1、Designation: E 2478 06aStandard Practice forDetermining Damage-Based Design Stress for FiberglassReinforced Plastic (FRP) Materials Using AcousticEmission1This standard is issued under the fixed designation E 2478; the number immediately following the designation indicates the year oforiginal adopti
2、on or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice details procedures for establishing thedirect stress and sh
3、ear stress damage-based design values foruse in the damage-based design criterion for materials to beused in FRP vessels and other composite structures. Thepractice uses data derived from acoustic emission examinationof four-point beam bending tests and in-plane shear tests (seeASME Section X, Artic
4、le RT-8).1.2 The onset of lamina damage is indicated by the presenceof significant acoustic emission during the reload portion ofload/reload cycles. “Significant emission” is defined withhistoric index.1.3 UnitsThe values stated in inch-pound units are to beregarded as standard. The values given in
5、brackets are math-ematical conversions to SI units which are provided forinformation only and are not considered standard.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-
6、priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 790 Test Methods for Flexural Properties of Unreinforcedand Reinforced Plastics and Electrical Insulating MaterialsD 4255/D 4255M Test Method for In
7、-Plane Shear Proper-ties of Polymer Matrix Composite Materials by the RailShear MethodD 3846 Test Method for In-Plane Shear Strength of Rein-forced PlasticsE 543 Specification for Agencies Performing Nondestruc-tive TestingE 976 Guide for Determining the Reproducibility of Acous-tic Emission Sensor
8、ResponseE 1316 Terminology for Nondestructive ExaminationsE 2374 Guide for Acoustic Emission System PerformanceVerification2.2 ASME Documents:3ASME Section X, Article RT-8 Test Method for Determin-ing Damage-Based Design CriterionASME Section V, Article 11 Acoustic Emission Examina-tion of Fiber-Rei
9、nforced Plastic Vessels2.3 Other Standards:ANSI/ASNT-CP-189 Qualification and Certification ofNondestructive Testing Personnel4SNT-TC-1A Recommended Practice for Personnel Qualifi-cation and Certification in Nondestructive Testing4NAS-410 Certification and Qualification of NondestructiveTest Personn
10、el53. Terminology3.1 Definitions of terms related to conventional acousticemission are in Terminology E 1316, Section B.3.2 Definitions of Terms Specific to This Standard:3.2.1 historic indexa measure of the change in MARSE(or other AE feature parameter such as AE Signal Strength orAE Energy) throug
11、hout an examination.3.2.2 measured area of the rectified signal envelope(MARSE)a measure of the area under the envelope of therectified linear voltage time signal from the sensor. (see ASMESection V, Article 11)3.2.3 significant emissiona level of emission that corre-sponds to the first time during
12、reloading that the historic indexattains a value of 1.4.1This practice is under the jurisdiction of ASTM Committee E07 on Nonde-structive Testing and is the direct responsibility of Subcommittee E07.04 onAcoustic Emission Method.Current edition approved Dec. 1, 2006. Published January 2007. Original
13、lyapproved in 2006. Last previous edition approved in 2006 as E 2478 - 06.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe
14、ASTM website.3Available from American Society of Mechanical Engineers (ASME), ASMEInternational Headquarters, Three Park Ave., New York, NY 10016-5990.4Available fromAmerican Society for Nondestructive Testing (ASNT), P.O. Box28518, 1711 Arlingate Ln., Columbus, OH 43228-0518.5Available from Aerospa
15、ce Industries Association of America, Inc. (AIA), 1250Eye St., NW, Washington, DC 20005.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.2.4 knee in the curvea dramatic change in the slope ofthe cumulative AE versus time curve.4. Su
16、mmary of Practice4.1 This practice uses acoustic emission instrumentationand examination techniques during load/reloading of materialsbeing examined, to determine the onset of significant acousticemission. The onset of significant emission is related to thedamage-based design stress by the Felicity
17、ratio.6,75. Significance and Use5.1 The damage-based design approach will permit anadditional method of design for FRP materials. This is a veryuseful technique to determine the performance of differenttypes of resins and composition of FRP materials in order todevelop a damage tolerant and reliable
18、 design. This AE-basedmethod is not unique, other damage-sensitive evaluation meth-ods can also be used.5.2 This practice involves the use of acoustic emissioninstrumentation and examination techniques as a means ofdamage detection to support a destructive test, in order toderive the damage-based de
