OF UNDERWATER ACOUSTIC PROPAGATION MODELS, NPL Report AC 12, 2014. [3] A. Kageyama and T. Sato: "Yin-Yang grid": An overset grid in spherical geometry, Geochem. Geophys. Geosyst., 5, Q09005, 2004. [4] Vladimir E. Ostashev et. al: Equations for finite-difference, time-domain simulation of sound propagation in moving inhomogeneous media and numerical implementation, Acoustical Society of America. DOI: 10.1121/1.1841531, 2005.

  12. Acoustic emission technique for characterisation of deformation, fatigue, fracture and phase transformation and for leak detection with high sensitivity- our experiences

    International Nuclear Information System (INIS)

    Jayakumar, T.; Mukhopadhyay, C.K.; Baldev Raj

    1996-01-01

    Acoustic emission technique has been used for studying tensile deformation, fracture behaviour, detection and assessment of fatigue crack growth and α-martensite phase transformation in austenitic alloys. A methodology for amplification of weak acoustic emission signals has been established. Acoustic emission technique with advanced spectral analysis has enabled detection with high sensitivity of minute leaks in noisy environments. (author)

  13. A Preliminary Study Application Clustering System in Acoustic Emission Monitoring

    Directory of Open Access Journals (Sweden)

    Saiful Bahari Nur Amira Afiza

    2017-01-01

    Full Text Available Acoustic Emission (AE is a non-destructive testing known as assessment on damage detection in structural engineering. It also can be used to discriminate the different types of damage occurring in a composite materials. The main problem associated with the data analysis is the discrimination between the different AE sources and analysis of the AE signal in order to identify the most critical damage mechanism. Clustering analysis is a technique in which the set of object are assigned to a group called cluster. The objective of the cluster analysis is to separate a set of data into several classes that reflect the internal structure of data. In this paper was used k-means algorithm for partitioned clustering method, numerous effort have been made to improve the performance of application k-means clustering algorithm. This paper presents a current review on application clustering system in Acoustic Emission.

  14. Design of an Acoustic Probe to Measure Otoacoustic Emissions Below 0.5 kHz

    DEFF Research Database (Denmark)

    Christensen, Anders Tornvig; Ordoñez, Rodrigo; Hammershøi, Dorte

    2015-01-01

    Our ability to hear is reflected in low-level acoustic signals emitted from the ear. These otoacoustic emissions (OAEs) can be measured with an acoustic probe assembly coupling one or more small loudspeakers and microphones into the sealed ear canal. The electroacoustic instrumentation of commerc...

  15. Bifurcation of ensemble oscillations and acoustic emissions from early stage cavitation clouds in focused ultrasound

    International Nuclear Information System (INIS)

    Gerold, Bjoern; Prentice, Paul; Rachmilevitch, Itay

    2013-01-01

    The acoustic emissions from single cavitation clouds at an early stage of development in 0.521 MHz focused ultrasound of varying intensity, are detected and directly correlated to high-speed microscopic observations, recorded at 1 × 10 6 frames per second. At lower intensities, a stable regime of cloud response is identified whereby bubble-ensembles exhibit oscillations at half the driving frequency, which is also detected in the acoustic emission spectra. Higher intensities generate clouds that develop more rapidly, with increased nonlinearity evidenced by a bifurcation in the frequency of ensemble response, and in the acoustic emissions. A single bubble oscillation model is subject to equivalent ultrasound conditions and fitted to features in the hydrophone and high-speed spectral data, allowing an effective quiescent radius to be inferred for the clouds that evolve at each intensity. The approach indicates that the acoustic emissions originate from the ensemble dynamics and that the cloud acts as a single bubble of equivalent radius in terms of the scattered field. Jetting from component cavities on the periphery of clouds is regularly observed at higher intensities. The results may be of relevance for monitoring and controlling cavitation in therapeutic applications of focused ultrasound, where the phenomenon has the potential to mediate drug delivery from vasculature. (paper)

  16. Acoustic emission monitoring of activation behavior of LaNi5 hydrogen storage alloy

    Directory of Open Access Journals (Sweden)

    Igor Maria De Rosa, Alessandro Dell'Era, Mauro Pasquali, Carlo Santulli and Fabrizio Sarasini

    2011-01-01

    Full Text Available The acoustic emission technique is proposed for assessing the irreversible phenomena occurring during hydrogen absorption/desorption cycling in LaNi5. In particular, we have studied, through a parametric analysis of in situ detected signals, the correlation between acoustic emission (AE parameters and the processes occurring during the activation of an intermetallic compound. Decreases in the number and amplitude of AE signals suggest that pulverization due to hydrogen loading involves progressively smaller volumes of material as the number of cycles increases. This conclusion is confirmed by electron microscopy observations and particle size distribution measurements.

  17. Control of inhomogeneous materials strength by method of acoustic emission

    Directory of Open Access Journals (Sweden)

    В. В. Носов

    2017-08-01

    Full Text Available The ambiguous connection between the results of acoustic emission control and the strength of materials makes acoustic-emission diagnosis ineffective and actualizes the problem of strength and metrological heterogeneity. Inhomogeneity is some deviation from a certain norm. The real object is always heterogeneous, homogeneity is an assumption that simplifies the image of the object and the solution of the tasks associated with it. The need to consider heterogeneity is due to the need to clarify a particular task and is a transition to a more complex level of research. Accounting for heterogeneity requires the definition of its type, criterion and method of evaluation. The type of heterogeneity depends on the problem being solved and should be related to the property that determines the function of the real object, the criterion should be informative, and the way of its evaluation is non-destructive. The complexity of predicting the behavior of heterogeneous materials necessitates the modeling of the destructive process that determines the operability, the formulation of the inhomogeneity criterion, the interpretation of the Kaiser effect, as showing inhomogeneity of the phenomenon of non-reproduction of acoustic emission (AE activity upon repeated loading of the examined object.The article gives an example of modeling strength and metrological heterogeneity, analyzes and estimates the informative effect of the Kaiser effect on the danger degree of state of diagnosed object from the positions of the micromechanical model of time dependencies of AE parameters recorded during loading of structural materials and technical objects.

  18. Measurement of acoustic emission signal energy. Calibration and tests

    International Nuclear Information System (INIS)

    Chretien, N.; Bernard, P.; Fayolle, J.

    1975-01-01

    The possibility of using an Audimat W device for analyzing the electric energy of signals delivered by a piezo-electric sensor for acoustic emission was investigated. The characteristics of the prototype device could be improved. The tests performed revealed that the 7075-T651 aluminium alloy can be used as a reference material [fr

  19. Directional and dynamic modulation of the optical emission of an individual GaAs nanowire using surface acoustic waves.

    Science.gov (United States)

    Kinzel, Jörg B; Rudolph, Daniel; Bichler, Max; Abstreiter, Gerhard; Finley, Jonathan J; Koblmüller, Gregor; Wixforth, Achim; Krenner, Hubert J

    2011-04-13

    We report on optical experiments performed on individual GaAs nanowires and the manipulation of their temporal emission characteristics using a surface acoustic wave. We find a pronounced, characteristic suppression of the emission intensity for the surface acoustic wave propagation aligned with the axis of the nanowire. Furthermore, we demonstrate that this quenching is dynamical as it shows a pronounced modulation as the local phase of the surface acoustic wave is tuned. These effects are strongly reduced for a surface acoustic wave applied in the direction perpendicular to the axis of the nanowire due to their inherent one-dimensional geometry. We resolve a fully dynamic modulation of the nanowire emission up to 678 MHz not limited by the physical properties of the nanowires.

  20. ACEMAN (II): a PDP-11 software package for acoustic emission analysis

    International Nuclear Information System (INIS)

    Tobias, A.

    1976-01-01

    A powerful, but easy-to-use, software package (ACEMAN) for acoustic emission analysis has been developed at Berkeley Nuclear Laboratories. The system is based on a PDP-11 minicomputer with 24 K of memory, an RK05 DISK Drive and a Tektronix 4010 Graphics terminal. The operation of the system is described in detail in terms of the functions performed in response to the various command mnemonics. The ACEMAN software package offers many useful facilities not found on other acoustic emission monitoring systems. Its main features, many of which are unique, are summarised. The ACEMAN system automatically handles arrays of up to 12 sensors in real-time operation during which data are acquired, analysed, stored on the computer disk for future analysis and displayed on the terminal if required. (author)

  1. Acoustic emission during fracture of ceramic superconducting materials

    International Nuclear Information System (INIS)

    Woźny, L; Kisiel, A; Łysy, K

    2016-01-01

    In the ceramic materials acoustic emission (AE) is associated with a rapid elastic energy release due to the formation and expansion of cracks, which causes generation and propagation of the elastic wave. AE pulses measurement allows monitoring of internal stresses changes and the development of macro- and micro-cracks in ceramic materials, and that in turn allows us to evaluate the time to failure of the object. In presented work the acoustic signals generated during cracking of superconducting ceramics were recorded. Results obtained were compared with other ceramic materials tested the same way. An analysis of the signals was carried out. The characteristics of the AE before destruction of the sample were determined, that allow the assessment of the condition of the material during operation and its expected lifetime. (paper)

  2. Cerenkov emission of acoustic phonons electrically generated from three-dimensional Dirac semimetals

    Energy Technology Data Exchange (ETDEWEB)

    Kubakaddi, S. S., E-mail: sskubakaddi@gmail.com [Department of Physics, Karnatak University, Dharwad 580 003, Karnataka (India)

    2016-05-21

    Cerenkov acoustic phonon emission is theoretically investigated in a three-dimensional Dirac semimetal (3DDS) when it is driven by a dc electric field E. Numerical calculations are made for Cd{sub 3}As{sub 2} in which mobility and electron concentration are large. We find that Cerenkov emission of acoustic phonons takes place when the electron drift velocity v{sub d} is greater than the sound velocity v{sub s}. This occurs at small E (∼few V/cm) due to large mobility. Frequency (ω{sub q}) and angular (θ) distribution of phonon emission spectrum P(ω{sub q}, θ) are studied for different electron drift velocities v{sub d} (i.e., different E) and electron concentrations n{sub e}. The frequency dependence of P(ω{sub q}, θ) shows a maximum P{sub m}(ω{sub q}, θ) at about ω{sub m} ≈ 1 THz and is found to increase with the increasing v{sub d} and n{sub e}. The value of ω{sub m} shifts to higher region for larger n{sub e}. It is found that ω{sub m}/n{sub e}{sup 1/3} and P{sub m}(ω{sub q}, θ)/n{sub e}{sup 2/3} are nearly constants. The latter is in contrast with the P{sub m}(ω{sub q}, θ)n{sub e}{sup 1/2 }= constant in conventional bulk semiconductor. Each maximum is followed by a vanishing spectrum at nearly “2k{sub f} cutoff,” where k{sub f} is the Fermi wave vector. Angular dependence of P(ω{sub q}, θ) and the intensity P(θ) of the phonon emission shows a maximum at an emission angle 45° and is found to increase with increasing v{sub d}. P(θ) is found to increase linearly with n{sub e} giving the ratio P(θ)/(n{sub e}v{sub d}) nearly a constant. We suggest that it is possible to have the controlled Cerenkov emission and generation of acoustic phonons with the proper choice of E, θ, and n{sub e}. 3DDS with large n{sub e} and mobility can be a good source of acoustic phonon generation in ∼THz regime.

  3. Acoustic emission monitoring of crack formation during alkali silica\

    Czech Academy of Sciences Publication Activity Database

    Lokajíček, Tomáš; Přikryl, R.; Šachlová, Š.; Kuchařová, A.

    2017-01-01

    Roč. 220, MAR 30 (2017), s. 175-182 ISSN 0013-7952 R&D Projects: GA ČR(CZ) GAP104/12/0915 Institutional support: RVO:67985831 Keywords : Alkali-silica reaction * accelerated expansion test * ultrasonic sounding * acoustic emission * backscattered electron imaging Subject RIV: JJ - Other Materials OBOR OECD: Materials engineering Impact factor: 2.569, year: 2016

  4. SPATIAL DISTRIBUTIONS OF ABSORPTION, LOCAL SUPPRESSION, AND EMISSIVITY REDUCTION OF SOLAR ACOUSTIC WAVES IN MAGNETIC REGIONS

    International Nuclear Information System (INIS)

    Chou, D.-Y.; Yang, M.-H.; Zhao Hui; Liang Zhichao; Sun, M.-T.

    2009-01-01

    Observed acoustic power in magnetic regions is lower than the quiet Sun because of absorption, emissivity reduction, and local suppression of solar acoustic waves in magnetic regions. In the previous studies, we have developed a method to measure the coefficients of absorption, emissivity reduction, and local suppression of sunspots. In this study, we go one step further to measure the spatial distributions of three coefficients in two active regions, NOAA 9055 and 9057. The maps of absorption, emissivity reduction, and local suppression coefficients correlate with the magnetic map, including plage regions, except the emissivity reduction coefficient of NOAA 9055 where the emissivity reduction coefficient is too weak and lost among the noise.

  5. Analysis of acoustic emission data for bearings subject to unbalance

    Directory of Open Access Journals (Sweden)

    Rapinder Sawhney

    2013-01-01

    Full Text Available Acoustic Emission (AE is an effective nondestructive method for investigating the behavior of materials under stress. In recent decades, AE applications in structural health monitoring have been extended to other areas such as rotating machineries and cutting tools. This research investigates the application of acoustic emission data for unbalance analysis and detection in rotary systems. The AE parameter of interest in this study is a discrete variable that covers the significance of count, duration and amplitude of AE signals. A statistical model based on Zero-Inflated Poisson (ZIP regression is proposed to handle over-dispersion and excess zeros of the counting data. The ZIP model indicates that faulty bearings can generate more transient wave in the AE waveform. Control charts can easily detect the faulty bearing using the parameters of the ZIP model. Categorical data analysis based on generalized linear models (GLM is also presented. The results demonstrate the significance of the couple unbalance.

  6. Correlated terahertz acoustic and electromagnetic emission in dynamically screened InGaN/GaN quantum wells

    DEFF Research Database (Denmark)

    van Capel, P. J. S.; Turchinovich, Dmitry; Porte, Henrik

    2011-01-01

    signals and THz electromagnetic radiation signals demonstrates that transient strain generation in InGaN/GaN MQWs is correlatedwith electromagnetic THz generation, and both types of emission find their origin in ultrafast dynamical screening of the built-in piezoelectric field in the MQWs. The measured......We investigate acoustic and electromagnetic emission from optically excited strained piezoelectric In0.2Ga0.8N/GaN multiple quantum wells (MQWs), using optical pump-probe spectroscopy, time-resolved Brillouin scattering, and THz emission spectroscopy. A direct comparison of detected acoustic...

  7. Large hoisting machinery local damage acoustic emission monitoring of optical information acquisition research

    Directory of Open Access Journals (Sweden)

    Wan Shuai

    2016-01-01

    Full Text Available AE technology, an advanced fault diagnosis technique,is impacted by environmental noise during monitoring equipment. The occurrence of interfere noise,the fashion of interfere and the effect to the system in the AE automatic online monitoring system is analyzed. At present, most of the acoustic emission signal transmission by cable, this way of transmission has a limited transmission distance, shortcomings and so on signal easily disturbed. Is proposed in this paper based on the optical fiber transmission technology, designed and developed a information collection system based on optical fiber acoustic emission monitoring.This way has the advantages of long distance transmission, strong anti-jamming capability.

  8. Application of acoustic emission testing as a non-destructive quality control of conrete

    International Nuclear Information System (INIS)

    Feineis, N.

    1982-01-01

    The time dependence of texture changes in concrete is studied in short-time pressure experiments, using the method of acoustic emission testing. These investigations have been performed as a function of strength and composition of the material under study. As a result, the method of acoustic emission testing is shown to be an adequate method to evaluate the evolution and the character of the structural changes. In the case where only the time developement is of interest, a simple electronic method, the pulse-sum-method or pulse rate method can be applied. However only a signal evaluation procedure can give information on the character of the structure changes. (orig./RW) [de

  9. Electroacoustical simulation of listening room acoustics for project ARCHIMEDES

    DEFF Research Database (Denmark)

    Bech, Søren

    1989-01-01

    ARCHIMEDES is a psychoacoustics research project, funded under the European EUREKA scheme. Three partners share the work involved: The Acoustics Laboratory of The Technical University of Denmark; Bang and Olufsen of Denmark; and KEF Electronics of England. Its primary object is to quantify...... the influence of listening room acoustics on the timbre of reproduced sound. For simulation of the acoustics of a standard listening room, an electroacoustic setup has been built in an anechoic chamber. The setup is based on a computer model of the listening room, and it consists of a number of loudspeakers...

  10. Intermittent flow under constant forcing: Acoustic emission from creep avalanches

    Science.gov (United States)

    Salje, Ekhard K. H.; Liu, Hanlong; Jin, Linsen; Jiang, Deyi; Xiao, Yang; Jiang, Xiang

    2018-01-01

    While avalanches in field driven ferroic systems (e.g., Barkhausen noise), domain switching of martensitic nanostructures, and the collapse of porous materials are well documented, creep avalanches (avalanches under constant forcing) were never observed. Collapse avalanches generate particularly large acoustic emission (AE) signals and were hence chosen to investigate crackling noise under creep conditions. Piezoelectric SiO2 has a strong piezoelectric response even at the nanoscale so that we chose weakly bound SiO2 spheres in natural sandstone as a representative for the study of avalanches under time-independent, constant force. We found highly non-stationary crackling noise with four activity periods, each with power law distributed AE emission. Only the period before the final collapse shows the mean field behavior (ɛ near 1.39), in agreement with previous dynamic measurements at a constant stress rate. All earlier event periods show collapse with larger exponents (ɛ = 1.65). The waiting time exponents are classic with τ near 2.2 and 1.32. Creep data generate power law mixing with "effective" exponents for the full dataset with combinations of mean field and non-mean field regimes. We find close agreement with the predicted time-dependent fiber bound simulations, including events and waiting time distributions. Båth's law holds under creep conditions.

  11. MEASUREMENTS OF ABSORPTION, EMISSIVITY REDUCTION, AND LOCAL SUPPRESSION OF SOLAR ACOUSTIC WAVES IN SUNSPOTS

    International Nuclear Information System (INIS)

    Chou, D.-Y.; Liang, Z.-C.; Yang, M.-H.; Zhao Hui; Sun, M.-T.

    2009-01-01

    The power of solar acoustic waves in magnetic regions is lower relative to the quiet Sun. Absorption, emissivity reduction, and local suppression of acoustic waves contribute to the observed power reduction in magnetic regions. We propose a model for the energy budget of acoustic waves propagating through a sunspot in terms of the coefficients of absorption, emissivity reduction, and local suppression of the sunspot. Using the property that the waves emitted along the wave path between two points have no correlation with the signal at the starting point, we can separate the effects of these three mechanisms. Applying this method to helioseismic data filtered with direction and phase-velocity filters, we measure the fraction of the contribution of each mechanism to the power deficit in the umbra of the leading sunspot of NOAA 9057. The contribution from absorption is 23.3 ± 1.3%, emissivity reduction 8.2 ± 1.4%, and local suppression 68.5 ± 1.5%, for a wave packet corresponding to a phase velocity of 6.98 x 10 -5 rad s -1 .

  12. Acoustic emission measurements in petroleum-related rock mechanics

    Energy Technology Data Exchange (ETDEWEB)

    Unander, Tor Erling

    2002-07-01

    Acoustic emission activity in rock has usually been studied in crystalline rock, which reflects that rock mechanics has also mostly been occupied with such rocks in relations to seismology, mining and tunneling. On the other hand, petroleum-related rock mechanics focuses on the behaviour of sedimentary rock. Thus, this thesis presents a general study of acoustic emission activity in sedimentary rock, primarily in sandstone. Chalk, limestone and shale have also been tested, but to much less degree because the AE activity in these materials is low. To simplify the study, pore fluids have not been used. The advent of the personal computer and computerized measuring equipment have made possible new methods both for measuring and analysing acoustic emissions. Consequently, a majority of this work is devoted to the development and implementation of new analysis techniques. A broad range of topics are treated: (1) Quantification of the AE activity level, assuming that the event rate best represents the activity. An algorithm for estimating the event rate and a methodology for objectively describing special changes in the activity e.g., onset determination, are presented. (2) Analysis of AE waveform data. A new method for determining the source energy of an AE event is presented, and it is shown how seismic source theory can be used to analyze even intermediate quality data. Based on these techniques, it is shown that a major part of the measured AE activity originates from a region close to the sensor, not necessarily representing the entire sample. (3) An improved procedure for estimating source locations is presented. The main benefit is a procedure that better handles arrival time data with large errors. Statistical simulations are used to quantify the uncertainties in the locations. The analysis techniques are developed with the application to sedimentary rock in mind, and in two articles, the techniques are used in the study of such materials. The work in the first

  13. Acoustic emission testing of piston check valves

    International Nuclear Information System (INIS)

    Stewart, D.L.

    1994-01-01

    Based on test experience at Comanche Peak Unit 1, an acoustic emission data evaluation matrix for piston check valves has been developed. The degradations represented in this matrix were selected based on Edwards piston check valve failure data reported in the Nuclear Plant Reliability Data System. Evidence to support this matrix was collected from site test data on a variety of valve types. Although still under refinement, the matrix provides three major attributes for closure verification, which have proven useful in developing test procedures for inservice testing and preventing unnecessary disassembly

  14. Condition Monitoring and Management from Acoustic Emissions

    DEFF Research Database (Denmark)

    Pontoppidan, Niels Henrik Bohl

    2005-01-01

    In the following, I will use technical terms without explanation as it gives the freedom to describe the project in a shorter form for those who already know. The thesis is about condition monitoring of large diesel engines from acoustic emission signals. The experiments have been focused...... is the analysis of the angular position changes of the engine related events such as fuel injection and valve openings, caused by operational load changes. With inspiration from speech recognition and voice effects the angular timing changes have been inverted with the event alignment framework. With the event...

  15. Acoustic Emission Behavior of Early Age Concrete Monitored by Embedded Sensors.

    Science.gov (United States)

    Qin, Lei; Ren, Hong-Wei; Dong, Bi-Qin; Xing, Feng

    2014-10-02

    Acoustic emission (AE) is capable of monitoring the cracking activities inside materials. In this study, embedded sensors were employed to monitor the AE behavior of early age concrete. Type 1-3 cement-based piezoelectric composites, which had lower mechanical quality factor and acoustic impedance, were fabricated and used to make sensors. Sensors made of the composites illustrated broadband frequency response. In a laboratory, the cracking of early age concrete was monitored to recognize different hydration stages. The sensors were also embedded in a mass concrete foundation to localize the temperature gradient cracks.

  16. Study of Acoustic Emission and Mechanical Characteristics of Coal Samples under Different Loading Rates

    Directory of Open Access Journals (Sweden)

    Huamin Li

    2015-01-01

    Full Text Available To study the effect of loading rate on mechanical properties and acoustic emission characteristics of coal samples, collected from Sanjiaohe Colliery, the uniaxial compression tests are carried out under various levels of loading rates, including 0.001 mm/s, 0.002 mm/s, and 0.005 mm/s, respectively, using AE-win E1.86 acoustic emission instrument and RMT-150C rock mechanics test system. The results indicate that the loading rate has a strong impact on peak stress and peak strain of coal samples, but the effect of loading rate on elasticity modulus of coal samples is relatively small. When the loading rate increases from 0.001 mm/s to 0.002 mm/s, the peak stress increases from 22.67 MPa to 24.99 MPa, the incremental percentage is 10.23%, and under the same condition the peak strain increases from 0.006191 to 0.007411 and the incremental percentage is 19.71%. Similarly, when the loading rate increases from 0.002 mm/s to 0.005 mm/s, the peak stress increases from 24.99 MPa to 28.01 MPa, the incremental percentage is 12.08%, the peak strain increases from 0.007411 to 0.008203, and the incremental percentage is 10.69%. The relationship between acoustic emission and loading rate presents a positive correlation, and the negative correlation relation has been determined between acoustic emission cumulative counts and loading rate during the rupture process of coal samples.

  17. Acoustic Emission from Elevator Wire Ropes During Tensile Testing

    Science.gov (United States)

    Bai, Wenjie; Chai, Mengyu; Li, Lichan; Li, Yongquan; Duan, Quan

    The acoustic emission (AE) technique was used to monitor the tensile testing process for two kinds of elevator wire ropes in our work. The AE signals from wire breaks were obtained and analyzed by AE parameters and waveforms. The results showed that AE technique can be a useful tool to monitor wire break phenomenon of wire ropes and effectively capture information of wire break signal. The relationship between AE signal characteristics and wire breaks is investigated and it is found that the most effective acoustic signal discriminators are amplitude and absolute energy. Moreover, the wire break signal of two kinds of ropes is a type of burst signal and it is believed that the waveform and spectrum can be applied to analyze the AE wire break signals.

  18. A study on the spectrum analyzing of internal leak in valve for power plant using acoustic emission method

    International Nuclear Information System (INIS)

    Lee, Sang Guk; Lee, Sun Ki; Lee, Jun Shin; Sohn, Seok Man

    2004-01-01

    The purpose of this study is to estimate the availability of acoustic emission method to the internal leak of the valves at nuclear power plants. The acoustic emission method was applied to the valves at the site, and the background noise was measured for the abnormal plant condition. From the comparison of the background noise data with the experimental results as to relation between leak flow and acoustic signal, the minimum leak flow rates that can be detected by acoustic signal was suggested. When the background levels are higher than the acoustic signal, the method described below was considered that the analysis the remainder among the background noise frequency spectrum and the acoustic signal spectrum become a very useful leak detection method. A few experimental examples of the spectrum analysis that varied the background noise characteristic were given

  19. Analysis of acoustic emission signals of fatigue crack growth and corrosion processes. Investigation of the possibilities for continuous condition monitoring of transport containers by acoustic emission testing

    International Nuclear Information System (INIS)

    Wachsmuth, Janne

    2016-01-01

    Fatigue crack growth and active corrosion processes are the main causes of structural failures of transport products like road tankers, railway tank cars and ships. To prevent those failures, preventive, time-based maintenance is performed. However, preventive inspections are costly and include the risk of not detecting a defect, which could lead to a failure within the next service period. An alternative is the idea of continuous monitoring of the whole structure by means of acoustic emission testing (AT). With AT, defects within the material shall be detected and repaired directly after their appearance. Acoustic emission testing is an online non-destructive testing method. Acoustic emission (AE) arises from changes within the material and is transported by elastic waves through the material. If the AE event generates enough energy, the elastic wave propagates to the boundaries of the component, produces a displacement in the picometre scale and can be detected by a piezoelectric sensor. The sensor produces an electrical signal. From this AE signal, AE features such as the maximum amplitude or the frequency can be extracted. Methods of signal analysis are used to investigate the time and frequency dependency of signal groups. The purpose of the signal analysis is to connect the AE signal with the originating AE source. If predefined damage mechanisms are identified, referencing the damage condition of the structure is possible. Acoustic emission from events of the actual crack propagation process can for example lead to the crack growth rate or the stress intensity factor, both specific values from fracture mechanics. A new development in the domain of acoustic emission testing is the pattern recognition of AE signals. Specific features are extracted from the AE signals to assign them to their damage mechanisms. In this thesis the AE signals from the damage mechanisms corrosion and fatigue crack growth are compared and analysed. The damage mechanisms were

  20. Novel types of surface acoustic wave microreflectors - Performance analysis and simulations

    Science.gov (United States)

    Golan, G.; Griffel, G.; Seidman, A.; Croitoru, N.

    1990-06-01

    Surface acoustic waves for micrograting reflectors have been characterized. Based on the perturbation theory, eight different types of structures on an acoustic waveguide were analyzed. Results of simulations of all eight types of corrugation structures were evaluated in order to find the least leaky waveguide, the most efficient reflector (with minimum necessary perturbations), and the optimal mode shape for improved performances. General design curves are presented in order to illustrate the behavior of the incident and reflected waves under a variety of structural conditions. Analytic expressions for the calculations of the mode amplitude and mode shape, and for general acoustic corrugations are derived and then the simulations results are presented.

  1. Investigation and Characterization of Acoustic Emissions of Tornadoes Using Arrays of Infrasound Sensors

    Science.gov (United States)

    Frazier, W. G.; Talmadge, C. L.; Waxler, R.; Knupp, K. R.; Goudeau, B.; Hetzer, C. H.

    2017-12-01

    Working in co-ordination with the NOAA Vortex Southeast (Vortex SE) research program, 9 infrasound sensor arrays were deployed at fixed sites across North Alabama, South-central Tennessee, and Northwest Georgia during March and April of 2017, to investigate the emission and characterization of infrasonic acoustic energy from tornadoes and related phenomena. Each array consisted of seven broadband acoustic sensors with calibrated frequency response from 0.02 Hz to 200 Hz. The arrays were configured in a pattern such that accurate bearings to acoustic sources could be obtained over a broad range of frequencies (nominally from 1 Hz to 100 Hz). Data were collected synchronously at a rate of 1000 samples per second. On 22 April 2017 a line of strong storms passed directly through the area being monitored producing at least three verified tornadoes. Two of these were rated at EF0 and the other an EF1. Subsequent processing of the data from several of the arrays revealed acoustic emissions from the tornadic storms ranging in frequencies below 1 Hz to frequencies greater than 10 Hz. Accurate bearings to the storms have been calculated from distances greater than 60 km. Preliminary analysis has revealed that continuous emissions occurred prior to the estimated touchdown times, while the storms were on the ground, and for short periods after the tornadoes lifted; however, the strongest emissions appeared to occur while the storms were on the ground. One of the storms passed near two arrays simultaneously, and therefore accurate an accurate track of the storm as it moved has been obtained only using the infrasound measurements. Initial results from the analysis of the infrasound data will be presented. Under Vortex SE meteorological data was collected on a large suite of sensors. Correlations between the infrasound data and the meteorological data will be investigated and discussed.

  2. Acoustic Emission Methodology to Evaluate the Fracture Toughness in Heat Treated AISI D2 Tool Steel

    Science.gov (United States)

    Mostafavi, Sajad; Fotouhi, Mohamad; Motasemi, Abed; Ahmadi, Mehdi; Sindi, Cevat Teymuri

    2012-10-01

    In this article, fracture toughness behavior of tool steel was investigated using Acoustic Emission (AE) monitoring. Fracture toughness ( K IC) values of a specific tool steel was determined by applying various approaches based on conventional AE parameters, such as Acoustic Emission Cumulative Count (AECC), Acoustic Emission Energy Rate (AEER), and the combination of mechanical characteristics and AE information called sentry function. The critical fracture toughness values during crack propagation were achieved by means of relationship between the integral of the sentry function and cumulative fracture toughness (KICUM). Specimens were selected from AISI D2 cold-work tool steel and were heat treated at four different tempering conditions (300, 450, 525, and 575 °C). The results achieved through AE approaches were then compared with a methodology proposed by compact specimen testing according to ASTM standard E399. It was concluded that AE information was an efficient method to investigate fracture characteristics.

  3. Acoustic Emission Weld Monitoring in the 2195 Aluminum-Lithium Alloy

    Science.gov (United States)

    Walker, James L.

    2005-01-01

    Due to its low density, the 2195 aluminum-lithium alloy was developed as a replacement for alloy 2219 in the Space Shuttle External Tank (ET). The external tank is the single largest component of the space shuttle system. It is 154 feet long and 27.6 feet in diameter, and serves as the structural backbone for the shuttle during launch, absorbing most of the 7 million plus pounds of thrust produced. The almost 4% decrease in density between the two materials provides an extra 7500 pounds of payload capacity necessary to put the International Space Station components into orbit. The ET is an all-welded structure; hence, the requirement is for up to five rewelds without hot cracking. Unfortunately, hot cracking during re-welding or repair operations was occurring and had to be dealt with before the new super lightweight tank could be used. Weld metal porosity formation was also of concern because it leads to hot cracking during weld repairs. Accordingly, acoustic emission (AE) nondestructive testing was employed to monitor the formation of porosity and hot cracks in order to select the best filler metal and optimize the weld schedule. The purpose of this work is to determine the feasibility of detecting hot cracking in welded aluminum-lithium (Al-Li) structures through the analysis of acoustic emission data. By acoustically characterizing the effects of reheating during a repair operation, the potential for hidden flaws coalescing and becoming "unstable" as the panel is repaired could be reduced. Identification of regions where microcrack growth is likely to occur and the location of active flaw growth in the repair weld will provide the welder with direct feedback as to the current weld quality enabling adjustments to the repair process be made in the field. An acoustic emission analysis of the source mechanisms present during welding has been conducted with the goals of locating regions in the weld line that are susceptible to damage from a repair operation

  4. Impact of the Test Device on the Behavior of the Acoustic Emission Signals: Contribution of the Numerical Modeling to Signal Processing

    Science.gov (United States)

    Issiaka Traore, Oumar; Cristini, Paul; Favretto-Cristini, Nathalie; Pantera, Laurent; Viguier-Pla, Sylvie

    2018-01-01

    In a context of nuclear safety experiment monitoring with the non destructive testing method of acoustic emission, we study the impact of the test device on the interpretation of the recorded physical signals by using spectral finite element modeling. The numerical results are validated by comparison with real acoustic emission data obtained from previous experiments. The results show that several parameters can have significant impacts on acoustic wave propagation and then on the interpretation of the physical signals. The potential position of the source mechanism, the positions of the receivers and the nature of the coolant fluid have to be taken into account in the definition a pre-processing strategy of the real acoustic emission signals. In order to show the relevance of such an approach, we use the results to propose an optimization of the positions of the acoustic emission sensors in order to reduce the estimation bias of the time-delay and then improve the localization of the source mechanisms.

  5. Acoustic emission monitoring of damage in ceramic matrix composites: Effects of weaves and feature

    Science.gov (United States)

    Ojard, Greg; Mordasky, Matt; Kumar, Rajesh

    2018-04-01

    Ceramic matrix composites (CMCs) are a class of high temperature materials with better damage tolerance properties compared to monolithic ceramics. The improved toughness is attributed to weak interface coating between the fiber and the matrix that allows for crack deflection and fiber pull-out. Thus, CMCs have gained consideration over monolithic materials for high temperature applications such as in gas turbines. The current standard fiber architecture for CMCs is a harness satin (HS) balanced weave (5HS and 8HS); however, other architectures such as uni-weave materials (tape layup) are now being considered due to fiber placement control and higher fiber volume fraction in the tensile loading direction. Engineering components require additional features in the CMC laminates, such as holes for attachments. Past work has shown that acoustic emission could differentiate the effect of changing interface conditions due to heat treatment effects. The focus of the present work is to investigate the effects of different weaves and the presence of a feature on damage behavior of CMCs as observed via acoustic emission technique. The results of the tensile testing with acoustic emission monitoring will be presented and discussed.

  6. Acoustic emission on thermoelastic martensitic transformations in alloys in the course of mechanical loading

    International Nuclear Information System (INIS)

    Plotnikov, V.A.; Kokhanenko, D.V.

    2004-01-01

    The connection of the emission process with the process of the deformation accumulation and relaxation in the cycle of the martensitic transformations is studied. The martensitic transformations cycling was investigated by cycling change in the temperature in the Ti 50 Ni 50 Cu 10 alloys. The deformation accumulation and recovery is observed in the alloys undergoing the thermoelastic martensitic transformations under the mechanical loading conditions. The acoustic emission, accompanying the martensitic transformations, reflects the peculiarities of the alloy deformation behavior by the martensitic transformations. The anomalous acoustic effect correlates with the reversible deformation accumulation and does not correlates with the irreversible deformation accumulation [ru

  7. Modeling of karst deformation and analysis of acoustic emission during sinkhole formation

    Science.gov (United States)

    Bakeev, R. A.; Stefanov, Yu. P.; Duchkov, A. A.; Myasnikov, A. V.

    2017-12-01

    In this paper, the fracture pattern and formation of a sinkhole are estimated depending on the rock properties. The possibility of using geophysical methods for recording and analyzing acoustic emission to monitor and predict the state of the medium is considered. The problem of deformation of the sedimentary cover over the growing karst cavity is solved on the basis of the elastoplastic Drucker-Prager-Nikolaevsky model and the equation of damage accumulation. The specified kinetics of accumulation of damages allows us to describe slow processes of degradation of the strength of the medium under stresses that are low for the development of inelastic deformations. The results are obtained for different values of the strength of karst rock; we show the influence of the kinetic parameters of damage accumulation on the shape of collapse depressions. We also model acoustic emission caused by the material fracture. One can follow different stages of the karst development by looking at patterns of cells which fail at a given time. Our observations show the relation between the intensity of material fracture and the intensity of seismic emission.

  8. The possibilities of the detection of boiling in the reactor core on the basis of acoustic emission method

    International Nuclear Information System (INIS)

    Liska, J.

    1978-01-01

    A method is described of detecting the crisis of boiling in the core of PWR type reactors which may lead to fuel element failure. The method can be applied both in reactor development and operation. It is based on boiling detection by acoustic emission testing. The acoustic signal is measured by means of a piezoelectric transducer immersed in water or attached to one end of a waveguide immersed in water. Signals may be measured in either a wide frequency range or in a band approaching the transducer resonance frequency. This is selected such as to be outside the noise band. Experiments in an open water tank and in a water loop showed that under favourable conditions, the acoustic emission testing method was very sensitive, the intensity of acoustic signals was proportional to boiling intensity, and information contained in the emission spectrum shape was primarily of a qualitative nature. The method remains to be tested in an actual reactor where many spurious noise sources exist. (O.K.)

  9. Deciphering acoustic emission signals in drought stressed branches: the missing link between source and sensor

    Directory of Open Access Journals (Sweden)

    Lidewei L Vergeynst

    2015-07-01

    Full Text Available When drought occurs in plants, acoustic emission signals can be detected, but the actual causes of these signals are still unknown. By analyzing the waveforms of the measured signals, it should however be possible to trace the characteristics of the acoustic emission source and get information about the underlying physiological processes. A problem encountered during this analysis is that the waveform changes significantly from source to sensor and lack of knowledge on wave propagation impedes research progress made in this field. We used finite element modeling and the well-known pencil lead break source to investigate wave propagation in a branch. A cylindrical rod of polyvinyl chloride was first used to identify the theoretical propagation modes. Two wave propagation modes could be distinguished and we used the finite element model to interpret their behavior in terms of source position for both the PVC rod and a wooden rod. Both wave propagation modes were also identified in drying-induced signals from woody branches, and we used the obtained insights to provide recommendations for further acoustic emission research in plant science.

  10. Fully kinetic simulation of ion acoustic and dust-ion acoustic waves

    International Nuclear Information System (INIS)

    Hosseini Jenab, S. M.; Kourakis, I.; Abbasi, H.

    2011-01-01

    A series of numerical simulations is presented, based on a recurrence-free Vlasov kinetic model using kinetic phase point trajectories. All plasma components are modeled kinetically via a Vlasov evolution equation, then coupled through Poisson's equation. The dynamics of ion acoustic waves in an electron-ion and in a dusty (electron-ion-dust) plasma configuration are investigated, focusing on wave decay due to Landau damping and, in particular, on the parametric dependence of the damping rate on the dust concentration and on the electron-to-ion temperature ratio. In the absence of dust, the occurrence of damping was observed, as expected, and its dependence to the relative magnitude of the electron vs ion temperature(s) was investigated. When present, the dust component influences the charge balance, enabling dust-ion acoustic waves to survive Landau damping even in the extreme regime where T e ≅ T i . The Landau damping rate is shown to be minimized for a strong dust concentration or/and for a high value of the electron-to-ion temperature ratio. Our results confirm earlier theoretical considerations and contribute to the interpretation of experimental observations of dust-ion acoustic wave characteristics.

