Journal of AE, Volume 23, 2005 (ca. 43 MB) - AEWG

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MEETING CALENDAR:The 49 th Meeting of AEWGThe next meeting of AEWG will be at University of California, Berkeley on June 19-21, 2006,organized by Professor Frank Beall. The primer will be held on June 19, 2006 organized by ProfessorDave Dornfeld on Acoustic Emission Monitoring of Precision Machining. Registration forms, as well ashotel information regarding this conference, can be found at:http://www.cecs.pdx.edu/~nordsr/AEWG/aewg-49.htmIAES18, The 18 th International AE SymposiumThe IAES-18 will be held in Tokyo on July 25-27, 2006. The venue will be Aoyama Gakuin Universityat Sagamihara. It is sponsored by Japan Society for Non-Destructive Inspection. Professor MikioTakemoto is the organizer.http://www.me.aoyama.ac.jp/IAES/EWGAE200627th European Conference on Acoustic Emission Testing will be held September 20-22, 2006, inCardiff, Wales, UK. The meeting is sponsored by EWGAE and Cardiff University. Dr. Karen M.Holford is the organizer. Meeting details can be seen athttp://www.ewgae.com/2006/2007 SUBSCRIPTION RATEBase rate (CD-ROM) for one year $ 103.00Add Postage of U.S. - Priority rate $ 8.00All others - Air mail rate $ 8.00CD-ROM + printed copy, US Media mail: add $ 40.00Print copy only with priority/air shipping $140.00For countries without Global Priority Service, $160.00Payment must be in U.S. dollars drawn on a U.S. bank. Bank transfer accepted atCalifornia Bank and Trust, San Fernando Valley Office (Account No. 080-03416470)16140 Ventura Blvd, Encino, CA 91436 USABack issues available; Inquiry and all orders should be sent to (or Fax 1-818-990-1686):Acoustic Emission GroupPMB 409, 4924 Balboa Blvd. Encino, CA 91316 USAFor inquiry through Internet, use the following address: kanjiono@gmail.comEditor-Publisher Kanji Ono Tel. (818) 430-5152Publication Date of This Issue (Volume 23): 28 February 2006.I - 9
EFFECTS OF NOISE ON LAMB-MODE ACOUSTIC-EMISSIONARRIVAL TIMES DETERMINED BY WAVELET TRANSFORM #∞M. A. HAMSTAD 1,2 and A. O’GALLAGHER 11)National Institute of Standards and Technology, Materials Reliability Division (853)325 Broadway, Boulder, CO 80305-3328 USA. 2) University of Denver, School of Engineeringand Computer Science, Department of Engineering, Denver, CO 80208, USA.AbstractPrecise acoustic emission (AE) signal arrival times of the fundamental Lamb modes can beobtained from the arrival time of the peak wavelet transform (WT) magnitude at a particular frequencyof interest. Since these arrival times are not determined from a fixed threshold, they arenot affected by dispersion, attenuation and source amplitude. They also correspond to a singlegroup velocity and lead to source location results more accurate than those obtained by traditionalAE location calculations based on threshold-based arrival times. In this research, noisefreefinite-element modeled (FEM) AE signals were combined with experimental widebandelectronic noise to form noisy signals. Since the noise-free signal was available, the changes inthe WT-based arrival times from noise-free to noise-altered signals could be quantitativelyevaluated. Several signal-to-noise (S/N) ratios were examined in a statistical fashion for threeimportant types of AE sources at three propagation distances and at different radiation angles.The arrival times determined by WTs were obtained for the two different frequency-mode combinations(A 0 at 60 kHz and S 0 at 522 kHz) that represent the most energetic portions of the signalsin a large 4.7 mm thick aluminum plate. From the arrival times, statistical calculations oflinear source location were also studied to evaluate errors in location accuracy caused by noise.Even at S/N ratios as low as 1 to 1, the location error was 2 % or less for a large majority of thecases. The errors in arrival time were also examined using two alternative time-frequency analysisapproaches to obtain the arrival times. One algorithm (Choi-Williams) provided significantlyimproved results for the noisy signals.Keywords: Acoustic emission modeling, Finite element modeling, Source location, Wavelettransform, Wideband acoustic emission.# Contribution of the U.S. National Institute of Standards and Technology; not subject to copyrightin the United States. ∞ Trade names are included only for complete scientific/technical description;endorsement is neither intended nor implied.1. IntroductionPrevious publications [1, 2] have demonstrated the use of wavelet transform (WT) results toextract accurate acoustic emission (AE) signal arrival times in plate structures. This techniquedetermines arrival times that are independent of threshold, source amplitude, attenuation basedon geometric spreading, radiation direction and signal dispersion based on propagation distance.Further, the arrival times correspond to a single group velocity (Lamb waves) of an energeticmode-frequency combination in the signal. A wideband AE signal database for several burieddipole-typesources in a thin aluminum plate was used for these demonstrations. This databasewas a subset of a broader database that was generated using a validated finite element modelingJ. Acoustic Emission, 23 (2005) 1 © 2005 Acoustic Emission Group
Page 2 and 3: JOURNAL OF ACOUSTIC EMISSIONVOLUME
Page 4 and 5: 23-196 AE AND ELECTROCHEMICAL NOISE
Page 6 and 7: Volume 23 (2005) AUTHORS INDEXA. AN
Page 12 and 13: code [3-5]. The level of numerical
Page 14 and 15: 0.6(a)Amplitude, pm0-0.60 0.3 0.6 0
Page 16 and 17: 10S/N 1 to 20-1010S/N 1 to 1Displac
Page 18 and 19: Examination of the results in Table
Page 21: Based on the results in Table 6, we
Page 24 and 25: Fig. 7 Signal and WT of the signal.