19、sign stress.5.3 This practice is not intended as a predictor of long-termperformance of FRP materials (such as those used in vessels).For this reason, many codes and standards require cyclic prooftesting of prototypes (for example, vessels) which are not a partof this practice.5.4 Other design metho
20、ds exist and are still permitted.6. Basis of Application6.1 The following items are subject to contractual agree-ment between the parties using or referencing this practice:6.1.1 Personnel QualificationIf specified in the contrac-tual agreement, personnel performing examinations to thispractice shal
21、l be qualified in accordance with a nationally orinternationally recognized NDT personnel qualification prac-tice or standard such as ANSI/ASNT-CP-189, SNT-TC-1A,NAS-410, or a similar document and certified by the employeror certifying agency, as applicable. The practice or standardused and its appl
22、icable revision shall be identified in thecontractual agreement between the using parties.6.1.2 Qualification of Nondestructive AgenciesIf speci-fied in the contractual agreement, NDT agencies shall bequalified and evaluated as described in Practice E 543. Theapplicable revision of Practice E 543 sh
23、all be specified in thecontractual agreement.6.1.3 Procedure and TechniquesThe procedures and tech-niques to be utilized shall be as specified in the contractualagreement.6.1.4 Timing of ExaminationThe timing of examinationshall be in accordance with 12.4 unless otherwise specified.6.1.5 Extent of E
24、xaminationThe extent of examinationshall be in accordance with Sections 9 and 10 unless otherwisespecified.6.1.6 Reporting CriteriaReporting criteria for the exami-nation results shall be in accordance with 15.1 unless otherwisespecified.7. ApparatusNOTE 1Refer to Fig. 1 for AE system block diagram
25、showing keycomponents of the AE system. It is recommended to use two AE sensorsto monitor the specimen, evaluated on a per channel basis.7.1 AE Sensors7.1.1 AE sensors shall be resonant in a 100 to 300 kHzfrequency band.7.1.2 Sensors shall have a peak sensitivity greater than 77dB (referred to 1 vol
26、t per microbar, determined by face-to-faceultrasonic examination) within the frequency range 100 to 300kHz. Sensitivity within the 100 to 300 kHz range shall not varymore than 3 dB within the temperature range of intended use.7.1.3 Sensors shall be shielded against electromagneticinterference throug
27、h proper design practice or differential(anti-coincidence) element design, or both.7.1.4 Sensors shall have omni-directional response, withvariations not exceeding 2 dB from the peak response.7.2 Couplant7.2.1 Commercially available couplants for ultrasonic flawdetection may be used. Silicone-based
28、high-vacuum grease hasbeen found to be particularly suitable. Adhesives may also beused.7.2.2 Couplant selection should be made to minimizechanges in coupling sensitivity during a complete examination.Consideration should be given to the time duration of theexamination and maintaining consistency of
29、 coupling through-out the examination.7.3 Sensor-Preamplifier Cable7.3.1 The cable connecting the sensor to the preamplifiershall not attenuate the sensor peak voltage in the 100 to 300kHz frequency range more than 3 dB (6 ft 1.8 m is a typicallength). Integral preamplifier sensors meet this require
30、ment.They have inherently short, internal, signal cables.7.3.2 The sensor-preamplifier cable shall be shielded againstelectromagnetic interference. Standard low-noise coaxial cableis generally adequate.7.4 Preamplifier7.4.1 The preamplifier shall have a noise level no greaterthan five microvolts rms
31、 (referred to a shorted input) within the100 to 300 kHz frequency range.7.4.2 Preamplifier gain shall vary no more than 61dBwithin the 100 to 300 kHz frequency band and temperaturerange of use.7.4.3 Preamplifiers shall be shielded from electromagneticinterference.7.4.4 Preamplifiers of differential
32、design shall have a mini-mum of 40 dB common-mode rejection.7.4.5 Preamplifiers shall include a bandpass filter with aminimum bandwidth of 100 kHz to 300 kHz. Note that thecrystal resonant characteristics provide additional filtering asdoes the bandpass filter in the signal conditioner.6Ramirez, G.,
33、 Ziehl, P., Fowler, T., 2004, “Nondestructive Evaluation of FRPDesign Criteria with Primary Consideration to Fatigue Loading”, ASME Journal ofPressure Vessel Technology, Vol. 126, pp. 113.7Ziehl, P. and Fowler, T., 2003, “Fiber Reinforced Polymer Vessel Design witha Damage Approach”, Journal of Comp
34、osite Structures, Vol. 61, Issue 4, pp.395-411.E 2478 06a27.4.6 It is preferred that the preamplifier be mounted insidethe sensor housing.7.5 Power-Signal Cable7.5.1 The cable and connectors that provide power topreamplifiers, and that conduct amplified signals to the mainprocessor, shall be shielde