  11. Analysis of Precursors Prior to Rock Burst in Granite Tunnel Using Acoustic Emission and Far Infrared Monitoring

    OpenAIRE

    Liang, Zhengzhao; Liu, Xiangxin; Zhang, Yanbo; Tang, Chunan

    2013-01-01

    To understand the physical mechanism of the anomalous behaviors observed prior to rock burst, the acoustic emission (AE) and far infrared (FIR) techniques were applied to monitor the progressive failure of a rock tunnel model subjected to biaxial stresses. Images of fracturing process, temperature changes of the tunnel, and spatiotemporal serials of acoustic emission were simultaneously recorded during deformation of the model. The b-value derived from the amplitude distribution data of AE wa...

  12. Particle filtering based structural assessment with acoustic emission sensing

    Science.gov (United States)

    Yan, Wuzhao; Abdelrahman, Marwa; Zhang, Bin; Ziehl, Paul

    2017-02-01

    Nuclear structures are designed to withstand severe loading events under various stresses. Over time, aging of structural systems constructed with concrete and steel will occur. This deterioration may reduce service life of nuclear facilities and/or lead to unnecessary or untimely repairs. Therefore, online monitoring of structures in nuclear power plants and waste storage has drawn significant attention in recent years. Of many existing non-destructive evaluation and structural monitoring approaches, acoustic emission is promising for assessment of structural damage because it is non-intrusive and is sensitive to corrosion and crack growth in reinforced concrete elements. To provide a rapid, actionable, and graphical means for interpretation Intensity Analysis plots have been developed. This approach provides a means for classification of damage. Since the acoustic emission measurement is only an indirect indicator of structural damage, potentially corrupted by non-genuine data, it is more suitable to estimate the states of corrosion and cracking in a Bayesian estimation framework. In this paper, we will utilize the accelerated corrosion data from a specimen at the University of South Carolina to develop a particle filtering-based diagnosis and prognosis algorithm. Promising features of the proposed algorithm are described in terms of corrosion state estimation and prediction of degradation over time to a predefined threshold.

  13. Acoustic Analysis and Design of the E-STA MSA Simulator

    Science.gov (United States)

    Bittinger, Samantha A.

    2016-01-01

    The Orion European Service Module Structural Test Article (E-STA) Acoustic Test was completed in May 2016 to verify that the European Service Module (ESM) can withstand qualification acoustic environments. The test article required an aft closeout to simulate the Multi-Purpose Crew Vehicle (MPCV) Stage Adapter (MSA) cavity, however, the flight MSA design was too cost-prohibitive to build. NASA Glenn Research Center (GRC) had 6 months to design an MSA Simulator that could recreate the qualification prediction MSA cavity sound pressure level to within a reasonable tolerance. This paper summarizes the design and analysis process to arrive at a design for the MSA Simulator, and then compares its performance to the final prediction models created prior to test.

  14. Simulation of the electron acoustic instability for a finite-size electron beam system

    International Nuclear Information System (INIS)

    Lin, C.S.; Winske, D.

    1987-01-01

    Satellite observations at midlatitudes (≅20,000 km) near the earth's dayside polar cusp boundary layer indicate that the upward electron beams have a narrow latitudinal width up to 0.1 0 . In the cusp boundary layer where the electron population consists of a finite-size electron beam in a background of uniform cold and hot electrons, the electron acoustic mode is unstable inside the electron beam but damped outside the electron beam. Simulations of the electron acoustic instability for a finite-size beam system are carried out with a particle-in-cell code to investigate the heating phenomena associated with the instability and the width of the heating region. The simulations show that the finite-size electron beam radiates electrostatic electron acoustic waves. The decay length of the electron acoustic waves outside the beam in the simulation agrees with the spatial decay length derived from the linear dispersion equation

  15. Acoustic noise simulation for switched reluctance motors with audible output p

    Energy Technology Data Exchange (ETDEWEB)

    Rasmussen, P.O.; Blaabjerg, F.; Pedersen, J.K.; Kjaer, P.C. [Aalborg Univ., Inst. of Energy Technology (Denmark); Miller, T.J.E. [Univ. of Glasgow, SPEED Lab., Dep. of Electronics and Electrical Engineering (United Kingdom)

    1999-07-01

    Acoustic noise in switched reluctance motors is one of the last problems which have to be solved before a more widespread use will come. In order to design a low noise Switched Reluctance Motor drive, simulation tools are needed, and this paper describes a design programme where acoustic noise of electromagnetic origin can be estimated and even be heard by the motor-designer. The design program is based on a new, simple developed vibrational and acoustic model where the parameters can be calculated based on the geometry of the motor. The vibrational and acoustic model is verified in both time and frequency domain where vibrations and acoustic noise have been considered. (au)

  16. Gary-scale stimulated acoustic emission: differential diagnosis between hepatocelluar carcinoma and metastastic adenocarcinoma

    Energy Technology Data Exchange (ETDEWEB)

    Ko, Jang Jae; Yoon, Kwon Ha [Wongwang Univ. School of Medicine, Wonkwang (Korea, Republic of)

    2001-01-01

    To assess the value of gray-scale stimulated acoustic emission in differential diagnosis between hepatocellular carcinoma and metastatic adenocarcinoma.Twenty-four cases of hepatocellular carcinoma (HCC) in 23 patients and 26 cases of metastatic adenocarcinoma in 14 patients were prospectively examined using the pluse-inversion harmonic technique after intravenous SH U 508A administration. Gray-scale stimulated acoustic emission (SAE) was measured 5 mins after bolus injection of a contrast agent (4g, 400 mg/ml). The presence or absence of SAE signas at internal and marginal areas of the tumor and the appearance (smooth or irregular) of its border were compared. In addition, the SAE index (SAE (parenchyma) - SAE (tumor)/ SAE (parenchyma)) was histographycally determined using a computerized program (PiView{sup TM}; Mediface, Seoul, Korea). The statistics were analysed using student's test. Of the 24 HCC cases, 20 (83%) showed internal SAE signals, while 23 (96%) marginal signals were emitted. Of the 26 cases of metaststic adenocarcinoma, one (4%) showed internal SAE signals, while in five 23 metastatic lesions (88%). For HCC and metastatic tumors, the mean SAE index was 0.38{+-}0.15 and 0.60{+-}0.08, respectively ({rho}< 0.001). Gray-scale stimulated acoustic emission can be a useful tool in differential diagnosis between hepatocellular carcinoma and metastatic adenocarcinoma.

  17. Monitoring of Acoustic Emission During the Disintegration of Rock

    Czech Academy of Sciences Publication Activity Database

    Tripathi, R.; Srivastava, M.; Hloch, Sergej; Adamčík, P.; Chattopadhyaya, S.; Das, A. K.

    2016-01-01

    Roč. 149, č. 149 (2016), s. 481-488 E-ISSN 1877-7058. [International Conference on Manufacturing Engineering and Materials, ICMEM 2016. Nový Smokovec, 06.06.2016-10.06.2016] R&D Projects: GA MŠk ED2.1.00/03.0082; GA MŠk(CZ) LO1406 Institutional support: RVO:68145535 Keywords : acoustic emission * rock disintegration * waterjet Subject RIV: JQ - Machines ; Tools http://www.sciencedirect.com/science/article/pii/S1877705816312127

  18. Evoked acoustic emissions from the human ear. III. Findings in neonates

    DEFF Research Database (Denmark)

    Johnsen, N J; Bagi, P; Elberling, C

    1983-01-01

    Stimulated acoustic emissions were recorded in a consecutive series of 20 full-term and otherwise normal neonates with the equipment and method previously used in adults. One ear randomly chosen was tested in each baby, and otoscopy and tympanometry were normal in all ears. A 2 kHz click stimulus...

  19. Planar location of the simulative acoustic source based on fiber optic sensor array

    Science.gov (United States)

    Liang, Yi-Jun; Liu, Jun-feng; Zhang, Qiao-ping; Mu, Lin-lin

    2010-06-01

    A fiber optic sensor array which is structured by four Sagnac fiber optic sensors is proposed to detect and locate a simulative source of acoustic emission (AE). The sensing loops of Sagnac interferometer (SI) are regarded as point sensors as their small size. Based on the derived output light intensity expression of SI, the optimum work condition of the Sagnac fiber optic sensor is discussed through the simulation of MATLAB. Four sensors are respectively placed on a steel plate to structure the sensor array and the location algorithms are expatiated. When an impact is generated by an artificial AE source at any position of the plate, the AE signal will be detected by four sensors at different times. With the help of a single chip microcomputer (SCM) which can calculate the position of the AE source and display it on LED, we have implemented an intelligent detection and location.

  20. Application of acoustic emission monitoring to pressure tests of a steam receiver vessel with flawed nozzle welds

    International Nuclear Information System (INIS)

    Woodward, B.; McDonald, N.R.; Hincksman, M.J.

    1976-01-01

    As part of the first stage of an Australian Welding Research Association co-operative research project, acoustic emission monitoring has been applied to a steam receiver vessel withdrawn from service owing to severe weld cracking. This technique is used to check acceptance standards for defects in nozzle welds and to apply modern methods of assessing the integrity of pressurised plant. Acoustic emission monitoring has been used, together with strain gauge measurements and ultrasonic scanning, to detect the occurrence of any significant defect growth during cyclic pressurisation of the vessel. During this first stage, no significant defect growth has been produced by 1000 cycles of pressure up to 24.1 MPa (3500 psi), subsequent pressurisation up to 35.8 MPa (5200 psi), or 97 per cent of the expected yield stress of the vessel shell. The small amount of acoustic emission detected was consistent with this result. (author)

  1. Acoustic emissions of digital data video projectors- Investigating noise sources and their change during product aging

    Science.gov (United States)

    White, Michael Shane

    2005-09-01

    Acoustic emission testing continues to be a growing part of IT and telecommunication product design, as product noise is increasingly becoming a differentiator in the marketplace. This is especially true for digital/video display companies, such as InFocus Corporation, considering the market shift of these products to the home entertainment consumer as retail prices drop and performance factors increase. Projectors and displays using Digital Light Processing(tm) [DLP(tm)] technology incorporate a device known as a ColorWheel(tm) to generate the colors displayed at each pixel in the image. These ColorWheel(tm) devices spin at very high speeds and can generate high-frequency tones not typically heard in liquid crystal displays and other display technologies. Also, acoustic emission testing typically occurs at the beginning of product life and is a measure of acoustic energy emitted at this point in the lifecycle. Since the product is designed to be used over a long period of time, there is concern as to whether the acoustic emissions change over the lifecycle of the product, whether these changes will result in a level of nuisance to the average customer, and does this nuisance begin to develop prior to the intended lifetime of the product.

  2. Acoustic emission: a bibliography for 1970--1972

    International Nuclear Information System (INIS)

    Drouillard, T.F.

    1975-01-01

    The bibliography includes nearly all references in the literature on acoustic emission published during the three-year period, 1970 through 1972. Included in the 412 references are several for each of the associated technologies including: signature analysis, boiling detection, cavitation, leak detection, seismology, and rock mechanics. Information has also been obtained from eight abstracting and indexing services searched in compiling the bibliography. The bibliography has been arranged alphabetically by author and is cross referenced with a list of approximately 400 authors. Also included is a subject index. Technical articles listed were published in some 90 different journals and in 8 different languages. (U.S.)

  3. On-line monitoring on thermal shock damage of ceramics using acoustic emission

    International Nuclear Information System (INIS)

    Lee, Jin Kyung; Lee, Joon Hyun; Song, Sang Hun

    1999-01-01

    The objective of this paper is to investigate the degree of the thermal shock damage on alumina ceramic using acoustic emission technique. For this purpose, alumina ceramic specimen was heated in the elastic furnace and then was quenched into the water tank. When the specimen was quenched into water tank, a lot of micro-cracks were generated on the surface of specimen due to the thermal shock damage. In this study, acoustic emission technique was used to evaluate the elastic waves generated by the crack initiation and propagation on the surface of specimen. It was found that when the micro-crack was initiated on the surface of specimen, AE signals were the higher in amplitude than those of bubbling effect and crack propagation. A lot of AE events were generated at the first thermal shock, the number of AE events decreased gradually as the thermal shock cycle increased.

  4. Acoustic emission mechanism at switching of ferroelectric crystals

    International Nuclear Information System (INIS)

    Belov, V.V.; Morozova, G.P.; Serdobol'skaya, O.Yu.

    1986-01-01

    Process of acoustic emission (AE) in lead germanate (PGO) representing pure ferroelectric, and gadolinium molybdate (GMO) representing ferroelectric-ferroelastic, for which switching may be conducted both by the field and pressure, were studied. A conclusion has been drawn that piezoelectric excitation of a crystal from the surface by pulses of overpolarization current in the process of domain coalescence is the main AE source in PGO. Not only piezoresponse, but also direct sound generation in the moment of domain penetration and collapse is considered as AE mechanism in GMO

  5. Acoustic emission mechanism at switching of ferroelectric crystals

    Energy Technology Data Exchange (ETDEWEB)

    Belov, V V; Morozova, G P; Serdobol' skaya, O Yu

    1986-01-01

    Process of acoustic emission (AE) in lead germanate (PGO) representing pure ferroelectric, and gadolinium molybdate (GMO) representing ferroelectric-ferroelastic, for which switching may be conducted both by the field and pressure, were studied. A conclusion has been drawn that piezoelectric excitation of a crystal from the surface by pulses of overpolarization current in the process of domain coalescence is the main AE source in PGO. Not only piezoresponse, but also direct sound generation in the moment of domain penetration and collapse is considered as AE mechanism in GMO.

  6. Diagnostics of Polymer Composite Materials and Analysis of Their Production Technology by Using the Method of Acoustic Emission

    Science.gov (United States)

    Bashkov, O. V.; Protsenko, A. E.; Bryanskii, A. A.; Romashko, R. V.

    2017-09-01

    The strength properties of glass-fiber-reinforced plastics produced by vacuum and vacuum autoclave molding techniques are studied. Based on acoustic emission data, a method of diagnostic and prediction of the bearing capacity of polymer composite materials by using data from three-point bending tests is developed. The method is based on evaluating changes in the exponent of a power function relating the total acoustic emission to the test stress.

  7. 31{sup st} conference of the European Working Group on Acoustic Emission (EWGAE)

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2014-11-01

    This CD-ROM contains lectures and posters which were held on the conference of the European Working Group on Acoustic Emission in Dresden (Germany). Six of the contributions are separately analyzed for the INIS database.

  8. Aero-acoustic simulation of a subsonic hot jet; Simulation aeroacoustique d'un jet chaud subsonique

    Energy Technology Data Exchange (ETDEWEB)

    Biancherin, A.; Rahier, G.; Prieur, J.; Vuillot, F.; Lupoglazoff, N.

    2002-07-01

    This paper presents a numerical simulation of subsonic a hot jet (M 0,7) and its acoustic analysis. The MSD code of the ONERA is used to resolve the Navier-Stokes equations. A detailed study, parametric and theoretical is realized to analyze the influence of the formulation, the position, the part and the nature of the control surface on the acoustic calculation results. The acoustic predictions in far field are compared to measures realized by the ONERA in the anechoic CEPRA 19 wind tunnel. (A.L.B.)

  9. Acoustic emission for on-line reactor monitoring: results from field tests

    International Nuclear Information System (INIS)

    Hutton, P.H.; Kurtz, R.J.

    1984-09-01

    The objective of the acoustic emission (AE)/flaw characterization program is to develop use of the AE method on a continuous basis (during operation and during hydrotest) to detect and analyze flaw growth in reactor pressure vessels and primary piping. AE has the unique capability for continuous monitoring, high sensitivity, and remote flaw location

  10. “Smart COPVs” - Continued Successful Development of JSC IR&D Acoustic Emissions (AE) SHM

    Data.gov (United States)

    National Aeronautics and Space Administration — Developed and applied promising quantitative pass/fail criteria to COPVs using acoustic emission (AE) and developed automated data analysis software. This lays the...

  11. Characteristic evaluation of acoustic emission sensors

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Hyun Kyu; Joo, Y. S.; Lee, N. H

    2000-12-01

    This report introduces the various kinds of Acoustic Emission(AE) sensors as well as the basic principle of AE sensors in order to select AE sensor suitably. The described sensors include : high sensitivity sensor, broadband sensor, underwater sensor, miniature sensor, directional sensor, integral pre-amplifier sensor. Sensor has two critical aspects of reliability and repeatability. For the high reliability, sensor has to be calibrated in accordance with ASTM standard E 1106 which explains to measure the characteristics of AE sensor accurately. For investigating the degradation of AE sensor under the severe environment for example the high radiation condition, It is important to perform the repeatability test which is described in detail in according to the ASTM standard E 976. Two kinds of AE sensor applications are also summarized.

  12. Validation of Acoustical Simulations in the "Bell Labs Box"

    OpenAIRE

    Tsingos , Nicolas; Carlbom , Ingrid; Elko , Gary; Funkhouser , Thomas; Kubli , Robert

    2002-01-01

    International audience; Computer simulated sound propagation through 3D environments is important in many applications, including computer-aided de-sign, training, and virtual reality. In many cases, the accuracy of the acoustical simulation is critical to the success of the application. For example, in concert hall and factory design (where OSHA sound limits must be met), the accuracy of the simulation may save costly re-engineering after construction. In virtual environments, experiments ha...

  13. Network sensor calibration for retrieving accurate moment tensors of acoustic emissions

    Czech Academy of Sciences Publication Activity Database

    Davi, Rosalia; Vavryčuk, Václav; Charalampidou, E.-M.; Kwiatek, G.

    2013-01-01

    Roč. 62, September (2013), s. 59-67 ISSN 1365-1609 R&D Projects: GA ČR(CZ) GAP210/12/1491 EU Projects: European Commission(XE) 230669 - AIM Institutional support: RVO:67985530 Keywords : acoustic emissions * focal mechanisms * fracturing * moment tensors * sensor calibration Subject RIV: DC - Siesmology, Volcanology, Earth Structure Impact factor: 1.424, year: 2013

  14. Acoustic emission during tensile deformation of M250 grade maraging steel

    Science.gov (United States)

    Mukhopadhyay, Chandan Kumar; Rajkumar, Kesavan Vadivelu; Chandra Rao, Bhaghi Purna; Jayakumar, Tamanna

    2012-05-01

    Acoustic emission (AE) generated during room temperature tensile deformation of varyingly heat treated (solution annealed and thermally aged) M250 grade maraging steel specimens have been studied. Deformation of microstructure corresponding to different heat treated conditions in this steel could be distinctly characterized using the AE parameters such as RMS voltage, counts and peak amplitude of AE hits (events).

  15. Acoustic emission and estimation of flaw significance in reactor pressure boundaries

    International Nuclear Information System (INIS)

    Hutton, P.H.; Kurtz, R.J.

    1982-01-01

    The work discussed is intended to establish the feasibility of using acoustic emission (AE) to detect and evaluate growing flaws in nuclear reactor pressure boundaries. Basic AE identification and interpretation methods have grown out of Phase 1. Phases 2 and 3 to test and demonstrate developed methodology on a vessel test and on a reactor are in progress

  16. Magneto acoustic emission and magnetic barkhausen noise

    International Nuclear Information System (INIS)

    Neyra Astudillo, M R; Nunez, N; Lopez Pumarega, M I; Ruzzante, J

    2012-01-01

    Results obtained in the characterization of a sample of A508 Class II steel, are showed. This material is usually used for pressure vessels construction. Two techniques not very spread in our country, but developed at our Research Group were used: Magnetic Barkhausen Noise (MBN) and Magneto Acoustic Emission (MAE). Both techniques only can be used with ferromagnetic materials. A sinusoidal low frequency magnetic field (10 Hz) was applied on the material under test, producing a sudden movement of the magnetic domain walls. This movement produces an induced EMF. In this case it is amplified and filtered in the wide band between 20 kHz and 300 kHz. The electrical signal generated at the sensing coil is called Magnetic Barkhausen Noise (MBN). The MBN was known since 1919 when it was observed for the first time. The movement of the magnetic domain walls generates at the same time elastic waves which propagate inside the material. Fixing a piezoelectric transducer on the sample surface, it is possible to detect these waves. This phenomenon is known as Magneto Acoustic Emission (MAE) and its frequency band is 20 kHz up to 1 MHz. As it is widely known, the domain structure and their walls movement are deeply influenced by the metal defects and microstructure (stress, grain size, precipitates, etc.). Then studying the domain wall movement it is possible to induce the material state. At the present study, we can infer that the material analyzed with these two techniques, has an anisotropy showed at the polar graphs, but does not totally showed at the metallographic study. Subsequent studies employing the Baumann imprint technique showed that manganese sulphides present an orientation similar to that founded with MNB and MAE. This work is completed with MEB and EDAX (author)

  17. Medidas imitanciométricas em crianças com ausência de emissões otoacústicas Acoustic immittance in children without otoacoustic emissions

    Directory of Open Access Journals (Sweden)

    Ana Emilia Linares

    2008-06-01

    Full Text Available Partindo da hipótese de que alterações da função de orelha média possam prejudicar a captação das EOAs, é possível que a ausência destas, em lactentes, esteja associada a discretas alterações timpanométricas. OBJETIVO: Verificar a associação entre resposta de EOAT e alteração imitanciométrica com a sonda de 226Hz em lactentes. MÉTODOS: Estudo de coorte contemporânea com corte transversal. Foram avaliados 20 lactentes com ausência de EOAT (grupo pesquisa e 101 lactentes com presença de EOAT (grupo comparação, com idades variando entre o nascimento e oito meses. Os lactentes foram submetidos a: timpanometria; pesquisa dos limiares de reflexo acústico contralateral com estímulos de 0,5k, 1k, 2k, 4kHz e ruído de faixa larga; emissões otoacústicas (transiente e por produtos de distorção. O potencial evocado auditivo de tronco encefálico para pesquisa do limiar de resposta foi realizado no grupo pesquisa. RESULTADOS: Observou-se diferença estatisticamente significante entre os grupos (pConsidering the hypothesis that middle ear changes can impair the recording of otoacoustic emissions, it is possible that absent otoacoustic emissions in infants could be associated with a light tympanometric change. AIM: To study the association between transient otoacoustic emissions and changes in acoustic immittance measurements with 226Hz probe tone in neonates. METHODS: Cross-sectional contemporary cohort study. 20 infants with no transient otoacoustic emissions (study group and 101 infants with transient otoacoustic emissions (control group, with ages ranged from birth to eight months, were assessed. Infants were submitted to: admittance tympanometry; contralateral acoustic reflex threshold with stimulus of 0.5, 1, 2, 4 kHz and broad band noise; transient and distortion product otoacoustic emissions. The auditory brain response was used to study the threshold in neonates without transient otoacoustic emissions. RESULTS

  18. Correlating Inertial Acoustic Cavitation Emissions with Material Erosion Resistance

    Science.gov (United States)

    Ibanez, I.; Hodnett, M.; Zeqiri, B.; Frota, M. N.

    The standard ASTM G32-10 concerns the hydrodynamic cavitation erosion resistance of materials by subjecting them to acoustic cavitation generated by a sonotrode. The work reported extends this technique by detecting and monitoring the ultrasonic cavitation, considered responsible for the erosion process, specifically for coupons of aluminium-bronze alloy. The study uses a 65 mm diameter variant of NPL's cavitation sensor, which detects broadband acoustic emissions, and logs acoustic signals generated in the MHz frequency range, using NPL's Cavimeter. Cavitation readings were made throughout the exposure duration, which was carried out at discrete intervals (900 to 3600 s), allowing periodic mass measurements to be made to assess erosion loss under a strict protocol. Cavitation measurements and erosion were compared for different separations of the sonotrode tip from the material under test. The maximum variation associated with measurement of cavitation level was between 2.2% and 3.3% when the separation (λ) between the transducer horn and the specimen increased from 0.5 to 1.0 mm, for a transducer (sonotrode) displacement amplitude of 43.5 μm. Experiments conducted at the same transducer displacement amplitude show that the mass loss of the specimen -a measure of erosion- was 67.0 mg (λ = 0.5 mm) and 66.0 mg (λ = 1.0 mm).

  19. Study on the simulation of acoustic logging measurements in horizontal and deviated wells

    Science.gov (United States)

    Liu, He; Wang, Bing; Tao, Guo; Zhang, Kuo; Yue, Wen-Zheng

    2017-09-01

    The conventional acoustic logging interpretation method, which is based on vertical wells that penetrate isotropic formations, is not suitable for horizontal and deviated wells penetrating anisotropic formations. This unsuitability is because during horizontal and deviated well drilling, cuttings will splash on the well wall or fall into the borehole bottom and form a thin bed of cuttings. In addition, the high velocity layers at different depths and intrinsic anisotropy may affect acoustic logging measurements. In this study, we examine how these factors affect the acoustic wave slowness measured in horizontal and deviated wells that are surrounded by an anisotropic medium using numerical simulation. We use the staggered-grid finite difference method in time domain (FDTD) combined with hybrid-PML. First, we acquire the acoustic slowness using a simulated array logging system, and then, we analyze how various factors affect acoustic slowness measurements and the differences between the effects of these factors. The factors considered are high-velocity layers, thin beds of cuttings, dipping angle, formation thickness, and anisotropy. The simulation results show that these factors affect acoustic wave slowness measurements differently. We observe that when the wavelength is much smaller than the distance between the borehole wall and high velocity layer, the true slowness of the formation could be acquired. When the wavelengths are of the same order (i.e., in the near-field scenarios), the geometrical acoustics theory is no longer applicable. Furthermore, when a thin bed of cuttings exists at the bottom of the borehole, Fermat's principle is still applicable, and true slowness can be acquired. In anisotropic formations, the measured slowness changes with increments in the dipping angle. Finally, for a measurement system with specific spacing, the slowness of a thin target layer can be acquired when the distance covered by the logging tool is sufficiently long. Based

  20. Design and simulation of a microfluidic device for acoustic cell separation.

    Science.gov (United States)

    Shamloo, Amir; Boodaghi, Miad

    2018-03-01

    Experimental acoustic cell separation methods have been widely used to perform separation for different types of blood cells. However, numerical simulation of acoustic cell separation has not gained enough attention and needs further investigation since by using numerical methods, it is possible to optimize different parameters involved in the design of an acoustic device and calculate particle trajectories in a simple and low cost manner before spending time and effort for fabricating these devices. In this study, we present a comprehensive finite element-based simulation of acoustic separation of platelets, red blood cells and white blood cells, using standing surface acoustic waves (SSAWs). A microfluidic channel with three inlets, including the middle inlet for sheath flow and two symmetrical tilted angle inlets for the cells were used to drive the cells through the channel. Two interdigital transducers were also considered in this device and by implementing an alternating voltage to the transducers, an acoustic field was created which can exert the acoustic radiation force to the cells. Since this force is dependent to the size of the cells, the cells are pushed towards the midline of the channel with different path lines. Particle trajectories for different cells were obtained and compared with a theoretical equation. Two types of separations were observed as a result of varying the amplitude of the acoustic field. In the first mode of separation, white blood cells were sorted out through the middle outlet and in the second mode of separation, platelets were sorted out through the side outlets. Depending on the clinical needs and by using the studied microfluidic device, each of these modes can be applied to separate the desired cells. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. The acoustical history of Hagia Sophia revived through computer simulations

    DEFF Research Database (Denmark)

    Rindel, Jens Holger; Weitze, C.A.; Christensen, Claus Lynge

    2002-01-01

    The present paper deals with acoustic computer simulations of Hagia Sophia, which is characterized not only by being one of the largest worship buildings in the world, but also by – in its 1500 year history – having served three purposes: as a church, as a mosque and today as a museum. The invest......The present paper deals with acoustic computer simulations of Hagia Sophia, which is characterized not only by being one of the largest worship buildings in the world, but also by – in its 1500 year history – having served three purposes: as a church, as a mosque and today as a museum....... The investigation is done as a part of the EU project - CAHRISMA....

  2. Acoustic emission in a superconductor (Nb-Ti) during magnetic field and current sweep

    International Nuclear Information System (INIS)

    Nomura, Harehiko

    1980-01-01

    Though superconducting magnets are indispensable in the fields of nuclear fusion, MHD power generation, high energy technology, and the trains using magnetic levitation, the safety of the magnets used for those fields is required to be fully investigated because their accumulating energy reaches up to several GJ. For this purpose, the improvement of monitoring techniques is extremely important to grasp exactly the magnetization of such large energy magnets. Although the detection of the terminal voltage of the magnets has been mainly used so far, the purpose has not yet been fulfilled because various phenomena appear in the form of noises in the terminal voltage. The authors have found the monitoring method using acoustic emission in a system completely independent from voltage observation. From this viewpoint, the experiments have been performed aiming at the generation of acoustic emission in conjunction with magnetization out of the fine structure of super-conductors, taking notice of the emitted sound frequency ranging over several hundred kHz. The results and investigation revealed that the superconductor itself emitted ultrasonic sound. It was found that the observation of this acoustic power intensity was able to monitor not only the magnetization of superconductors but also its current sweep. Since the motion of the magnetic flux is converted into the signal of acoustic field, this measuring method is less affected by noise disturbance from electromagnetic systems, and is expected to be useful for the researches on analyzing superconductor characteristics. (Wakatsuki, Y.)

  3. Inspection of nuclear reactor welding by acoustic emission

    International Nuclear Information System (INIS)

    Prine, D.W.

    1977-01-01

    The objective of the work described is to evaluate in-process acoustic emission weld monitoring with the goal of upgrading the inspection techniques for assuring better weld quality in nuclear reactor piping and pressure vessels. To accomplish this overall objective, the following specific goals have been set within a three year program: (1) prove the feasibility of in-process AE under shop conditions and validate the AE findings by currently acceptable NDE techniques; (2) develop and build a prototype monitor for use in Nuclear Fabrication shops; and (3) provide data for NRC/ASME acceptance of the inspection practice

  4. An automatic microseismic or acoustic emission arrival identification scheme with deep recurrent neural networks

    Science.gov (United States)

    Zheng, Jing; Lu, Jiren; Peng, Suping; Jiang, Tianqi

    2018-02-01

    The conventional arrival pick-up algorithms cannot avoid the manual modification of the parameters for the simultaneous identification of multiple events under different signal-to-noise ratios (SNRs). Therefore, in order to automatically obtain the arrivals of multiple events with high precision under different SNRs, in this study an algorithm was proposed which had the ability to pick up the arrival of microseismic or acoustic emission events based on deep recurrent neural networks. The arrival identification was performed using two important steps, which included a training phase and a testing phase. The training process was mathematically modelled by deep recurrent neural networks using Long Short-Term Memory architecture. During the testing phase, the learned weights were utilized to identify the arrivals through the microseismic/acoustic emission data sets. The data sets were obtained by rock physics experiments of the acoustic emission. In order to obtain the data sets under different SNRs, this study added random noise to the raw experiments' data sets. The results showed that the outcome of the proposed method was able to attain an above 80 per cent hit-rate at SNR 0 dB, and an approximately 70 per cent hit-rate at SNR -5 dB, with an absolute error in 10 sampling points. These results indicated that the proposed method had high selection precision and robustness.

  5. Acoustic Emission Monitoring of Lightning-Damaged CFRP Laminates during Compression-after-Impact Test

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Oh Yang; Shin, Jae Ha [Department of Mechanical Engineering, Inha University, Incheon (Korea, Republic of)

    2012-06-15

    Carbon-fiber reinforced plastic(CFRP) laminates made of nano-particle-coated carbon fibers and damaged by a simulated lightning strike were tested under compression-after-impact(CAI) mode, during which the damage progress due to compressive loading has been monitored by acoustic emission(AE). The impact damage was induced not by mechanical loading but by a simulated lightning strike. Conductive nano-particles were coated directly on the fibers, from which CFRP coupons were made. The coupon were subjected to the strikes with a high voltage/current impulse of 10-40 kA within a few . The effects of nano-particle coating and the degree of damage induced by the simulated lightning strikes on AE activities were examined, and the relationship between the compressive residual strength and AE behavior has been evaluated in terms of AE event counts and the onset of AE activity with the compressive loading. The degree of impact damage was also measured in terms of damage area by using ultrasonic C-scan images. The assessment during the CAI tests of damaged CFRP showed that AE monitoring appeared to be useful to differentiate the degree of damage hence the mechanical integrity of composite structures damaged by lightning strikes.

  6. Sensoring fusion data from the optic and acoustic emissions of electric arcs in the GMAW-S process for welding quality assessment.

    Science.gov (United States)

    Alfaro, Sadek Crisóstomo Absi; Cayo, Eber Huanca

    2012-01-01

    The present study shows the relationship between welding quality and optical-acoustic emissions from electric arcs, during welding runs, in the GMAW-S process. Bead on plate welding tests was carried out with pre-set parameters chosen from manufacturing standards. During the welding runs interferences were induced on the welding path using paint, grease or gas faults. In each welding run arc voltage, welding current, infrared and acoustic emission values were acquired and parameters such as arc power, acoustic peaks rate and infrared radiation rate computed. Data fusion algorithms were developed by assessing known welding quality parameters from arc emissions. These algorithms have showed better responses when they are based on more than just one sensor. Finally, it was concluded that there is a close relation between arc emissions and quality in welding and it can be measured from arc emissions sensing and data fusion algorithms.

  7. Sensoring Fusion Data from the Optic and Acoustic Emissions of Electric Arcs in the GMAW-S Process for Welding Quality Assessment

    Directory of Open Access Journals (Sweden)

    Eber Huanca Cayo

    2012-05-01

    Full Text Available The present study shows the relationship between welding quality and optical-acoustic emissions from electric arcs, during welding runs, in the GMAW-S process. Bead on plate welding tests was carried out with pre-set parameters chosen from manufacturing standards. During the welding runs interferences were induced on the welding path using paint, grease or gas faults. In each welding run arc voltage, welding current, infrared and acoustic emission values were acquired and parameters such as arc power, acoustic peaks rate and infrared radiation rate computed. Data fusion algorithms were developed by assessing known welding quality parameters from arc emissions. These algorithms have showed better responses when they are based on more than just one sensor. Finally, it was concluded that there is a close relation between arc emissions and quality in welding and it can be measured from arc emissions sensing and data fusion algorithms.

  8. An assessment of acoustic emission for nuclear pressure vessel monitoring

    International Nuclear Information System (INIS)

    Scruby, C.B.

    1983-01-01

    Recent research has greatly improved our understanding of the basic mechanisms of deformation and fracture that generate detectable acoustic emission signals in structural steels. A critical review of the application of acoustic emission (AE) to the fabrication, proof testing and in-service monitoring of nuclear pressure vessels is presented in the light of this improved understanding. The detectability of deformation and fracture processes in pressure vessel steels is discussed, and recommendations made for improving source location accuracy and the development of quantitative source assessment techniques. Published data suggest that AE can make an important contribution to fabrication monitoring, and to the detection of defects in lower toughness materials during vessel proof testing. In high toughness materials, however, the signals generated during ductile crack growth may frequently be too weak for reliable detection. The feasibility of AE for continuous monitoring has not yet been adequately demonstrated because of high background noise levels and uncertainty about AE signal strengths from the defect growth processes that occur in service. In-service leak detection by AE shows considerable promise. It is recommended that further tests are carried out with realistic defects, and under realistic conditions of loading (including thermal shock and fatigue) and of environment. (author)

  9. Acoustic emission as a screening tool for ceramic matrix composites

    Science.gov (United States)

    Ojard, Greg; Goberman, Dan; Holowczak, John

    2017-02-01

    Ceramic matrix composites are composite materials with ceramic fibers in a high temperature matrix of ceramic or glass-ceramic. This emerging class of materials is viewed as enabling for efficiency improvements in many energy conversion systems. The key controlling property of ceramic matrix composites is a relatively weak interface between the matrix and the fiber that aids crack deflection and fiber pullout resulting in greatly increased toughness over monolithic ceramics. United Technologies Research Center has been investigating glass-ceramic composite systems as a tool to understand processing effects on material performance related to the performance of the weak interface. Changes in the interface have been shown to affect the mechanical performance observed in flexural testing and subsequent microstructural investigations have confirmed the performance (or lack thereof) of the interface coating. Recently, the addition of acoustic emission testing during flexural testing has aided the understanding of the characteristics of the interface and its performance. The acoustic emission onset stress changes with strength and toughness and this could be a quality tool in screening the material before further development and use. The results of testing and analysis will be shown and additional material from other ceramic matrix composite systems may be included to show trends.

  10. Validation and Simulation of Ares I Scale Model Acoustic Test - 3 - Modeling and Evaluating the Effect of Rainbird Water Deluge Inclusion

    Science.gov (United States)

    Strutzenberg, Louise L.; Putman, Gabriel C.

    2011-01-01

    The Ares I Scale Model Acoustics Test (ASMAT) is a series of live-fire tests of scaled rocket motors meant to simulate the conditions of the Ares I launch configuration. These tests have provided a well documented set of high fidelity measurements useful for validation including data taken over a range of test conditions and containing phenomena like Ignition Over-Pressure and water suppression of acoustics. Building on dry simulations of the ASMAT tests with the vehicle at 5 ft. elevation (100 ft. real vehicle elevation), wet simulations of the ASMAT test setup have been performed using the Loci/CHEM computational fluid dynamics software to explore the effect of rainbird water suppression inclusion on the launch platform deck. Two-phase water simulation has been performed using an energy and mass coupled lagrangian particle system module where liquid phase emissions are segregated into clouds of virtual particles and gas phase mass transfer is accomplished through simple Weber number controlled breakup and boiling models. Comparisons have been performed to the dry 5 ft. elevation cases, using configurations with and without launch mounts. These cases have been used to explore the interaction between rainbird spray patterns and launch mount geometry and evaluate the acoustic sound pressure level knockdown achieved through above-deck rainbird deluge inclusion. This comparison has been anchored with validation from live-fire test data which showed a reduction in rainbird effectiveness with the presence of a launch mount.

  11. Experimental study of advanced continuous acoustic-emission monitoring of BWR components. Final report

    International Nuclear Information System (INIS)

    McElroy, J.W.

    1982-01-01

    This report presents the results of a four year research program on the utilization of acoustic emission techniques on light water reactor component applications. Two techniques of the acoustic emission technology were applied to specific problems occurring within the light water reactor system. Crack detection AE monitoring was applied to thermal cycle fatigue cracking problems and stress corrosion cracking problems. Leak detection AE monitoring was applied to valve leakage in the main steam safety relief valves and incontainment packing gland valves. The report provides AE data showing how AE crack detection can be used as an on-line diagnostic monitoring tool. By having an active monitor on light water reactor components, the inservice inspection of the components is being performed during operation rather than refueling periods, thereby reducing critical path time during outages. The resultant benefit is increased plant availability and a reduction in accumulated radiation exposure

  12. Multipoint dynamically reconfigure adaptive distributed fiber optic acoustic emission sensor (FAESense) system for condition based maintenance

    Science.gov (United States)

    Mendoza, Edgar; Prohaska, John; Kempen, Connie; Esterkin, Yan; Sun, Sunjian; Krishnaswamy, Sridhar

    2010-09-01

    This paper describes preliminary results obtained under a Navy SBIR contract by Redondo Optics Inc. (ROI), in collaboration with Northwestern University towards the development and demonstration of a next generation, stand-alone and fully integrated, dynamically reconfigurable, adaptive fiber optic acoustic emission sensor (FAESense™) system for the in-situ unattended detection and localization of shock events, impact damage, cracks, voids, and delaminations in new and aging critical infrastructures found in ships, submarines, aircraft, and in next generation weapon systems. ROI's FAESense™ system is based on the integration of proven state-of-the-art technologies: 1) distributed array of in-line fiber Bragg gratings (FBGs) sensors sensitive to strain, vibration, and acoustic emissions, 2) adaptive spectral demodulation of FBG sensor dynamic signals using two-wave mixing interferometry on photorefractive semiconductors, and 3) integration of all the sensor system passive and active optoelectronic components within a 0.5-cm x 1-cm photonic integrated circuit microchip. The adaptive TWM demodulation methodology allows the measurement of dynamic high frequnency acoustic emission events, while compensating for passive quasi-static strain and temperature drifts. It features a compact, low power, environmentally robust 1-inch x 1-inch x 4-inch small form factor (SFF) package with no moving parts. The FAESense™ interrogation system is microprocessor-controlled using high data rate signal processing electronics for the FBG sensors calibration, temperature compensation and the detection and analysis of acoustic emission signals. Its miniaturized package, low power operation, state-of-the-art data communications, and low cost makes it a very attractive solution for a large number of applications in naval and maritime industries, aerospace, civil structures, the oil and chemical industry, and for homeland security applications.

