1、Designation: E2076/E2076M 15Standard Practice forExamination of Fiberglass Reinforced Plastic Fan BladesUsing Acoustic Emission1This standard is issued under the fixed designation E2076/E2076M; the number immediately following the designation indicates the yearof original adoption or, in the case of
2、 revision, the year of last revision. A number in parentheses indicates the year of last reapproval.A superscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This practice provides guidelines for acoustic emission(AE) examinations of fiberglass reinfor
3、ced plastic (FRP) fanblades of the type used in industrial cooling towers and heatexchangers.1.2 This practice uses simulated service loading to deter-mine structural integrity.1.3 This practice will detect sources of acoustic emission inareas of sensor coverage that are stressed during the course o
4、fthe 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 FRPconstruction, with length (hub centerline to tip) of less than 3m 10 ft, and with fiberglass content greater than 15 % byweight.1.6 AE measurements are used to
5、 detect emission sources.Other nondestructive examination (NDE) methods may beused to evaluate the significance of AE sources. Procedures forother NDE methods are beyond the scope of this practice.1.7 UnitsThe values stated in either SI units or inch-pound units are to be regarded separately as stan
6、dard. Thevalues stated in each system may not be exact equivalents;therefore, each system shall be used independently of the other.Combining values from the two systems may result in non-conformance with the standard.1.8 This standard does not purport to address all of thesafety concerns, if any, as
7、sociated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2E543 Specification for Agencies Performing Nondestructi
8、veTestingE650 Guide for Mounting Piezoelectric Acoustic EmissionSensorsE750 Practice for Characterizing Acoustic Emission Instru-mentationE976 Guide for Determining the Reproducibility ofAcousticEmission Sensor ResponseE1067 Practice forAcoustic Emission Examination of Fiber-glass Reinforced Plastic
9、 Resin (FRP) Tanks/VesselsE1106 Test Method for Primary Calibration of AcousticEmission SensorsE1316 Terminology for Nondestructive ExaminationsE2374 Guide for Acoustic Emission System PerformanceVerification2.2 ASNT Documents:3SNT-TC-1A Recommended Practice for NondestructiveTesting Personnel Quali
10、fication and CertificationANSI/ASNT CP-189 Standard for Qualification and Certifi-cation of Nondestructive Testing Personnel2.3 Aerospace Industries Association Document:4NAS 410 Certification and Qualification of NondestructiveTesting Personnel2.4 ISO Standard:5ISO 9712 Non-Destructive TestingQuali
11、fication and Cer-tification of NDT Personnel3. Terminology3.1 DefinitionsFor definitions of terms used in thispractice, see Terminology E1316.1This practice is under the jurisdiction of ASTM Committee E07 on Nonde-structive Testing and is the direct responsibility of Subcommittee E07.04 onAcoustic E
12、mission Method.Current edition approved Dec. 1, 2015. Published December 2015. Originallyapproved in 2000. Last previous edition approved in 2010 as E2076 - 10. DOI:10.1520/E2076_E2076M-15.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at servic
13、eastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available fromAmerican Society for Nondestructive Testing (ASNT), P.O. Box28518, 1711 Arlingate Ln., Columbus, OH 43228-0518, http:/www.asnt.org.4Available from Aerospace
14、Industries Association of America, Inc. (AIA), 1000Wilson Blvd., Suite 1700,Arlington, VA22209-3928, http:/www.aia-aerospace.org.5Available from International Organization for Standardization (ISO), ISOCentral Secretariat, BIBC II, Chemin de Blandonnet 8, CP 401, 1214 Vernier,Geneva, Switzerland, ht
15、tp:/www.iso.org.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States14. Summary of Practice4.1 This practice consists of subjecting individual FRP fanblades to increasing loa
16、d while monitoring with sensors thatare sensitive to acoustic emission (transient stress waves)caused by growing flaws.4.2 This practice provides guidelines to determine the zonallocation of structural flaws in FRP fan blades.4.3 The test load, applied at the blade tip is calculated toprovide 100 %
17、of the maximum allowable operating (bending)load at the blade-hub interface.4.4 This practice is intended to simulate the bending load.Torsional and centrifugal loads are not simulated by thispractice.4.5 Structurally insignificant flaws may produce acousticemission.5. Significance and Use5.1 The AE
18、 examination method detects structurally signifi-cant flaws in FRP structures via test loading. The damagemechanisms that are detected in FRP include resin cracking,fiber debonding, fiber pullout, fiber breakage, delamination,and secondary bond failure.5.2 Flaws in unstressed areas will not generate