Page 26: Then the absolute value differences
Page 29 and 30: two modes not being the same and bo
Page 31 and 32: 14. Comparison of Results with the
Page 36 and 37: understand the similitude on damage
Page 39 and 40: curve. During loading in this direc
Page 41 and 42: detected (i.e. interfacial debondin
Page 43 and 44: RTM material in course direction (9
Page 45 and 46: detected, at higher strain values t
Page 47 and 48: ACOUSTIC EMISSION DETECTION OF IMPA
Page 49 and 50: detected from this foam impact even
Page 51: Foam impact tests were also perform
Page 55 and 56: Fig. 10 Key components of the Shutt
Page 57 and 58: MOMENT TENSORS OF IN-PLANE WAVES AN
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equired. So far, numerical solution
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Fig. 4 (a) Shear dislocation model,
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plate-like sample. In this case, th
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3. IN-PLANE THEORETICAL WAVEFORMS3.
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Fig. 11 Source model of out-of-plan
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Fig. 13 Slit model for a defect (di
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the large events, of which first ar
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Fig. 18 Crack orientations for shea
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the precise control of the gap leng
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3. Design and Fabrication of the Se
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Fig. 7: Interferometeric pattern fo
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Fig. 9: Trace and power spectral de
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2. Optical Fiber AE Sensor SystemA
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Fig. 4 Detected waves by the develo
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Fig. 10 Sensitivity distribution of
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Fig. 14 Experimental setup for dete
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HIGH PRECISION GEOPHONE CALIBRATION
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Fig. 3 Geophone response.the amplit
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Fig. 11 Imagenary short circuit.Fig
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Re22S0 12 0m0 0Z1= r +(14)222( )
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from G3. A geophone shakes the enti
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DEVELOPMENT OF HEAT-RESISTANT OPTIC
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2. Experiments2.1 Optical Fiber Sen
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Fig. 7 Detected quasi-AE waves.Fig.