  13. Progress toward acoustic emission characterization for continuous monitoring of reactor pressure vessels

    International Nuclear Information System (INIS)

    Hutton, P.H.; Schwenk, E.B.; Kurtz, R.J.

    1980-01-01

    The purpose of this work is to evaluate the feasibility of detecting and analyzing flaw growth in an operating reactor vessel using acoustic emission (AE) data. A preliminary AE-flaw growth relationship has been developed encompassing six variables. This model relates AE count and energy to fatigue crack driving force ΔK. Pattern recognition has been examined as a means of distinguishing crack growth AE from other acoustic signals with encouraging results. The program is moving into hardware implementation of relationships for testing and refinement by monitoring tests in heavy section specimens and subscale structures. The hardware system will become a reactor monitor prototype. (orig.) [de

  14. Monitoring the viscosity of diesel engine lubricating oil by using acoustic emission technique, the selection of measurement parameters

    International Nuclear Information System (INIS)

    Othman Inayatullah; Nordin Jamaludin; Fauziah Mat

    2009-04-01

    Acoustic emission technique has been developed through years of monitoring and diagnosis of bearing, but it is still new in the diagnosis and monitoring of lubrication oil to bearings drive. The propagation of acoustic emission signal is generated when the signal piston on the cylinder liner lubricating oil which is a par. The signal is analyzed in time domain to obtain the parameters of root mean squared, amplitude, energy and courtesy. Lubricant viscosity will undergo changes due to temperature, pressure and useful. This study focuses on the appropriate parameters for the diagnosis and monitoring of lubricating oil viscosity. Studies were conducted at a constant rotational speed and temperature, but use a different age. The results showed that the energy parameter is the best parameter used in this monitoring. However, this parameter cannot be used directly and it should be analyzed using mathematical formulas. This mathematical formula is a relationship between acoustic emission energy with the viscosity of lubricating oil. (author)

  15. Structure Integrity Testing of Mineral Feed by Means of Acoustic Emission

    Directory of Open Access Journals (Sweden)

    Jaroslav Začal

    2016-01-01

    Full Text Available This work deals with specific method of non-destructive testing – Acoustic emission (AE. Theoretical part of article is focused on underlying principle of this method and its applicability. The experimental part is focused on research of pressure resistance in mineral feed using the AE. Mineral feed is condensed cube of rock salt (sodium chloride with supplementary minerals, which is fed to livestock and game to supply the mineral elements necessary for their health and condition. Using the AE sensor is possible to provide monitoring of internal changes in the material. AE gives the overview of internal changes in material structure. With use of specific software we can interpret the acoustic signal and identify the current state of material integrity in real time.

  16. Measurement of effective solvus temperature of hydrogen in Zr - 2. 5 wt % Nb using acoustic emission

    Energy Technology Data Exchange (ETDEWEB)

    Coleman, C.E.; Ambler, J.F.R.

    1978-01-01

    The effect of applied tensile stress on the solvus temperature of hydrogen in cold-worked Zr - 2.5 wt % Nb has been measured using acoustic emission. Hydrides are necessary for delayed hydrogen cracking and the lowest temperature at which hydride cracking cannot be detected by acoustic emission was taken as the solvus temperature. The results show that any effect of tensile stress on terminal solubility, Cs, is undetectable. Between about 2 and 100 ppM hydrogen, the results can be described by: C/sub s/ = 1.40 x 10/sup 5/ exp - (36100/RT) ppM. They also suggest that the equilibrium phase, delta-hydride, is responsible for delayed hydrogen cracking.

  17. Monitoring of martensite formation during welding by means of acoustic emission

    International Nuclear Information System (INIS)

    Bohemen, S.M.C. van; Hermans, M.J.M.; Ouden, G. den

    2001-01-01

    The martensitic transformation during gas tungsten arc (GTA) welding of steel 42CrMo4 has been studied using the acoustic emission (AE) monitoring technique. Welds were produced under static conditions (spot welding) and under stationary conditions (travelling arc welding). After spot welding, the root mean square (RMS) value of the continuous acoustic emission was measured, revealing a peak that reflects the evolution of martensite formation during cooling of the spot weld. The RMS value was also measured during travelling arc welding at different heat inputs and corrected for the noise of the welding process to obtain the RMS value due to martensite formation. After welding, optical metallography was carried out to quantify the amount of martensite formed during cooling of the weld. An analysis of the results shows that the squared RMS value is proportional to the volume rate of martensite formation during welding, which is consistent with theory and in good agreement with the results obtained in the case of spot welding. The obtained results suggest that AE can be applied as a real time monitoring technique for the detection of martensite formation during steel welding. (author)

  18. Acoustic emission during the elastic-plastic deformation of low alloy reactor pressure vessel steels. I

    International Nuclear Information System (INIS)

    Holt, J.; Goddard, D.J.

    1980-01-01

    Measurements of the acoustic emission behaviour of A533B and C-Mn low alloy reactor pressure vessel steels subjected to uniaxial tensile deformation are described. The effects on the emission activity of the rolling plane orientation and the carbide morphology were examined. Detailed discussions are given of the stress dependence of the emission activity below yield and of its recovery by annealing at the stress relief temperature. It is shown that the dominant emission source is the same in both steels and is associated with inclusions, such as MnS, elongated by the rolling process, the carbide morphology being relatively unimportant. A criterion for the occurrence of an emission is obtained which is directly analogous to the general criterion for yielding. It is also shown that a large fraction, at least, of the emission activity arises from a recoverable process such as localized yielding around inclusions or limited inclusion decohesion and not from inclusion fracture. Low activity in C-Mn steel taken from reactor pressure vessels, previously attributed to spheroidization of carbides, is shown to be due to the limited acoustic recovery of these relatively high sulphur content steels when annealed at the stress relief temperature. It is concluded that the limited amplitudes of these emissions during deformation severely restrict their potential application in practice. (Auth.)

  19. Scattering from objects and surfaces in room acoustical simulations

    DEFF Research Database (Denmark)

    Marbjerg, Gerd Høy; Brunskog, Jonas; Jeong, Cheol-Ho

    2016-01-01

    been implemented in the simulation tool PARISM (Phased Acoustical Radiosity and Image Source Method). Scattering from objects and surfaces is likely to be strongly frequency dependent and the frequency dependence can depend on their sizes, shapes and structure. The importance of the frequency...

  20. Research on Relationship Between Parameters Correlation of Acoustic Emission and Rock Failure

    Directory of Open Access Journals (Sweden)

    Duan Dong

    2014-12-01

    Full Text Available Analyzes that granite AE signal parameters under uniaxial loading by that way of Pearson linear correlation, research that correlation of characterization parameters within that separate group with various characteristics, and analyzes that relationship between each parameter and destruction. This study shows that: impact, events and ringing are mainly used to describe the damage degree of rock, amplitude characteristics, time characteristics and frequency characteristics are mainly used for acoustic emission source properties, and energy characteristics can not only be used to describe the damage degree of rock, but also be used to analyze the acoustic emission source. That ringing counts are highly interrelated with energy, intensity, duration, RMS and ASL have high correlation, a high correlation is in the three parameters of the energy characteristics, and there is a higher correlation between the two parameters of the timing characteristics. The correlation between the parameters of frequency is very low, and the acoustic emission parameters can't be replaced for each other in analysis, which need separate analysis. Characteristics of ringing and energy can be a very good description of failure, but failure precursors can't be quantized. However, the amplitude, RMS, ASL, can quantify characterization of that precursor of failure, such as the effective voltage value 0.7 V as the precursor of destruction, the emergence of amplitude exceeding 95 dB as that destructive precursor. The relationship between the timing characteristics and damage is not obvious, so you can't use those parameters analysis that fracture of rocks. But those parameters can be used to describe AE source characteristics. The peak frequency, inverse frequency and the center frequency can't reflect AE source characteristics, and that average frequency and initial frequency can reflect AE source characteristics.

  1. Development of an acoustic emission equipment for valves of the Nuclear Power Station Atucha 1

    International Nuclear Information System (INIS)

    Giaccheta, R.; Lopez Pumarega, I.; Straus, A.; Ruzzante, J.; Herzovich, P.

    1994-01-01

    A four channel Acoustic Emission was developed by the Acoustic Emission Group, INEND Department, of the Atomic Energy Commission of Argentina, for the detection of leaks in valves of the pressurized air system: ''Sistema de desconexion de emergencias por acido deuteroborico''. Basically, the system consists of four piezoelectric transducers with their corresponding preamplifiers coupled to the piping close to the valves. The following stages: amplifiers, threshold levels, channel identifications and visual alarm system are gathered in a box. The system was installed in the controlled zone of the Nuclear Power Stations Atucha I. It was calibrated and works on line. The values shown on the display are registered daily in order to separate the normal values from the leak ones. (author). 4 refs, 9 figs

  2. Monitoring of Carbon Fiber-Reinforced Old Timber Beams via Strain and Multiresonant Acoustic Emission Sensors

    Directory of Open Access Journals (Sweden)

    Francisco J. Rescalvo

    2018-04-01

    Full Text Available This paper proposes the monitoring of old timber beams with natural defects (knots, grain deviations, fissures and wanes, reinforced using carbon composite materials (CFRP. Reinforcement consisted of the combination of a CFRP laminate strip and a carbon fabric discontinuously wrapping the timber element. Monitoring considered the use and comparison of two types of sensors: strain gauges and multi-resonant acoustic emission (AE sensors. Results demonstrate that: (1 the mechanical behavior of the beams can be considerably improved by means of the use of CFRP (160% in bending load capacity and 90% in stiffness; (2 Acoustic emission sensors provide comparable information to strain gauges. This fact points to the great potential of AE techniques for in-service damage assessment in real wood structures.

  3. Band-limited Green's Functions for Quantitative Evaluation of Acoustic Emission Using the Finite Element Method

    Science.gov (United States)

    Leser, William P.; Yuan, Fuh-Gwo; Leser, William P.

    2013-01-01

    A method of numerically estimating dynamic Green's functions using the finite element method is proposed. These Green's functions are accurate in a limited frequency range dependent on the mesh size used to generate them. This range can often match or exceed the frequency sensitivity of the traditional acoustic emission sensors. An algorithm is also developed to characterize an acoustic emission source by obtaining information about its strength and temporal dependence. This information can then be used to reproduce the source in a finite element model for further analysis. Numerical examples are presented that demonstrate the ability of the band-limited Green's functions approach to determine the moment tensor coefficients of several reference signals to within seven percent, as well as accurately reproduce the source-time function.

  4. Monitoring of Carbon Fiber-Reinforced Old Timber Beams via Strain and Multiresonant Acoustic Emission Sensors.

    Science.gov (United States)

    Rescalvo, Francisco J; Valverde-Palacios, Ignacio; Suarez, Elisabet; Roldán, Andrés; Gallego, Antolino

    2018-04-17

    This paper proposes the monitoring of old timber beams with natural defects (knots, grain deviations, fissures and wanes), reinforced using carbon composite materials (CFRP). Reinforcement consisted of the combination of a CFRP laminate strip and a carbon fabric discontinuously wrapping the timber element. Monitoring considered the use and comparison of two types of sensors: strain gauges and multi-resonant acoustic emission (AE) sensors. Results demonstrate that: (1) the mechanical behavior of the beams can be considerably improved by means of the use of CFRP (160% in bending load capacity and 90% in stiffness); (2) Acoustic emission sensors provide comparable information to strain gauges. This fact points to the great potential of AE techniques for in-service damage assessment in real wood structures.

  5. Fatigue crack propagation of super duplex stainless steel and time-frequency analysis of acoustic emission

    International Nuclear Information System (INIS)

    Lee, Sang Kee; Nam, Ki Woo; Kang, Chang Yong; Do, Jae Yoon

    2000-01-01

    On this study, the fatigue crack propagation of super duplex stainless steel is investigated in conditions of various volume fraction of austenite phase by changing heat treatment temperature. And we analysed acoustic emission signals during the fatigue test by time-frequency analysis methods. As the temperature of heat treatment increased, volume fraction of austenite decreased and coarse grain was obtained. The specimen heat treated at 1200 deg. C had longer fatigue life and slower rate of crack growth. As a result of time-frequency analyze of acoustic emission signals during fatigue test, main frequency was 200∼300 kHz having no correlation with heat treatment and crack length, and 500 kHz was obtained by dimple and separate of inclusion

  6. Computer-assisted acoustic emission analysis in alternating current magnetization and hardness testing of reactor pressure vessel steels

    International Nuclear Information System (INIS)

    Blochwitz, M.; Kretzschmar, F.; Rattke, R.

    1985-01-01

    Non-destructive determination of material characteristics such as nilductility transition temperature is of high importance in component monitoring during long-term operation. An attempt has been made to obtain characteristics correlating with mechanico-technological material characteristics by both acoustic resonance through magnetization (ARDM) and acoustic emission analysis in Vickers hardness tests. Taking into account the excitation mechanism of acoustic emission generation, which has a quasistationary stochastic character in a.c. magnetization and a transient nature in hardness testing, a microcomputerized device has been constructed for frequency analysis of the body sound level in ARDM evaluation and for measuring the pulse sum and/or pulse rate during indentation of the test specimen in hardness evaluation. Prerequisite for evaluating the measured values is the knowledge of the frequency dependence of the sensors and the instrument system. The results obtained are presented. (author)

  7. Experimental analysis of crack evolution in concrete by the acoustic emission technique

    Directory of Open Access Journals (Sweden)

    J. Saliba

    2015-10-01

    Full Text Available The fracture process zone (FPZ was investigated on unnotched and notched beams with different notch depths. Three point bending tests were realized on plain concrete under crack mouth opening displacement (CMOD control. Crack growth was monitored by applying the acoustic emission (AE technique. In order to improve our understanding of the FPZ, the width and length of the FPZ were followed based on the AE source locations maps and several AE parameters were studied during the entire loading process. The bvalue analysis, defined as the log-linear slope of the frequency-magnitude distribution of acoustic emissions, was also carried out to describe quantitatively the influence of the relative notch depth on the fracture process. The results show that the number of AE hits increased with the decrease of the relative notch depth and an important AE energy dissipation was observed at the crack initiation in unnotched beams. In addition, the relative notch depth influenced the AE characteristics, the process of crack propagation, and the brittleness of concrete.

  8. Why and how acoustic emission in pressure vessel first hydrotest

    International Nuclear Information System (INIS)

    Panzani, C.; Tonolini, F.; Villa, G.; Regis, V.

    1985-01-01

    The main advantages obtained performing the Acoustic Emission (AE) examination during pressure vessel first hydrotest are presented. The characteristics and performance of the AE instrumentation to be used for a correct test are illustrated. The main criteria for AE source characterization (location, typical AE parameters and their correlation with pressure value), the calibration and test procedures are discussed. The ndt post-test examinations and laboratory specimen experiments are also outlined. Personnel qualification requirements are finally indicated. (Author) [pt

  9. Inspection of nuclear reactor welding by acoustic emission, May 1976--March 1977

    International Nuclear Information System (INIS)

    Prine, D.W.; Mathieson, T.A.

    1977-03-01

    Evaluation of acoustic emission monitoring of welds in heavy section steel under pressure vessel shop conditions is described for a nuclear pressure vessel inlet nozzle weld and a repair weld on a test pressure vessel (V-7) for ORNL. On-line analysis of the AE results indicates that both welds should be free of code rejectable flaws

  10. Evaluation on damage of pipe using ultrasonic and acoustic emission

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jin Kyung; Lee, Sang Pill; Lee, Moon Hee [Dongeui Univ., Busan (Korea, Republic of); Lee, Joon Hyun [Pusan National Univ., Busan (Korea, Republic of)

    2008-07-01

    An elastic waves like ultrasonic and acoustic emission were used to evaluate the propagating properties of the wave in pipe, and study on mode conversion of the elastic wave due to the defects on the pipe was performed. In this study an Acoustic Emission (AE) sensor was used to receive the propagated ultrasonic wave. AE technique has a advantage that it can identify the received ultrasonic wave by the analysis of the AE parameters such as count, energy, frequency, duration time and amplitude. For transmitting and receiving of the wave, an universal angle wedge was manufactured. The optimum angles for transmitting of ultrasonic wave and signal receiving at the attached AE sensor on the pipe were determined. Theoretical dispersion curve was compared with the results of the time-frequency analysis based on the wavelet transformation. The received modes showed a good agreement with theoretical one. The used ultrasonic sensor was 1MHz, and AE sensor was broadband. The artificial cracks were induced in the pipe to measure the propagation characteristics of the elastic wave for the cracks. AE parameters for the received signals were also varied with the crack types in the pipe. AE parameters of amplitude and duration time were more effective factors than the analysis of mode conversion for evaluation of the cracks in the pipe.

  11. Characterization by acoustic emission and electrochemical impedance spectroscopy of the cathodic disbonding of Zn coating

    International Nuclear Information System (INIS)

    Amami, Souhail; Lemaitre, Christian; Laksimi, Abdelouahed; Benmedakhene, Salim

    2010-01-01

    Galvanized steel has been tested in a synthetic sea water solution under different cathodic overprotection conditions. The generated hydrogen flux caused the damage of the metal-zinc interface and led to a progressive coating detachment. Scanning electron microscopy, electrochemical impedance spectroscopy and acoustic emission technique were used to characterize the damage chronology under different cathodic potentials. A damage mechanism was proposed and the acoustic signature related to the coating degradation was statistically identified using clustering techniques.

  12. Characterization by acoustic emission and electrochemical impedance spectroscopy of the cathodic disbonding of Zn coating

    Energy Technology Data Exchange (ETDEWEB)

    Amami, Souhail [Universite de Technologie de Compiegne, Departement de Genie Mecanique, Laboratoire Roberval, UMR 6066 du CNRS, B.P. 20529, 60206 Compiegne Cedex (France)], E-mail: souhail.amami@utc.fr; Lemaitre, Christian; Laksimi, Abdelouahed; Benmedakhene, Salim [Universite de Technologie de Compiegne, Departement de Genie Mecanique, Laboratoire Roberval, UMR 6066 du CNRS, B.P. 20529, 60206 Compiegne Cedex (France)

    2010-05-15

    Galvanized steel has been tested in a synthetic sea water solution under different cathodic overprotection conditions. The generated hydrogen flux caused the damage of the metal-zinc interface and led to a progressive coating detachment. Scanning electron microscopy, electrochemical impedance spectroscopy and acoustic emission technique were used to characterize the damage chronology under different cathodic potentials. A damage mechanism was proposed and the acoustic signature related to the coating degradation was statistically identified using clustering techniques.

  13. Use of acoustic vortices in acoustic levitation

    DEFF Research Database (Denmark)

    Cutanda Henriquez, Vicente; Santillan, Arturo Orozco; Juhl, Peter Møller

    2009-01-01

    Acoustic fields are known to exert forces on the surfaces of objects. These forces are noticeable if the sound pressure is sufficiently high. Two phenomena where acoustic forces are relevant are: i) acoustic levitation, where strong standing waves can hold small objects at certain positions......, counterbalancing their weight, and ii) acoustic vortices, spinning sound fields that can impinge angular momentum and cause rotation of objects. In this contribution, both force-creating sound fields are studied by means of numerical simulations. The Boundary Element Method is employed to this end. The simulation...... of acoustical vortices uses an efficient numerical implementation based on the superposition of two orthogonal sound fields with a delay of 90° between them. It is shown that acoustic levitation and the use of acoustic vortices can be combined to manipulate objects in an efficient and controlled manner without...

  14. Numerical simulations on ion acoustic double layers

    International Nuclear Information System (INIS)

    Sato, T.; Okuda, H.

    1980-07-01

    A comprehensive numerical study of ion acoustic double layers has been performed for both periodic as well as for nonperiodic systems by means of one-dimensional particle simulations. For a nonperiodic system, an external battery and a resistance are used to model the magnetospheric convection potential and the ionospheric Pedersen resistance. It is found that the number of double layers and the associated potential buildup across the system increases with the system length

  15. The use of the acoustic emission for the components of the primary circuit of the nuclear power plants

    International Nuclear Information System (INIS)

    Svoboda, V.

    1992-01-01

    Full text: The Modrany Engineering Works (Modranske strojirny) is a producer and a final supplier of the main connecting piping circuit systems and valves for the nuclear power plants (type VVER 440 and VVER 1000) built in Czechoslovakia. Besides the delivery and assembly of valves and components methods there were developed for a monitoring of the stated equipment ability of a service in the Material and Diagnostic Laboratory, which is a part of the company. An important object of this work is to obtain a sufficient set of data and to work out suitable methods, on the basis of which it would be possible to perform a serious estimation of residual service life of the main piping components after certain service operation of the nuclear power plant. During the operation of a nuclear power station a failure of the main piping circuit could happen in either of two possible modes: 1.) A sudden break - by an unstable defect propagation leading to a. final fracture of the piping; 2) A fatigue failure - which is characterised by a gradual subcritical growth of defect in relation to the loading parameters. This process is frequently accelerated by further processes, e.g. corrosion. It is therefore suitable to use such physical and mechanical quantities, which characterize the material damage. Acoustic emission signals belongs to these quantities. A knowledge of the response of these signals in relation to the damage of the material gives us the possibility to evaluate the residual life of the piping containing defects. The importance of this is increasing mainly after a long period of service. She paper deals in details with experience gained in application of acoustic emission, during pressure tests of primary circuit components (elbow, welds, T- junction etc) in laboratory conditions which imitate those in service. There are shown some results of cyclic fatigue tests by internal pressure on prototypes models and specimen. Acoustic emission method represents the

  16. Artificial Boundary Conditions for the Numerical Simulation of Unsteady Acoustic Waves

    National Research Council Canada - National Science Library

    Tsynkov, S. V

    2003-01-01

    We construct non-local artificial boundary conditions (ABCs) for the numerical simulation of genuinely time-dependent acoustic waves that propagate from a compact source in an unbounded unobstructed space...

  17. Simulation of Shuttle launch G forces and acoustic loads using the NASA Ames Research Center 20G centrifuge

    Science.gov (United States)

    Shaw, T. L.; Corliss, J. M.; Gundo, D. P.; Mulenburg, G. M.; Breit, G. A.; Griffith, J. B.

    1994-01-01

    The high cost and long times required to develop research packages for space flight can often be offset by using ground test techniques. This paper describes a space shuttle launch and reentry simulating using the NASA Ames Research Center's 20G centrifuge facility. The combined G-forces and acoustic environment during shuttle launch and landing were simulated to evaluate the effect on a payload of laboratory rates. The launch G force and acoustic profiles are matched to actual shuttle launch data to produce the required G-forces and acoustic spectrum in the centrifuge test cab where the rats were caged on a free-swinging platform. For reentry, only G force is simulated as the aero-acoustic noise is insignificant compared to that during launch. The shuttle G-force profiles of launch and landing are achieved by programming the centrifuge drive computer to continuously adjust centrifuge rotational speed to obtain the correct launch and landing G forces. The shuttle launch acoustic environment is simulated using a high-power, low-frequency audio system. Accelerometer data from STS-56 and microphone data from STS-1 through STS-5 are used as baselines for the simulations. This paper provides a description of the test setup and the results of the simulation with recommendations for follow-on simulations.

  18. Bearing Fault Detection Based on Empirical Wavelet Transform and Correlated Kurtosis by Acoustic Emission.

    Science.gov (United States)

    Gao, Zheyu; Lin, Jing; Wang, Xiufeng; Xu, Xiaoqiang

    2017-05-24

    Rolling bearings are widely used in rotating equipment. Detection of bearing faults is of great importance to guarantee safe operation of mechanical systems. Acoustic emission (AE), as one of the bearing monitoring technologies, is sensitive to weak signals and performs well in detecting incipient faults. Therefore, AE is widely used in monitoring the operating status of rolling bearing. This paper utilizes Empirical Wavelet Transform (EWT) to decompose AE signals into mono-components adaptively followed by calculation of the correlated kurtosis (CK) at certain time intervals of these components. By comparing these CK values, the resonant frequency of the rolling bearing can be determined. Then the fault characteristic frequencies are found by spectrum envelope. Both simulation signal and rolling bearing AE signals are used to verify the effectiveness of the proposed method. The results show that the new method performs well in identifying bearing fault frequency under strong background noise.

  19. Dynamic behaviour of magneto-acoustic emission in a grain-oriented steel

    Czech Academy of Sciences Publication Activity Database

    Stupakov, Alexandr; Perevertov, Oleksiy; Landa, Michal

    2017-01-01

    Roč. 426, Mar (2017), s. 685-690 ISSN 0304-8853 R&D Projects: GA ČR GB14-36566G; GA ČR GA13-18993S Institutional support: RVO:68378271 ; RVO:61388998 Keywords : magneto-acoustic emission * magnetization dynamics * Barkhausen noise * surface field measurement * magnetization waveform control Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 2.630, year: 2016

  20. Auralization fundamentals of acoustics, modelling, simulation, algorithms and acoustic virtual reality

    CERN Document Server

    Vorlander, Michael

    2007-01-01

    "Auralization" is the technique of creation and reproduction of sound on the basis of computer data. With this tool is it possible to predict the character of sound signals which are generated at the source and modified by reinforcement, propagation and transmission in systems such as rooms, buildings, vehicles or other technical devices. This book is organized as a comprehensive collection of the basics of sound and vibration, acoustic modelling, simulation, signal processing and audio reproduction. Implementations of the auralization technique are described using examples drawn from various fields in acoustic’s research and engineering, architecture, sound design and virtual reality.

  1. Extruded Bread Classification on the Basis of Acoustic Emission Signal With Application of Artificial Neural Networks

    Science.gov (United States)

    Świetlicka, Izabela; Muszyński, Siemowit; Marzec, Agata

    2015-04-01

    The presented work covers the problem of developing a method of extruded bread classification with the application of artificial neural networks. Extruded flat graham, corn, and rye breads differening in water activity were used. The breads were subjected to the compression test with simultaneous registration of acoustic signal. The amplitude-time records were analyzed both in time and frequency domains. Acoustic emission signal parameters: single energy, counts, amplitude, and duration acoustic emission were determined for the breads in four water activities: initial (0.362 for rye, 0.377 for corn, and 0.371 for graham bread), 0.432, 0.529, and 0.648. For classification and the clustering process, radial basis function, and self-organizing maps (Kohonen network) were used. Artificial neural networks were examined with respect to their ability to classify or to cluster samples according to the bread type, water activity value, and both of them. The best examination results were achieved by the radial basis function network in classification according to water activity (88%), while the self-organizing maps network yielded 81% during bread type clustering.

  2. A new mode of acoustic NDT via resonant air-coupled emission

    Science.gov (United States)

    Solodov, Igor; Dillenz, Alexander; Kreutzbruck, Marc

    2017-06-01

    Resonant modes of non-destructive testing (NDT) which make use of local damage resonance (LDR) have been developed recently and demonstrated a significant increase in efficiency and sensitivity of hybrid inspection techniques by laser vibrometry, ultrasonic thermography, and shearography. In this paper, a new fully acoustic version of resonant NDT is demonstrated for defects in composite materials relevant to automotive and aviation applications. This technique is based on an efficient activation of defect vibrations by using a sonic/ultrasonic wave matched to a fundamental LDR frequency of the defect. On this condition, all points of the faulty area get involved in synchronous out-of-plane vibrations which produce a similar in-phase wave motion in ambient air. This effect of resonant air-coupled emission results in airborne waves emanating from the defect area, which can be received by a commercial microphone (low LDR frequency) or an air-coupled ultrasonic transducer (high frequency LDR). A series of experiments confirm the feasibility of both contact and non-contact versions of the technique for NDT and imaging of simulated and realistic defects (impacts, delaminations, and disbonds) in composites.

  3. Tasks tolerating application of analogue methods for determining acoustic emission source co-ordinates

    International Nuclear Information System (INIS)

    Artyukhov, V.I.; Vakar, K.B.; Makarov, V.I.; Ovchinnikov, N.I.; Perevezentsev, V.N.; Rzhevkin, V.R.; Shemyakin, V.V.; Yakovlev, G.V.

    1980-01-01

    Described are cases of coordinate detection of the acoustic emission (AE) sources during AE-testing of power reactors using analog systems. Five testing variants of design linear elements are considered and fields of their practical application to welded joint testing are pointed out. Described is the method of coordinate detection based on ''multibeam'' effect

  4. Acoustic emission: technical review for PWR applications

    International Nuclear Information System (INIS)

    Bentley, P.G.

    1981-07-01

    Acoustic emission has been studied since the early 1960's, particularly with a view to periodic or continuous monitoring of steel pressure vessels. In the years 1970-75 it was realised that ductile steels, used in nuclear vessels, give small amplitude signals which are barely detectable by available instruments. The technique for application in periodic or continuous monitoring and also as applied to leak detection and weld fabrication monitoring is reviewed. It is concluded that manufacturing defects may be detectable during pre-service hydrotest, but that there is insufficient evidence on which to base an estimate of detection probability. In-service hydrotest or continuous monitoring is unlikely to detect growing cracks because of the quiet nature of the material and the noisy reactor background. Both leak detection and fabrication weld monitoring show some promise of successful application in the future. (author)

  5. Evaluation of Acoustic Emission NDE of Kevlar Composite Over Wrapped Pressure Vessels

    Science.gov (United States)

    Horne, Michael R.; Madaras, Eric I.

    2008-01-01

    Pressurization and failure tests of small Kevlar/epoxy COPV bottles were conducted during 2006 and 2007 by Texas Research Institute Austin, Inc., at TRI facilities. This is a report of the analysis of the Acoustic Emission (AE) data collected during those tests. Results of some of the tests indicate a possibility that AE can be used to track the stress-rupture degradation of COPV vessels.

  6. The application of acoustic emission measurements on laboratory testpieces to large scale pressure vessel monitoring

    International Nuclear Information System (INIS)

    Ingham, T.; Dawson, D.G.

    1975-01-01

    A test pressure vessel containing 4 artificial defects was monitored for emission whilst pressure cycling to failure. Testpieces cut from both the failed vessel and from as-rolled plate material were tested in the laboratory. A marked difference in emission characteristics was observed between plate and vessel testpieces. Activity from vessel material was virtually constant after general yield and emission amplitudes were low. Plate testpieces showed maximum activity at general yield and more frequent high amplitude emissions. An attempt has been made to compare the system sensitivities between the pressure vessel test and laboratory tests. In the absence of an absolute calibration device, system sensitivities were estimated using dummy signals generated by the excitation of an emission sensor. The measurements have shown an overall difference in sensitivity between vessel and laboratory tests of approximately 25db. The reduced sensitivity in the vessel test is attributed to a combination of differences in sensors, acoustic couplant, attenuation, and dispersion relative to laboratory tests and the relative significance of these factors is discussed. Signal amplitude analysis of the emissions monitored from laboratory testpieces showed that, whith losses of the order of 25 to 30db, few emissions would be detected from the pressure vessel test. It is concluded that no reliable prediction of acoustic behaviour of a structure may be made from laboratory test unless testpieces of the actual structural material are used. A considerable improvement in detection sensitivity, is also required for reliable detection of defects in low strength ductile materials and an absolute method of system calibration is required between tests

  7. Simulation of acoustic streaming by means of the finite-difference time-domain method

    DEFF Research Database (Denmark)

    Santillan, Arturo Orozco

    2012-01-01

    Numerical simulations of acoustic streaming generated by a standing wave in a narrow twodimensional cavity are presented. In this case, acoustic streaming arises from the viscous boundary layers set up at the surfaces of the walls. It is known that streaming vortices inside the boundary layer have...... directions of rotation that are opposite to those of the outer streaming vortices (Rayleigh streaming). The general objective of the work described in this paper has been to study the extent to which it is possible to simulate both the outer streaming vortices and the inner boundary layer vortices using...... the finite-difference time-domain method. To simplify the problem, thermal effects are not considered. The motivation of the described investigation has been the possibility of using the numerical method to study acoustic streaming, particularly under non-steady conditions. Results are discussed for channels...

  8. Experimental investigation of acoustic emissions and their moment tensors in rock during failure

    Czech Academy of Sciences Publication Activity Database

    Aker, E.; Kühn, D.; Vavryčuk, Václav; Soldal, M.; Oye, V.

    2014-01-01

    Roč. 70, September (2014), s. 286-295 ISSN 1365-1609 R&D Projects: GA ČR(CZ) GAP210/12/1491 EU Projects: European Commission(XE) 230669 - AIM Institutional support: RVO:67985530 Keywords : acoustic emissions * focal mechanisms * moment tensors * rock fracturing * hoop stresses * laboratory experiment Subject RIV: DC - Siesmology, Volcanology, Earth Structure Impact factor: 1.686, year: 2014

  9. Probability of acoustic transmitter detections by receiver lines in Lake Huron: results of multi-year field tests and simulations

    Science.gov (United States)

    Hayden, Todd A.; Holbrook, Christopher M.; Binder, Thomas; Dettmers, John M.; Cooke, Steven J.; Vandergoot, Christopher S.; Krueger, Charles C.

    2016-01-01

    BackgroundAdvances in acoustic telemetry technology have led to an improved understanding of the spatial ecology of many freshwater and marine fish species. Understanding the performance of acoustic receivers is necessary to distinguish between tagged fish that may have been present but not detected and from those fish that were absent from the area. In this study, two stationary acoustic transmitters were deployed 250 m apart within each of four acoustic receiver lines each containing at least 10 receivers (i.e., eight acoustic transmitters) located in Saginaw Bay and central Lake Huron for nearly 2 years to determine whether the probability of detecting an acoustic transmission varied as a function of time (i.e., season), location, and distance between acoustic transmitter and receiver. Distances between acoustic transmitters and receivers ranged from 200 m to >10 km in each line. The daily observed probability of detecting an acoustic transmission was used in simulation models to estimate the probability of detecting a moving acoustic transmitter on a line of receivers.ResultsThe probability of detecting an acoustic transmitter on a receiver 1000 m away differed by month for different receiver lines in Lake Huron and Saginaw Bay but was similar for paired acoustic transmitters deployed 250 m apart within the same line. Mean probability of detecting an acoustic transmitter at 1000 m calculated over the study period varied among acoustic transmitters 250 m apart within a line and differed among receiver lines in Lake Huron and Saginaw Bay. The simulated probability of detecting a moving acoustic transmitter on a receiver line was characterized by short periods of time with decreased detection. Although increased receiver spacing and higher fish movement rates decreased simulated detection probability, the location of the simulated receiver line in Lake Huron had the strongest effect on simulated detection probability.ConclusionsPerformance of receiver

  10. Application of acoustic emission measurements in the evaluation of prestressed cast in-between decks

    NARCIS (Netherlands)

    Van Hemert, P.H.A.; Fennis-Huijben, S.A.A.M.; Hordijk, D.A.

    2014-01-01

    A large number of concrete structures, that is built in the sixties and seventies of the twentieth century, need to be re-evaluated. It should be judged whether their capacity is still sufficient for the increased traffic loads. Acoustic emission (AE) is a non-destructive technique that can possibly

  11. Evaluation of the successive approximations method for acoustic streaming numerical simulations.

    Science.gov (United States)

    Catarino, S O; Minas, G; Miranda, J M

    2016-05-01

    This work evaluates the successive approximations method commonly used to predict acoustic streaming by comparing it with a direct method. The successive approximations method solves both the acoustic wave propagation and acoustic streaming by solving the first and second order Navier-Stokes equations, ignoring the first order convective effects. This method was applied to acoustic streaming in a 2D domain and the results were compared with results from the direct simulation of the Navier-Stokes equations. The velocity results showed qualitative agreement between both methods, which indicates that the successive approximations method can describe the formation of flows with recirculation. However, a large quantitative deviation was observed between the two methods. Further analysis showed that the successive approximation method solution is sensitive to the initial flow field. The direct method showed that the instantaneous flow field changes significantly due to reflections and wave interference. It was also found that convective effects contribute significantly to the wave propagation pattern. These effects must be taken into account when solving the acoustic streaming problems, since it affects the global flow. By adequately calculating the initial condition for first order step, the acoustic streaming prediction by the successive approximations method can be improved significantly.

  12. Qualitative internal surface roughness classification using acoustic emission

    International Nuclear Information System (INIS)

    Mohd Hafizi Zohari; Mohd Hanif Saad

    2009-04-01

    This paper describes a novel new nondestructive method of qualitative internal surface roughness classification for pipes utilizing Acoustic Emission (AE) signal. Two different flowrate are introduced in a pipe obstructed using normally available components (e.g.: valve). The AE signal at suitable location from the obstruction are obtained and the peak amplitudes, RMS amplitude and energy of the AE signal are obtained. A dimensionless number, the Bangi Number, AB, is then calculated as a ratio of the AE parameters (peak amplitude, RMS amplitude or energy) in low flowrate measurement compared to the AE parameters in high flowrate measurement. It was observed that the Bangi Number, AB obtained can then be used to successfully discriminate between rough and smooth internal surface roughness. (author)

  13. Acoustic monitoring techniques for corrosion degradation in cemented waste canisters

    International Nuclear Information System (INIS)

    Naish, C.C.; Buttle, D.; Wallace-Sims, R.; O'Brien, T.M.

    1991-01-01

    This report describes work carried out to investigate acoustic emission as a monitor of corrosion and degradation of wasteforms where the waste is potentially reactive metal. Electronic monitoring equipment has been designed, built and tested to allow long-term monitoring of a number of waste packages simultaneously. Acoustic monitoring experiments were made on a range of 1 litre cemented Magnox and aluminium samples cast into canisters comparing the acoustic events with hydrogen gas evolution rates and electrochemical corrosion rates. The attenuation of the acoustic signals by the cement grout under a range of conditions has been studied to determine the volume of wasteform that can be satisfactorily monitored by one transducer. The final phase of the programme monitored the acoustic events from full size (200 litre) cemented, inactive, simulated aluminium swarf wastepackages prepared at the AEA waste cementation plant at Winfrith. (Author)

  14. Fundamental and assessment of concrete structure monitoring by using acoustic emission technique testing: A review

    Science.gov (United States)

    Desa, M. S. M.; Ibrahim, M. H. W.; Shahidan, S.; Ghadzali, N. S.; Misri, Z.