19、 detectableAE.5.3 Flaws located with AE may be examined by othermethods.6. Basis of Application6.1 The following items are subject to contractual agree-ment between the parties using or referencing this practice.6.2 Personnel Qualification6.2.1 If specified in the contractual agreement, personnelper
20、forming examinations to this practice shall be qualified inaccordance with a nationally or internationally recognizedNDT personnel qualification practice or standard such asANSI/ASNT-CP-189, SNT-TC-1A, NAS-410, ISO 9712, or asimilar document and certified by the employer or certifyingagency, as appl
21、icable. The practice or standard used and itsapplicable revision shall be specified in the contractual agree-ment between the using parties.6.3 Qualification of Nondestructive AgenciesIf specifiedin the contractual agreement, NDT agencies shall be qualifiedand evaluated as described in Practice E543
22、. The applicableedition of Practice E543 shall be specified in the contractualagreement.6.4 Extent of ExaminationThe extent of examination shallbe in accordance with 10.2 unless otherwise specified.6.5 Reporting Criteria/Acceptance CriteriaReporting cri-teria for the examination results shall be in
23、accordance withSection 12 unless otherwise specified. Since acceptancecriteria, for example, for reference radiographs, are not speci-fied in this practice, they shall be specified in the contractualagreement.6.6 Reexamination of Repaired/Reworked ItemsReexamination of repaired/reworked items is not
24、 addressed inthis practice, and if required, shall be specified in the contrac-tual agreement.6.7 Personnel TrainingIt is recommended that personnelperforming the examination have additional training on thefollowing topics:6.7.1 Basic technology of AE from FRP;6.7.2 Failure mechanisms of FRP;6.7.3 A
25、E instrument and sensor checkout on FRP;6.7.4 Loading of FRP components for AE testing;6.7.5 Data collection and interpretation; and6.7.6 Examination report preparation.7. Apparatus7.1 Essential features of the apparatus required for thispractice are shown in Fig. 1. Specifications are provided onAn
26、nex A1.7.2 Couplant must be used to acoustically couple sensors tothe blade surface. Adhesives that have acceptable acousticproperties and ultrasonic couplants are acceptable.7.3 Sensors may be held in place with elastic straps,adhesive tape, or other mechanical means. (See Guide E650.)FIG. 1 Appara
27、tusE2076/E2076M 1527.4 Sensors are to be positioned on the fan mounting drivehub for background noise detection only; on the blade within150 mm 6 in. of the shank; on the blade midway between theshank and the blade tip; and within 150 mm 6 in. of the bladetip for background noise detection only. Add
28、itional sensorsmay be added when more complete coverage is desired.NOTE 1The sensors indicated in Fig. 1 may be placed on either the topor bottom surface of the blade.7.5 Instrumentation shall be capable of recording AE hitsabove a low-amplitude threshold, AE hits above a high-amplitude threshold (b
29、oth within a specific frequency range)and have sufficient channels to localizeAE sources in real time.(See Practice E750.) Hit detection is required for each channel.An AE hit amplitude measurement is recommended for sensi-tivity verification. Amplitude distributions are recommendedfor flaw characte
30、rization.7.6 Preamplifiers may be enclosed in the sensor housing orin a separate enclosure. If a separate preamplifier is used,sensor cable length, between the sensor and the preamplifier,must not result in a signal loss of greater than 3 dB. Typically,2 m 6 ft, is acceptable.7.7 Power/signal cable
31、length (between preamplifier andsignal processor) shall not result in a signal loss of greater than3 dB. Typically, 150 m 500 ft is acceptable.7.8 Signal processors are computerized instruments withindependent channels that filter, measure, and convert analoginformation into digital form for display
32、 and permanent stor-age. A signal processor must have sufficient speed and capa-bility to independently process data from all sensors simulta-neously. The signal processor should provide capability to filterdata for replay.7.9 A video monitor is used to display processed data invarious formats. Disp
33、lay format may be selected by theexaminer.7.10 A data storage device, such as a hard disk, is used tostore data for replay and archiving.7.11 Hard-copy capability should be available from a graph-ics printer or equivalent device.8. Safety Precautions8.1 SafetyAll site safety requirements unique to t
34、he testlocation shall be met.9. Calibration and Verification9.1 Annual calibration and verification of AE sensors,preamplifiers, if applicable, signal processor, andAE electronicwaveform generator should be performed. Equipment shouldbe adjusted so that it conforms to the equipment manufactur-ers sp