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2. Outline of Damage Detection Syst
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Fig. 5 Outline of specimen (RN47) a
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2) The damage index transmitted fro
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microscopy [e.g., 1] or optical mic
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MPa. Under these conditions, a rock
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3. Damage Model Based on Sub-Critic
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in a positive relation. The larger
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well by the theoretical model consi
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MEASUREMENT OF HYDRAULICALLY ACTIVA
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Fig. 1 Source locations of induced
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P C means the increase of fluid pre
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A MODELING METHOD ON FRACTAL DISTRI
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as constant, Eight sensors were sel
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The number of AE events tends to de
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Fig. 10 Plan view of longwall minin
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Fig. 14 Crack distribution model of
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INTERPRETATION OF RESERVOIR CREATIO
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Fig. 2: Pumping data during the fir
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4. Focal MechanismWe observed the p
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AcknowledgementsThe seismic monitor
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Fig. 1 Arrangement of AE sensors an
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surface crack. Relations between AE
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4. ConclusionThe traces of the surf
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2. Sliding Experiments Using a Rock
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AE events accompanying sliding were
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though a limited number of m-values
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indicator for the contact state of
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2. Experimental Procedures2.1 Prepa
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Fig. 4 AE generation behavior and c
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1) The crack growth behavior under
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Fig. 1 AE monitoring system for cyc
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Fig. 4 (a) Surface photograph of in
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Fig. 8 Depth at lateral crack initi
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µm from the surface. This depth ag
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Fig. 1Conceptofthisstudy.following
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(b) By comparing the features in th
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ange K. From this result, it is und
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Figure 9 shows the relationship bet
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ACOUSTIC EMISSION BEHAVIOR OF FAILU
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Fig. 1. Statistical result of stren
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The AE signals indicating the onset
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occurrence of individual mechanisms
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ROLLING CONTACT FATIGUE DAMAGE OFWC
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and by 1.8 dB at 1 MHz. Without the
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Fig. 7 Sectional view of grooves at
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The analyzed locations are distribu
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BORON EFFECTS ON AE EVENT RATE PEAK
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Fig. 1 Stress-strain curves, AE eve
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Fig. 4 Relation between AE active s
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(2) Boron has a large strengthening
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produced during loading. Indentatio
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Fig. 3 Typical AE waveforms detecte
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formation. Thus, the crack morpholo
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Fig. 11 Examples of RD-type ENs wit
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(4) R. Ikeda, Y. Hayashi, M. Takemo
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averaged over a certain duration. O
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Fig. 3 Wavelet transform of continu
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Parameters used in time-series anal
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a minor contribution, but keeps the
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PRECURSOR OF HYDROIGEN INDUCED GLAS
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Table 1 Acoustic and elastic proper
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Fig. 5 Surface and transverse sketc
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Fig. 9 Chipped glass lining and sou
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ground coat. Crack volume and rise
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Figure 1 shows a schematic image of
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According to this process, the loca
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Fig. 5 Orientation dependence of th
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Fig. 9 Example of detected AE signa
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INVESTIGATION ON AE SIGNAL/NOISE PR
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Fig. 2 History of AE hit rates (upp
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Fig. 6 Source location of AE data i
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Fig. 9 Amplitude (upper) and hit ra
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Fig. 12 Amplitude (upper) and hit r
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EXAMINATION OF AE WAVE PROPAGATION
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Fig. 3 Waveguide for in water AE so
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and the rest through water, the obs
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INTEGRITY EVALUATION OF GLASS-FIBER
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Fig. 2 Deformation of GFRP vessel w
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Fig. 6 Load-deflection curves and c
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3.1 Test Vessels and Experimental P
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Fig. 12 Typical AE waves for vessel
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Fig. 15 Correlation between AE dura
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Fig. 1. Railway concrete piers to b
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Fig. 4 Arrangement of AE sensors wi
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5.2 Acoustic EmissionFig. 7 Develop
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Fig. 9 AE sources in three-dimensio
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Fig. 13 Amplitude distributions in
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4) T. Yasuda, S. Taniguchi, S. Kame
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Fig. 1 Water leakage in a joint sec
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A-FRQ(kHz)800600400200Normal Sectio
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ACOUSTIC EMISSION FOR FATIGUE DAMAG
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Fig. 3 Group velocity dispersion cu
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thick flange as shown in Fig. 8. Th
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Fig. 13 Relationship between load P
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PLASTIC REGION BOLT TIGHTENING CONT
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3. Experimental Results3.1 Result f
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4. Discriminant AnalysisMany noise
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Fig. 13 Cumulative AE counts select
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intra-grain mechanism, can also tak
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(a)(b)(c)(d)Fig. 4 AEsignals during
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where (σ - σ y ) is the decrease
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AN ACOUSTIC EMISSION TEST SYSTEM FO
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Fig. 1 Oxygen cylinder test system.
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5. Sensor FixtureThe sensor fixture
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Fig. 5 A block diagram of the test
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10. Experimental ResultsSeventy-one
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3. There was no indication at all o
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such modulated waveforms is difficu
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temperature distribution of the sam
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4.2 AE BehaviorFigure 4 shows a typ
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elatively low densification range.
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analysis applied for the evaluation
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• AE hits (Patterns) in the same
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3. Limitations, Errors and Classifi
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friction at the time just before th
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5. Pressure Spheres-AE/PR Case Stud
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6. Reactor Cool-Down - AE/PR Case S
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THE ACOUSTIC EMISSION HALON 1301 FI
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adius of the sphere). This definiti
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Second: any test, which did not det
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Fig. 3 Distribution of located even
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The spacing between the clusters on
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This test is included as the system
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Journal of AE, Volume 23, 2005 (ca. 43 MB) - AEWG

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