    2018-04-01

    Acoustic emission (AE) technique is one of the non-destructive (NDT) testing, where it can be used to determine the damage of concrete structures such as crack, corrosion, stability, sensitivity, as structure monitoring and energy formed within cracking opening growth in the concrete structure. This article gives a comprehensive review of the acoustic emission (AE) technique testing due to its application in concrete structure for structural health monitoring (SHM). Assessment of AE technique used for structural are reviewed to give the perception of its structural engineering such as dam, bridge and building, where the previous research has been reviewed based on AE application. The assessment of AE technique focusing on basic fundamental of parametric and signal waveform analysis during analysis process and its capability in structural monitoring. Moreover, the assessment and application of AE due to its function have been summarized and highlighted for future references

  15. Size Effect on Acoustic Emission Characteristics of Coal-Rock Damage Evolution

    OpenAIRE

    Wen, Zhijie; Wang, Xiao; Chen, Lianjun; Lin, Guan; Zhang, Hualei

    2017-01-01

    Coal-gas outburst, rock burst, and other mine dynamic disasters are closely related to the instability and failure of coal-rock. Coal-rock is the assemblies of mineral particles of varying sizes and shapes bonded together by cementing materials. The damage and rupture process of coal-rock is accompanied by acoustic emission (AE), which can be used as an effective means to monitor and predict the instability of coal-rock body. In this manuscript, considering the size effect of coal-rock, the i...

  16. Study on Leak Detection of the Pipeline System by Acoustic Emission

    International Nuclear Information System (INIS)

    Yoon, D. J.; Kim, C. J.

    1987-01-01

    Leak detection testing for the pipeline system was performed by the acoustic emission method. It was found that the detected signal spectrum was influenced by the frequency response of sensors and pressure changes. AE parameters and frequency spectrum distributions were used to analyze the leak signals. The slope rise time of AE parameters were the important factors for distinguishing leak signals. The amplitude of leak signal was more affected by the changes of leak, rate and pressure than those of leak type

  17. Three-dimensional point-cloud room model in room acoustics simulations

    DEFF Research Database (Denmark)

    Markovic, Milos; Olesen, Søren Krarup; Hammershøi, Dorte

    2013-01-01

    acquisition and its representation with a 3D point-cloud model, as well as utilization of such a model for the room acoustics simulations. A room is scanned with a commercially available input device (Kinect for Xbox360) in two different ways; the first one involves the device placed in the middle of the room...... and rotated around the vertical axis while for the second one the device is moved within the room. Benefits of both approaches were analyzed. The device's depth sensor provides a set of points in a three-dimensional coordinate system which represents scanned surfaces of the room interior. These data are used...... to build a 3D point-cloud model of the room. Several models are created to meet requirements of different room acoustics simulation algorithms: plane fitting and uniform voxel grid for geometric methods and triangulation mesh for the numerical methods. Advantages of the proposed method over the traditional...

  18. Three-dimensional point-cloud room model for room acoustics simulations

    DEFF Research Database (Denmark)

    Markovic, Milos; Olesen, Søren Krarup; Hammershøi, Dorte

    2013-01-01

    acquisition and its representation with a 3D point-cloud model, as well as utilization of such a model for the room acoustics simulations. A room is scanned with a commercially available input device (Kinect for Xbox360) in two different ways; the first one involves the device placed in the middle of the room...... and rotated around the vertical axis while for the second one the device is moved within the room. Benefits of both approaches were analyzed. The device's depth sensor provides a set of points in a three-dimensional coordinate system which represents scanned surfaces of the room interior. These data are used...... to build a 3D point-cloud model of the room. Several models are created to meet requirements of different room acoustics simulation algorithms: plane fitting and uniform voxel grid for geometric methods and triangulation mesh for the numerical methods. Advantages of the proposed method over the traditional...

  19. Acoustic signal emission monitoring as a novel method to predict steam pops during radiofrequency ablation: preliminary observations.

    Science.gov (United States)

    Chik, William W B; Kosobrodov, Roman; Bhaskaran, Abhishek; Barry, Michael Anthony Tony; Nguyen, Doan Trang; Pouliopoulos, Jim; Byth, Karen; Sivagangabalan, Gopal; Thomas, Stuart P; Ross, David L; McEwan, Alistair; Kovoor, Pramesh; Thiagalingam, Aravinda

    2015-04-01

    Steam pop is an explosive rupture of cardiac tissue caused by tissue overheating above 100 °C, resulting in steam formation, predisposing to serious complications associated with radiofrequency (RF) ablations. However, there are currently no reliable techniques to predict the occurrence of steam pops. We propose the utility of acoustic signals emitted during RF ablation as a novel method to predict steam pop formation and potentially prevent serious complications. Radiofrequency generator parameters (power, impedance, and temperature) were temporally recorded during ablations performed in an in vitro bovine myocardial model. The acoustic system consisted of HTI-96-min hydrophone, microphone preamplifier, and sound card connected to a laptop computer. The hydrophone has the frequency range of 2 Hz to 30 kHz and nominal sensitivity in the range -240 to -165 dB. The sound was sampled at 96 kHz with 24-bit resolution. Output signal from the hydrophone was fed into the camera audio input to synchronize the video stream. An automated system was developed for the detection and analysis of acoustic events. Nine steam pops were observed. Three distinct sounds were identified as warning signals, each indicating rapid steam formation and its release from tissue. These sounds had a broad frequency range up to 6 kHz with several spectral peaks around 2-3 kHz. Subjectively, these warning signals were perceived as separate loud clicks, a quick succession of clicks, or continuous squeaking noise. Characteristic acoustic signals were identified preceding 80% of pops occurrence. Six cardiologists were able to identify 65% of acoustic signals accurately preceding the pop. An automated system identified the characteristic warning signals in 85% of cases. The mean time from the first acoustic signal to pop occurrence was 46 ± 20 seconds. The automated system had 72.7% sensitivity and 88.9% specificity for predicting pops. Easily identifiable characteristic acoustic emissions

  20. Sensitivity of simulated transcranial ultrasound fields to acoustic medium property maps

    Science.gov (United States)

    Robertson, James; Martin, Eleanor; Cox, Ben; Treeby, Bradley E.

    2017-04-01

    High intensity transcranial focused ultrasound is an FDA approved treatment for essential tremor, while low-intensity applications such as neurostimulation and opening the blood brain barrier are under active research. Simulations of transcranial ultrasound propagation are used both for focusing through the skull, and predicting intracranial fields. Maps of the skull acoustic properties are necessary for accurate simulations, and can be derived from medical images using a variety of methods. The skull maps range from segmented, homogeneous models, to fully heterogeneous models derived from medical image intensity. In the present work, the impact of uncertainties in the skull properties is examined using a model of transcranial propagation from a single element focused transducer. The impact of changes in bone layer geometry and the sound speed, density, and acoustic absorption values is quantified through a numerical sensitivity analysis. Sound speed is shown to be the most influential acoustic property, and must be defined with less than 4% error to obtain acceptable accuracy in simulated focus pressure, position, and volume. Changes in the skull thickness of as little as 0.1 mm can cause an error in peak intracranial pressure of greater than 5%, while smoothing with a 1 \\text{m}{{\\text{m}}3} kernel to imitate the effect of obtaining skull maps from low resolution images causes an increase of over 50% in peak pressure. The numerical results are confirmed experimentally through comparison with sonications made through 3D printed and resin cast skull bone phantoms.

  1. Translational illusion of acoustic sources by transformation acoustics.

    Science.gov (United States)

    Sun, Fei; Li, Shichao; He, Sailing

    2017-09-01

    An acoustic illusion of creating a translated acoustic source is designed by utilizing transformation acoustics. An acoustic source shifter (ASS) composed of layered acoustic metamaterials is designed to achieve such an illusion. A practical example where the ASS is made with naturally available materials is also given. Numerical simulations verify the performance of the proposed device. The designed ASS may have some applications in, e.g., anti-sonar detection.

  2. Feasibility of evaluating the integrity of FTR duct to end fixture welds using acoustic emission monitoring

    International Nuclear Information System (INIS)

    Trantow, R.L.

    1975-11-01

    A method of applying real-time acoustic emission (AE) source location to evaluate the integrity of duct-to-end fixture welds was developed and evaluated using the HEDL R8-4 AE monitor coupled with a PDP-8e minicomputer. Operational software was developed to control the system's data acquisition, storage, and display functions. Performance was evaluated on the basis of comparisons between AE source location data and subsequent destructive examination of six duct-to-transition ring qualification welds. Ten separate discontinuities seen in the metallography performed at 35 locations along these welds correlated with the averaged acoustic emission activity revealed by the AE source location maps. This relationship is not presently considered to be usable as a system calibration method however, because of the limited range of discontinuity lengths (from 0.0003 to 0.004 in. long) that were correlated. The presence of six other discontinuities, found in regions showing low levels of emission activity, indicated that significant stress risers can go undetected under the conditions investigated

  3. Simulation of an Underwater Acoustic Communication Channel Characterized by Wind-Generated Surface Waves and Bubbles

    NARCIS (Netherlands)

    Dol, H.S.; Colin, M.E.G.D.; Ainslie, M.A.; Walree, P.A. van; Janmaat, J.

    2012-01-01

    Sea surface scattering by wind-generated waves and bubbles is regarded to be the main non-platform related cause of the time variability of shallow acoustic communication channels. Simulations for predicting the quality of acoustic communication links in such channels thus require adequate modeling

  4. Online monitoring of Accessories for Underground Electrical Installations through Acoustics Emissions

    Directory of Open Access Journals (Sweden)

    Casals-Torrens P.

    2012-04-01

    Full Text Available The acoustic waves caused by Partial Discharges inside the dielectric materials, can be detected by acoustic emission (AE sensors and analyzed in the time domain. The experimental results presented, show the online detection capability of these sensors in the environment near a cable accessory, such as a splice or terminal. The AE sensors are immune to electromagnetic interference and constitute a detection method non-intrusive and non-destructive, which ensures a galvanic decoupling with respect to electric networks, this technique of partial discharge detection can be applied as a test method for preventive or predictive maintenance (condition-based maintenance to equipments or facilities of medium and high voltage in service and represents an alternative method to electrical detection systems, conventional or not, that continue to rely on the detection of current pulses. This paper presents characterization tests of the sensors AE through comparative tests of partial discharge on accessories for underground power cables.

  5. TU-G-210-03: Acoustic Simulations in Transcranial MRgFUS: Treatment Prediction and Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Vyas, U. [Stanford University (United States)

    2015-06-15

    Modeling can play a vital role in predicting, optimizing and analyzing the results of therapeutic ultrasound treatments. Simulating the propagating acoustic beam in various targeted regions of the body allows for the prediction of the resulting power deposition and temperature profiles. In this session we will apply various modeling approaches to breast, abdominal organ and brain treatments. Of particular interest is the effectiveness of procedures for correcting for phase aberrations caused by intervening irregular tissues, such as the skull in transcranial applications or inhomogeneous breast tissues. Also described are methods to compensate for motion in targeted abdominal organs such as the liver or kidney. Douglas Christensen – Modeling for Breast and Brain HIFU Treatment Planning Tobias Preusser – TRANS-FUSIMO - An Integrative Approach to Model-Based Treatment Planning of Liver FUS Urvi Vyas – Acoustic Simulations in Transcranial MRgFUS: Treatment Prediction and Analysis Learning Objectives: Understand the role of acoustic beam modeling for predicting the effectiveness of therapeutic ultrasound treatments. Apply acoustic modeling to specific breast, liver, kidney and transcranial anatomies. Determine how to obtain appropriate acoustic modeling parameters from clinical images. Understand the separate role of absorption and scattering in energy delivery to tissues. See how organ motion can be compensated for in ultrasound therapies. Compare simulated data with clinical temperature measurements in transcranial applications. Supported by NIH R01 HL172787 and R01 EB013433 (DC); EU Seventh Framework Programme (FP7/2007-2013) under 270186 (FUSIMO) and 611889 (TRANS-FUSIMO)(TP); and P01 CA159992, GE, FUSF and InSightec (UV)

  6. Mechanical Properties and Acoustic Emission Properties of Rocks with Different Transverse Scales

    OpenAIRE

    Yan, Xi; Jun, Li; Gonghui, Liu; Xueli, Guo

    2017-01-01

    Since the stability of engineering rock masses has important practical significance to projects like mining, tunneling, and petroleum engineering, it is necessary to study mechanical properties and stability prediction methods for rocks, cementing materials that are composed of minerals in all shapes and sizes. Rocks will generate acoustic emission during damage failure processes, which is deemed as an effective means of monitoring the stability of coal rocks. In the meantime, actual mining a...

  7. STUDIES OF ACOUSTIC EMISSION SIGNATURES FOR QUALITY ASSURANCE OF SS 316L WELDED SAMPLES UNDER DYNAMIC LOAD CONDITIONS

    Directory of Open Access Journals (Sweden)

    S. V. RANGANAYAKULU

    2016-10-01

    Full Text Available Acoustic Emission (AE signatures of various weld defects of stainless steel 316L nuclear grade weld material are investigated. The samples are fabricated by Tungsten Inert Gas (TIG Welding Method have final dimension of 140 mm x 15 mm x 10 mm. AE signals from weld defects such as Pinhole, Porosity, Lack of Penetration, Lack of Side Fusion and Slag are recorded under dynamic load conditions by specially designed mechanical jig. AE features of the weld defects were attained using Linear Location Technique (LLT. The results from this study concluded that, stress release and structure deformation between the sections in welding area are load conditions major part of Acoustic Emission activity during loading.

  8. Background noise of acoustic emission signals in sodium piping loop

    International Nuclear Information System (INIS)

    Mori, Y.; Aoki, K.; Kuribayashi, K.; Kishi, T.; Sakakibara, Y.

    1985-01-01

    Background noise measurement in the frequency range of acoustic emission (AE) signals was made on the sodium piping loops of a 50 MW steam generator test facility in the Power Reactor and Nuclear Fuel Development Corporation (PNC). During the dynamic characteristics test of the steam generator over a wide range of operating conditions, the background noise generated on the pipe surface was measured using wideband AE sensor externally mounted with waveguide. Data were obtained for the effect of power loads of steam generator on both amplitude and frequency spectra of background noise signals. Source and nature of background noise were established

  9. Electrical Resistance and Acoustic Emission Measurements for Monitoring the Structural Behavior of CFRP Laminate

    KAUST Repository

    Zhou, Wei

    2015-07-12

    Electrical resistance and acoustic emission (AE) measurement are jointly used to monitor the degradation in CFRP laminates subjected to tensile tests. The objective of this thesis is to perform a synergertic analysis between a passive and an active methods to better access how these perform when used for Structural Health Moni- toring (SHM). Laminates with three different stacking sequences: [0]4, [02/902]s and [+45/ − 45]2s are subjected to monotonic and cyclic tensile tests. In each laminate, we carefully investigate which mechanisms of degradation can or cannot be detect- ed by each technique. It is shown that most often, that acoustic emission signals start before any electrical detection is possible. This is is explained based on the redundance of the electrical network that makes it less sensitive to localized damages. Based on in depth study of AE signals clustering, a new classification is proposed to recognize the different damage mechanims based on only two parameters: the RA (rise time/amplitude) and the duration of the signal.

  10. Application of biorthogonal eigenfunction system for extraction of Tollmien-Schlichting waves in acoustic receptivity simulations

    OpenAIRE

    Shahriari, Nima; Hanifi, Ardeshir; Henningson, Dan S.

    2016-01-01

    Acoustic receptivity of a two-dimensional boundary layer on a flat plate with elliptic leading edge is studied through direct numerical simulation (DNS). Sound waves are modelled by a uniform oscillation of freestream boundaries in time which results to an infinite-wavelength acoustic wave. Acoustic disturbances interact with strong streamwise gradients at the leading edge or surface non- homogeneities and create Tollmien-Schlichting (TS) waves inside the boundary layer. Measuring amplitude o...

  11. Multivariate data-driven modelling and pattern recognition for damage detection and identification for acoustic emission and acousto-ultrasonics

    International Nuclear Information System (INIS)

    Torres-Arredondo, M-A; Fritzen, C-P; Tibaduiza, D-A; Mujica, L E; Rodellar, J; McGugan, M; Toftegaard, H; Borum, K-K

    2013-01-01

    Different methods are commonly used for non-destructive testing in structures; among others, acoustic emission and ultrasonic inspections are widely used to assess structures. The research presented in this paper is motivated by the need to improve the inspection capabilities and reliability of structural health monitoring (SHM) systems based on ultrasonic guided waves with focus on the acoustic emission and acousto-ultrasonics techniques. The use of a guided wave based approach is driven by the fact that these waves are able to propagate over relatively long distances, and interact sensitively and uniquely with different types of defect. Special attention is paid here to the development of efficient SHM methodologies. This requires robust signal processing techniques for the correct interpretation of the complex ultrasonic waves. Therefore, a variety of existing algorithms for signal processing and pattern recognition are evaluated and integrated into the different proposed methodologies. As a contribution to solve the problem, this paper presents results in damage detection and classification using a methodology based on hierarchical nonlinear principal component analysis, square prediction measurements and self-organizing maps, which are applied to data from acoustic emission tests and acousto-ultrasonic inspections. At the end, the efficiency of these methodologies is experimentally evaluated in diverse anisotropic composite structures. (paper)

  12. Use of Modal Acoustic Emission to Monitor Damage Progression in Carbon Fiber/Epoxy and Implications for Composite Structures

    Science.gov (United States)

    Waller, J. M.; Nichols, C. T.; Wentzel, D. J.; Saulsberry R. L.

    2010-01-01

    Broad-band modal acoustic emission (AE) data was used to characterize micromechanical damage progression in uniaxial IM7 and T1000 carbon fiber-epoxy tows and an IM7 composite overwrapped pressure vessel (COPV) subjected to an intermittent load hold tensile stress profile known to activate the Felicity ratio (FR). Damage progression was followed by inspecting the Fast Fourier Transforms (FFTs) associated with acoustic emission events. FFT analysis revealed the occurrence of cooperative micromechanical damage events in a frequency range between 100 kHz and 1 MHz. Evidence was found for the existence of a universal damage parameter, referred to here as the critical Felicity ratio, or Felicity ratio at rupture (FR*), which had a value close to 0.96 for the tows and the COPV tested. The implications of using FR* to predict failure in carbon/epoxy composite materials and related composite components such as COPVs are discussed. Trends in the FFT data are also discussed; namely, the difference between the low and high energy events, the difference between early and late-life events, comparison of IM7 and T1000 damage progression, and lastly, the similarity of events occurring at the onset of significant acoustic emission used to calculate the FR.

  13. Analytical modelling of acoustic emission from buried or surface-breaking cracks under stress

    International Nuclear Information System (INIS)

    Ben Khalifa, W; Jezzine, K; Hello, G; Grondel, S

    2012-01-01

    Acoustic emission (AE) is a non-destructive testing method used in various industries (aerospace, petrochemical and pressure-vessel industries in general, power generation, civil engineering, mechanical engineering, etc...) for the examination of large structures subjected to various stresses (e.g. mechanical loading).The energy released by a defect under stress (the AE phenomenon) can propagate as guided waves in thin structures or as surface Rayleigh waves in thick ones. Sensors (possibly permanently) are positioned at various locations on the structure under examination and are assumed to be sensitive to these waves. Then, post-processing tools typically based on signal processing and triangulation algorithms can be used to inverse these data, allowing one to estimate the position of the defect from which emanates the waves measured. The French Atomic Energy Commission is engaged in the development of tools for simulating AE examinations. These tools are based on specific models for the AE sources, for the propagation of guided or Rayleigh waves and for the behaviour of AE sensors. Here, the coupling of a fracture mechanics based model for AE source and surface/guided wave propagation models is achieved through an integral formulation relying on the elastodynamic reciprocity principle. As a first approximation, a simple piston-like model is used to predict the sensitivity of AE sensors. Predictions computed by our simulation tool are compared to results from the literature for validation purpose.

  14. The design and simulation of new downhole vibration device about acoustic oil recovery technology

    Directory of Open Access Journals (Sweden)

    Yongjun Hou

    2015-09-01

    Full Text Available More and more oilfields are using acoustic technology to enhance oil recovery. In order to know the mechanism of acoustic oil recovery technology, the sound radiator of a new downhole vibration device is modeled and analyzed. Based on the theoretical background, this paper firstly analyzes the acoustic mechanism for the oil reservoir and then makes a acoustic response analysis on the sound radiator model for frequency and time-domain investigation by using professional acoustic simulation software–LMS Virtual.lab Acoustics, finally calculates the acoustic transmission loss in the downhole oil reservoir. The research reveals that firstly, acoustic waves have influences on the oil & water fluidity in the oil reservoir, the oil pressure gradient and the interfacial tension of capillary; secondly, the acoustic radiation power and sound pressure of field point attain a peak on the natural frequency of the sound radiator; thirdly, with the acoustic impact, the sound pressure of oil reservoir would fluctuate so as to improve the oil recovery ratio; the last but not the least one is both the sound pressure of oil reservoir point and the transmission loss of rock have a positive correlation with the vibration frequency. Therefore, it is of great importance for the research of vibration frequency and structure optimization of sound radiator.

  15. Relationship of acoustic emission to the kinetics and micromechanism of fatigue failure of high-strength steel with a martensitic structure

    International Nuclear Information System (INIS)

    Romaniv, O.N.; Kirillov, K.I.; Zima, Yu.V.; Nikiforchin, G.N.

    1987-01-01

    Techniques and results are presented for the rules of change in acoustic emission in fatigue crack propagation in hardened and low-temperature tempered 40Kh steel intended, in this study, for use as a reactor material. The results of the acoustic measurements are compared with data of quantitative aimed microfractography conducted during mechanical fracture tests

  16. Quantitative Acoustic Emission Fatigue Crack Characterization in Structural Steel and Weld

    Directory of Open Access Journals (Sweden)

    Adutwum Marfo

    2013-01-01

    Full Text Available The fatigue crack growth characteristics of structural steel and weld connections are analyzed using quantitative acoustic emission (AE technique. This was experimentally investigated by three-point bending testing of specimens under low cycle constant amplitude loading using the wavelet packet analysis. The crack growth sequence, that is, initiation, crack propagation, and fracture, is extracted from their corresponding frequency feature bands, respectively. The results obtained proved to be superior to qualitative AE analysis and the traditional linear elastic fracture mechanics for fatigue crack characterization in structural steel and welds.

  17. Acoustic Noise Prediction of the Amine Swingbed ISS ExPRESS Rack Payload

    Science.gov (United States)

    Welsh, David; Smith, Holly; Wang, Shuo

    2010-01-01

    Acoustics plays a vital role in maintaining the health, safety, and comfort of crew members aboard the International Space Station (ISS). In order to maintain this livable and workable environment, acoustic requirements have been established to ensure that ISS hardware and payload developers account for the acoustic emissions of their equipment and develop acoustic mitigations as necessary. These requirements are verified by an acoustic emissions test of the integrated hardware. The Amine Swingbed ExPRESS (Expedite the PRocessing of ExperimentS to Space) rack payload creates a unique challenge to the developers in that the payload hardware is transported to the ISS in phases, making an acoustic emissions test on the integrated flight hardware impossible. In addition, the payload incorporates a high back pressure fan and a diaphragm vacuum pump, which are recognized as significant and complex noise sources. In order to accurately predict the acoustic emissions of the integrated payload, the individual acoustic noise sources and paths are first characterized. These characterizations are conducted though a series of acoustic emissions tests on the individual payload components. Secondly, the individual acoustic noise sources and paths are incorporated into a virtual model of the integrated hardware. The virtual model is constructed with the use of hybrid method utilizing the Finite Element Acoustic (FEA) and Statistical Energy Analysis (SEA) techniques, which predict the overall acoustic emissions. Finally, the acoustic model is validated though an acoustic characterization test performed on an acoustically similar mock-up of the flight unit. The results of the validated acoustic model are then used to assess the acoustic emissions of the flight unit and define further acoustic mitigation efforts.

  18. Standard practice for determining damage-Based design Stress for fiberglass reinforced plastic (FRP) materials using acoustic emission

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2006-01-01

    1.1 This practice details procedures for establishing the direct stress and shear stress damage-based design values for use in the damage-based design criterion for materials to be used in FRP vessels and other composite structures. The practice uses data derived from acoustic emission examination of four-point beam bending tests and in-plane shear tests (see ASME Section X, Article RT-8). 1.2 The onset of lamina damage is indicated by the presence of significant acoustic emission during the reload portion of load/reload cycles. "Significant emission" is defined with historic index. 1.3 Units - The values stated in inch-pound units are to be regarded as standard. The values given in brackets are mathematical conversions to SI units which are provided for information only and are not considered standard. 1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health pr...

  19. Diagnostics of glass fiber reinforced polymers and comparative analysis of their fabrication techniques with the use of acoustic emission

    Science.gov (United States)

    Bashkov, O. V.; Bryansky, A. A.; Panin, S. V.; Zaikov, V. I.

    2016-11-01

    Strength properties of the glass fiber reinforced polymers (GFRP) fabricated by vacuum and vacuum autoclave molding techniques were analyzed. Measurements of porosity of the GFRP parts manufactured by various molding techniques were conducted with the help of optical microscopy. On the basis of experimental data obtained by means of acoustic emission hardware/software setup, the technique for running diagnostics and forecasting the bearing capacity of polymeric composite materials based on the result of three-point bending tests has been developed. The operation principle of the technique is underlined by the evaluation of the power function index change which takes place on the dependence of the total acoustic emission counts versus the loading stress.

  20. Automated valve fault detection based on acoustic emission parameters and support vector machine

    Directory of Open Access Journals (Sweden)

    Salah M. Ali

    2018-03-01

    Full Text Available Reciprocating compressors are one of the most used types of compressors with wide applications in industry. The most common failure in reciprocating compressors is always related to the valves. Therefore, a reliable condition monitoring method is required to avoid the unplanned shutdown in this category of machines. Acoustic emission (AE technique is one of the effective recent methods in the field of valve condition monitoring. However, a major challenge is related to the analysis of AE signal which perhaps only depends on the experience and knowledge of technicians. This paper proposes automated fault detection method using support vector machine (SVM and AE parameters in an attempt to reduce human intervention in the process. Experiments were conducted on a single stage reciprocating air compressor by combining healthy and faulty valve conditions to acquire the AE signals. Valve functioning was identified through AE waveform analysis. SVM faults detection model was subsequently devised and validated based on training and testing samples respectively. The results demonstrated automatic valve fault detection model with accuracy exceeding 98%. It is believed that valve faults can be detected efficiently without human intervention by employing the proposed model for a single stage reciprocating compressor. Keywords: Condition monitoring, Faults detection, Signal analysis, Acoustic emission, Support vector machine

  1. On the design of a (H)EV steerable warning device using acoustic beam forming and advanced numerical acoustic simulation

    NARCIS (Netherlands)

    Van Genechten, B.; Vansant, K.; Berkhoff, Arthur P.

    2014-01-01

    This paper describes the simulation-based design methodology used in the eVADER project for the development of targeted acoustic warning devices for increased detectability of Hybrid and Electric Vehicles (HEVs) while, at the same time, reducing urban noise pollution. A key component of this system

  2. In situ Probe Microphone Measurement for Testing the Direct Acoustical Cochlear Stimulator

    Directory of Open Access Journals (Sweden)

    Christof Stieger

    2017-08-01

    Full Text Available Hypothesis: Acoustical measurements can be used for functional control of a direct acoustic cochlear stimulator (DACS.Background: The DACS is a recently released active hearing implant that works on the principle of a conventional piston prosthesis driven by the rod of an electromagnetic actuator. An inherent part of the DACS actuator is a thin titanium diaphragm that allows for movement of the stimulation rod while hermetically sealing the housing. In addition to mechanical stimulation, the actuator emits sound into the mastoid cavity because of the motion of the diaphragm.Methods: We investigated the use of the sound emission of a DACS for intra-operative testing. We measured sound emission in the external auditory canal (PEAC and velocity of the actuators stimulation rod (Vact in five implanted ears of whole-head specimens. We tested the influence various positions of the loudspeaker and a probe microphone on PEAC and simulated implant malfunction in one example.Results: Sound emission of the DACS with a signal-to-noise ratio >10 dB was observed between 0.5 and 5 kHz. Simulated implant misplacement or malfunction could be detected by the absence or shift in the characteristic resonance frequency of the actuator. PEAC changed by <6 dB for variations of the microphone and loudspeaker position.Conclusion: Our data support the feasibility of acoustical measurements for in situ testing of the DACS implant in the mastoid cavity as well as for post-operative monitoring of actuator function.

  3. Monitoring and Failure Analysis of Corroded Bridge Cables under Fatigue Loading Using Acoustic Emission Sensors

    Directory of Open Access Journals (Sweden)

    Hui Li

    2012-03-01

    Full Text Available Cables play an important role in cable-stayed systems, but are vulnerable to corrosion and fatigue damage. There is a dearth of studies on the fatigue damage evolution of corroded cable. In the present study, the acoustic emission (AE technology is adopted to monitor the fatigue damage evolution process. First, the relationship between stress and strain is determined through a tensile test for corroded and non-corroded steel wires. Results show that the mechanical performance of corroded cables is changed considerably. The AE characteristic parameters for fatigue damage are then established. AE energy cumulative parameters can accurately describe the fatigue damage evolution of corroded cables. The failure modes in each phase as well as the type of acoustic emission source are determined based on the results of scanning electron microscopy. The waveform characteristics, damage types, and frequency distribution of the corroded cable at different damage phases are collected. Finally, the number of broken wires and breakage time of the cables are determined according to the variation in the margin index.

  4. Monitoring and Failure Analysis of Corroded Bridge Cables under Fatigue Loading Using Acoustic Emission Sensors

    Science.gov (United States)

    Li, Dongsheng; Ou, Jinping; Lan, Chengming; Li, Hui

    2012-01-01

    Cables play an important role in cable-stayed systems, but are vulnerable to corrosion and fatigue damage. There is a dearth of studies on the fatigue damage evolution of corroded cable. In the present study, the acoustic emission (AE) technology is adopted to monitor the fatigue damage evolution process. First, the relationship between stress and strain is determined through a tensile test for corroded and non-corroded steel wires. Results show that the mechanical performance of corroded cables is changed considerably. The AE characteristic parameters for fatigue damage are then established. AE energy cumulative parameters can accurately describe the fatigue damage evolution of corroded cables. The failure modes in each phase as well as the type of acoustic emission source are determined based on the results of scanning electron microscopy. The waveform characteristics, damage types, and frequency distribution of the corroded cable at different damage phases are collected. Finally, the number of broken wires and breakage time of the cables are determined according to the variation in the margin index. PMID:22666009

  5. Development of Advanced Electrochemical Emission Spectroscopy for Monitoring Corrosion in Simulated DOE Liquid Waste

    Energy Technology Data Exchange (ETDEWEB)

    Digby Macdonald; Brian Marx; Balaji Soundararajan; Morgan Smith

    2005-07-28

    The different tasks that have been carried out under the current program are as follows: (1) Theoretical and experimental assessment of general corrosion of iron/steel in borate buffer solutions by using electrochemical impedance spectroscopy (EIS), ellipsometry and XPS techniques; (2) Development of a damage function analysis (DFA), which would help in predicting the accumulation of damage due to pitting corrosion in an environment prototypical of DOE liquid waste systems; (3) Experimental measurement of crack growth rate, acoustic emission signals, and coupling currents for fracture in carbon and low alloy steels as functions of mechanical (stress intensity), chemical (conductivity), electrochemical (corrosion potential, ECP), and microstructural (grain size, precipitate size, etc) variables in a systematic manner, with particular attention being focused on the structure of the noise in the current and its correlation with the acoustic emissions; (4) Development of fracture mechanisms for carbon and low alloy steels that are consistent with the crack growth rate, coupling current data and acoustic emissions; (5) Inserting advanced crack growth rate models for SCC into existing deterministic codes for predicting the evolution of corrosion damage in DOE liquid waste storage tanks; (6) Computer simulation of the anodic and cathodic activity on the surface of the steel samples in order to exactly predict the corrosion mechanisms; (7) Wavelet analysis of EC noise data from steel samples undergoing corrosion in an environment similar to that of the high level waste storage containers, to extract data pertaining to general, pitting and stress corrosion processes, from the overall data. The work has yielded a number of important findings, including an unequivocal demonstration of the role of chloride ion in passivity breakdown on nickel in terms of cation vacancy generation within the passive film, the first detection and characterization of individual micro fracture

  6. Fatigue crack propagation of super duplex stainless steel with dispersed structure and time-frequency analysis of acoustic emission

    Science.gov (United States)

    Nam, Ki-Woo; Kang, Chang-Yong; Do, Jae-Yoon; Ahn, Seok-Hwan; Lee, Sang-Kee

    2001-06-01

    The fatigue crack propagation of super duplex stainless steel was investigated for the effect of various volume fractions of the austenite phase by changing the heat treatment temperature. We also analyzed acoustic emission signals obtained during the fatigue crack propagation by the time-frequency analysis method. As the temperature of the heat treatment increased, the volume fraction of austenite decreased and coarse grain was obtained. The specimen treated at 1200 had a longer fatigue life and slower rate of crack growth. Results of time-frequency analysis of acoustic emission signals during the fatigue test showed the main frequency of 200-300 kHz to have no correlation with heat treatment and crack length, and the 500 kHz signal to be due to dimples and separation of inclusion.

  7. Validation of simulations of an underwater acoustic communication channel characterized by wind-generated surface waves and bubbles

    NARCIS (Netherlands)

    Dol, H.S.; Colin, M.E.G.D.; Ainlie, M.A.; Gerdes, F.; Schäfke, A.; Özkan Sertlekc, H.

    2013-01-01

    This paper shows that it is possible to simulate realistic shallow-water acoustic communication channels using available acoustic propagation models. Key factor is the incorporation of realistic time-dependent sea surface conditions, including both waves and bubbles due to wind.

  8. Mechanical seal monitoring technique by acoustic emission measurements

    Energy Technology Data Exchange (ETDEWEB)

    Kataoka, Tadashi; Fujita, Yoshihiro; Kawaguchi, Kazunori; Saito, Kazuhiro; Yokota, Setsuo; Hisada, Yasuhide; Masahiro, Komatsu

    1987-09-20

    This report describes a technique for mechanical seal monitoring through acoustic emission (AE) measurement. The equipment consists of an AE sensor, preamplifier, multiplexer, main amplifier, effective value transducer and computer system. When the sealed liquid pressure undergoes a large change, the seal surface configuration is monitored and evaluated accurately through AE measurement. If the mechanical seal surface id damaged or worn, the AE level is kept high or continues to fluctuate largely for a rather long period. When leak occurs, the AE value shows great fluctuations either at extremely low levels or at high levels. The former trend is considered to result from a decrease in solid contact due to an excessive amount of liquid film being formed at the seal surface during leak. In the latter case, the leak is attributed to severe damage to the seal surface. (18 figs, 1 tab, 5 photos, 3 refs)

  9. Relaxor-like behavior of BaTiO.sub.3./sub. crystals from acoustic emission study

    Czech Academy of Sciences Publication Activity Database

    Dul´kin, E.; Petzelt, Jan; Kamba, Stanislav; Mojaev, E.; Roth, M.

    2010-01-01

    Roč. 97, č. 3 (2010), 032903/1-032903/3 ISSN 0003-6951 R&D Projects: GA ČR GAP204/10/0616; GA ČR(CZ) GA202/09/0682 Institutional research plan: CEZ:AV0Z10100520 Keywords : relaxor ferroelectrics * acoustic emission * phase transitions Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.820, year: 2010

  10. Continuous and recurrent testing of acoustic emission sensors; Kontinuierliche und wiederkehrende Pruefung von Schallemissionssensoren

    Energy Technology Data Exchange (ETDEWEB)

    Sause, Markus G.R.; Schmitt, Stefan; Potstada, Philipp [Augsburg Univ. (Germany). Inst. fuer Materials Resource Management, Mechanical Engineering

    2017-08-01

    In many fields of application of acoustic emission, the testing can lead to a lasting change in the sensor characteristics. This can be caused by mechanical damage, thermal stress or use under aggressive environmental conditions. Irrespective of visually testable damages of the sensors, a shift in the spectral sensitivity, a reduction in the absolute sensitivity or a reduction in the signal-to-noise ratio can occur. During the test, this requires a possibility to periodically check the sensors, including the coupling aids used. For recurring testing, recommendations are given in Directive SE 02 ''Verification of acoustic emission sensors and their coupling in the laboratory''. This paper discusses possibilities for continuous monitoring of the sensors during the test and presents an application example for the partly automated recurring testing of acoustic emission sensors using Directive SE 02. For this purpose, a test stand for the supply of the sensors to be tested was constructed and the signal recording and data reduction implemented in freely available software programs. The operating principle is demonstrated using selected case studies. [German] In vielen Anwendungsbereichen der Schallemission kann es bei der Pruefung zu einer nachhaltigen Veraenderung der Sensorcharakteristik kommen. Dies kann durch mechanische Beschaedigung, thermische Belastung oder Verwendung unter aggressiven Umweltbedingungen geschehen. Unabhaengig von visuell pruefbaren Beschaedigungen der Sensoren kann es dabei zu einer Verschiebung der spektralen Empfindlichkeit, einer Verringerung der absoluten Empfindlichkeit oder einer Erniedrigung des Signal-Rausch Verhaeltnis kommen. Bei der Pruefung erfordert dies eine Moeglichkeit zur periodischen Ueberpruefung der Sensoren inklusive der verwendeten Koppelhilfsmittel. Fuer die wiederkehrende Pruefung finden sich entsprechende Handlungsempfehlungen in der Richtlinie SE 02 ''Verifizierung von

  11. Fatigue characteristics of high strength fire resistance steel for frame structure and time-frequency analysis its acoustic emission signal

    International Nuclear Information System (INIS)

    Kim, Hyun Soo; Nam, Ki Woo; Kang, Chang Young

    2000-01-01

    Demand for now nondestructive evaluation are growing to detect fatigue crack growth behavior to predict long term performance of materials and structure in aggressive environments, especially when they are in non-visible area. Acoustic emission technique is well suited to these problems and has drawn a keen interests because of its dynamic detection ability, extreme sensitivity and location of growing defects. In this study, we analysed acoustic emission signals obtained in fatigue and tensile test of high strength fire resistance steel for frame structure with time-frequency analysis methods. The main frequency range is different in the noise and the fatigue crack propagation. It could be classified that it were also generated by composite fracture mechanics of cleavage, dimple, inclusion separation etc

  12. Anomalous acoustic effect during martensitic transformations in titanium nickelide base alloys

    International Nuclear Information System (INIS)

    Plotnikov, V.A.; Kokhanenko, D.V.

    2002-01-01

    One carried out experiments to determine effect of external static stress on martensitic transformations and acoustic emission, Martensitic transformations in titanium nickelide base alloys under mechanical stress were determined to change nature of acoustic emission to anomalous one - cycling of transformations under gradual increase of mechanical stress during direct martensitic transformation was followed by increase of acoustic emission energy instead of reduction. The mentioned nature of acoustic emission is indicative of essential effect of external stress on martensitic transformations and energy dissipation during transformations [ru

  13. Acoustic Emission Based In-process Monitoring in Robot Assisted Polishing

    DEFF Research Database (Denmark)

    Pilny, Lukas; Bissacco, Giuliano; De Chiffre, Leonardo

    The applicability of acoustic emission (AE) measurements for in-process monitoring in the Robot Assisted Polishing (RAP) process was investigated. Surface roughness measurements require interruption of the process, proper surface cleaning and measurements that sometimes necessitate removal...... improving the efficiency of the process. It also allows for intelligent process control and generally enhances the robustness and reliability of the automated RAP system in industrial applications....... of the part from the machine tool. In this study, development of surface roughness during polishing rotational symmetric surfaces by the RAP process was inferred from AE measurements. An AE sensor was placed on a polishing tool, and a cylindrical rod of Vanadis 4E steel having an initial turned surface...