35、ecifications. Instruments used for calibration must havecurrent accuracy certification that is traceable to the NationalInstitute for Standards and Technology (NIST).9.2 Routine electronic evaluations must be performed on amonthly basis or at any time there is concern about signalprocessor performan
36、ce. An AE electronic waveform generatorshould be used in routine electronic checks. Each signalprocessor channel must respond with peak amplitude readingswithin 62dBAEof the electronic waveform generator output.9.3 Routine sensor evaluations must be performed on amonthly basis or at any time that th
37、ere is concern about thesensor performance. Peak amplitude response and electronicnoise level should be recorded. Sensors can be stimulated by apencil lead break in accordance with Guide E976. Sensorswhich are found to have peak amplitudes or electronic noisemore than 3 dB greater than the average o
38、f the group of sensorsto be used during the examination shall be replaced.9.4 A system verification must be conducted immediatelybefore and immediately after each examination. A systemverification utilizes a mechanical device to induce stress wavesinto the structure. The induced stress waves must be
39、 nonde-structive and simulate emission from a flaw. System perfor-mance checks verify the sensitivity of each system channel,including the couplant. See Guide E2374.9.4.1 The preferred technique for conducting a systemperformance check utilizes a pencil lead break. Lead should bebroken on the surfac
40、e (see Fig. 5 of Guide E976) at a specifieddistance, typically 100 mm 4 in. from the sensor.9.4.2 System channels which are found to have performanceoutside of specified values shall be repaired or replaced. Valuesshall be specified such that the sensitivity of channels used inthe same test differ b
41、y no more than 3 dB.10. Test Procedure10.1 General GuidelinesEach fan blade is subjected toprogrammed increasing tip load, up to a predetermined maxi-mum value (test load), while being monitored by sensors thatdetect acoustic emission (stress waves) caused by growingstructural flaws.10.1.1 Blade tip
42、 load shall be controlled so as to not exceeda load rate of 33 % of test load per minute.10.1.2 Background noise shall be minimized and identified.Excessive background noise is cause for suspension of theloading. In the analysis of examination results, backgroundnoise should be properly discounted,
43、if the source is deter-mined to be irrelevant to mechanical integrity.10.2 LoadingDetermine the test load from the blademanufacturers specifications. The blade may be loaded onceor twice depending upon the outcome of the first loading. If theacoustic emission activity generated by the first loading
44、ex-ceeds the criteria then an immediate second loading shall beapplied. If the blade meets the acceptance criteria on the firstloading then the second loading is not required. Fig. 2 showsthe recommended loading sequence. The following is a prac-tical way to achieve the desired blade tip load.10.2.1
45、 Secure the shank of the blade in an appropriateholder at its operating pitch (blade parallel to the floor). Thiswill usually be the blade manufacturers drive hub arrangement(see also Fig. 1).10.2.2 Suspend an empty water container at the tip end ofthe blade. Padding is recommended to reduce the pos
46、sibility ofextraneous noise and physical damage to the surface of theblade tip.E2076/E2076M 15310.2.3 Fill the water container with a sufficient amount ofwater to equal the maximum desired test load at the blade tip.For example, for a typical 25-kg 50-lb test load, the fillingrate should not exceed
47、7.5 L 2 gal/min (see 10.1.1).10.2.4 Hold the test load for two minutes and record testresults.10.2.5 Remove the load from the blade tip.10.2.6 Evaluate the acoustic emission activity in accordancewith Section 11. If the blade meets the acceptance criteria, nofurther testing is required. If it fails
48、to meet the criteria proceedwith steps 7 and 8.10.2.7 Immediately replace the empty water container andrefill the container with water equal to the maximum desiredtest load at the blade tip. Filling rate should not exceed therequirement in 10.1.1.10.2.8 Hold the test load for two minutes and record
49、testresults.10.3 Data RecordingThe following AE data are to berecorded for each blade examined by this procedure:10.3.1 Maximum dB during loading, or number of hitsabove the high-amplitude threshold. (See Practice E1067,Annex A2).10.3.2 Number of hits above the low-amplitude threshold(see Practice E1067, Annex A2) during two-minute hold at testload.10.3.3 Total number of hits above the low-amplitude thresh-old during loading.10.3.4 Indicate most active sensor location.11. Evaluation11.1 Evaluation based on emissions during load hold isparticularly
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