35、d against electromagnetic interfer-ence. Signal loss shall be less than 3 dB over the length of thecable. (When standard coaxial cable is used, 1000 ft is themaximum recommended cable length to avoid excessive signalattenuation).7.6 Power Supply7.6.1 Astable, grounded, power supply that meets the si
36、gnalprocessor manufacturers specification shall be used.7.7 Main Signal Processor7.7.1 The main processor shall have circuitry through whichsensor data will be processed. It shall be capable of processinghits, hit arrival time, duration, counts, peak amplitude, andMARSE (or similar AE feature parame
37、ters such as SignalStrength or Energy) on each channel.7.7.2 Electronic circuitry shall be stable within 61dBinthetemperature range 40 to 100F 4 to 38C.7.7.3 Threshold shall be accurate within 61 dB.7.7.4 MARSE shall be measured on a per channel basis andshall have a resolution of 1 % of the value o
38、btained from a onemillisecond duration, 150 kHz sine burst having an amplitude25 dB above the data analysis threshold. Usable dynamic rangeshall be a minimum of 40 dB.NOTE 2Instead of MARSE, other AE feature parameters such as“Signal Strength” or “Energy” may be used.7.7.5 Amplitude shall be measure
39、d in decibels referenced to0 dB as 1 microvolt at the preamplifier input. Usable systemdynamic range shall be a minimum of 60 dB with 1 dBresolution over the frequency band of 100 to 300 kHz, and thetemperature range of 40 to 100F 4 to 38C. Not more than61 dB variation in peak detection accuracy sha
40、ll be allowedover the stated temperature range.7.7.6 Hit duration (AE signal duration) shall be accurate to65 s and is measured from the first threshold crossing to thelast threshold crossing of the AE signal.7.7.7 Hit arrival time shall be recorded globally for eachchannel accurate to within one mi
41、llisecond, minimum.7.7.8 The system deadtime of each channel of the systemshall be no greater than 200 s.7.7.9 The hit definition time shall be 400 s.7.7.10 The examination threshold shall be set at 40 dB(depending on background noise of the system setup whensubjected to a constant load of 10 % or l
42、ess of the estimatedfailure load). Threshold should remain constant during theentire examination.8. Calibration and Verification8.1 Annual calibration and verification of AE sensors,preamplifiers (if applicable), signal processor, and AE elec-tronic waveform generator (or simulator) should be perfor
43、med.Equipment should be adjusted so that it conforms to equipmentmanufacturers specifications. Instruments used for calibra-tions must have current accuracy certification that is traceableto the National Institute for Standards and Technology (NIST).8.2 Routine electronic evaluations must be perform
44、ed anytime there is concern about signal processor performance. AnAE electronic waveform generator or simulator, should be usedin making evaluations. Each signal processor channel mustFIG. 1 AE System Block DiagramE 2478 06a3respond with peak amplitude reading within 62dBoftheelectronic waveform gen
45、erator output.8.3 A system performance verification must be conductedimmediately before, and immediately after, each examination.A performance verification uses a mechanical device to inducestress waves into the material under examination, at a specifieddistance from each sensor. Induced stress wave
46、s stimulate asensor in the same way as emission from a flaw. Performanceverifications verify performance of the entire system (includingcouplant). (Refer to Guide E 2374 for AE system performanceverification techniques).8.3.1 The preferred technique for conducting a performanceverification is a penc
47、il lead break (PLB). Lead should bebroken on the material surface at a specified distance from eachsensor. The 2H lead, 0.3-mm diameter, and 2 to 3-mm longshould be used (see Fig. 5 of Guide E 976 and Guide E 2374).8.3.2 Auto Sensor Test (AST)An electromechanical devicesuch as a piezoelectric pulser
48、 (and sensor which contains thisfunction) can be used in conjunction with pencil lead break(8.3.1) as a means to assure system performance. This devicecan be used to replace the PLB post examination, systemperformance verification (8.3). (Refer to Guide E 2374.)9. Test Methods9.1 The evaluation setu
49、p, loading arrangement, and speci-men dimensions for the flexure test shall be in accordance withProcedure B of Test Methods D 790. Typically, specimens willbe38-in. 9.5-mm thick and shall have sufficient width,clearance, and overhang to permit mounting of an acousticemission sensor. Sensors should not be mounted in the middlethird of the specimen.9.2 The evaluation setup, loading arrangement, and speci-men dimensions for the in-plane shear test shall be in accor-dance with Procedure B of Test Method D 4255/D 4255M.10. Evaluation Specimens10.1 Specim