  14. The simulation calculation of acoustics energy transfer through the material structure

    Directory of Open Access Journals (Sweden)

    Zvolenský Peter

    2016-01-01

    Full Text Available The paper deals with the modification of the rail passenger coach floor design aimed at improvement of sound reduction index. Refurbishing was performed by using a new acoustic material with a filamentary microstructure. The materials proposed in research were compared by simulation calculation of acoustic energy transfer trough porous microstructure of filamentary material, and the effect of material porosity on sound reduction index and sound absorption coefficient were observed. This proposed filamentary material can be used in the railway bed structure, too. High degree of noise absorbing, resistance to climate conditions, low specific mass, enable to choose a system of low anti-noise barriers having similar properties as standard high anti-noise walls..

  15. Calibration of a microscopic simulation model for emission calculation

    NARCIS (Netherlands)

    Jie, L.; Zuylen, H. van; Chen, Y.; Viti, F.; Wilmink, I.

    2013-01-01

    Emissions by road traffic can be reduced by optimising traffic control. The impact of this optimisation on emission can be analysed ex ante by simulation. The simulation programs used for this analysis should be valid with respect to the traffic characteristics that determine the emissions. Thus

  16. Optimum Position of Acoustic Emission Sensors for Ship Hull Structural Health Monitoring Based on Deep Machine Learning

    DEFF Research Database (Denmark)

    Kappatos, Vassilios; Karvelis, Petros; Georgoulas, George

    2018-01-01

    In this paper a method for the estimation of the optimum sensor positions for acoustic emission localization on ship hull structures is presented. The optimum sensor positions are treated as a classification (localization) problem based on a deep learning paradigm. In order to avoid complex...

  17. Application of acoustic emission testing to quality control: examples and forecasting

    International Nuclear Information System (INIS)

    Dumousseau, P.

    1979-01-01

    A several years experience to evaluate and promote acoustic emission in the field of mechanical industries has permitted to recognize the domains of industrial interest. The first is detection of defective parts according to emissivity. Examples concerning forged, cast or welded fabrications are presented. It is concluded that signal processing is decisive but that its sophistication must be graded according to the case considered. The second is control of welding process. Examples concerning submerged arc, TIG and electron-beam welds are analyzed. It appears that automatic control is chiefly possible for welding under vacuum or inert gaz conditions. The third is monitoring of pressure vessels during hydrotest or in-service. Problems concerning materials behaviour, wave propagation, location accuracy are reviewed. To conclude prospects of future development are evaluated. Via signal processing the most important progresses are needed in characterization of defect severity and life time prediction. Importance of improving transducer calibration and codifying methods is also outlined [fr

  18. Shear dilatancy and acoustic emission in dry and saturated granular materials

    Science.gov (United States)

    Brodsky, E. E.; Siman-Tov, S.

    2017-12-01

    Shearing of granular materials plays a strong role in naturally sheared systems as landslides and faults. Many works on granular flows have concentrated on dry materials, but relatively little work has been done on water saturated sands. Here we experimentally investigate dry versus saturated quartz-rich sand to understand the effect of the fluid medium on the rheology and acoustic waves emission of the sheared sand. The sand was sheared in a rotary shear rheometer under applied constant normal stress boundary at low (100 µm/s) to high (1 m/s) velocities. Mechanical, acoustic data and deformation were continuously recorded and imaged. For dry and water saturated experiments the granular volume remains constant for low shear velocities ( 10-3 m/s) and increases during shearing at higher velocities ( 1 m/s). Continuous imaging of the sheared sand show that the steady state shear band thickness is thicker during the high velocity steps. No significant change observed in the shear band thickness between dry and water saturated experiments. In contrast, the amount of dilation during water saturated experiments is about half the value measured for dry material. The measured decrease cannot be explained by shear band thickness change as such is not exist. However, the reduced dilation is supported by our acoustic measurements. In general, the event rate and acoustic event amplitudes increase with shear velocity. While isolated events are clearly detected during low velocities at higher the events overlap, resulting in a noisy signal. Although detection is better for saturated experiments, during the high velocity steps the acoustic energy measured from the signal is lower compared to that recorded for dry experiments. We suggest that the presence of fluid suppresses grain motion and particles impacts leading to mild increase in the internal pressure and therefore for the reduced dilation. In addition, the viscosity of fluids may influence the internal pressure via

  19. A monitoring of superconducting magnets by acoustic emission

    International Nuclear Information System (INIS)

    Nomura, Harehiko; Tateishi, Hiroshi; Onishi, Toshitada

    1990-01-01

    Since superconducting magnets (SCM) are going to be indispensable to magnetic levitated train, nuclear fusion, magnetic resonating imaging, rotational machines, etc., they must be placed great reliance on its repetitional operations. But without appropriate evaluating methods, these promising techniques must remain still in science levels and hard to be transferable to real human technologies. SCM, being used under dynamical operation with linking other electro-magnetic systems as said above, induce high voltage from which monitoring superconducting to normal transitional voltage is difficult to distinguish. To solve this problem, monitoring SCM by Acoustic Emission (AE) from themselves, have been found effective, in particular, during the dynamical energizing of them. As for a demonstration, this paper will report mainly how to monitor 3 MJ-SCM and a few results of the experiments aquired both by counting and locational mode of AE in pulsed and repeated operations of the magnet. Some discussions on the AE monitorings are also made along the main issues to be solved in future. (author)

  20. Acoustic emission for interlaminar toughness testing of CFRP: Evaluation of the crack growth due to burst analysis

    Czech Academy of Sciences Publication Activity Database

    Lissek, F.; Haegerb, A.; Knoblauch, V.; Hloch, Sergej; Pude, F.; Kaufeld, M.

    2018-01-01

    Roč. 136, č. 1 (2018), s. 55-62 ISSN 1359-8368 Institutional support: RVO:68145535 Keywords : DCB * interlaminar toughness testing * acoustic emission * CFRP * burst analysis Subject RIV: JQ - Machines ; Tools Impact factor: 4.727, year: 2016 http://www.sciencedirect.com/science/article/pii/S1359836817313720

  1. Acoustic emission for interlaminar toughness testing of CFRP: Evaluation of the crack growth due to burst analysis

    Czech Academy of Sciences Publication Activity Database

    Lissek, F.; Haegerb, A.; Knoblauch, V.; Hloch, Sergej; Pude, F.; Kaufeld, M.

    2018-01-01

    Roč. 136, č. 1 (2018), s. 55-62 ISSN 1359-8368 Institutional support: RVO:68145535 Keywords : DCB * interlaminar toughness testing * acoustic emission * CFRP * burst analysis Subject RIV: JQ - Machines ; Tools Impact factor: 4.727, year: 2016 http://www. science direct.com/ science /article/pii/S1359836817313720

  2. Nondestructive Online Detection of Welding Defects in Track Crane Boom Using Acoustic Emission Technique

    Directory of Open Access Journals (Sweden)

    Yong Tao

    2014-04-01

    Full Text Available Nondestructive detection of structural component of track crane is a difficult and costly problem. In the present study, acoustic emission (AE was used to detect two kinds of typical welding defects, that is, welding porosity and incomplete penetration, in the truck crane boom. Firstly, a subsidiary test specimen with special preset welding defect was designed and added on the boom surface with the aid of steel plates to get the synchronous deformation of the main boom. Then, the AE feature information of the welding defect could be got without influencing normal operation of equipment. As a result, the rudimentary location analysis can be attained using the linear location method and the two kinds of welding defects can be distinguished clearly using AE characteristic parameters such as amplitude and centroid frequency. Also, through the comparison of two loading processes, we concluded that the signal produced during the first loading process was mainly caused by plastic deformation damage and during the second loading process the stress release and structure friction between sections in welding area are the main acoustic emission sources. Thus, the AE is an available tool for nondestructive online detection of latent welding defects of structural component of track crane.

  3. Determination of bearing steel heat treatment with the use of the acoustic emission method

    Directory of Open Access Journals (Sweden)

    T. Z. Wozniak

    2010-10-01

    Full Text Available A study on the control of an extremely important stage of the martensitic-bainitic austempering and obtaining the M-B structure in the 100CrMnSi6-4 steel with the use of the acoustic emission (AE has been undertaken. In order to enrich retained austenite with carbon, steels are austempered at appropriately low temperatures. A martensitic transformation, resulting from diffusionless and displacive transformation is associated with significant AE signs. The strain energy produced during growth due to the shape change is reduced by plastic deformation. Predominant source of (AE is the movement of dislocations in order to relieve internal stresses.The heat treatment was performed in a modern, purpose-constructed device which simultaneously records acoustic emission effects. The signals were recorded with the use of an AE analyzer 20–800 kHz, and they were received by means of a broadband piezoelectric transducer with the use of a specialist card with a sampling frequency of 1200 kHz. The results regarding a correlation of austempering temperature and the maximum number of AE events and dilatometric results have been presented. This parameter can be used for precise Ms temperature estimation. Basing on microstructural investigations, it has been found that previously formed martensite with midrib morphology also accelerates the bainitic transformation.

  4. Determination of bearing steel heat treatment with the use of the acoustic emission method

    Directory of Open Access Journals (Sweden)

    T.Z. Woźniak

    2010-07-01

    Full Text Available A study on the control of an extremely important stage of the martensitic-bainitic austempering and obtaining the M-B structure in the 100CrMnSi6-4 steel with the use of the acoustic emission (AE has been undertaken. In order to enrich retained austenite with carbon,steels are austempered at appropriately low temperatures. A martensitic transformation, resulting from diffusionless and displacive transformation is associated with significant AE signs. The strain energy produced during growth due to the shape change is reduced by plastic deformation. Predominant source of (AE is the movement of dislocations in order to relieve internal stresses.The heat treatment was performed in a modern, purpose-constructed device which simultaneously records acoustic emission effects. The signals were recorded with the use of an AE analyzer 20–800 kHz, and they were received by means of a broadband piezoelectric transducer with the use of a specialist card with a sampling frequency of 1200 kHz. The results regarding a correlation of austempering temperature and the maximum number of AE events and dilatometric results have been presented. This parameter can be used for precise Ms temperatureestimation. Basing on microstructural investigations, it has been found that previously formed martensite with midrib morphology alsoaccelerates the bainitic transformation.

  5. Correlation analysis between ceramic insulator pollution and acoustic emissions

    Directory of Open Access Journals (Sweden)

    Benjamín Álvarez-Nasrallah

    2015-01-01

    Full Text Available Most of the studies related to insulator pollution are normally performed based on individual analysis among leakage current, relative humidity and equivalent salt deposit density (ESDD. This paper presents a correlation analysis between the leakage current and the acoustic emissions measured in a 230 kV electrical substations in the city of Barranquilla, Colombia. Furthermore, atmospheric variables were considered to develop a characterization model of the insulator contamination process. This model was used to demonstrate that noise emission levels are a reliable indicator to detect and characterize pollution on high voltage insulators. The correlation found amount the atmospheric, electrical and sound variables allowed to determine the relations for the maintenance of ceramic insulators in high-polluted areas. In this article, the results on the behavior of the leakage current in ceramic insulators and the sound produced with different atmospheric conditions are shown, which allow evaluating the best time to clean the insulator at the substation. Furthermore, by experimentation on site and using statistical models, the correlation between ambient variables and the leakage current of insulators in an electrical substation was obtained. Some of the problems that bring the external noise were overcome using multiple microphones and specialized software that enabled properly filter the sound and better measure the variables.

  6. Laser method of acoustical emission control from vibrating surfaces

    Science.gov (United States)

    Motyka, Zbigniew

    2013-01-01

    For limitation of the noise in environment, the necessity occurs of determining and location of sources of sounds emitted from surfaces of many machines and devices, assuring in effect the possibility of suitable constructional changes implementation, targeted at decreasing of their nuisance. In the paper, the results of tests and calculations are presented for plane surface sources emitting acoustic waves. The tests were realized with the use of scanning laser vibrometer which enabled remote registration and the spectral analysis of the surfaces vibrations. The known hybrid digital method developed for determination of sound wave emission from such surfaces divided into small finite elements was slightly modified by distinguishing the phase correlations between such vibrating elements. The final method being developed may find use in wide range of applications for different forms of vibrations of plane surfaces.

  7. A technique for the deconvolution of the pulse shape of acoustic emission signals back to the generating defect source

    International Nuclear Information System (INIS)

    Houghton, J.R.; Packman, P.F.; Townsend, M.A.

    1976-01-01

    Acoustic emission signals recorded after passage through the instrumentation system can be deconvoluted to produce signal traces indicative of those at the generating source, and these traces can be used to identify characteristics of the source

  8. Spatial Release From Masking in Simulated Cochlear Implant Users With and Without Access to Low-Frequency Acoustic Hearing

    Directory of Open Access Journals (Sweden)

    Ben Williges

    2015-12-01

    Full Text Available For normal-hearing listeners, speech intelligibility improves if speech and noise are spatially separated. While this spatial release from masking has already been quantified in normal-hearing listeners in many studies, it is less clear how spatial release from masking changes in cochlear implant listeners with and without access to low-frequency acoustic hearing. Spatial release from masking depends on differences in access to speech cues due to hearing status and hearing device. To investigate the influence of these factors on speech intelligibility, the present study measured speech reception thresholds in spatially separated speech and noise for 10 different listener types. A vocoder was used to simulate cochlear implant processing and low-frequency filtering was used to simulate residual low-frequency hearing. These forms of processing were combined to simulate cochlear implant listening, listening based on low-frequency residual hearing, and combinations thereof. Simulated cochlear implant users with additional low-frequency acoustic hearing showed better speech intelligibility in noise than simulated cochlear implant users without acoustic hearing and had access to more spatial speech cues (e.g., higher binaural squelch. Cochlear implant listener types showed higher spatial release from masking with bilateral access to low-frequency acoustic hearing than without. A binaural speech intelligibility model with normal binaural processing showed overall good agreement with measured speech reception thresholds, spatial release from masking, and spatial speech cues. This indicates that differences in speech cues available to listener types are sufficient to explain the changes of spatial release from masking across these simulated listener types.

  9. [Acoustic emission diagnostic techniques for high-field high current-density super inducting poles

    International Nuclear Information System (INIS)

    1990-01-01

    Acoustic emission technology was introduced in the late 1970's to monitor superconducting magnets. It has now been firmly established that acoustic signals in superconducting magnets are emitted principally by mechanical events such as conductor strain, conductor motion, frictional motion, and epoxy cracking. Despite earlier suggestions, flux motion, except during flux jumping, does not appear to be an important source of AE signals in superconducting magnets. Of these several potential sources of AE signals in superconducting magnets, mechanical disturbances have been identified to be most important in high-performance, ''adiabatic'' magnets such as the dipoles used in accelerators. These mechanical disturbances are transitory, each generating a packet of AE signals that can be located with sensors. Source identification and location has been achieved with a number of superconducting magnets. In this section, the basic principle for the operation of adiabatic magnets is discussed, followed by presentation of some of the important experimental results relevant to the question of premature quench obtained at MIT

  10. Simulations of emission from microcavity tandem organic light-emitting diodes

    International Nuclear Information System (INIS)

    Biswas, Rana; Xu, Chun; Zhao, Weijun; Liu, Rui; Shinar, Ruth; Shinar, Joseph

    2011-01-01

    Microcavity tandem organic light-emitting diodes (OLEDs) are simulated and compared to experimental results. The simulations are based on two complementary techniques: rigorous finite element solutions of Maxwell's equations and Fourier space scattering matrix solutions. A narrowing and blue shift of the emission spectrum relative to the noncavity single unit OLED is obtained both theoretically and experimentally. In the simulations, a distribution of emitting sources is placed near the interface of the electron transport layer tris(8-hydroxyquinoline) Al (Alq 3 ) and the hole transport layer (N,N'-bis(naphthalen-1-yl)-N,N'-bis(phenyl)benzidine) (α-NPB). Far-field electric field intensities are simulated. The simulated widths of the emission peaks also agree with the experimental results. The simulations of the 2-unit tandem OLEDs shifted the emission to shorter wavelength, in agreement with experimental measurements. The emission spectra's dependence on individual layer thicknesses also agreed well with measurements. Approaches to simulate and improve the light emission intensity from these OLEDs, in particular for white OLEDs, are discussed.

  11. Effect of gas adsorption on acoustic wave propagation in MFI zeolite membrane materials: experiment and molecular simulation.

    Science.gov (United States)

    Manga, Etoungh D; Blasco, Hugues; Da-Costa, Philippe; Drobek, Martin; Ayral, André; Le Clezio, Emmanuel; Despaux, Gilles; Coasne, Benoit; Julbe, Anne

    2014-09-02

    The present study reports on the development of a characterization method of porous membrane materials which consists of considering their acoustic properties upon gas adsorption. Using acoustic microscopy experiments and atomistic molecular simulations for helium adsorbed in a silicalite-1 zeolite membrane layer, we showed that acoustic wave propagation could be used, in principle, for controlling the membranes operando. Molecular simulations, which were found to fit experimental data, showed that the compressional modulus of the composite system consisting of silicalite-1 with adsorbed He increases linearly with the He adsorbed amount while its shear modulus remains constant in a large range of applied pressures. These results suggest that the longitudinal and Rayleigh wave velocities (VL and VR) depend on the He adsorbed amount whereas the transverse wave velocity VT remains constant.

  12. Acoustic emission results obtained from testing the ZB-1 intermediate scale pressure vessel

    International Nuclear Information System (INIS)

    Hutton, P.H.; Kurtz, R.J.; Pappas, R.A.; Dawson, J.F.; Dake, L.S.; Skorpik, J.R.

    1985-09-01

    Acoustic emission (AE) monitoring of flaw growth in an intermediate scale vessel during cyclic loading at 65 0 C and 288 0 C is described in this report. The report deals with background, methodology, and results. The work discussed is of major significance in a program supported by NRC to develop and demonstrate application of AE monitoring for continuous surveillance of reactor pressure boundaries to detect and evaluate growing flaws. Several areas of technical concern are addressed. Results support the feasibility of effective continuous monitoring

  13. [Real world instantaneous emission simulation for light-duty diesel vehicle].

    Science.gov (United States)

    Huang, Cheng; Chen, Chang-Hong; Dai, Pu; Li, Li; Huang, Hai-Ying; Cheng, Zhen; Jia, Ji-Hong

    2008-10-01

    Core architecture and input parameters of CMEM model were introduced to simulation the second by second vehicle emission rate on real world by taking a light-duty diesel car as a case. On-board test data by a portable emission measurement system were then used to validate the simulation results. Test emission factors of CO, THC, NO(x) and CO2 were respectively 0.81, 0.61, 2.09, and 193 g x km(-1), while calculated emission factors were 0.75, 0.47, 2.47, and 212 g x km(-1). The correlation coefficients reached 0.69, 0.69, 0.75, and 0.72. Simulated instantaneous emissions of the light duty diesel vehicle by CMEM model were strongly coherent with the transient driving cycle. By analysis, CO, THC, NO(x), and CO2 emissions would be reduced by 50%, 47%, 45%, and 44% after improving the traffic situation at the intersection. The result indicated that it is necessary and feasible to simulate the instantaneous emissions of mixed vehicle fleet in some typical traffic areas by the micro-scale vehicle emission model.

  14. Acoustic Emission Monitoring of Incipient Failure in Journal Bearings( III ) - Development of AE Diagnosis System for Journal Bearings -

    International Nuclear Information System (INIS)

    Chung, Min Hwa; Cho, Yong Sang; Yoon, Dong Jin; Kwon, Oh Yang

    1996-01-01

    For the condition monitoring of the journal bearing in rotating machinery, a system for their diagnosis by acoustic emission(AE) was developed. AE has been used to detect abnormal conditions in the bearing system. It was found from the field application study as well as the laboratory experiment using a simulated journal bearing system that AE RMS voltage was the most efficient parameter for the purpose of current study. Based on the above results, algorithms and judgement criteria for the diagnosis system was established. The system is composed of four parts as follows: the sensing part including AE sensor and preamplifier, the signal processing part for RMS-to-DC conversion to measure AE ms voltage, the interface part for transferring RMS voltage data into PC using A/D converter, and the software part including the graphic display of bearing conditions and the diagnosis program

  15. Flat acoustic lens by acoustic grating with curled slits

    KAUST Repository

    Peng, Pai

    2014-10-01

    We design a flat sub-wavelength lens that can focus acoustic wave. We analytically study the transmission through an acoustic grating with curled slits, which can serve as a material with tunable impedance and refractive index for acoustic waves. The effective parameters rely on the geometry of the slits and are independent of frequency. A flat acoustic focusing lens by such acoustic grating with gradient effective refractive index is designed. The focusing effect is clearly observed in simulations and well predicted by the theory. We demonstrate that despite the large impedance mismatch between the acoustic lens and the matrix, the intensity at the focal point is still high due to Fabry-Perot resonance.

  16. Simulation of sound transmission through the porous material, determining the parameters of acoustic absorption and sound reduction

    Directory of Open Access Journals (Sweden)

    Zvolenský Peter

    2018-01-01

    Full Text Available Currently, the quality of structural design of a railway coach is evaluated by so called acoustic comfort, which is characterized by achieved levels of internal noise. Therefore, acoustic parameters of car body are being developed purposely. The paper presents the results of the computer simulation of noise transmission through the wagon walls and the use of noise tests from the train running. The acoustic properties of the original and new materials in the care body are compared.

  17. Avalanche dynamics of structural phase transitions in shape memory alloys by acoustic emission spectroscopy

    International Nuclear Information System (INIS)

    Ludwig, Benno

    2009-01-01

    In this work the avalanche dynamics of five shape memory samples has been analyzed by acoustic emission spectroscopy. The acoustic emission spectroscopy is particularly suitable for this analysis as it couples with high sensitivity to small structural changes caused by nucleation processes, interface movements, or variant rearrangements [91]. Owing to its high time resolution it provides a statistical approach to describe the jerky and intermittent character of the avalanche dynamics [20]. Rate-dependent cooling and heating runs have been conducted in order to study time-dependent aspects of the transition dynamics of the single crystals Ni 63 Al 37 , Au 50.5 Cd 49.5 , and Fe 68.8 Pd single 31.2 , and the polycrystalline sample Fe 68.8 Pd poly 31.2 . Moreover, a ferromagnetic Ni 52 Mn 23 Ga 25 single crystal has been studied by temperature cycles under an applied magnetic field and additionally by magnetic-field cycles at a constant temperature in the martensitic phase. All samples analyzed in this work show power law behavior in the acoustic emission features amplitude, energy, and duration, which indicates scale-free behavior. The access to these power law spectra allows an investigation of energy barriers separating the metastable states, which give rise to avalanche transition dynamics. By performing rate-dependent experiments the importance of thermal fluctuations and the impact of martensite respectively twin stabilization processes have been examined. In the case of the Ni 52 Mn 23 Ga 25 sample, the magnetic-field-induced variant rearrangement at slow field cycles leads to stronger signals than the rearrangement at quick cycles. This behavior can be explained by twin stabilization processes, which are accompanied by a reduction of the twin boundary mobility. For Ni 63 Al 37 , the combination of relevant thermal fluctuations, different involved time scales, and a high degree of intrinsic disorder leads to a lower acoustic activity and weaker signals under

  18. Avalanche dynamics of structural phase transitions in shape memory alloys by acoustic emission spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Ludwig, Benno

    2009-09-24

    In this work the avalanche dynamics of five shape memory samples has been analyzed by acoustic emission spectroscopy. The acoustic emission spectroscopy is particularly suitable for this analysis as it couples with high sensitivity to small structural changes caused by nucleation processes, interface movements, or variant rearrangements [91]. Owing to its high time resolution it provides a statistical approach to describe the jerky and intermittent character of the avalanche dynamics [20]. Rate-dependent cooling and heating runs have been conducted in order to study time-dependent aspects of the transition dynamics of the single crystals Ni{sub 63}Al{sub 37}, Au{sub 50.5}Cd{sub 49.5}, and Fe{sub 68.8}Pd{sup single}{sub 31.2}, and the polycrystalline sample Fe{sub 68.8}Pd{sup poly}{sub 31.2}. Moreover, a ferromagnetic Ni{sub 52}Mn{sub 23}Ga{sub 25} single crystal has been studied by temperature cycles under an applied magnetic field and additionally by magnetic-field cycles at a constant temperature in the martensitic phase. All samples analyzed in this work show power law behavior in the acoustic emission features amplitude, energy, and duration, which indicates scale-free behavior. The access to these power law spectra allows an investigation of energy barriers separating the metastable states, which give rise to avalanche transition dynamics. By performing rate-dependent experiments the importance of thermal fluctuations and the impact of martensite respectively twin stabilization processes have been examined. In the case of the Ni{sub 52}Mn{sub 23}Ga{sub 25} sample, the magnetic-field-induced variant rearrangement at slow field cycles leads to stronger signals than the rearrangement at quick cycles. This behavior can be explained by twin stabilization processes, which are accompanied by a reduction of the twin boundary mobility. For Ni{sub 63}Al{sub 37}, the combination of relevant thermal fluctuations, different involved time scales, and a high degree of

  19. Waves on a Hele-Shaw Cell: Simulations of Acoustic Emissions During Aerofracture

    Science.gov (United States)

    Turkaya, Semih; Toussaint, Renaud; Kvalheim Eriksen, Fredrik; Daniel, Guillaume; Grude Flekkøy, Eirik; Jørgen Måløy, Knut

    2016-04-01

    In this work, we develop a numerical model to explain the lab scale experimental setup [1] modeling the aerofractures in a porous medium. The mentioned experimental setup consists in a rectangular Hele-Shaw cell with three closed boundaries and one semi-permeable boundary which enables the flow of the fluid but not the solid particles. During the experiments, the fluid (pressurized air) is injected into the system with a constant injection pressure from the point opposite to the semi-permeable boundary. At the large enough injection pressures, the fluid also displaces grains (80 μm grain size) and creates channels and fractures towards the semi-permeable boundary. This analogue model is developed in a linear geometry, with confinement and at a lower porosity to study the instabilities developing during the fast motion of a fluid in dense porous materials: fracturing, fingering, and channeling. Different sources of the signal (air vibration in the carved area, changes in the effective stress due to fluid-solid interactions [2]) are separately analyzed and are investigated further using a far field approximation of Lamb waves presented by Goyder & White [3]. In the analysis phase, power spectrum of different timewindows (5 ms) obtained from the recorded signal are computed. Then, the evolution of this power spectrum is compared with the experimental findings. In the power spectrum, it is possible to see some characteristic structure like peaks in specific frequency ranges. These "peaks" are strongly influenced by the size and branching of the channels, compaction of the medium, vibration of air in the pores and the fundamental frequency of the plate. We found that, in the synthetic dataset, the peaks in the low frequency range (f Daniel G, Flekkøy EG, Måløy KJ. "Bridging aero-fracture evolution with the characteristics of the acoustic emissions in a porous medium." Front. Phys., 3 (2015): 70. doi: 10.3389/fphy.2015.00070 2. Niebling MJ, Toussaint R, Flekkøy EG

  20. Simulation of the acoustic wave propagation using a meshless method

    Directory of Open Access Journals (Sweden)

    Bajko J.

    2017-01-01

    Full Text Available This paper presents numerical simulations of the acoustic wave propagation phenomenon modelled via Linearized Euler equations. A meshless method based on collocation of the strong form of the equation system is adopted. Moreover, the Weighted least squares method is used for local approximation of derivatives as well as stabilization technique in a form of spatial ltering. The accuracy and robustness of the method is examined on several benchmark problems.

  1. Enhanced sources of acoustic power surrounding AR 11429

    International Nuclear Information System (INIS)

    Donea, Alina; Hanson, Christopher

    2013-01-01

    Multi-frequency power maps of the local acoustic oscillations show acoustic enhancements (''acoustic-power halos'') at high frequencies surrounding large active region. Computational seismic holography reveals a high-frequency ''acoustic-emission halo'', or ''seismic glory'' surrounding large active regions. In this study, we have applied computational seismic holography to map the seismic seismic source density surrounding AR 11429. Studies of HMI/SDO Doppler data, shows that the ''acoustic halos'' and the ''seismic glories'' are prominent at high frequencies 5–8 mHz. We investigate morphological properties of acoustic-power and acoustic emission halos around an active region to see if they are spatially correlated. Details about the local magnetic field from vectormagnetograms of AR 11429 are included. We identify a 15'' region of seismic deficit power (dark moat) shielding the white-light boundary of the active region. The size of the seismic moat is related to region of intermediate magnetic field strength. The acoustic moat is circled by the halo of enhanced seismic amplitude as well as enhanced seismic emission. Overall, the results suggest that features are related. However, if we narrow the frequency band to 5.5 – 6.5 mHz, we find that the seismic source density dominates over the local acoustic power, suggesting the existence of sources that emit more energy downward into the solar interior than upward toward the solar surface.

  2. Monitoring of pipeline hydrostatic testing with artificial flaws applying acoustic emission and ultra-sonic techniques; Monitoracao de teste hidrostatico de tubos com descontinuidades artificiais empregando as tecnicas de emissao acustica e ultra-som

    Energy Technology Data Exchange (ETDEWEB)

    Soares, Sergio Damasceno [PETROBRAS, Rio de Janeiro, RJ (Brazil). Centro de Pesquisas (CENPES)

    2003-07-01

    Charts and parameters used to perform and analyzing the acoustic emission data collected during the hydrostatic test in pipe samples build in API XL 60 with 20 inches of diameter and 14 millimeters of thickness are shown. These pipes had internal and external artificial flaws done by electro-erosion process with aspect ratio 1 x 20. A relationship between acoustic emission results, ultrasound and J-Integral were established using the applied pressurization sequence. Characteristics values of acoustic emission signals were shown as a criteria of field tests. (author)

  3. Simulation investigation of storage ring optical klystron spontaneous emission

    International Nuclear Information System (INIS)

    Xu Hongliang; Liu Jinying; He Duohui; Diao Caozheng; Jia Qika; Sun Baogen

    1998-01-01

    The spontaneous emission of TOK in Hefei storage ring was simulated with Monte Carlo method. Section one described the structure of the permanent magnet TOK and the magnet field of TOK. Section two simulated results, and simulated results illustrated how the energy spread and emittance of electron beam impose on the spectrum of spontaneous emission. And with help of simulated results, the causes of small modulation factor which was measured by experiment was discussed

  4. Feasibility of using acoustic emission to determine in-process tool wear

    Energy Technology Data Exchange (ETDEWEB)

    Lazarus, L.J.

    1996-04-01

    Acoustic emission (AE) was evaluated for its ability to predict and recognize failure of cutting tools during machining processes when the cutting tool rotates and the workpiece is stationary. AE output was evaluated with a simple algorithm. AE was able to detect drill failure when the transducer was mounted on the workpiece holding fixture. Drill failure was recognized as size was reduced to 0.0003 in. diameter. The ability to predict failure was reduced with drill size, drill material elasticity, and tool coating. AE output for the turning process on a lathe was compared to turning tool insert wear. The turning tool must have sufficient wear to produce a detectable change in AE output to predict insert failure.

  5. In-situ acoustic signature monitoring in additive manufacturing processes

    Science.gov (United States)

    Koester, Lucas W.; Taheri, Hossein; Bigelow, Timothy A.; Bond, Leonard J.; Faierson, Eric J.

    2018-04-01

    Additive manufacturing is a rapidly maturing process for the production of complex metallic, ceramic, polymeric, and composite components. The processes used are numerous, and with the complex geometries involved this can make quality control and standardization of the process and inspection difficult. Acoustic emission measurements have been used previously to monitor a number of processes including machining and welding. The authors have identified acoustic signature measurement as a potential means of monitoring metal additive manufacturing processes using process noise characteristics and those discrete acoustic emission events characteristic of defect growth, including cracks and delamination. Results of acoustic monitoring for a metal additive manufacturing process (directed energy deposition) are reported. The work investigated correlations between acoustic emissions and process noise with variations in machine state and deposition parameters, and provided proof of concept data that such correlations do exist.

  6. Investigating deformation processes in AM60 magnesium alloy using the acoustic emission technique

    International Nuclear Information System (INIS)

    Mathis, K.; Chmelik, F.; Janecek, M.; Hadzima, B.; Trojanova, Z.; Lukac, P.

    2006-01-01

    Microstructure changes in an AM60 magnesium alloy were monitored using the acoustic emission (AE) technique during tensile tests in the temperature range from 20 to 300 deg. C. The correlation of the AE signal and the deformation processes is discussed. It is shown, using transmission electron and light microscopy, that the character of the AE response is associated with various modes of mechanical twinning at lower temperatures, whereas at higher temperatures also the influence of non-basal dislocations on the AE response must be taken into account

  7. Acoustic emission monitoring of preservice testing at Watts Bar Unit 1 Nuclear Reactor

    International Nuclear Information System (INIS)

    Hutton, P.H.; Pappas, R.A.; Friesel, M.A.

    1985-02-01

    Acoustic emission (AE) monitoring of selected pressure boundary areas at TVA's Watts Bar, Unit 1 Nuclear Plant in the US during hot functional preservice testing is described. Background, methodology, and results are included. The work discussed here is a major milestone in a program supported by the US NRC to develop and demonstrate application of AE monitoring for continuous surveillance of reactor pressure boundaries to detect and evaluate growing flaws. The subject work demonstrated that anticipated problem areas can be overcome. Work is continuing to AE monitoring during reactor operation. 3 refs., 6 figs

  8. Electron-acoustic Instability Simulated By Modified Zakharov Equations

    Science.gov (United States)

    Jásenský, V.; Fiala, V.; Vána, O.; Trávnícek, P.; Hellinger, P.

    We present non-linear equations describing processes in plasma when electron - acoustic waves are excited. These waves are present for instance in the vicinity of Earth's bow shock and in the polar ionosphere. Frequently they are excited by an elec- tron beam in a plasma with two electron populations, a cold and hot one. We derive modified Zakharov equations from kinetic theory for such a case together with numer- ical method for solving of this type of equations. Bispectral analysis is used to show which non-linear wave processes are of importance in course of the instability. Finally, we compare these results with similar simulations using Vlasov approach.

  9. ANALYSIS OF CHIP FORMATION DURING HARD TURNING THROUGH ACOUSTIC EMISSION

    Directory of Open Access Journals (Sweden)

    Miroslav Neslušan

    2012-01-01

    Full Text Available The paper deals with analysis of chip formation and related aspects of the chip formation during turning hardened steel 100Cr6. The paper draws a comparison of some aspects of the chip formation between turning annealed and hardened roll bearing steel. The results of the analysis show that there is the formation of a segmented chip in the case of hard turning. Frequency of segmentation is very high. A conventional piezoelectric dynamometer limits the frequency response to about 3.5 kHz. On the other hand, the frequency of process fluctuation may by obtained by using accelerometers or acoustic emission. This paper reports about the dynamic character of cutting process when hard turning and correlation among the calculated segmentation frequencies and the experimental analysis.

  10. Characteristics of Acceleration and Acoustic Emission Signals from Mechanical Seals

    International Nuclear Information System (INIS)

    Lee, Do Hwan; Ha, Che Woong

    2015-01-01

    Based on these results, the applicability of acceleration signals for condition monitoring of mechanical seals is examined in the present study. Mechanical seals are used for pumps to prevent excessive leakage that might be occurred between rotational and stationary parts. The mechanical seals account for the major pump component failures. In spite of its importance, there have been few studies on condition monitoring of the components. Recently, some researchers have paid attention to the application of acoustic emission (AE) sensors for the fault detection of seals. The characteristics of acceleration and AE signals obtained from various defects are investigated. In order to prevent excessive leakage from mechanical seals, a condition monitoring technique is necessary. Based on the previous studies on AE techniques for seal monitoring, the signal characteristics from accelerometer

  11. Characteristics of Acceleration and Acoustic Emission Signals from Mechanical Seals

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Do Hwan; Ha, Che Woong [KHNP Central Research Institute, Daejeon (Korea, Republic of)

    2015-10-15

    Based on these results, the applicability of acceleration signals for condition monitoring of mechanical seals is examined in the present study. Mechanical seals are used for pumps to prevent excessive leakage that might be occurred between rotational and stationary parts. The mechanical seals account for the major pump component failures. In spite of its importance, there have been few studies on condition monitoring of the components. Recently, some researchers have paid attention to the application of acoustic emission (AE) sensors for the fault detection of seals. The characteristics of acceleration and AE signals obtained from various defects are investigated. In order to prevent excessive leakage from mechanical seals, a condition monitoring technique is necessary. Based on the previous studies on AE techniques for seal monitoring, the signal characteristics from accelerometer.

  12. Acoustic Parametric Array for Identifying Standoff Targets

    Science.gov (United States)

    Hinders, M. K.; Rudd, K. E.

    2010-02-01

    An integrated simulation method for investigating nonlinear sound beams and 3D acoustic scattering from any combination of complicated objects is presented. A standard finite-difference simulation method is used to model pulsed nonlinear sound propagation from a source to a scattering target via the KZK equation. Then, a parallel 3D acoustic simulation method based on the finite integration technique is used to model the acoustic wave interaction with the target. Any combination of objects and material layers can be placed into the 3D simulation space to study the resulting interaction. Several example simulations are presented to demonstrate the simulation method and 3D visualization techniques. The combined simulation method is validated by comparing experimental and simulation data and a demonstration of how this combined simulation method assisted in the development of a nonlinear acoustic concealed weapons detector is also presented.

  13. Development of ion-acoustic double layers through ion-acoustic fluctuations

    International Nuclear Information System (INIS)

    Sekar, A.N.; Saxena, Y.C.

    1985-01-01

    Experimental results on the formation of ion acoustic double layers resembling asymmetric ion-holes are presented. In a double plasma device, modified suitably to inject electron beam into the target plasma, modulation of the beam through step potential leads to excitation of ion-acoustic fluctuation. The ion-acoustic fluctuation, growing away from the grids separating source and target plasmas, developed into weak asymmetric ion-acoustic double layer. The observations are in qualitative agreement with theoretical models and computer simulations. (author)

  14. Responsive acoustic surfaces

    DEFF Research Database (Denmark)

    Peters, Brady; Tamke, Martin; Nielsen, Stig Anton

    2011-01-01

    Acoustic performance is defined by the parameter of reverberation time; however, this does not capture the acoustic experience in some types of open plan spaces. As many working and learning activities now take place in open plan spaces, it is important to be able to understand and design...... for the acoustic conditions of these spaces. This paper describes an experimental research project that studied the design processes necessary to design for sound. A responsive acoustic surface was designed, fabricated and tested. This acoustic surface was designed to create specific sonic effects. The design...... was simulated using custom integrated acoustic software and also using Odeon acoustic analysis software. The research demonstrates a method for designing space- and sound-defining surfaces, defines the concept of acoustic subspace, and suggests some new parameters for defining acoustic subspaces....

  15. Acoustic Emission Technique Applied in Textiles Mechanical Characterization

    Directory of Open Access Journals (Sweden)

    Rios-Soberanis Carlos Rolando

    2017-01-01

    Full Text Available The common textile architecture/geometry are woven, braided, knitted, stitch boded, and Z-pinned. Fibres in textile form exhibit good out-of-plane properties and good fatigue and impact resistance, additionally, they have better dimensional stability and conformability. Besides the nature of the textile, the architecture has a great role in the mechanical behaviour and mechanisms of damage in textiles, therefore damage mechanisms and mechanical performance in structural applications textiles have been a major concern. Mechanical damage occurs to a large extent during the service lifetime consequently it is vital to understand the material mechanical behaviour by identifying its mechanisms of failure such as onset of damage, crack generation and propagation. In this work, textiles of different architecture were used to manufacture epoxy based composites in order to study failure events under tensile load by using acoustic emission technique which is a powerful characterization tool due to its link between AE data and fracture mechanics, which makes this relation a very useful from the engineering point of view.

  16. Acoustic emission of fire damaged fiber reinforced concrete

    Science.gov (United States)

    Mpalaskas, A. C.; Matikas, T. E.; Aggelis, D. G.

    2016-04-01

    The mechanical behavior of a fiber-reinforced concrete after extensive thermal damage is studied in this paper. Undulated steel fibers have been used for reinforcement. After being exposed to direct fire action at the temperature of 850°C, specimens were subjected to bending and compression in order to determine the loss of strength and stiffness in comparison to intact specimens and between the two types. The fire damage was assessed using nondestructive evaluation techniques, specifically ultrasonic pulse velocity (UPV) and acoustic emission (AE). Apart from the strong, well known, correlation of UPV to strength (both bending and compressive), AE parameters based mainly on the frequency and duration of the emitted signals after cracking events showed a similar or, in certain cases, better correlation with the mechanical parameters and temperature. This demonstrates the sensitivity of AE to the fracture incidents which eventually lead to failure of the material and it is encouraging for potential in-situ use of the technique, where it could provide indices with additional characterization capability concerning the mechanical performance of concrete after it subjected to fire.

  17. Numerical simulation of 3D boundary-driven acoustic streaming in microfluidic devices.

    Science.gov (United States)

    Lei, Junjun; Hill, Martyn; Glynne-Jones, Peter

    2014-02-07

    This article discusses three-dimensional (3D) boundary-driven streaming in acoustofluidic devices. Firstly, the 3D Rayleigh streaming pattern in a microchannel is simulated and its effect on the movement of microparticles of various sizes is demonstrated. The results obtained from this model show good comparisons with 3D experimental visualisations and demonstrate the fully 3D nature of the acoustic streaming field and the associated acoustophoretic motion of microparticles in acoustofluidic devices. This method is then applied to another acoustofluidic device in order to gain insights into an unusual in-plane streaming pattern. The origin of this streaming has not been fully described and its characteristics cannot be explained from the classical theory of Rayleigh streaming. The simulated in-plane streaming pattern was in good agreement with the experimental visualisation. The mechanism behind it is shown to be related to the active sound intensity field, which supports our previous findings on the mechanism of the in-plane acoustic streaming pattern visualised and modelled in a thin-layered capillary device.

  18. Standard practice for examination of liquid-Filled atmospheric and Low-pressure metal storage tanks using acoustic emission

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2007-01-01

    1.1 This practice covers guidelines for acoustic emission (AE) examinations of new and in-service aboveground storage tanks of the type used for storage of liquids. 1.2 This practice will detect acoustic emission in areas of sensor coverage that are stressed during the course of the examination. For flat-bottom tanks these areas will generally include the sidewalls (and roof if pressure is applied above the liquid level). The examination may not detect flaws on the bottom of flat-bottom tanks unless sensors are located on the bottom. 1.3 This practice may require that the tank experience a load that is greater than that encountered in normal use. The normal contents of the tank can usually be used for applying this load. 1.4 This practice is not valid for tanks that will be operated at a pressure greater than the examination pressure. 1.5 It is not necessary to drain or clean the tank before performing this examination. 1.6 This practice applies to tanks made of carbon steel, stainless steel, aluminum and oth...

  19. Investigation of correlation of LF power modulation of light in natural and artificial illumination situations and acoustic emission

    Science.gov (United States)

    Kleeberg, Florian P.; Gutzmann, Holger L.; Weyer, Cornelia; Weiß, Jürgen; Dörfler, Joachim; Hahlweg, Cornelius F.

    2014-09-01

    The present paper is a follow up of a paper presented in 2013 at the Novel Optical Systems conference in the session on Optics and Music. It is derived from an ongoing study on the human perception of combined optical and acoustical periodical stimuli. Originating from problems concerning artificial illumination and certain machinery with coherent optical and acoustical emissions there are effects to be observed which are interesting in the context of occupational medicine. It seems, that acoustic stimuli in the frequency range of the flicker fusion and below might lead to unexpected perceptible effects beyond those of the single stimuli. The effect of infrasound stimuli as a whole body perception seems to be boosted. Because of the difficulties in evaluation of physical and psychological effects of such coherent stimuli in a first step we question if such coherence is perceivable at all. Further, the problem of modulation of optical signals by acoustical signal is concerned. A catalogue of scenarios and 'effects to look for' including measurement concepts is presented and discussed.

  20. Thermal Cracking in Westerly Granite Monitored Using Direct Wave Velocity, Coda Wave Interferometry, and Acoustic Emissions

    Science.gov (United States)

    Griffiths, L.; Lengliné, O.; Heap, M. J.; Baud, P.; Schmittbuhl, J.

    2018-03-01

    To monitor both the permanent (thermal microcracking) and the nonpermanent (thermo-elastic) effects of temperature on Westerly Granite, we combine acoustic emission monitoring and ultrasonic velocity measurements at ambient pressure during three heating and cooling cycles to a maximum temperature of 450°C. For the velocity measurements we use both P wave direct traveltime and coda wave interferometry techniques, the latter being more sensitive to changes in S wave velocity. During the first cycle, we observe a high acoustic emission rate and large—and mostly permanent—apparent reductions in velocity with temperature (P wave velocity is reduced by 50% of the initial value at 450°C, and 40% upon cooling). Our measurements are indicative of extensive thermal microcracking during the first cycle, predominantly during the heating phase. During the second cycle we observe further—but reduced—microcracking, and less still during the third cycle, where the apparent decrease in velocity with temperature is near reversible (at 450°C, the P wave velocity is decreased by roughly 10% of the initial velocity). Our results, relevant for thermally dynamic environments such as geothermal reservoirs, highlight the value of performing measurements of rock properties under in situ temperature conditions.

  1. High transmission acoustic focusing by impedance-matched acoustic meta-surfaces

    KAUST Repository

    Al Jahdali, Rasha

    2016-01-19

    Impedance is an important issue in the design of acoustic lenses because mismatched impedance is detrimental to real focusing applications. Here, we report two designs of acoustic lenses that focus acoustic waves in water and air, respectively. They are tailored by acoustic meta-surfaces, which are rigid thin plates decorated with periodically distributed sub-wavelength slits. Their respective building blocks are constructed from the coiling-up spaces in water and the layered structures in air. Analytic analysis based on coupled-mode theory and transfer matrix reveals that the impedances of the lenses are matched to those of the background media. With these impedance-matched acoustic lenses, we demonstrate the acoustic focusing effect by finite-element simulations.

  2. High transmission acoustic focusing by impedance-matched acoustic meta-surfaces

    KAUST Repository

    Al Jahdali, Rasha; Wu, Ying

    2016-01-01

    Impedance is an important issue in the design of acoustic lenses because mismatched impedance is detrimental to real focusing applications. Here, we report two designs of acoustic lenses that focus acoustic waves in water and air, respectively. They are tailored by acoustic meta-surfaces, which are rigid thin plates decorated with periodically distributed sub-wavelength slits. Their respective building blocks are constructed from the coiling-up spaces in water and the layered structures in air. Analytic analysis based on coupled-mode theory and transfer matrix reveals that the impedances of the lenses are matched to those of the background media. With these impedance-matched acoustic lenses, we demonstrate the acoustic focusing effect by finite-element simulations.

  3. Leak Detection in Water-Filled Small-Diameter Polyethylene Pipes by Means of Acoustic Emission Measurements

    OpenAIRE

    Alberto Martini; Marco Troncossi; Alessandro Rivola

    2016-01-01

    The implementation of effective strategies to manage leaks represents an essential goal for all utilities involved with drinking water supply in order to reduce water losses affecting urban distribution networks. This study concerns the early detection of leaks occurring in small-diameter customers’ connections to water supply networks. An experimental campaign was carried out in a test bed to investigate the sensitivity of Acoustic Emission (AE) monitoring to water leaks. Damages were artifi...

  4. Cluster observations and simulations of He+ EMIC triggered emissions

    Science.gov (United States)

    Grison, B.; Shoji, M.; Santolik, O.; Omura, Y.

    2012-12-01

    EMIC triggered emissions have been reported in the inner magnetosphere at the edge of the plasmapause nightside [Pickett et al., 2010]. The generation mechanism proposed by Omura et al. [2010] is very similar to the one of the whistler chorus emissions and simulation results agree with observations and theory [Shoji et Omura, 2011]. The main characteristics of these emissions generated in the magnetic equatorial plane region are a frequency with time dispersion and a high level of coherence. The start frequency of previously mentioned observations is above half of the proton gyrofrequency. It means that the emissions are generated on the proton branch. On the He+ branch, generation of triggered emissions, in the same region, requests more energetic protons and the triggering process starts below the He+ gyrofrequency. It makes their identification in Cluster data rather difficult. Recent simulation results confirm the possibility of EMIC triggered emission on the He+ branch. In the present contribution we propose to compare a Cluster event to simulation results in order to investigate the possibility to identify observations to a He+ triggered emission. The impact of the observed waves on particle precipitation is also investigated.

  5. Analysis of acoustic emission signals of fatigue crack growth and corrosion processes. Investigation of the possibilities for continuous condition monitoring of transport containers by acoustic emission testing; Analyse der Schallemissionssignale aus Ermuedungsrisswachstum und Korrosionsprozessen. Untersuchung der Moeglichkeiten fuer die kontinuierliche Zustandsueberwachung von Transportbehaeltern mittels Schallemissionspruefung

    Energy Technology Data Exchange (ETDEWEB)

    Wachsmuth, Janne

    2016-05-01

    Fatigue crack growth and active corrosion processes are the main causes of structural failures of transport products like road tankers, railway tank cars and ships. To prevent those failures, preventive, time-based maintenance is performed. However, preventive inspections are costly and include the risk of not detecting a defect, which could lead to a failure within the next service period. An alternative is the idea of continuous monitoring of the whole structure by means of acoustic emission testing (AT). With AT, defects within the material shall be detected and repaired directly after their appearance. Acoustic emission testing is an online non-destructive testing method. Acoustic emission (AE) arises from changes within the material and is transported by elastic waves through the material. If the AE event generates enough energy, the elastic wave propagates to the boundaries of the component, produces a displacement in the picometre scale and can be detected by a piezoelectric sensor. The sensor produces an electrical signal. From this AE signal, AE features such as the maximum amplitude or the frequency can be extracted. Methods of signal analysis are used to investigate the time and frequency dependency of signal groups. The purpose of the signal analysis is to connect the AE signal with the originating AE source. If predefined damage mechanisms are identified, referencing the damage condition of the structure is possible. Acoustic emission from events of the actual crack propagation process can for example lead to the crack growth rate or the stress intensity factor, both specific values from fracture mechanics. A new development in the domain of acoustic emission testing is the pattern recognition of AE signals. Specific features are extracted from the AE signals to assign them to their damage mechanisms. In this thesis the AE signals from the damage mechanisms corrosion and fatigue crack growth are compared and analysed. The damage mechanisms were

  6. Acoustic emission diagnosis of concrete-piles damaged by earthquakes

    International Nuclear Information System (INIS)

    Shiotami, Tomoki; Sakaino, Norio; Ohtsu, Masayasu; Shigeishi, Mitsuhiro

    1997-01-01

    Earthquakes often impose unexpected damage on structures. Concerning the soundness of the structure, the upper portion is easily estimated by visual observation, while the lower portion located in deep underground is difficult to be estimated. Thus there exist few effective methods to investigate underground structures. In this paper, a new inspection technique for damage evaluation of concrete-piles utilizing acoustic emission (AE) is proposed, and is verified by a series of experiments. Firstly, such basic characteristics as the attenuation and effective wave-guides for detecting AE underground, are examined through laboratory tests. Secondary, fracture tests of full-scale prefabricated concrete piles are conducted, and the characteristics of the AE are examined. Finally, actual concrete-piles attacked by the 1995 Great Hanshin Earthquake are investigated. Results confirm that the estimated damages by the proposed method are in good agreement with actual damaged locations. Thus, the method is very effective for the diagnosis of the concrete-piles.

  7. A wireless acoustic emission sensor remotely powered by light

    International Nuclear Information System (INIS)

    Zahedi, F; Huang, H

    2014-01-01

    In this paper, wireless sensing of acoustic emission (AE) signals using a battery-free sensor node remotely powered by light is presented. The wireless sensor consists of a piezoelectric wafer active sensor (PWAS) for AE signal acquisition and a wireless transponder that performs signal conditioning, frequency conversion, and wireless transmission. For signal conditioning, a voltage follower that consumes less than 2 mW was introduced to buffer the high impedance of the PWAS from the low impedance of the wireless transponder. A photocell-based energy harvester with a stable voltage output was developed to power the voltage follower so that the wireless AE sensor can operate without an external power source. The principle of operation of the battery-free wireless AE sensor node and the sensor interrogation system is described, followed by a detailed description of the hardware implementation. The voltage follower and the wireless channel were characterized by ultrasound pitch–catch and pencil lead break experiments. (paper)

  8. Acoustic emission monitoring of recycled aggregate concrete under bending

    Science.gov (United States)

    Tsoumani, A. A.; Barkoula, N.-M.; Matikas, T. E.

    2015-03-01

    The amount of construction and demolition waste has increased considerably over the last few years, making desirable the reuse of this waste in the concrete industry. In the present study concrete specimens are subjected at the age of 28 days to four-point bending with concurrent monitoring of their acoustic emission (AE) activity. Several concrete mixtures prepared using recycled aggregates at various percentages of the total coarse aggregate and also a reference mix using natural aggregates, were included to investigate their influence of the recycled aggregates on the load bearing capacity, as well as on the fracture mechanisms. The results reveal that for low levels of substitution the influence of using recycled aggregates on the flexural strength is negligible while higher levels of substitution lead into its deterioration. The total AE activity, as well as the AE signals emitted during failure, was related to flexural strength. The results obtained during test processing were found to be in agreement with visual observation.

  9. Acoustic Emission Analysis of Damage Progression in Thermal Barrier Coatings Under Thermal Cyclic Conditions

    Science.gov (United States)

    Appleby, Matthew; Zhu, Dongming; Morscher, Gregory

    2015-01-01

    Damage evolution of electron beam-physical vapor deposited (EBVD-PVD) ZrO2-7 wt.% Y2O3 thermal barrier coatings (TBCs) under thermal cyclic conditions was monitored using an acoustic emission (AE) technique. The coatings were heated using a laser heat flux technique that yields a high reproducibility in thermal loading. Along with AE, real-time thermal conductivity measurements were also taken using infrared thermography. Tests were performed on samples with induced stress concentrations, as well as calcium-magnesium-alumino-silicate (CMAS) exposure, for comparison of damage mechanisms and AE response to the baseline (as-produced) coating. Analysis of acoustic waveforms was used to investigate damage development by comparing when events occurred, AE event frequency, energy content and location. The test results have shown that AE accumulation correlates well with thermal conductivity changes and that AE waveform analysis could be a valuable tool for monitoring coating degradation and provide insight on specific damage mechanisms.

  10. Characterization of martensitic transformations using acoustic emission

    International Nuclear Information System (INIS)

    Tatro, C.A.

    1984-01-01

    Acoustic emission (AE) is a highly sensitive technique which can reveal changes in materials not detectable by other means. The goal of this project was to obtain basic information on the AE response to martensitic transformation in steel. This information will enable the use of AE for improved quality assurance testing of rough-cut component blanks and semifinished parts. The AE response was measured as a function of temperature in four steels undergoing martensitic transformation, and the AE response was compared with martensitic start temperature M/sub s/ and finish temperature M/sub f/ obtained by other methods. As measured by AE activity, M/sub s/ occurred as much as 26 0 C higher than previously reported using less sensitive measurement techniques. It was also found that 10 to 30% of an alloy of Fe-0.2% C-27% Ni transformed to martensite during one AE burst. These results show that AE can be used to study transformations both inside and outside the classical M/sub s/-M/sub f/ ranges. The findings will help to achieve the goal of using AE for quality assurance testing, and will add to the knowledge of the basic materials science of martensitic transformations

  11. Experimental study of ultra-thin films mechanical integrity by combined nanoindentation and nano-acoustic emission

    Science.gov (United States)

    Zhang, Zihou

    Advancement of interconnect technology has imposed significant challenge on interface characterization and reliability for blurred interfaces between layers. There is a need for material properties and these miniaturized length scales and assessment of reliability; including the intrinsic film fracture toughness and the interfacial fracture toughness. The nano-meter range of film thicknesses currently employed, impose significant challenges on evaluating these physical quantities and thereby impose significant challenge on the design cycle. In this study we attempted to use a combined nano-indentation and nano-acoustic emission to qualitatively and quantitatively characterize the failure modes in ultra-thin blanket films on Si substrates or stakes of different characteristics. We have performed and analyzed an exhaustive group of testes that cove many diverge combination of film-substrate combination, provided by both Intel and IBM. When the force-indentation depth curve shows excursion, a direct measure of the total energy release rate is estimated. The collected acoustic emission signal is then used to partition the total energy into two segments, one associated with the cohesive fracture toughness of the film and the other is for the adhesive fracture toughness of the interface. The acoustic emission signal is analyzed in both the time and frequency domain to achieve such energy division. In particular, the signal time domain analysis for signal skewness, time of arrival and total energy content are employed with the proper signal to noise ratio. In the frequency domain, an expansive group of acoustic emission signals are utilized to construct the details of the power spectral density. A bank of band-pass filters are designed to sort the individual signals to those associated with adhesive interlayer cracking, cohesive channel cracking, or other system induced noise. The attenuation time and the energy content within each spectral frequency were the key elements

  12. Structural investigation and simulation of acoustic properties of some tellurite glasses using artificial intelligence technique

    International Nuclear Information System (INIS)

    Gaafar, M.S.; Abdeen, Mostafa A.M.; Marzouk, S.Y.

    2011-01-01

    Research highlights: → Simulation the acoustic properties of some tellurite glasses using one of the artificial intelligence techniques (artificial neural network). → The glass network is strengthened by enhancing the linkage of Te-O chains. The tellurite network will also come to homogenization, because of uniform distribution of Nb 5+ ions among the Te-O chains, though some of the tellurium-oxide polyhedra still link each other in edge sharing. → Excellent agreements between the measured values and the predicted values were obtained for over 50 different tellurite glass compositions. → The model we designed gives a better agreement as compared with Makishima and Machenzie model. - Abstract: The developments in the field of industry raise the need for simulating the acoustic properties of glass materials before melting raw material oxides. In this paper, we are trying to simulate the acoustic properties of some tellurite glasses using one of the artificial intelligence techniques (artificial neural network). The artificial neural network (ANN) technique is introduced in the current study to simulate and predict important parameters such as density, longitudinal and shear ultrasonic velocities and elastic moduli (longitudinal and shear moduli). The ANN results were found to be in successful good agreement with those experimentally measured parameters. Then the presented ANN model is used to predict the acoustic properties of some new tellurite glasses. For this purpose, four glass systems xNb 2 O 5 -(1 - x)TeO 2 , 0.1PbO-xNb 2 O 5 -(0.9 - x)TeO 2 , 0.2PbO-xNb 2 O 5 -(0.8 - x)TeO 2 and 0.05Bi 2 O 3 -xNb 2 O 5 -(0.95 - x)TeO 2 were prepared using melt quenching technique. The results of ultrasonic velocities and elastic moduli showed that the addition of Nb 2 O 5 as a network modifier provides oxygen ions to change [TeO 4 ] tbps into [TeO 3 ] tps.

  13. Structural investigation and simulation of acoustic properties of some tellurite glasses using artificial intelligence technique

    Energy Technology Data Exchange (ETDEWEB)

    Gaafar, M.S., E-mail: mohamed_s_gaafar@hotmail.com [Ultrasonic Department, National Institute for Standards, Giza (Egypt); Physics Department, Faculty of Science, Majmaah University, Zulfi (Saudi Arabia); Abdeen, Mostafa A.M., E-mail: mostafa_a_m_abdeen@hotmail.com [Dept. of Eng. Math. and Physics, Faculty of Eng., Cairo University, Giza (Egypt); Marzouk, S.Y., E-mail: samir_marzouk2001@yahoo.com [Arab Academy of Science and Technology, Al-Horria, Heliopolis, Cairo (Egypt)

    2011-02-24

    Research highlights: > Simulation the acoustic properties of some tellurite glasses using one of the artificial intelligence techniques (artificial neural network). > The glass network is strengthened by enhancing the linkage of Te-O chains. The tellurite network will also come to homogenization, because of uniform distribution of Nb{sup 5+} ions among the Te-O chains, though some of the tellurium-oxide polyhedra still link each other in edge sharing. > Excellent agreements between the measured values and the predicted values were obtained for over 50 different tellurite glass compositions. > The model we designed gives a better agreement as compared with Makishima and Machenzie model. - Abstract: The developments in the field of industry raise the need for simulating the acoustic properties of glass materials before melting raw material oxides. In this paper, we are trying to simulate the acoustic properties of some tellurite glasses using one of the artificial intelligence techniques (artificial neural network). The artificial neural network (ANN) technique is introduced in the current study to simulate and predict important parameters such as density, longitudinal and shear ultrasonic velocities and elastic moduli (longitudinal and shear moduli). The ANN results were found to be in successful good agreement with those experimentally measured parameters. Then the presented ANN model is used to predict the acoustic properties of some new tellurite glasses. For this purpose, four glass systems xNb{sub 2}O{sub 5}-(1 - x)TeO{sub 2}, 0.1PbO-xNb{sub 2}O{sub 5}-(0.9 - x)TeO{sub 2}, 0.2PbO-xNb{sub 2}O{sub 5}-(0.8 - x)TeO{sub 2} and 0.05Bi{sub 2}O{sub 3}-xNb{sub 2}O{sub 5}-(0.95 - x)TeO{sub 2} were prepared using melt quenching technique. The results of ultrasonic velocities and elastic moduli showed that the addition of Nb{sub 2}O{sub 5} as a network modifier provides oxygen ions to change [TeO{sub 4}] tbps into [TeO{sub 3}] tps.

  14. Study of brittle crack jump rate using acoustic emission method

    International Nuclear Information System (INIS)

    Yasnij, P.V.; Pokrovskij, V.V.; Strizhalo, V.A.; Dobrovol'skij, Yu.V.

    1987-01-01

    A new peocedure is elaborated to detect brittle jumps of small length (0.1...5mm) occuring both inside the specimen and along the crack front under static and cyclic loading using the phenomena of acoustic emission (AE). Recording of the crack start and stop moments with an AE sensor as well as evaluation of the brittle crack jump length by the after-failure specimen fracture make it possible to find the mean crack propagation rate. Experimental dependences are obtained for the crack propagation rate with a brittle crack jump in steel 15Kh2MFA (σ B =1157 MPa, σ 0.2 =100 MPa) at 293 K and under cyclic loading as a function of the jump length and also as a function of the critical stress intensity factor K jc i corresponding to the crack jump

  15. Design of crude oil storage tank for acoustic emission testing

    International Nuclear Information System (INIS)

    Shukri Mohd; Masrul Nizam Salleh; Abd Razak Hamzah; Norasiah Abd Kasim

    2005-01-01

    The integrity of crude oil storage tank needs to be well managed because they can contain a large inventory of hazardous material and because of the high cost such as cleaning and waste disposal prior to disposal and maintenance. Costs involved in cleaning and inspection can be up to several hundreds thousand Malaysian Ranting. If the floor then proves to be in good condition, these costs have been wasted. Acoustic Emission (AE) is proposed to be use for monitoring the floor of the storage tank on line without doing cleaning and waste disposal. A storage tank will be fabricated for storing the crude oil and then the corrosion process will be monitor using AE method. This paper will discuss the background, material and is technical specification, design and also the difficulties faced during design and fabrication process. (Author)

  16. Springer handbook of acoustics

    CERN Document Server

    2014-01-01

    Acoustics, the science of sound, has developed into a broad interdisciplinary field encompassing the academic disciplines of physics, engineering, psychology, speech, audiology, music, architecture, physiology, neuroscience, and electronics. The Springer Handbook of Acoustics is also in his 2nd edition an unparalleled modern handbook reflecting this richly interdisciplinary nature edited by one of the acknowledged masters in the field, Thomas Rossing. Researchers and students benefit from the comprehensive contents. This new edition of the Handbook features over 11 revised and expanded chapters, new illustrations, and 2 new chapters covering microphone arrays  and acoustic emission.  Updated chapters contain the latest research and applications in, e.g. sound propagation in the atmosphere, nonlinear acoustics in fluids, building and concert hall acoustics, signal processing, psychoacoustics, computer music, animal bioacousics, sound intensity, modal acoustics as well as new chapters on microphone arrays an...

  17. Direct Numerical Simulation of Acoustic Noise Generation from the Nozzle Wall of a Hypersonic Wind Tunnel

    Science.gov (United States)

    Huang, Junji; Duan, Lian; Choudhari, Meelan; Missouri Univ of Sci; Tech Team; NASA Langley Research Center Team

    2017-11-01

    Direct numerical simulations (DNS) are used to examine the acoustic noise generation from the turbulent boundary layer on the nozzle wall of a Mach 6 Ludwieg Tube. The emphasis is on characterizing the freestream acoustic pressure disturbances radiated from the nozzle-wall turbulent boundary layer and comparing it with acoustic noise generated from a single, flat wall in an unconfined setting at a similar freestream Mach number to assess the effects of noise reverberation. In particular, the numerical database is used to provide insights into the pressure disturbance spectrum and amplitude scaling with respect to the boundary-layer parameters as well as to understand the acoustic source mechanisms. Such information is important for characterizing the freestream disturbance environment in conventional (i.e., noisy) hypersonic wind tunnels. Air Force Office of Scientific Research Award No. FA9550-14-1-0170.

  18. Tuning avalanche criticality: acoustic emission during the martensitic transformation of a compressed Ni-Mn-Ga single crystal

    Czech Academy of Sciences Publication Activity Database

    Niemann, R.; Baró, J.; Heczko, Oleg; Schultz, L.; Fähler, S.; Vives, E.; Mañosa, L.; Planes, A.

    2012-01-01

    Roč. 86, č. 21 (2012), "214101-1"-"214101-6" ISSN 1098-0121 R&D Projects: GA ČR(CZ) GAP107/11/0391 Institutional research plan: CEZ:AV0Z10100520 Keywords : stress -induced martensitic transformation * Ni-Mn-Ga * magnetic shape memory alloy * ferromagnetic martensite * acoustic emission during transformation Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.767, year: 2012

  19. Model simulations of line-of-sight effects in airglow imaging of acoustic and fast gravity waves from ground and space

    Science.gov (United States)

    Aguilar Guerrero, J.; Snively, J. B.

    2017-12-01

    Acoustic waves (AWs) have been predicted to be detectable by imaging systems for the OH airglow layer [Snively, GRL, 40, 2013], and have been identified in spectrometer data [Pilger et al., JASP, 104, 2013]. AWs are weak in the mesopause region, but can attain large amplitudes in the F region [Garcia et al., GRL, 40, 2013] and have local impacts on the thermosphere and ionosphere. Similarly, fast GWs, with phase speeds over 100 m/s, may propagate to the thermosphere and impart significant local body forcing [Vadas and Fritts, JASTP, 66, 2004]. Both have been clearly identified in ionospheric total electron content (TEC), such as following the 2013 Moore, OK, EF5 tornado [Nishioka et al., GRL, 40, 2013] and following the 2011 Tohoku-Oki tsunami [e.g., Galvan et al., RS, 47, 2012, and references therein], but AWs have yet to be unambiguously imaged in MLT data and fast GWs have low amplitudes near the threshold of detection; nevertheless, recent imaging systems have sufficient spatial and temporal resolution and sensitivity to detect both AWs and fast GWs with short periods [e.g., Pautet et al., AO, 53, 2014]. The associated detectability challenges are related to the transient nature of their signatures and to systematic challenges due to line-of-sight (LOS) effects such as enhancements and cancelations due to integration along aligned or oblique wavefronts and geometric intensity enhancements. We employ a simulated airglow imager framework that incorporates 2D and 3D emission rate data and performs the necessary LOS integrations for synthetic imaging from ground- and space-based platforms to assess relative intensity and temperature perturbations. We simulate acoustic and fast gravity wave perturbations to the hydroxyl layer from a nonlinear, compressible model [e.g., Snively, 2013] for different idealized and realistic test cases. The results show clear signal enhancements when acoustic waves are imaged off-zenith or off-nadir and the temporal evolution of these

  20. Near-Field Acoustic Power Level Analysis of F31/A31 Open Rotor Model at Simulated Cruise Conditions, Technical Report II

    Science.gov (United States)

    Sree, Dave

    2015-01-01

    Near-field acoustic power level analysis of F31A31 open rotor model has been performed to determine its noise characteristics at simulated cruise flight conditions. The non-proprietary parts of the test data obtained from experiments in the 8x6 supersonic wind tunnel were provided by NASA-Glenn Research Center. The tone and broadband components of total noise have been separated from raw test data by using a new data analysis tool. Results in terms of sound pressure levels, acoustic power levels, and their variations with rotor speed, freestream Mach number, and input shaft power, with different blade-pitch setting angles at simulated cruise flight conditions, are presented and discussed. Empirical equations relating models acoustic power level and input shaft power have been developed. The near-field acoustic efficiency of the model at simulated cruise conditions is also determined. It is hoped that the results presented in this work will serve as a database for comparison and improvement of other open rotor blade designs and also for validating open rotor noise prediction codes.

  1. On the state of acoustic emission analysis in pressure vessel and model vessel testing

    International Nuclear Information System (INIS)

    Morgner, W.; Theis, K.; Henke, F.; Imhof, D.

    1985-01-01

    In the GDR acoustic emission analysis is being applied primarily in connection with hydraulic pressure testing of vessels in chemical industry. It is, however, also used for testing and monitoring of equipment and components in other branches of industry. The state-of-the-art is presented with regard to equipment needed, training of personnel, licensing of testing methods and appropriate testing procedures. In particular, the evaluation of the sum curves and amplitude distributions is explained, using rupture tests of two oxygen cylinders and a compressed-air bottle as examples. (author)

  2. Investigation into the Effect of Acoustic Radiation Force and Acoustic Streaming on Particle Patterning in Acoustic Standing Wave Fields

    Directory of Open Access Journals (Sweden)

    Shilei Liu

    2017-07-01

    Full Text Available Acoustic standing waves have been widely used in trapping, patterning, and manipulating particles, whereas one barrier remains: the lack of understanding of force conditions on particles which mainly include acoustic radiation force (ARF and acoustic streaming (AS. In this paper, force conditions on micrometer size polystyrene microspheres in acoustic standing wave fields were investigated. The COMSOL® Mutiphysics particle tracing module was used to numerically simulate force conditions on various particles as a function of time. The velocity of particle movement was experimentally measured using particle imaging velocimetry (PIV. Through experimental and numerical simulation, the functions of ARF and AS in trapping and patterning were analyzed. It is shown that ARF is dominant in trapping and patterning large particles while the impact of AS increases rapidly with decreasing particle size. The combination of using both ARF and AS for medium size particles can obtain different patterns with only using ARF. Findings of the present study will aid the design of acoustic-driven microfluidic devices to increase the diversity of particle patterning.

  3. Investigation into the Effect of Acoustic Radiation Force and Acoustic Streaming on Particle Patterning in Acoustic Standing Wave Fields

    Science.gov (United States)

    Yang, Yanye; Ni, Zhengyang; Guo, Xiasheng; Luo, Linjiao; Tu, Juan; Zhang, Dong

    2017-01-01

    Acoustic standing waves have been widely used in trapping, patterning, and manipulating particles, whereas one barrier remains: the lack of understanding of force conditions on particles which mainly include acoustic radiation force (ARF) and acoustic streaming (AS). In this paper, force conditions on micrometer size polystyrene microspheres in acoustic standing wave fields were investigated. The COMSOL® Mutiphysics particle tracing module was used to numerically simulate force conditions on various particles as a function of time. The velocity of particle movement was experimentally measured using particle imaging velocimetry (PIV). Through experimental and numerical simulation, the functions of ARF and AS in trapping and patterning were analyzed. It is shown that ARF is dominant in trapping and patterning large particles while the impact of AS increases rapidly with decreasing particle size. The combination of using both ARF and AS for medium size particles can obtain different patterns with only using ARF. Findings of the present study will aid the design of acoustic-driven microfluidic devices to increase the diversity of particle patterning. PMID:28753955

  4. Detecting the Activation of a Self-Healing Mechanism in Concrete by Acoustic Emission and Digital Image Correlation

    Directory of Open Access Journals (Sweden)

    E. Tsangouri

    2013-01-01

    Full Text Available Autonomous crack healing in concrete is obtained when encapsulated healing agent is embedded into the material. Cracking damage in concrete elements ruptures the capsules and activates the healing process by healing agent release. Previously, the strength and stiffness recovery as well as the sealing efficiency after autonomous crack repair was well established. However, the mechanisms that trigger capsule breakage remain unknown. In parallel, the conditions under which the crack interacts with embedded capsules stay black-box. In this research, an experimental approach implementing an advanced optical and acoustic method sets up scopes to monitor and justify the crack formation and capsule breakage of concrete samples tested under three-point bending. Digital Image Correlation was used to visualize the crack opening. The optical information was the basis for an extensive and analytical study of the damage by Acoustic Emission analysis. The influence of embedding capsules on the concrete fracture process, the location of capsule damage, and the differentiation between emissions due to capsule rupture and crack formation are presented in this research. A profound observation of the capsules performance provides a clear view of the healing activation process.

  5. An Overview of Virtual Acoustic Simulation of Aircraft Flyover Noise

    Science.gov (United States)

    Rizzi, Stephen A.

    2013-01-01

    Methods for testing human subject response to aircraft flyover noise have greatly advanced in recent years as a result of advances in simulation technology. Capabilities have been developed which now allow subjects to be immersed both visually and aurally in a three-dimensional, virtual environment. While suitable for displaying recorded aircraft noise, the true potential is found when synthesizing aircraft flyover noise because it allows the flexibility and freedom to study sounds from aircraft not yet flown. A virtual acoustic simulation method is described which is built upon prediction-based source noise synthesis, engineering-based propagation modeling, and empirically-based receiver modeling. This source-path-receiver paradigm allows complete control over all aspects of flyover auralization. With this capability, it is now possible to assess human response to flyover noise by systematically evaluating source noise reductions within the context of a system level simulation. Examples of auralized flyover noise and movie clips representative of an immersive aircraft flyover environment are made in the presentation.

  6. Experimental investigation of starting characteristics and wave propagation from a shallow open cavity and its acoustic emission at supersonic speed

    Science.gov (United States)

    Pandian, S.; Desikan, S. L. N.; Niranjan, Sahoo

    2018-01-01

    Experiments were carried out on a shallow open cavity (L/D = 5) at a supersonic Mach number (M = 1.8) to understand its transient starting characteristics, wave propagation (inside and outside the cavity) during one vortex shedding cycle, and acoustic emission. Starting characteristics and wave propagation were visualized through time resolved schlieren images, while acoustic emissions were captured through unsteady pressure measurements. Results showed a complex shock system during the starting process which includes characteristics of the bifurcated shock system, shock train, flow separation, and shock wave boundary layer interaction. In one vortex shedding cycle, vortex convection from cavity leading edge to cavity trailing edge was observed. Flow features outside the cavity demonstrated the formation and downstream movement of a λ-shock due to the interaction of shock from the cavity leading edge and shock due to vortex and generation of waves on account of shear layer impingement at the cavity trailing edge. On the other hand, interesting wave structures and its propagation were monitored inside the cavity. In one vortex shedding cycle, two waves such as a reflected compression wave from a cavity leading edge in the previous vortex shedding cycle and a compression wave due to the reflection of Mach wave at the cavity trailing edge corner in the current vortex shedding cycle were visualized. The acoustic emission from the cavity indicated that the 2nd to 4th modes/tones are dominant, whereas the 1st mode contains broadband spectrum. In the present studies, the cavity feedback mechanism was demonstrated through a derived parameter coherence coefficient.

  7. Study of the performances of acoustic emission testing for glass fibre reinforced plastic pipes containing defects

    International Nuclear Information System (INIS)

    Villard, D.; Vidal, M.C.

    1995-08-01

    Glass fibre reinforced plastic pipes are more and more often used, in nuclear power plants, for building or replacement of water pipings classified 'nuclear safety'. Tests have been performed to evaluate the performances of acoustic emission testing for in service inspection of these components. The tests were focused on glass fibre reinforced polyester and vinyl-ester pipes, in as received conditions or containing impacts, and intentionally introduced defects. They have been carried out by CETIM, following the ASTM Standard E 1118 (code CARP), to a maximum pressure lever of 25 Bar The results show that the CARP procedure can be used for detection of defects and evaluation of their noxiousness towards internal pressure: most of the tubes containing low energy impacts could not be distinguished from tubes without defect; on the other hand the important noxiousness of lacks of impregnation of roving layer appeared clearly. Complementary tests have been performed on some tubes at a more important pressure lever, for which the damage of the tubes in enough to deteriorate there elastic properties. The results showed that CARP procedure give valuable informations on damage level. It would be interesting to evaluate acoustic emission on tubes containing realistic in-service degradations. (author). 11 refs., 15 figs., 6 tabs., 2 appends

  8. Real-time measurement of electron beam weld penetration in uranium by acoustic emission monitoring

    International Nuclear Information System (INIS)

    Whittaker, J.W.; Murphy, J.L.

    1991-07-01

    High quality electron beam (EB) welds are required in uranium test articles. Acoustic emission (AE) techniques are under development with the goal of measuring weld penetration in real-time. One technique, based on Average Signal Level (ASL) measurement was used to record weld AE signatures. Characteristic AE signatures were recorded for bead-on-plate (BOP) and butt joint (BJ) welds made under varied welding conditions. AE waveforms were sampled to determine what microscopic AE behavior led to the observed macroscopic signature features. Deformation twinning and weld expulsion are two of the main sources of emission. AE behavior was correlated with weld penetration as measured by standard metallographic techniques. The ASL value was found to increase approximately linearly with weld penetration in BJ welds. These results form the basis for a real-time monitoring technique for weld penetration. 5 refs

  9. Magnetic Barkhausen noise and magneto acoustic emission in pressure vessel steel

    Energy Technology Data Exchange (ETDEWEB)

    Neyra Astudillo, Miriam Rocío, E-mail: neyra@cnea.gov.ar [IT Sabato, Universidad Nacional de San Martín, UNSAM, Av. General Paz 1499, Buenos Aires (Argentina); Universidad Tecnológica Nacional UTN, Regional Delta, Buenos Aires (Argentina); López Pumarega, María Isabel, E-mail: lopezpum@cnea.gov.ar [Comisión Nacional de Energía Atómica, CNEA, Av. General Paz 1499, Buenos Aires (Argentina); Núñez, Nicolás Marcelo, E-mail: nnunez@cnea.gov.ar [Comisión Nacional de Energía Atómica, CNEA, Av. General Paz 1499, Buenos Aires (Argentina); Pochettino, Alberto, E-mail: alberto.poch@gmail.com [Comisión Nacional de Energía Atómica, CNEA, Av. General Paz 1499, Buenos Aires (Argentina); Instituto de Investigación e Ingeniería Ambiental (3iA), Campus Miguelete, UNSAM, Av. 25 de Mayo y Francia, 1650 San Martín Argentina (Argentina); Ruzzante, José, E-mail: ruzzante@gmail.com [Universidad Tecnológica Nacional UTN, Regional Delta, Buenos Aires (Argentina); Universidad Nacional de Tres de Febrero UNTREF, Caseros, Buenos Aires (Argentina); Universidad Nacional de Chilecito, UNdeC, La Rioja (Argentina)

    2017-03-15

    Magnetic Barkhausen Noise (MBN) and Magneto Acoustic Emission (MAE) were studied in A508 Class II forged steel used for pressure vessels in nuclear power stations. The magnetic experimental determinations were completed with a macro graphic study of sulfides and the texture analysis of the material. The analysis of these results allows us to determine connections between the magnetic anisotropy, texture and microstructure of the material. Results clearly suggest that the plastic flow direction is different from the forging direction indicated by the material supplier - Highlights: • MBN and MAE studied in nuclear power pressure vessel steel. • Comparison with macro graphic study of sulfides and texture analysis of the material. • Connections with magnetic anisotropy, texture and microstructure of material. • Plastic flow direction different from the forging direction indicated.

  10. Magnetic Barkhausen noise and magneto acoustic emission in pressure vessel steel

    International Nuclear Information System (INIS)

    Neyra Astudillo, Miriam Rocío; López Pumarega, María Isabel; Núñez, Nicolás Marcelo; Pochettino, Alberto; Ruzzante, José

    2017-01-01

    Magnetic Barkhausen Noise (MBN) and Magneto Acoustic Emission (MAE) were studied in A508 Class II forged steel used for pressure vessels in nuclear power stations. The magnetic experimental determinations were completed with a macro graphic study of sulfides and the texture analysis of the material. The analysis of these results allows us to determine connections between the magnetic anisotropy, texture and microstructure of the material. Results clearly suggest that the plastic flow direction is different from the forging direction indicated by the material supplier - Highlights: • MBN and MAE studied in nuclear power pressure vessel steel. • Comparison with macro graphic study of sulfides and texture analysis of the material. • Connections with magnetic anisotropy, texture and microstructure of material. • Plastic flow direction different from the forging direction indicated.

  11. Effects of the Distance from a Diffusive Surface on the Objective and Perceptual Evaluation of the Sound Field in a Small Simulated Variable-Acoustics Hall

    Directory of Open Access Journals (Sweden)

    Louena Shtrepi

    2017-02-01

    Full Text Available Simulations of the acoustic effects that diffusive surfaces have on the objective acoustic parameters and on sound perception have not yet been fully understood. To this end, acoustic simulations have been performed in Odeon in the model of a variable-acoustic concert hall. This paper is presented as a follow-up study to a previous paper that dealt with in-field measurements only. As in measurements, a diffusive and a reflective condition of one of the lateral walls have been considered in the room models. Two modeling alternatives of the diffusive condition, that is, (a a flat surface with high scattering coefficient applied; and (b a triangular relief modeled including edge diffraction, have been investigated. Objective acoustic parameters, such as early decay time (EDT, reverberation time (T30, clarity (C80, definition (D50, and interaural cross correlation (IACC, have been compared between the two conditions. Moreover, an auditory experiment has been performed to determine the maximum distance from a diffusive surface at which the simulated acoustic scattering effects are still audible. Although the simulated objective results showed a good match with measured values, the subjective results showed that the differences between the diffuse and reflective conditions become significant when model (b is used.

  12. Delamination of plasters applied to historical masonry walls: analysis by acoustic emission technique and numerical model

    Science.gov (United States)

    Grazzini, A.; Lacidogna, G.; Valente, S.; Accornero, F.

    2018-06-01

    Masonry walls of historical buildings are subject to rising damp effects due to capillary or rain infiltrations, which in the time produce decay and delamination of historical plasters. In the restoration of masonry buildings, the plaster detachment frequently occurs because of mechanical incompatibility in repair mortar. An innovative laboratory procedure is described for test mechanical adhesion of new repair mortars. Compression static tests were carried out on composite specimens stone block-repair mortar, which specific geometry can test the de-bonding process of mortar in adherence with a stone masonry structure. The acoustic emission (AE) technique was employed for estimating the amount of energy released from fracture propagation in adherence surface between mortar and stone. A numerical simulation was elaborated based on the cohesive crack model. The evolution of detachment process of mortar in a coupled stone brick-mortar system was analysed by triangulation of AE signals, which can improve the numerical model and predict the type of failure in the adhesion surface of repair plaster. Through the cohesive crack model, it was possible to interpret theoretically the de-bonding phenomena occurring at the interface between stone block and mortar. Therefore, the mechanical behaviour of the interface is characterized.

  13. Acoustic emission-based in-process monitoring of surface generation in robot-assisted polishing

    DEFF Research Database (Denmark)

    Pilny, Lukas; Bissacco, Giuliano; De Chiffre, Leonardo

    2016-01-01

    The applicability of acoustic emission (AE) measurements for in-process monitoring of surface generation in the robot-assisted polishing (RAP) was investigated. Surface roughness measurements require interruption of the process, proper surface cleaning and measurements that sometimes necessitate...... automatic detection of optimal process endpoint allow intelligent process control, creating fundamental elements in development of robust fully automated RAP process for its widespread industrial application....... removal of the part from the machine tool. In this study, stabilisation of surface roughness during polishing rotational symmetric surfaces by the RAP process was monitored by AE measurements. An AE sensor was placed on a polishing arm in direct contact with a bonded abrasive polishing tool...

  14. Damage Accumulation in Cyclically-Loaded Glass-Ceramic Matrix Composites Monitored by Acoustic Emission

    Directory of Open Access Journals (Sweden)

    D. G. Aggelis

    2013-01-01

    Full Text Available Barium osumilite (BMAS ceramic matrix composites reinforced with SiC-Tyranno fibers are tested in a cyclic loading protocol. Broadband acoustic emission (AE sensors are used for monitoring the occurrence of different possible damage mechanisms. Improved use of AE indices is proposed by excluding low-severity signals based on waveform parameters, rather than only threshold criteria. The application of such improvements enhances the accuracy of the indices as accumulated damage descriptors. RA-value, duration, and signal energy follow the extension cycles indicating moments of maximum or minimum strain, while the frequency content of the AE signals proves very sensitive to the pull-out mechanism.

  15. Comparison between sensitivities of quality control methods using ultrasonic waves, radiography and acoustic emission for the thick welded joint testing

    International Nuclear Information System (INIS)

    Asty, Michel; Birac, Claude

    1981-09-01

    The testing of the thick welded joints of the nuclear industry is carried out by radiography and ultrasonics on completion of welding. When a fault is found, its repair requires a sometimes deep cut down to the position of the fault, then filling in of the cut by hand welding with a coated electrode. This very costly operation also involves the risk of causing new defects when building up by hand. Listening to the acoustic emission during the welding has been considered in order to seek the possibility of detecting defects when they appear, or soon after. The industrial use of this method would make an instant repair of the defective areas possible at less cost and with greater reliability. The study presented concerns the comparison between the results of the various non-destructive testing methods: radiography, ultrasonics and acoustic emission, for a thick welded joint in which the defects have been brought about [fr

  16. A Fiber-Optic Sensor for Acoustic Emission Detection in a High Voltage Cable System

    Science.gov (United States)

    Zhang, Tongzhi; Pang, Fufei; Liu, Huanhuan; Cheng, Jiajing; Lv, Longbao; Zhang, Xiaobei; Chen, Na; Wang, Tingyun

    2016-01-01

    We have proposed and demonstrated a Michelson interferometer-based fiber sensor for detecting acoustic emission generated from the partial discharge (PD) of the accessories of a high-voltage cable system. The developed sensor head is integrated with a compact and relatively high sensitivity cylindrical elastomer. Such a sensor has a broadband frequency response and a relatively high sensitivity in a harsh environment under a high-voltage electric field. The design and fabrication of the sensor head integrated with the cylindrical elastomer is described, and a series of experiments was conducted to evaluate the sensing performance. The experimental results demonstrate that the sensitivity of our developed sensor for acoustic detection of partial discharges is 1.7 rad/(m⋅Pa). A high frequency response up to 150 kHz is achieved. Moreover, the relatively high sensitivity for the detection of PD is verified in both the laboratory environment and gas insulated switchgear. The obtained results show the great potential application of a Michelson interferometer-based fiber sensor integrated with a cylindrical elastomer for in-situ monitoring high-voltage cable accessories for safety work. PMID:27916900

  17. Acoustic energy harvesting based on a planar acoustic metamaterial

    Science.gov (United States)

    Qi, Shuibao; Oudich, Mourad; Li, Yong; Assouar, Badreddine

    2016-06-01

    We theoretically report on an innovative and practical acoustic energy harvester based on a defected acoustic metamaterial (AMM) with piezoelectric material. The idea is to create suitable resonant defects in an AMM to confine the strain energy originating from an acoustic incidence. This scavenged energy is converted into electrical energy by attaching a structured piezoelectric material into the defect area of the AMM. We show an acoustic energy harvester based on a meta-structure capable of producing electrical power from an acoustic pressure. Numerical simulations are provided to analyze and elucidate the principles and the performances of the proposed system. A maximum output voltage of 1.3 V and a power density of 0.54 μW/cm3 are obtained at a frequency of 2257.5 Hz. The proposed concept should have broad applications on energy harvesting as well as on low-frequency sound isolation, since this system acts as both acoustic insulator and energy harvester.

  18. A case for Acoustic Emission surveillance of operating reactors

    International Nuclear Information System (INIS)

    Hartman, W.F.

    1985-01-01

    In the nuclear power industry, the potential consequences of cracks and leaks, the problems of personnel and public exposure to radiation, are certainly as serious as ever. The costs of repairing advanced damage soar higher every year and the established inspection methods, taken together, still leave some gaps which Acoustic Emission (AE) can potentially close. The intergranular stress corrosion cracking (IGSCC) problem not only poses safety problems, but entails remedies costing the industry billions of dollars. If crack growth could be detected during plant operation, particular welds could be designated as requiring inspection during the next outage. Furthermore, if a highly sensitive, reliable leak-detection capability were applied to the system, any through-wall crack would be instantaneously detected. AE monitoring has the potential for both of these, on-line, in real time. So, there is renewed interest in what AE can do to solve these problems. Reviewing the progress in AE, relevant to nuclear applications, indicates that a strong case can be made for AE surveillance of operating reactors. This progress can be reviewed under two headings: leak detection and crack detection

  19. Simulation of secondary emission calorimeter for future colliders

    Science.gov (United States)

    Yetkin, E. A.; Yetkin, T.; Ozok, F.; Iren, E.; Erduran, M. N.

    2018-03-01

    We present updated results from a simulation study of a conceptual sampling electromagnetic calorimeter based on secondary electron emission process. We implemented the secondary electron emission process in Geant4 as a user physics list and produced the energy spectrum and yield of secondary electrons. The energy resolution of the SEE calorimeter was σ/E = (41%) GeV1/2/√E and the response linearity to electromagnetic showers was to within 1.5%. The simulation results were also compared with a traditional scintillator calorimeter.

  20. Direct Numerical Simulation of Acoustic Noise Generation from the Nozzle Wall of a Hypersonic Wind Tunnel

    Science.gov (United States)

    Huang, Junji; Duan, Lian; Choudhari, Meelan M.

    2017-01-01

    The acoustic radiation from the turbulent boundary layer on the nozzle wall of a Mach 6 Ludwieg Tube is simulated using Direct Numerical Simulations (DNS), with the flow conditions falling within the operational range of the Mach 6 Hypersonic Ludwieg Tube, Braunschweig (HLB). The mean and turbulence statistics of the nozzle-wall boundary layer show good agreement with those predicted by Pate's correlation and Reynolds Averaged Navier-Stokes (RANS) computations. The rms pressure fluctuation P'(rms)/T(w) plateaus in the freestream core of the nozzle. The intensity of the freestream noise within the nozzle is approximately 20% higher than that radiated from a single at pate with a similar freestream Mach number, potentially because of the contributions to the acoustic radiation from multiple azimuthal segments of the nozzle wall.

  1. Simulating Gamma-Ray Emission in Star-forming Galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Pfrommer, Christoph [Leibniz-Institut für Astrophysik Potsdam (AIP), An der Sternwarte 16, D-14482 Potsdam (Germany); Pakmor, Rüdiger; Simpson, Christine M.; Springel, Volker, E-mail: cpfrommer@aip.de [Heidelberg Institute for Theoretical Studies, Schloss-Wolfsbrunnenweg 35, D-69118 Heidelberg (Germany)

    2017-10-01

    Star-forming galaxies emit GeV and TeV gamma-rays that are thought to originate from hadronic interactions of cosmic-ray (CR) nuclei with the interstellar medium. To understand the emission, we have used the moving-mesh code Arepo to perform magnetohydrodynamical galaxy formation simulations with self-consistent CR physics. Our galaxy models exhibit a first burst of star formation that injects CRs at supernovae. Once CRs have sufficiently accumulated in our Milky Way–like galaxy, their buoyancy force overcomes the magnetic tension of the toroidal disk field. As field lines open up, they enable anisotropically diffusing CRs to escape into the halo and to accelerate a bubble-like, CR-dominated outflow. However, these bubbles are invisible in our simulated gamma-ray maps of hadronic pion-decay and secondary inverse-Compton emission because of low gas density in the outflows. By adopting a phenomenological relation between star formation rate (SFR) and far-infrared emission and assuming that gamma-rays mainly originate from decaying pions, our simulated galaxies can reproduce the observed tight relation between far-infrared and gamma-ray emission, independent of whether we account for anisotropic CR diffusion. This demonstrates that uncertainties in modeling active CR transport processes only play a minor role in predicting gamma-ray emission from galaxies. We find that in starbursts, most of the CR energy is “calorimetrically” lost to hadronic interactions. In contrast, the gamma-ray emission deviates from this calorimetric property at low SFRs due to adiabatic losses, which cannot be identified in traditional one-zone models.

  2. Simulating Gamma-Ray Emission in Star-forming Galaxies

    Science.gov (United States)

    Pfrommer, Christoph; Pakmor, Rüdiger; Simpson, Christine M.; Springel, Volker

    2017-10-01

    Star-forming galaxies emit GeV and TeV gamma-rays that are thought to originate from hadronic interactions of cosmic-ray (CR) nuclei with the interstellar medium. To understand the emission, we have used the moving-mesh code Arepo to perform magnetohydrodynamical galaxy formation simulations with self-consistent CR physics. Our galaxy models exhibit a first burst of star formation that injects CRs at supernovae. Once CRs have sufficiently accumulated in our Milky Way-like galaxy, their buoyancy force overcomes the magnetic tension of the toroidal disk field. As field lines open up, they enable anisotropically diffusing CRs to escape into the halo and to accelerate a bubble-like, CR-dominated outflow. However, these bubbles are invisible in our simulated gamma-ray maps of hadronic pion-decay and secondary inverse-Compton emission because of low gas density in the outflows. By adopting a phenomenological relation between star formation rate (SFR) and far-infrared emission and assuming that gamma-rays mainly originate from decaying pions, our simulated galaxies can reproduce the observed tight relation between far-infrared and gamma-ray emission, independent of whether we account for anisotropic CR diffusion. This demonstrates that uncertainties in modeling active CR transport processes only play a minor role in predicting gamma-ray emission from galaxies. We find that in starbursts, most of the CR energy is “calorimetrically” lost to hadronic interactions. In contrast, the gamma-ray emission deviates from this calorimetric property at low SFRs due to adiabatic losses, which cannot be identified in traditional one-zone models.

  3. Diagnostics of flexible workpiece using acoustic emission, acceleration and eddy current sensors in milling operation

    Science.gov (United States)

    Filippov, A. V.; Tarasov, S. Yu.; Filippova, E. O.; Chazov, P. A.; Shamarin, N. N.; Podgornykh, O. A.

    2016-11-01

    Monitoring of the edge clamped workpiece deflection during milling has been carried our using acoustic emission, accelerometer and eddy current sensors. Such a monitoring is necessary in precision machining of vital parts used in air-space engineering where a majority of them made by milling. The applicability of the AE, accelerometers and eddy current sensors has been discussed together with the analysis of measurement errors. The appropriate sensor installation diagram has been proposed for measuring the workpiece elastic deflection exerted by the cutting force.

  4. Accoustic emission measurements during phase change

    Energy Technology Data Exchange (ETDEWEB)

    Tensi, H M; Radtke, W [Technische Univ. Muenchen (Germany, F.R.). Inst. fuer Werkstoff- und Verarbeitungswissenschaften

    1978-07-01

    Acoustic emission measurements during solidification and melting of metals are heavily disturbed by noise originating from frictional movements between crucible and specimen. These disturbances may be cancelled by means of specially arranged crucibles. Thus it was possible to use acoustic emission generated during solidification of residual eutectic liquid for real-time judgement of macrosegregation and microsegregation. With the help of crucibles made of silicone tubes the effect of melting velocity and concentration on acoustic emission generated by melting of bismuth and bismuth alloys was measured.

  5. Monte Carlo simulations of secondary electron emission due to ion beam milling

    Energy Technology Data Exchange (ETDEWEB)

    Mahady, Kyle [Univ. of Tennessee, Knoxville, TN (United States); Tan, Shida [Intel Corp., Santa Clara, CA (United States); Greenzweig, Yuval [Intel Israel Ltd., Haifa (Israel); Livengood, Richard [Intel Corp., Santa Clara, CA (United States); Raveh, Amir [Intel Israel Ltd., Haifa (Israel); Fowlkes, Jason D. [Univ. of Tennessee, Knoxville, TN (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Rack, Philip [Univ. of Tennessee, Knoxville, TN (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2017-07-01

    We present a Monte Carlo simulation study of secondary electron emission resulting from focused ion beam milling of a copper target. The basis of this study is a simulation code which simulates ion induced excitation and emission of secondary electrons, in addition to simulating focused ion beam sputtering and milling. This combination of features permits the simulation of the interaction between secondary electron emission, and the evolving target geometry as the ion beam sputters material. Previous ion induced SE Monte Carlo simulation methods have been restricted to predefined target geometries, while the dynamic target in the presented simulations makes this study relevant to image formation in ion microscopy, and chemically assisted ion beam etching, where the relationship between sputtering, and its effects on secondary electron emission, is important. We focus on a copper target, and validate our simulation against experimental data for a range of: noble gas ions, ion energies, ion/substrate angles and the energy distribution of the secondary electrons. We then provide a detailed account of the emission of secondary electrons resulting from ion beam milling; we quantify both the evolution of the yield as high aspect ratio valleys are milled, as well as the emission of electrons within these valleys that do not escape the target, but which are important to the secondary electron contribution to chemically assisted ion induced etching.

  6. Solid waves and acoustic emission first phase: Problems direct and inverse and equations elasto dynamics fields

    International Nuclear Information System (INIS)

    Suarez Antola, R.

    2002-07-01

    The present work is the first of a series of three memoirs briefs, destinadas to revise the classic theoretical foundations that allow to understand the generation,la diffusion and the detection of the elastic waves in those been accustomed to from the point of view of the mechanics of the means continuos. The study is faced in the mark of the non destructive rehearsals, emphasizing aspects related with the rehearsals based on the acoustic emission of the material defects

  7. Numerical Models for the Assessment of Historical Masonry Structures and Materials, Monitored by Acoustic Emission

    Directory of Open Access Journals (Sweden)

    Stefano Invernizzi

    2016-04-01

    Full Text Available The paper reviews some recent numerical applications for the interpretation and exploitation of acoustic emission (AE monitoring results obtained from historical masonry structures and materials. Among possible numerical techniques, the finite element method and the distinct method are considered. The analyzed numerical models cover the entire scale range, from microstructure and meso-structure, up to full-size real structures. The micro-modeling includes heterogeneous concrete-like materials, but mainly focuses on the masonry texture meso-structure, where each brick and mortar joint is modeled singularly. The full-size models consider the different typology of historical structures such as masonry towers, cathedrals and chapels. The main difficulties and advantages of the different numerical approaches, depending on the problem typology and scale, are critically analyzed. The main insight we can achieve from micro and meso numerical modeling concerns the scaling of AE as a function of volume and time, since it is also able to simulate the b-value temporal evolution as the damage spread into the structure. The finite element modeling of the whole structure provides useful hints for the optimal placement of the AE sensors, while the combination of AE monitoring results is crucial for a reliable assessment of structural safety.

  8. Arguments for fundamental emission by the parametric process L yields T + S in interplanetary type III bursts. [langmuir, electromagnetic, ion acoustic waves (L, T, S)

    Science.gov (United States)

    Cairns, I. H.

    1984-01-01

    Observations of low frequency ion acoustic-like waves associated with Langmuir waves present during interplanetary Type 3 bursts are used to study plasma emission mechanisms and wave processes involving ion acoustic waves. It is shown that the observed wave frequency characteristics are consistent with the processes L yields T + S (where L = Langmuir waves, T = electromagnetic waves, S = ion acoustic waves) and L yields L' + S proceeding. The usual incoherent (random phase) version of the process L yields T + S cannot explain the observed wave production time scale. The clumpy nature of the observed Langmuir waves is vital to the theory of IP Type 3 bursts. The incoherent process L yields T + S may encounter difficulties explaining the observed Type 3 brightness temperatures when Langmuir wave clumps are incorporated into the theory. The parametric process L yields T + S may be the important emission process for the fundamental radiation of interplanetary Type 3 bursts.

  9. An efficient closed-form solution for acoustic emission source location in three-dimensional structures

    Directory of Open Access Journals (Sweden)

    Xibing Li

    2014-02-01

    Full Text Available This paper presents an efficient closed-form solution (ECS for acoustic emission(AE source location in three-dimensional structures using time difference of arrival (TDOA measurements from N receivers, N ≥ 6. The nonlinear location equations of TDOA are simplified to linear equations. The unique analytical solution of AE sources for unknown velocity system is obtained by solving the linear equations. The proposed ECS method successfully solved the problems of location errors resulting from measured deviations of velocity as well as the existence and multiplicity of solutions induced by calculations of square roots in existed close-form methods.

  10. A discrete element and ray framework for rapid simulation of acoustical dispersion of microscale particulate agglomerations

    Science.gov (United States)

    Zohdi, T. I.

    2016-03-01

    In industry, particle-laden fluids, such as particle-functionalized inks, are constructed by adding fine-scale particles to a liquid solution, in order to achieve desired overall properties in both liquid and (cured) solid states. However, oftentimes undesirable particulate agglomerations arise due to some form of mutual-attraction stemming from near-field forces, stray electrostatic charges, process ionization and mechanical adhesion. For proper operation of industrial processes involving particle-laden fluids, it is important to carefully breakup and disperse these agglomerations. One approach is to target high-frequency acoustical pressure-pulses to breakup such agglomerations. The objective of this paper is to develop a computational model and corresponding solution algorithm to enable rapid simulation of the effect of acoustical pulses on an agglomeration composed of a collection of discrete particles. Because of the complex agglomeration microstructure, containing gaps and interfaces, this type of system is extremely difficult to mesh and simulate using continuum-based methods, such as the finite difference time domain or the finite element method. Accordingly, a computationally-amenable discrete element/discrete ray model is developed which captures the primary physical events in this process, such as the reflection and absorption of acoustical energy, and the induced forces on the particulate microstructure. The approach utilizes a staggered, iterative solution scheme to calculate the power transfer from the acoustical pulse to the particles and the subsequent changes (breakup) of the pulse due to the particles. Three-dimensional examples are provided to illustrate the approach.

  11. Analysis of Measured and Simulated Supraglottal Acoustic Waves.

    Science.gov (United States)

    Fraile, Rubén; Evdokimova, Vera V; Evgrafova, Karina V; Godino-Llorente, Juan I; Skrelin, Pavel A

    2016-09-01

    To date, although much attention has been paid to the estimation and modeling of the voice source (ie, the glottal airflow volume velocity), the measurement and characterization of the supraglottal pressure wave have been much less studied. Some previous results have unveiled that the supraglottal pressure wave has some spectral resonances similar to those of the voice pressure wave. This makes the supraglottal wave partially intelligible. Although the explanation for such effect seems to be clearly related to the reflected pressure wave traveling upstream along the vocal tract, the influence that nonlinear source-filter interaction has on it is not as clear. This article provides an insight into this issue by comparing the acoustic analyses of measured and simulated supraglottal and voice waves. Simulations have been performed using a high-dimensional discrete vocal fold model. Results of such comparative analysis indicate that spectral resonances in the supraglottal wave are mainly caused by the regressive pressure wave that travels upstream along the vocal tract and not by source-tract interaction. On the contrary and according to simulation results, source-tract interaction has a role in the loss of intelligibility that happens in the supraglottal wave with respect to the voice wave. This loss of intelligibility mainly corresponds to spectral differences for frequencies above 1500 Hz. Copyright © 2016 The Voice Foundation. Published by Elsevier Inc. All rights reserved.

  12. Mesoscale analysis of failure in quasi-brittle materials: comparison between lattice model and acoustic emission data.

    Science.gov (United States)

    Grégoire, David; Verdon, Laura; Lefort, Vincent; Grassl, Peter; Saliba, Jacqueline; Regoin, Jean-Pierre; Loukili, Ahmed; Pijaudier-Cabot, Gilles

    2015-10-25

    The purpose of this paper is to analyse the development and the evolution of the fracture process zone during fracture and damage in quasi-brittle materials. A model taking into account the material details at the mesoscale is used to describe the failure process at the scale of the heterogeneities. This model is used to compute histograms of the relative distances between damaged points. These numerical results are compared with experimental data, where the damage evolution is monitored using acoustic emissions. Histograms of the relative distances between damage events in the numerical calculations and acoustic events in the experiments exhibit good agreement. It is shown that the mesoscale model provides relevant information from the point of view of both global responses and the local failure process. © 2015 The Authors. International Journal for Numerical and Analytical Methods in Geomechanics published by John Wiley & Sons Ltd.

  13. Listening in on Friction: Stick-Slip Acoustical Signatures in Velcro

    Science.gov (United States)

    Hurtado Parra, Sebastian; Morrow, Leslie; Radziwanowski, Miles; Angiolillo, Paul

    2013-03-01

    The onset of kinetic friction and the possible resulting stick-slip motion remain mysterious phenomena. Moreover, stick-slip dynamics are typically accompanied by acoustic bursts that occur temporally with the slip event. The dry sliding dynamics of the hook-and-loop system, as exemplified by Velcro, manifest stick-slip behavior along with audible bursts that are easily micrphonically collected. Synchronized measurements of the friction force and acoustic emissions were collected as hooked Velcro was driven at constant velocity over a bed of looped Velcro in an anechoic chamber. Not surprising, the envelope of the acoustic bursts maps well onto the slip events of the friction force time series and the intensity of the bursts trends with the magnitude of the difference of the friction force during a stick-slip event. However, the analysis of the acoustic emission can serve as a sensitive tool for revealing some of the hidden details of the evolution of the transition from static to kinetic friction. For instance, small acoustic bursts are seen prior to the Amontons-Coulomb threshold, signaling precursor events prior to the onset of macroscopically observed motion. Preliminary spectral analysis of the acoustic emissions including intensity-frequency data will be presented.

  14. Solar radio emissions: 2D full PIC simulations

    Science.gov (United States)

    Pierre, H.; Sgattoni, A.; Briand, C.; Amiranoff, F.; Riconda, C.

    2016-12-01

    Solar radio emissions are electromagnetic waves observed at the local plasma frequency and/or at twice the plasma frequency. To describe their origin a multi-stage model has been proposed by Ginzburg & Zhelezniakov (1958) and further developed by several authors, which consider a succession of non-linear three-wave interaction processes. Electron beams accelerated by solar flares travel in the interplanetary plasma and provide the free energy for the development of plasma instabilities. The model describes how part of the free energy of these beams can be transformed in a succession of plasma waves and eventually into electromagnetic waves. Following the work of Thurgood & Tsiklauri (2015) we performed several 2D Particle In Cell simulations. The simulations follow the entire set of processes from the electron beam propagation in the background plasma to the generation of the electromagnetic waves in particular the 2ωp emission, including the excitation of the low frequency waves. As suggested by Thurgood & Tsiklauri (2015) it is possible to identify regimes where the radiation emission can be directly linked to the electron beams. Our attention was devoted to estimate the conversion efficiency from electron kinetic energy to the em energy, and the growth rate of the several processes which can be identified. We studied the emission angles of the 2ωpradiation and compared them with the theoretical predictions of Willes et. al. (1995). We also show the role played by some numerical parameters i.e. the size and shape of the simulation box. This work is the first step to prepare laser-plasma experiments. V. L. Ginzburg, V. V. Zhelezniakov On the Possible Mechanisms of Sporadic Solar Radio Emission (Radiation in an Isotropic Plasma) Soviet Astronomy, Vol. 2, p.653 (1958) J. O. Thurgood and D. Tsiklauri Self-consistent particle-in-cell simulations of funda- mental and harmonic plasma radio emission mechanisms. Astronomy & Astrophysics 584, A83 (2015). A. Willes, P

  15. Analysis of Precursors Prior to Rock Burst in Granite Tunnel Using Acoustic Emission and Far Infrared Monitoring

    Directory of Open Access Journals (Sweden)

    Zhengzhao Liang

    2013-01-01

    Full Text Available To understand the physical mechanism of the anomalous behaviors observed prior to rock burst, the acoustic emission (AE and far infrared (FIR techniques were applied to monitor the progressive failure of a rock tunnel model subjected to biaxial stresses. Images of fracturing process, temperature changes of the tunnel, and spatiotemporal serials of acoustic emission were simultaneously recorded during deformation of the model. The b-value derived from the amplitude distribution data of AE was calculated to predict the tunnel rock burst. The results showed that the vertical stress enhanced the stability of the tunnel, and the tunnels with higher confining pressure demonstrated a more abrupt and strong rock burst. Abnormal temperature changes around the wall were observed prior to the rock burst of the tunnel. Analysis of the AE events showed that a sudden drop and then a quiet period could be considered as the precursors to forecast the rock burst hazard. Statistical analysis indicated that rock fragment spalling occurred earlier than the abnormal temperature changes, and the abnormal temperature occurred earlier than the descent of the AE b-value. The analysis indicated that the temperature changes were more sensitive than the AE b-value changes to predict the tunnel rock bursts.

  16. Simulation and Optimization of Surface Acoustic Wave Devises

    DEFF Research Database (Denmark)

    Dühring, Maria Bayard

    2007-01-01

    In this paper a method to model the interaction of the mechanical field from a surface acoustic wave and the optical field in the waveguides of a Mach-Zehnder interferometer is presented. The surface acoustic waves are generated by interdigital transducers using a plane strain model...... in effective refractive index introduced in the Mach-Zehnder interferometer arms by the stresses from the surface acoustic wave is calculated. It is shown that the effective refractive index of the fundamental optical mode increases at a surface acoustic wave crest and decreases at a trough. The height...... of a piezoelectric, inhomogeneous material and reflections from the boundaries are avoided by applying perfectly matched layers. The optical modes in the waveguides are modeled by the time-harmonic wave equation for the magnetic field. The two models are coupled using the stress-optical relation and the change...

  17. Coupling creep and damage in concrete under high sustained loading: Experimental investigation on bending beams and application of Acoustic Emission technique

    Directory of Open Access Journals (Sweden)

    Grondin F.

    2010-06-01

    had a strengthening effect on concrete, probably because of the consolidation of the hardened cement paste. The influence of creep on fracture energy, fracture toughness, and characteristic length of concrete is also studied. The fracture energy and the characteristic length of concrete increases slightly when creep occurs prior to failure and the size of the fracture process zone increases too. The load-CMOD relationship is linear in the ascending portion and gradually drops off after the peak value in the descending portion. The length of the tail end portion of the softening curve increases with beams subjected to creep. Relatively more ductile fracture behavior was observed with beams subjected to creep. The contribution of non-destructive and instrumental investigation methods is currently exploited to check and measure the evolution of some negative structural phenomena, such as micro-and macro-cracking, finally resulting in a creep-like behaviour. Among these methods, the non-destructive technique based on acoustic Emission proves to be very effective, especially to check and measure micro-cracking that takes place inside a structure under mechanical loading. Thus as a part of the investigation quantitative acoustic emission techniques were applied to investigate microcracking and damage localization in concrete beams. The AE signals were captured with the AE WIN software and further analyzed with Noesis software analysis of acoustic emission data. AE waveforms were generated as elastic waves in concrete due to crack nucleation. And a multichannel data acquisition system was used to record the AE waveforms. During the three point bending tests, quantitative acoustic emission (AE techniques were used to monitor crack growth and to deduce micro fracture mechanics in concrete beams before and after creep. Several specimens are experimented in order to match each cluster with corresponding damage mechanism of the material under loading. At the same time acoustic

  18. Coupling creep and damage in concrete under high sustained loading: Experimental investigation on bending beams and application of Acoustic Emission technique

    Science.gov (United States)

    Saliba, J.; Loukili, A.; Grondin, F.

    2010-06-01

    effect on concrete, probably because of the consolidation of the hardened cement paste. The influence of creep on fracture energy, fracture toughness, and characteristic length of concrete is also studied. The fracture energy and the characteristic length of concrete increases slightly when creep occurs prior to failure and the size of the fracture process zone increases too. The load-CMOD relationship is linear in the ascending portion and gradually drops off after the peak value in the descending portion. The length of the tail end portion of the softening curve increases with beams subjected to creep. Relatively more ductile fracture behavior was observed with beams subjected to creep. The contribution of non-destructive and instrumental investigation methods is currently exploited to check and measure the evolution of some negative structural phenomena, such as micro-and macro-cracking, finally resulting in a creep-like behaviour. Among these methods, the non-destructive technique based on acoustic Emission proves to be very effective, especially to check and measure micro-cracking that takes place inside a structure under mechanical loading. Thus as a part of the investigation quantitative acoustic emission techniques were applied to investigate microcracking and damage localization in concrete beams. The AE signals were captured with the AE WIN software and further analyzed with Noesis software analysis of acoustic emission data. AE waveforms were generated as elastic waves in concrete due to crack nucleation. And a multichannel data acquisition system was used to record the AE waveforms. During the three point bending tests, quantitative acoustic emission (AE) techniques were used to monitor crack growth and to deduce micro fracture mechanics in concrete beams before and after creep. Several specimens are experimented in order to match each cluster with corresponding damage mechanism of the material under loading. At the same time acoustic emission was used to

  19. Standard practice for examination of Gas-Filled filament-wound composite pressure vessels using acoustic emission

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2010-01-01

    1.1 This practice provides guidelines for acoustic emission (AE) examination of filament-wound composite pressure vessels, for example, the type used for fuel tanks in vehicles which use natural gas fuel. 1.2 This practice requires pressurization to a level equal to or greater than what is encountered in normal use. The tanks' pressurization history must be known in order to use this practice. Pressurization medium may be gas or liquid. 1.3 This practice is limited to vessels designed for less than 690 bar [10,000 psi] maximum allowable working pressure and water volume less than 1 m3 or 1000 L [35.4 ft3]. 1.4 AE measurements are used to detect emission sources. Other nondestructive examination (NDE) methods may be used to gain additional insight into the emission source. Procedures for other NDE methods are beyond the scope of this practice. 1.5 This practice applies to examination of new and in-service filament-wound composite pressure vessels. 1.6 This practice applies to examinations conducted at amb...

  20. Study of the loading mode dependence of the twinning in random textured cast magnesium by acoustic emission and neutron diffraction methods

    Czech Academy of Sciences Publication Activity Database

    Čapek, J.; Máthis, K.; Clausen, B.; Stráská, J.; Beran, Přemysl; Lukáš, Petr

    2014-01-01

    Roč. 602, APR (2014), s. 25-32 ISSN 0921-5093 R&D Projects: GA ČR(CZ) GAP204/12/1360 Institutional support: RVO:61389005 Keywords : magnesium * acoustic emission * neutron diffraction * deformation twinning Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.567, year: 2014

  1. Acoustic Emission Analysis of Prestressed Concrete Structures

    Science.gov (United States)

    Elfergani, H. A.; Pullin, R.; Holford, K. M.

    2011-07-01

    Corrosion is a substantial problem in numerous structures and in particular corrosion is very serious in reinforced and prestressed concrete and must, in certain applications, be given special consideration because failure may result in loss of life and high financial cost. Furthermore corrosion cannot only be considered a long term problem with many studies reporting failure of bridges and concrete pipes due to corrosion within a short period after they were constructed. The concrete pipes which transport water are examples of structures that have suffered from corrosion; for example, the pipes of The Great Man-Made River Project of Libya. Five pipe failures due to corrosion have occurred since their installation. The main reason for the damage is corrosion of prestressed wires in the pipes due to the attack of chloride ions from the surrounding soil. Detection of the corrosion in initial stages has been very important to avoid other failures and the interruption of water flow. Even though most non-destructive methods which are used in the project are able to detect wire breaks, they cannot detect the presence of corrosion. Hence in areas where no excavation has been completed, areas of serious damage can go undetected. Therefore, the major problem which faces engineers is to find the best way to detect the corrosion and prevent the pipes from deteriorating. This paper reports on the use of the Acoustic Emission (AE) technique to detect the early stages of corrosion prior to deterioration of concrete structures.

  2. Acoustic Emission Analysis of Prestressed Concrete Structures

    International Nuclear Information System (INIS)

    Elfergani, H A; Pullin, R; Holford, K M

    2011-01-01

    Corrosion is a substantial problem in numerous structures and in particular corrosion is very serious in reinforced and prestressed concrete and must, in certain applications, be given special consideration because failure may result in loss of life and high financial cost. Furthermore corrosion cannot only be considered a long term problem with many studies reporting failure of bridges and concrete pipes due to corrosion within a short period after they were constructed. The concrete pipes which transport water are examples of structures that have suffered from corrosion; for example, the pipes of The Great Man-Made River Project of Libya. Five pipe failures due to corrosion have occurred since their installation. The main reason for the damage is corrosion of prestressed wires in the pipes due to the attack of chloride ions from the surrounding soil. Detection of the corrosion in initial stages has been very important to avoid other failures and the interruption of water flow. Even though most non-destructive methods which are used in the project are able to detect wire breaks, they cannot detect the presence of corrosion. Hence in areas where no excavation has been completed, areas of serious damage can go undetected. Therefore, the major problem which faces engineers is to find the best way to detect the corrosion and prevent the pipes from deteriorating. This paper reports on the use of the Acoustic Emission (AE) technique to detect the early stages of corrosion prior to deterioration of concrete structures.

  3. Aespoe Hard Rock Laboratory. Prototype Repository. Acoustic emission and ultrasonic monitoring results from deposition hole DA3545G01 in the Prototype Repository between October 2007 and March 2008

    Energy Technology Data Exchange (ETDEWEB)

    Duckworth, D.; Haycox, J.; Pettitt, W.S. (Applied Seismology Consultants, Shrewsbury (United Kingdom))

    2008-12-15

    This report describes results from acoustic emission (AE) and ultrasonic monitoring around a canister deposition hole (DA3545G01) in the Prototype Repository Experiment at SKB's Hard Rock Laboratory (HRL), Sweden. The experiment has been designed to simulate a disposal tunnel in a real deep repository environment for storage of high-level radioactive waste. The test consists of a 90 m long, 5 m diameter subhorizontal tunnel excavated in dioritic granite. The monitoring aims to examine changes in the rock mass caused by an experimental repository environment, in particular due to thermal stresses induced from canister heating and pore pressures induced from tunnel sealing.

  4. Aespoe Hard Rock Laboratory. Prototype Repository. Acoustic emission and ultrasonic monitoring results from deposition hole DA3545G01 in the Prototype Repository between October 2007 and March 2008

    International Nuclear Information System (INIS)

    Duckworth, D.; Haycox, J.; Pettitt, W.S.

    2008-12-01

    This report describes results from acoustic emission (AE) and ultrasonic monitoring around a canister deposition hole (DA3545G01) in the Prototype Repository Experiment at SKB's Hard Rock Laboratory (HRL), Sweden. The experiment has been designed to simulate a disposal tunnel in a real deep repository environment for storage of high-level radioactive waste. The test consists of a 90 m long, 5 m diameter subhorizontal tunnel excavated in dioritic granite. The monitoring aims to examine changes in the rock mass caused by an experimental repository environment, in particular due to thermal stresses induced from canister heating and pore pressures induced from tunnel sealing

  5. Evaluation of temper embrittlement of martensitic and ferritic-martensitic steels by acoustic emission

    International Nuclear Information System (INIS)

    Lu, Yusho; Takahashi, Hideaki; Shoji, Tetsuo

    1987-01-01

    Martensitic (HT-9) and ferritic-martensitic steels (9Cr-2Mo) are considered as fusion first wall materials. In this investigation in order to understand the sensitivity of temper embrittlement in these steels under actual service condition, fracture toughness testing was made by use of acoustic emission technique. The temper embrittlement was characterized in terms of fracture toughness. The fracture toughness of these steels under 500 deg C, 100 hrs, and 1000 hrs heat treatment was decreased and their changes in micro-fracture process have been observed. The fracture toughness changes by temper embrittlement was discussed by the characteristic of AE, AE spectrum analysis and fractographic investigation. The relation between micro-fracture processes and AE has been clarified. (author)

  6. Standard practice for examination of seamless, Gas-Filled, pressure vessels using acoustic emission

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2009-01-01

    1.1 This practice provides guidelines for acoustic emission (AE) examinations of seamless pressure vessels (tubes) of the type used for distribution or storage of industrial gases. 1.2 This practice requires pressurization to a level greater than normal use. Pressurization medium may be gas or liquid. 1.3 This practice does not apply to vessels in cryogenic service. 1.4 The AE measurements are used to detect and locate emission sources. Other nondestructive test (NDT) methods must be used to evaluate the significance of AE sources. Procedures for other NDT techniques are beyond the scope of this practice. See Note 1. Note 1—Shear wave, angle beam ultrasonic examination is commonly used to establish circumferential position and dimensions of flaws that produce AE. Time of Flight Diffraction (TOFD), ultrasonic examination is also commonly used for flaw sizing. 1.5 The values stated in inch-pound units are to be regarded as the standard. The values given in parentheses are for information only. 1.6 This standa...

  7. Investigation of active vibration drilling using acoustic emission and cutting size analysis

    Directory of Open Access Journals (Sweden)

    Yingjian Xiao

    2018-04-01

    Full Text Available This paper describes an investigation of active bit vibration on the penetration mechanisms and bit-rock interaction for drilling with a diamond impregnated coring bit. A series of drill-off tests (DOTs were conducted where the drilling rate-of-penetration (ROP was measured at a series of step-wise increasing static bit thrusts or weight-on-bits (WOBs. Two active DOTs were conducted by applying 60 Hz axial vibration at the bit-rock interface using an electromagnetic vibrating table mounted underneath the drilling samples, and a passive DOT was conducted where the bit was allowed to vibrate naturally with lower amplitude due to the compliance of the drilling sample mountings. During drilling, an acoustic emission (AE system was used to record the AE signals generated by the diamond cutter penetration and the cuttings were collected for grain size analysis. The instrumented drilling system recorded the dynamic motions of the bit-rock interface using a laser displacement sensor, a load cell, and an LVDT (linear variable differential transformer recorded the dynamic WOB and the ROP, respectively. Calibration with the drilling system showed that rotary speed was approximately the same at any given WOB, facilitating comparison of the results at the same WOB. Analysis of the experimental results shows that the ROP of the bit at any given WOB increased with higher amplitude of axial bit-rock vibration, and the drill cuttings increased in size with a higher ROP. Spectral analysis of the AEs indicated that the higher ROP and larger cutting size were correlated with a higher AE energy and a lower AE frequency. This indicated that larger fractures were being created to generate larger cutting size. Overall, these results indicate that a greater magnitude of axial bit-rock vibration produces larger fractures and generates larger cuttings which, at the same rotary speed, results in a higher ROP. Keywords: Active bit vibration, Diamond coring drilling, Drill

  8. Acoustic energy propagation around railways

    Science.gov (United States)

    Cizkova, Petra

    2017-09-01

    The article deals with the issues of acoustic energy propagation around railways. The research subject was noise emission spreading into the surroundings during the passage of trains over a directly travelled steel bridge construction. Noise emissions were measured using direct measurements in the field. The measurements were performed in two measurement profiles. The noise exposures A LAE measured near the steel bridge construction were compared against the noise exposures A LAE captured on an open track. From the difference of these data, the noise level of the steel bridge structure was determined. Part of the research was to evaluate the effect of the reconstruction of the railway track superstructure on the acoustic situation in the given section of the railway track. The article describes the methodology of measurements, including the processing and evaluation of measured data. The article points out the noise levels of the steel bridge construction and assesses changes in the acoustic situation after the reconstruction.

  9. Time-resolved tomography using acoustic emissions in the laboratory, and application to sandstone compaction

    Science.gov (United States)

    Brantut, Nicolas

    2018-06-01

    Acoustic emission (AE) and active ultrasonic wave velocity monitoring are often performed during laboratory rock deformation experiments, but are typically processed separately to yield homogenized wave velocity measurements and approximate source locations. Here, I present a numerical method and its implementation in a free software to perform a joint inversion of AE locations together with the 3-D, anisotropic P-wave structure of laboratory samples. The data used are the P-wave first arrivals obtained from AEs and active ultrasonic measurements. The model parameters are the source locations and the P-wave velocity and anisotropy parameter (assuming transverse isotropy) at discrete points in the material. The forward problem is solved using the fast marching method, and the inverse problem is solved by the quasi-Newton method. The algorithms are implemented within an integrated free software package called FaATSO (Fast Marching Acoustic Emission Tomography using Standard Optimisation). The code is employed to study the formation of compaction bands in a porous sandstone. During deformation, a front of AEs progresses from one end of the sample, associated with the formation of a sequence of horizontal compaction bands. Behind the active front, only sparse AEs are observed, but the tomography reveals that the P-wave velocity has dropped by up to 15 per cent, with an increase in anisotropy of up to 20 per cent. Compaction bands in sandstones are therefore shown to produce sharp changes in seismic properties. This result highlights the potential of the methodology to image temporal variations of elastic properties in complex geomaterials, including the dramatic, localized changes associated with microcracking and damage generation.

  10. Beam Dynamics Simulations of Optically-Enhanced Field Emission from Structured Cathodes

    Energy Technology Data Exchange (ETDEWEB)

    Seymour, A. [Northern Illinois U.; Grote, D. [LLNL, Livermore; Mihalcea, D. [Northern Illinois U.; Piot, P. [Fermilab; Vay, J.-L. [LBNL, Berkeley

    2014-01-01

    Structured cathodes - cathodes with a segmented emission surface - are finding an increasing number of applications and can be combined with a variety of emission mechanisms, including photoemission and field emission. These cathodes have been used to enhance the quantum efficiency of metallic cathodes when operated as plasmonic cathodes, have produced high-current electron bunches though field emission from multiple tips, and can be used to form beams with transverse segmentations necessary for improving the performance of accelerator-based light sources. In this report we present recent progress towards the development of finite-difference time-domain particle-in-cell simulations using the emission process in structured cathodes based on the WARP framework. The simulations give further insight on the localized source of the emitted electrons which could be used for additional high-fidelity start-to-end simulations of electron accelerators that employ this type of electron source.

  11. Aero-acoustic Computations of Wind Turbines

    DEFF Research Database (Denmark)

    Shen, Wen Zhong; Michelsen, Jess; Sørensen, Jens Nørkær

    2002-01-01

    A numerical algorithm for acoustic noise generation is extended to 3D flows. The approach involves two parts comprising a viscous incompressible flow part and an inviscid acoustic part. In order to simulate noise generated from a wind turbine, the incompressible and acoustic equations are written...

  12. Acoustic emission of heat treated compared graphite iron under 873-1173 K

    Energy Technology Data Exchange (ETDEWEB)

    Nam, Ki Woo; Lee, Soo Chul [Pukyong National University, Busan (Korea, Republic of); Ahn, Byung Kun [Korea Polytechnic, Busan Campus, Busan (Korea, Republic of)

    2013-10-15

    CGI is gaining popularity in applications that require either greater strength, or lower weight than cast iron. Recently, compacted graphite iron has been used for diesel engine blocks, turbo housings and exhaust manifolds. This paper were assessed acoustic emission characteristics according to the mechanical properties change of degraded CGI340 during 1-24 hours at 873-1173 K. In results of pencil lead fracture test, the dominant frequency and the velocity of base metal were 97 kHz and 5490 m/sec, respectively. The base metal in a tensile test was obtained relatively high dominant frequency. However, the heat treated materials, the longer the heat treatment time, the higher the heat treatment temperature, were obtained in the area of lower frequencies. This phenomenon appears by long-term use.

  13. Acoustic emission of heat treated compared graphite iron under 873-1173 K

    International Nuclear Information System (INIS)

    Nam, Ki Woo; Lee, Soo Chul; Ahn, Byung Kun

    2013-01-01

    CGI is gaining popularity in applications that require either greater strength, or lower weight than cast iron. Recently, compacted graphite iron has been used for diesel engine blocks, turbo housings and exhaust manifolds. This paper were assessed acoustic emission characteristics according to the mechanical properties change of degraded CGI340 during 1-24 hours at 873-1173 K. In results of pencil lead fracture test, the dominant frequency and the velocity of base metal were 97 kHz and 5490 m/sec, respectively. The base metal in a tensile test was obtained relatively high dominant frequency. However, the heat treated materials, the longer the heat treatment time, the higher the heat treatment temperature, were obtained in the area of lower frequencies. This phenomenon appears by long-term use.

  14. Electrical circuit modeling and analysis of microwave acoustic interaction with biological tissues.

    Science.gov (United States)

    Gao, Fei; Zheng, Qian; Zheng, Yuanjin

    2014-05-01

    Numerical study of microwave imaging and microwave-induced thermoacoustic imaging utilizes finite difference time domain (FDTD) analysis for simulation of microwave and acoustic interaction with biological tissues, which is time consuming due to complex grid-segmentation and numerous calculations, not straightforward due to no analytical solution and physical explanation, and incompatible with hardware development requiring circuit simulator such as SPICE. In this paper, instead of conventional FDTD numerical simulation, an equivalent electrical circuit model is proposed to model the microwave acoustic interaction with biological tissues for fast simulation and quantitative analysis in both one and two dimensions (2D). The equivalent circuit of ideal point-like tissue for microwave-acoustic interaction is proposed including transmission line, voltage-controlled current source, envelop detector, and resistor-inductor-capacitor (RLC) network, to model the microwave scattering, thermal expansion, and acoustic generation. Based on which, two-port network of the point-like tissue is built and characterized using pseudo S-parameters and transducer gain. Two dimensional circuit network including acoustic scatterer and acoustic channel is also constructed to model the 2D spatial information and acoustic scattering effect in heterogeneous medium. Both FDTD simulation, circuit simulation, and experimental measurement are performed to compare the results in terms of time domain, frequency domain, and pseudo S-parameters characterization. 2D circuit network simulation is also performed under different scenarios including different sizes of tumors and the effect of acoustic scatterer. The proposed circuit model of microwave acoustic interaction with biological tissue could give good agreement with FDTD simulated and experimental measured results. The pseudo S-parameters and characteristic gain could globally evaluate the performance of tumor detection. The 2D circuit network

  15. Compaction of a Bed of Fragmentable Particles and Associated Acoustic Emission

    International Nuclear Information System (INIS)

    Hegron, L.; Sornay, P.; Favretto-Cristini, N.

    2013-06-01

    The nuclear fuel of light water power reactors are manufactured by powder metallurgy. This is also the method that is used for the production of fuels containing minor actinides that have high activity and long life. Given their radiotoxicity, it is necessary to simplify the manufacturing process to the maximum, limiting dissemination and retention of matter. In addition, the fuel must have a mostly open porosity. Implementation of particles of a few hundred micrometers and controlled cohesion could meet this dual objective. However, it should be ensured that the mechanical strength of compacts before sintering is sufficient without adding binder. The phenomena that occur during the manufacture of compact are thus analyzed and quantified. It is shown that only a portion of the particles breaks upon application of a stress up to 600 MPa and it is possible to detect this fragmentation by acoustic emission (AE). (authors)

  16. A Fiber-Optic Sensor for Acoustic Emission Detection in a High Voltage Cable System

    Directory of Open Access Journals (Sweden)

    Tongzhi Zhang

    2016-11-01

    Full Text Available We have proposed and demonstrated a Michelson interferometer-based fiber sensor for detecting acoustic emission generated from the partial discharge (PD of the accessories of a high-voltage cable system. The developed sensor head is integrated with a compact and relatively high sensitivity cylindrical elastomer. Such a sensor has a broadband frequency response and a relatively high sensitivity in a harsh environment under a high-voltage electric field. The design and fabrication of the sensor head integrated with the cylindrical elastomer is described, and a series of experiments was conducted to evaluate the sensing performance. The experimental results demonstrate that the sensitivity of our developed sensor for acoustic detection of partial discharges is 1.7 rad / ( m ⋅ Pa . A high frequency response up to 150 kHz is achieved. Moreover, the relatively high sensitivity for the detection of PD is verified in both the laboratory environment and gas insulated switchgear. The obtained results show the great potential application of a Michelson interferometer-based fiber sensor integrated with a cylindrical elastomer for in-situ monitoring high-voltage cable accessories for safety work.

  17. Multi reflection of Lamb wave emission in an acoustic waveguide sensor.

    Science.gov (United States)

    Schmitt, Martin; Olfert, Sergei; Rautenberg, Jens; Lindner, Gerhard; Henning, Bernd; Reindl, Leonhard Michael

    2013-02-27

    Recently, an acoustic waveguide sensor based on multiple mode conversion of surface acoustic waves at the solid-liquid interfaces has been introduced for the concentration measurement of binary and ternary mixtures, liquid level sensing, investigation of spatial inhomogenities or bubble detection. In this contribution the sound wave propagation within this acoustic waveguide sensor is visualized by Schlieren imaging for continuous and burst operation the first time. In the acoustic waveguide the antisymmetrical zero order Lamb wave mode is excited by a single phase transducer of 1 MHz on thin glass plates of 1 mm thickness. By contact to the investigated liquid Lamb waves propagating on the first plate emit pressure waves into the adjacent liquid, which excites Lamb waves on the second plate, what again causes pressure waves traveling inside the liquid back to the first plate and so on. The Schlieren images prove this multi reflection within the acoustic waveguide, which confirms former considerations and calculations based on the receiver signal. With this knowledge the sensor concepts with the acoustic waveguide sensor can be interpreted in a better manner.

  18. Auto-inflammatory challenge of the endolymphatic sac - Cochlear damage measured by distortion product oto-acoustic emissions

    DEFF Research Database (Denmark)

    Larsen, Michael; Friis, Morten; Karlsen, Charlotte Vestrup

    2015-01-01

    CONCLUSION: Twenty-five rats were challenged by an immunologic attack of the endolymphatic sac. After 6 months, distortion product oto-acoustic emissions (DPOAE) revealed a dysfunction of the outer hair cells and immunological active cells were observed in the endolymphatic sac. This information...... could contribute to the understanding of Ménière's disease. OBJECTIVES: This study investigated if an autoimmune challenge of the endolymphatic sac could affect DPOAE output measurements in rats. Also, a potential autoimmune cell infiltration of the endolymphatic sac was investigated. METHODS: Eighteen...

  19. An overview of development and application of acoustic emission methods in the United States

    International Nuclear Information System (INIS)

    Hutten, P.H.

    1989-01-01

    Beneficial uses being made of acoustic emission (AE) technology for flaw or fault detection both inside of and outside of the nuclear industry tend to be obscured by some of the earlier disappointing efforts to utilize the technology. The objective of this paper is to counter that tendency by providing an overview of a variety of AE applications being made in the United States. In addition to nuclear power applications, the paper discusses applications in other nuclear areas, fossil power plant applications, and other industrial uses including aircraft monitoring. Major AE research and development programs in progress in the United States are also summarized. (orig.)

  20. Acoustic leak detection at complicated geometrical structures using fuzzy logic and neural networks

    International Nuclear Information System (INIS)

    Hessel, G.; Schmitt, W.; Weiss, F.P.

    1993-10-01

    An acoustic method based on pattern recognition is being developed. During the learning phase, the localization classifier is trained with sound patterns that are generated with simulated leaks at all locations endangered by leak. The patterns are extracted from the signals of an appropriate sensor array. After training unknown leak positions can be recognized through comparison with the training patterns. The experimental part is performed at an acoustic 1:3 model of the reactor vessel and head and at an original VVER-440 reactor in the former NPP Greifswald. The leaks were simulated at the vessel head using mobile sound sources driven either by compressed air, a piezoelectric transmitter or by a thin metal blade excited through a jet of compressed air. The sound patterns of the simulated leaks are simultaneously detected with an AE-sensor array and with high frequency microphones measuring structure-borne sound and airborne sound, respectively. Pattern classifiers based on Fuzzy Pattern Classification (FPC) and Artificial Neural Networks (ANN) are currently tested for validation of the acoustic emission-sensor array (FPC), leak localization via structure-borne sound (FPC) and the leak localization using microphones (ANN). The initial results show the used classifiers principally to be capable of detecting and locating leaks, but they also show that further investigations are necessary to develop a reliable method applicable at NPPs. (orig./HP)

  1. Education in acoustics in Argentina

    Science.gov (United States)

    Miyara, Federico

    2002-11-01

    Over the last decades, education in acoustics (EA) in Argentina has experienced ups and downs due to economic and political issues interfering with long term projects. Unlike other countries, like Chile, where EA has reached maturity in spite of the acoustical industry having shown little development, Argentina has several well-established manufacturers of acoustic materials and equipment but no specific career with a major in acoustics. At the university level, acoustics is taught as a complementary--often elective--course for careers such as architecture, communication engineering, or music. In spite of this there are several research centers with programs covering environmental and community noise, effects of noise on man, acoustic signal processing, musical acoustics and acoustic emission, and several national and international meetings are held each year in which results are communicated and discussed. Several books on a variety of topics such as sound system, architectural acoustics, and noise control have been published as well. Another chapter in EA is technical and vocational education, ranging between secondary and postsecondary levels, with technical training on sound system operation or design. Over the last years there have been several attempts to implement master degrees in acoustics or audio engineering, with little or no success.

  2. Micromachined silicon acoustic delay line with improved structural stability and acoustic directivity for real-time photoacoustic tomography

    Science.gov (United States)

    Cho, Young; Kumar, Akhil; Xu, Song; Zou, Jun

    2017-03-01

    Recent studies have shown that micromachined silicon acoustic delay lines can provide a promising solution to achieve real-time photoacoustic tomography without the need for complex transducer arrays and data acquisition electronics. However, as its length increases to provide longer delay time, the delay line becomes more vulnerable to structural instability due to reduced mechanical stiffness. In addition, the small cross-section area of the delay line results in a large acoustic acceptance angle and therefore poor directivity. To address these two issues, this paper reports the design, fabrication, and testing of a new silicon acoustic delay line enhanced with 3D printed polymer micro linker structures. First, mechanical deformation of the silicon acoustic delay line (with and without linker structures) under gravity was simulated by using finite element method. Second, the acoustic crosstalk and acoustic attenuation caused by the polymer micro linker structures were evaluated with both numerical simulation and ultrasound transmission testing. The result shows that the use of the polymer micro linker structures significantly improves the structural stability of the silicon acoustic delay lines without creating additional acoustic attenuation and crosstalk. In addition, a new tapered design for the input terminal of the delay line was also investigate to improve its acoustic directivity by reducing the acoustic acceptance angle. These two improvements are expected to provide an effective solution to eliminate current limitations on the achievable acoustic delay time and out-of-plane imaging resolution of micromachined silicon acoustic delay line arrays.

  3. Preliminary Development of Online Monitoring Acoustic Emission System for the Integrity of Research Reactor Components

    Science.gov (United States)

    Bakhri, S.; Sumarno, E.; Himawan, R.; Akbar, T. Y.; Subekti, M.; Sunaryo, G. R.

    2018-02-01

    Three research reactors owned by BATAN have been more than 25 years. Aging of (Structure, System and Component) SSC which is mainly related to mechanical causes become the most important issue for the sustainability and safety operation. Acoustic Emission (AE) is one of the appropriate and recommended methods by the IAEA for inspection as well as at the same time for the monitoring of mechanical SSC related. However, the advantages of AE method in detecting the acoustic emission both for the inspection and the online monitoring require a relatively complex measurement system including hardware software system for the signal detection and analysis purposes. Therefore, aim of this work was to develop an AE system based on an embedded system which capable for doing both the online monitoring and inspection of the research reactor’s integrity structure. An embedded system was selected due to the possibility to install the equipment on the field in extreme environmental condition with capability to store, analyses, and send the required information for further maintenance and operation. The research was done by designing the embedded system based on the Field Programmable Gate Array (FPGA) platform, because of their execution speed and system reconfigurable opportunities. The AE embedded system is then tested to identify the AE source location and AE characteristic under tensile material testing. The developed system successfully acquire the AE elastic waveform and determine the parameter-based analysis such as the amplitude, peak, duration, rise time, counts and the average frequency both for the source location test and the tensile test.

  4. Acoustic Characteristics of Simulated Respiratory-Induced Vocal Tremor

    Science.gov (United States)

    Lester, Rosemary A.; Story, Brad H.

    2013-01-01

    Purpose: The purpose of this study was to investigate the relation of respiratory forced oscillation to the acoustic characteristics of vocal tremor. Method: Acoustical analyses were performed to determine the characteristics of the intensity and fundamental frequency (F[subscript 0]) for speech samples obtained by Farinella, Hixon, Hoit, Story,…

  5. Vibration impact acoustic emission technique for identification and analysis of defects in carbon steel tubes: Part B Cluster analysis

    Energy Technology Data Exchange (ETDEWEB)

    Halim, Zakiah Abd [Universiti Teknikal Malaysia Melaka (Malaysia); Jamaludin, Nordin; Junaidi, Syarif [Faculty of Engineering and Built, Universiti Kebangsaan Malaysia, Bangi (Malaysia); Yahya, Syed Yusainee Syed [Universiti Teknologi MARA, Shah Alam (Malaysia)

    2015-04-15

    Current steel tubes inspection techniques are invasive, and the interpretation and evaluation of inspection results are manually done by skilled personnel. Part A of this work details the methodology involved in the newly developed non-invasive, non-destructive tube inspection technique based on the integration of vibration impact (VI) and acoustic emission (AE) systems known as the vibration impact acoustic emission (VIAE) technique. AE signals have been introduced into a series of ASTM A179 seamless steel tubes using the impact hammer. Specifically, a good steel tube as the reference tube and four steel tubes with through-hole artificial defect at different locations were used in this study. The AEs propagation was captured using a high frequency sensor of AE systems. The present study explores the cluster analysis approach based on autoregressive (AR) coefficients to automatically interpret the AE signals. The results from the cluster analysis were graphically illustrated using a dendrogram that demonstrated the arrangement of the natural clusters of AE signals. The AR algorithm appears to be the more effective method in classifying the AE signals into natural groups. This approach has successfully classified AE signals for quick and confident interpretation of defects in carbon steel tubes.

  6. Vibration impact acoustic emission technique for identification and analysis of defects in carbon steel tubes: Part B Cluster analysis

    International Nuclear Information System (INIS)

    Halim, Zakiah Abd; Jamaludin, Nordin; Junaidi, Syarif; Yahya, Syed Yusainee Syed

    2015-01-01

    Current steel tubes inspection techniques are invasive, and the interpretation and evaluation of inspection results are manually done by skilled personnel. Part A of this work details the methodology involved in the newly developed non-invasive, non-destructive tube inspection technique based on the integration of vibration impact (VI) and acoustic emission (AE) systems known as the vibration impact acoustic emission (VIAE) technique. AE signals have been introduced into a series of ASTM A179 seamless steel tubes using the impact hammer. Specifically, a good steel tube as the reference tube and four steel tubes with through-hole artificial defect at different locations were used in this study. The AEs propagation was captured using a high frequency sensor of AE systems. The present study explores the cluster analysis approach based on autoregressive (AR) coefficients to automatically interpret the AE signals. The results from the cluster analysis were graphically illustrated using a dendrogram that demonstrated the arrangement of the natural clusters of AE signals. The AR algorithm appears to be the more effective method in classifying the AE signals into natural groups. This approach has successfully classified AE signals for quick and confident interpretation of defects in carbon steel tubes.

  7. Vibration impact acoustic emission technique for identification and analysis of defects in carbon steel tubes: Part A Statistical analysis

    Energy Technology Data Exchange (ETDEWEB)

    Halim, Zakiah Abd [Universiti Teknikal Malaysia Melaka (Malaysia); Jamaludin, Nordin; Junaidi, Syarif [Faculty of Engineering and Built, Universiti Kebangsaan Malaysia, Bangi (Malaysia); Yahya, Syed Yusainee Syed [Universiti Teknologi MARA, Shah Alam (Malaysia)

    2015-04-15

    Current steel tubes inspection techniques are invasive, and the interpretation and evaluation of inspection results are manually done by skilled personnel. This paper presents a statistical analysis of high frequency stress wave signals captured from a newly developed noninvasive, non-destructive tube inspection technique known as the vibration impact acoustic emission (VIAE) technique. Acoustic emission (AE) signals have been introduced into the ASTM A179 seamless steel tubes using an impact hammer, and the AE wave propagation was captured using an AE sensor. Specifically, a healthy steel tube as the reference tube and four steel tubes with through-hole artificial defect at different locations were used in this study. The AE features extracted from the captured signals are rise time, peak amplitude, duration and count. The VIAE technique also analysed the AE signals using statistical features such as root mean square (r.m.s.), energy, and crest factor. It was evident that duration, count, r.m.s., energy and crest factor could be used to automatically identify the presence of defect in carbon steel tubes using AE signals captured using the non-invasive VIAE technique.

  8. Acoustic emission studies of cermet BK structural modifications under thermal and radiation action and hydrogenation

    International Nuclear Information System (INIS)

    Ul'yanov, V.L.; Chernov, I.P.; Botaki, A.A.; Chakhlov, B.V.

    1992-01-01

    Elastic wave attenuation and acoustic emission (AE) in tungsten monocarbide base cermets were investigated with the purpose of studying structural changes and microplastic strains under heating within the range of 100-1000 K, gamma-irradiation up to absorbed dose of 10 7 J·kg -1 and hydrogenation. Interrelations were revealed of AE signals and a decrement of elastic wave damping to temperature- and radiation-induced transformations in microstructure of 94 % WC -6 % Co and 92 % WC - 8 % Co hard alloys. AE peaks under thermal action were found to be associated with cobalt phase microstrain or with dislocation of hydrogen in preliminary hyudrogenated alloys

  9. The 'spontaneous' acoustic emission of the shock front in a perfect fluid: solving a riddle

    International Nuclear Information System (INIS)

    Brun, Louis

    2013-06-01

    In the fifties, S. D'yakov discovered that theory allows for suitable EOS shock fronts to emit acoustic waves 'spontaneously'. Section 90 of Fluid Mechanics of Landau and Lifshitz, 2. Ed., deals with the phenomenon, leaving it unexplained. This open question was chosen to introduce a monograph in progress about 'the shock front in the perfect fluid'. The novelty of our approach consists in having the phenomenon generated - which means it is non-spontaneous -- from an appropriate solicitation of the front and studying its development analytically. The non classical source and mechanism of the emission are thus brought to light. (author)

  10. Kinetic Simulations of Type II Radio Burst Emission Processes

    Science.gov (United States)

    Ganse, U.; Spanier, F. A.; Vainio, R. O.

    2011-12-01

    The fundamental emission process of Type II Radio Bursts has been under discussion for many decades. While analytic deliberations point to three wave interaction as the source for fundamental and harmonic radio emissions, sparse in-situ observational data and high computational demands for kinetic simulations have not allowed for a definite conclusion to be reached. A popular model puts the radio emission into the foreshock region of a coronal mass ejection's shock front, where shock drift acceleration can create eletrcon beam populations in the otherwise quiescent foreshock plasma. Beam-driven instabilities are then assumed to create waves, forming the starting point of three wave interaction processes. Using our kinetic particle-in-cell code, we have studied a number of emission scenarios based on electron beam populations in a CME foreshock, with focus on wave-interaction microphysics on kinetic scales. The self-consistent, fully kinetic simulations with completely physical mass-ratio show fundamental and harmonic emission of transverse electromagnetic waves and allow for detailled statistical analysis of all contributing wavemodes and their couplings.

  11. Radiation dominated acoustophoresis driven by surface acoustic waves.

    Science.gov (United States)

    Guo, Jinhong; Kang, Yuejun; Ai, Ye

    2015-10-01

    Acoustophoresis-based particle manipulation in microfluidics has gained increasing attention in recent years. Despite the fact that experimental studies have been extensively performed to demonstrate this technique for various microfluidic applications, numerical simulation of acoustophoresis driven by surface acoustic waves (SAWs) has still been largely unexplored. In this work, a numerical model taking into account the acoustic-piezoelectric interaction was developed to simulate the generation of a standing surface acoustic wave (SSAW) field and predict the acoustic pressure field in the liquid. Acoustic radiation dominated particle tracing was performed to simulate acoustophoresis of particles with different sizes undergoing a SSAW field. A microfluidic device composed of two interdigital transducers (IDTs) for SAW generation and a microfluidic channel was fabricated for experimental validation. Numerical simulations could well capture the focusing phenomenon of particles to the pressure nodes in the experimental observation. Further comparison of particle trajectories demonstrated considerably quantitative agreement between numerical simulations and experimental results with fitting in the applied voltage. Particle switching was also demonstrated using the fabricated device that could be further developed as an active particle sorting device. Copyright © 2015 Elsevier Inc. All rights reserved.

  12. Acoustic waves in M dwarfs: Maintaining a corona

    Science.gov (United States)

    Mullan, D. J.; Cheng, Q. Q.

    1994-01-01

    We use a time-dependent hydrodynamics code to follow the propagation of acoustic waves into the corona of an M dwarf star. An important qualitative difference between M dwarfs and stars such as the Sun is that the acoustic spectrum in M dwarfs is expected to peak at periods close to the acoustic cutoff P(sub A): this allows more effective penetration of waves into the corona. In our code, radiative losses in the photosphere, chromosphere, and corona are computed using Rosseland mean opacities, Mg II kappa and Ly alpha emission, and optically thin emissivities respectively. We find that acoustic heating can maintain a corona with a temperature of order 0.7-1 x 10(exp 6) K and a surface X-ray flux as large as 10(exp 5)ergs/sq cm/s. In a recent survey of X-rays from M dwarfs, some (20%-30%) of the stars lie at or below this limiting X-ray flux: we suggest that such stars may be candidates for acoustically maintained coronae.

  13. Failure Mechanism of Rock Bridge Based on Acoustic Emission Technique

    Directory of Open Access Journals (Sweden)

    Guoqing Chen

    2015-01-01

    Full Text Available Acoustic emission (AE technique is widely used in various fields as a reliable nondestructive examination technology. Two experimental tests were carried out in a rock mechanics laboratory, which include (1 small scale direct shear tests of rock bridge with different lengths and (2 large scale landslide model with locked section. The relationship of AE event count and record time was analyzed during the tests. The AE source location technology and comparative analysis with its actual failure model were done. It can be found that whether it is small scale test or large scale landslide model test, AE technique accurately located the AE source point, which reflected the failure generation and expansion of internal cracks in rock samples. Large scale landslide model with locked section test showed that rock bridge in rocky slope has typical brittle failure behavior. The two tests based on AE technique well revealed the rock failure mechanism in rocky slope and clarified the cause of high speed and long distance sliding of rocky slope.

  14. Use of Acoustic Emission to Monitor Progressive Damage Accumulation in KEVLAR® 49 Composites

    Science.gov (United States)

    Waller, J. M.; Andrade, E.; Saulsberry, R. L.

    2010-02-01

    Acoustic emission (AE) data acquired during intermittent load hold tensile testing of epoxy impregnated Kevlar® 49 (K/Ep) composite strands were analyzed to monitor progressive damage during the approach to tensile failure. Insight into the progressive damage of K/Ep strands was gained by monitoring AE event rate and energy. Source location based on energy attenuation and arrival time data was used to discern between significant AE attributable to microstructural damage and spurious AE attributable to noise. One of the significant findings was the observation of increasing violation of the Kaiser effect (Felicity ratio <1.0) with damage accumulation. The efficacy of three different intermittent load hold stress schedules that allowed the Felicity ratio to be determined analytically is discussed.

  15. Observation of damage process in RC beams under cucle bending by acoustic emission

    International Nuclear Information System (INIS)

    Shigeishi, Mitsuhiro; Ohtsu, Masayasu; Tsuji, Nobuyuki; Yasuoka, Daisuke

    1997-01-01

    Reinforced concrete (RC) structures are generally applied to construction of buildings and bridges, and are imposed on cyclic loading incessantly. It is considered that detected acoustic emission (AE) waveforms are associated with the damage degree and the fracture mechanisms of RC structures. Therefor, the cyclic bending tests are applied to damaged RC beam specimens. To evaluate the interior of the damaged RC beams, the AE source kinematics are determined by 'SiGMA' procedure for AE moment tensor analysis. By using 'SiGMA' procedure, AE source kinematics, such as source locations, crack types, crack orientations and crack motions, can be identified. The results show the applicability to observation of the fracture process under cyclic bending load and evaluation the degree of damage of RC beam.

  16. Implant test and acoustic emission technique used to investigate hydrogen assisted cracking in the melted zone of a welded HSLA-80 steel

    International Nuclear Information System (INIS)

    Fals, H. C.; Trevisan, R. E.

    1999-01-01

    Weld metal hydrogen assisted cracking was studied using two flux cored wire (AWS E 70T-5 and AWS E 120 T5-K4) and a mixture gas of CO 2 +5% H 2 to induce values of diffusible hydrogen in high strength low alloy steel (HSLA-80) weldments. An acoustical Emission Measurement System (AEMS) RMS voltmeter was coupled to the implant test (NF 89-100) apparatus to determine energy, amplitude and event numbers of signal. All cracks were initiated in the partially melted zone and propagated into the coarse-grained region of the heat affected zone when E 70 T5 consumable was used, and the quasi-cleavage fracture mode was predominant. When E 120 T5 K4 consumable was used the cracks propagated vertically across the fusion zone, and a mixed fracture mode was the most important. A significant relationship between acoustic emission parameters and fracture modes was found. (Author) 12 refs

  17. Acoustic Research on the Damage Mechanism of Carbon Fiber Composite Materials

    Science.gov (United States)

    Wang, Bing; Liu, Yanlei; Sheng, Shuiping

    This thesis involves the study about different processes including the tensile fracture, inter-layer tear or avulsion, as well as the interlaminar shear or split regarding carbon fiber composite materials with the aid of acoustic emission technique. Also, various acoustic emission signals that are released by composite samples in the process of fracture are analyzed. As is indicated by the test results, different acoustic emissive signals that are released by carbon fiber layers in various stages of damage and fracture bear different characteristics. Acoustic detection can effectively monitor the whole stage of elastic deformation, the damage development, and even the accumulation process while figuring out in an efficient manner about the internal activities of the composites, plus the diverse types of damages. In addition, its fabulous application value lies in its relevant structural evaluation as well as the evaluation of integrity with regard to carbon fiber composite.

  18. Preliminary studies for monitoring erosion in pipelines by the acoustic emission technique

    Energy Technology Data Exchange (ETDEWEB)

    Tiboni, G.B. [Universidade Tecnologica Federal do Parana (UTFPR), Curitiba, PR (Brazil). Programa de Pos-graduacao em Engenharia Mecanica e de Materiais; Marquardt, T.A.S; SantaMaria, V.A.R.; Silva, C.H. [Universidade Tecnologica Federal do Parana (UTFPR), Curitiba, PR (Brazil)

    2009-07-01

    The aim of this work is to present some applications of Acoustic Emission (AE), which is a powerful technique for nondestructive testing in Tribology, treated here as tests of friction, wear by contact fatigue, wear by slip and wear by erosion. In this work a special attention is given to solid particle erosion and hydro-abrasive erosion, problems found in almost every pipeline that lead to local loss of material and eventually rupture of the line. The technique of AE can be used as an efficient online tool when, primarily, to monitor tribological aspects such as the rate of wear of materials, as well as detect the spread of flaws in them. In wear by erosion, specifically, the parameters of RMS and acoustic energy are capable of correlation with the type of mechanism for removal of material. As a preliminary goal, erosive tests were performed with gas (air) without erosive particles, monitored by AE, varying the surface of the samples and the internal diameter the nozzle, taking the differences in signs of AE. Correlation between parameters of RMS and amplitude were noticed with the variables of the tests, such as roughness and fluid velocity. The RMS parameter showed a exponential correction with the fluid velocity, however the amplitude signals had a linear behavior. The knowledge of these parameters is essential for the development of a system that is able to quantify the wear rate of a pipeline without taking it out of operation. (author)

  19. Integration of an acoustic drive simulator in the engine development process; Einbindung eines akustischen Fahrsimulators in den Motorenentwicklungsprozess

    Energy Technology Data Exchange (ETDEWEB)

    Nettelbeck, C.; Riemann, D.; Sellerbeck, P. [HEAD acoustics GmbH, Herzogenrath (Germany)

    2005-07-01

    Due to constantly decreasing development time the integration of tools for simulation and generation of a virtual reality is an efficient way in order to identify weak spots or possible improvements of products as early as possible. Referring to the engine development the NVH division becomes increasingly interesting and thus an important element of the demands on new products. With the help of the Binaural Transfer Path Analysis and Synthesis (BTPA/BTPS), a tool developed at HEAD acoustics, a binaural interior noise can be generated from engine test rig multi-channel measurements. The interactive acoustical driving simulator H3S provides the opportunity of a very realistic evaluation of the NVH behavior of vehicle interior noise and vibration. The combination of the BTPA/BTPS procedure and the driving simulator offers an product in a realistic surrounding and in combination with other NVH components like wind or tire noise for all operating conditions already at an early stage in the project phase.

  20. Focusing of Acoustic Waves through Acoustic Materials with Subwavelength Structures

    KAUST Repository

    Xiao, Bingmu

    2013-05-01

    In this thesis, wave propagation through acoustic materials with subwavelength slits structures is studied. Guided by the findings, acoustic wave focusing is achieved with a specific material design. By using a parameter retrieving method, an effective medium theory for a slab with periodic subwavelength cut-through slits is successfully derived. The theory is based on eigenfunction solutions to the acoustic wave equation. Numerical simulations are implemented by the finite-difference time-domain (FDTD) method for the two-dimensional acoustic wave equation. The theory provides the effective impedance and refractive index functions for the equivalent medium, which can reproduce the transmission and reflection spectral responses of the original structure. I analytically and numerically investigate both the validity and limitations of the theory, and the influences of material and geometry on the effective spectral responses are studied. Results show that large contrasts in impedance and density are conditions that validate the effective medium theory, and this approximation displays a better accuracy for a thick slab with narrow slits in it. Based on the effective medium theory developed, a design of a at slab with a snake shaped" subwavelength structure is proposed as a means of achieving acoustic focusing. The property of focusing is demonstrated by FDTD simulations. Good agreement is observed between the proposed structure and the equivalent lens pre- dicted by the theory, which leads to robust broadband focusing by a thin at slab.