1、Designation: E1736 10Standard Practice forAcousto-Ultrasonic Assessment of Filament-WoundPressure Vessels1This standard is issued under the fixed designation E1736; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last r
2、evision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice covers a procedure for acousto-ultrasonic(AU) assessment of filament-wound pressure vessels. Guide-lines are g
3、iven for the detection of defect states and flawpopulations that arise during materials processing or manufac-turing or upon exposure to aggressive service environments.Although this practice describes an automated scanning mode,similar results can be obtained with a manual scanning mode.1.2 This pr
4、ocedure recommends technical details and rulesfor the reliable and reproducible AU detection of defect statesand flaw populations. The AU procedure described herein canbe a basis for assessing the serviceability of filament-woundpressure vessels.1.3 The objective of the AU method is primarily theass
5、essment of defect states and diffuse flaw populations thatinfluence the mechanical strength and ultimate reliability offilament-wound pressure vessels. The AU approach and probeconfiguration are designed specifically to determine compositeproperties in lateral rather than through-the-thickness direc
6、-tions.21.4 The AU method is not for flaw detection in the conven-tional sense. The AU method is most useful for materialscharacterization, as explained in Guide E1495, which gives therationale and basic technology for the AU method. Flaws anddiscontinuities such as large voids, disbonds, or extende
7、d lackof contact of interfaces can be found by other nondestructiveexamination (NDE) methods such as immersion pulse-echoultrasonics.1.5 UnitsThe values stated in SI units are to be regardedas standard. No other units of measurement are included in thispractice.1.6 This standard does not purport to
8、address all of thesafety concerns, if any, associated 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:3E543 Speci
9、fication for Agencies Performing Nondestruc-tive TestingE1001 Practice for Detection and Evaluation of Disconti-nuities by the Immersed Pulse-Echo Ultrasonic MethodUsing Longitudinal WavesE1067 Practice for Acoustic Emission Examination of Fi-berglass Reinforced Plastic Resin (FRP) Tanks/VesselsE131
10、6 Terminology for Nondestructive ExaminationsE1495 Guide for Acousto-Ultrasonic Assessment of Com-posites, Laminates, and Bonded Joints2.2 ASNT Standards:4ANSI/ASNT CP-189 Personnel Qualification and Certifica-tion in Nondestructive TestingASNT SNT-TC-1A Personnel Qualification and Certifica-tion in
11、 Nondestructive Testing2.3 AIA Standard:5NAS-410 Certification and Qualification of NondestructiveTest Personnel3. Terminology3.1 DefinitionsRelevant terminology and nomenclatureare defined in Terminology E1316 and Guide E1495.3.2 Definitions of Terms Specific to This Standard:3.2.1 composite shella
12、 multilayer filament-winding thatcomprises a second shell that reinforces the inner shell. Thecomposite shell consists of continuous fibers, impregnated witha matrix material, wound around the inner shell, and cured inplace. An example is the Kevlar-epoxy filament-wound spheri-cal shell shown in Fig
13、. 1. The number of layers, fiberorientation, and composite shell thickness may vary from point1This 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 June 1,
14、2010. Published July 2010. Originally approvedin 1995. Last previous edition approved in 2005 as E1736 - 05. DOI: 10.1520/E1736-10.2Vary, A., “Acousto-Ultrasonics,” Nondestructive Testing of Fibre-ReinforcedPlastics Composites, Vol 2, J. Summerscales, ed., Elsevier Science Publishers Ltd.,Barking, E
15、ssex, England, 1990, Chapter 1, pp. 1-54.3For 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 ASTM website.4Available fromAmeri
16、can Society for Nondestructive Testing (ASNT), P.O. Box28518, 1711 Arlingate Ln., Columbus, OH 43228-0518, http:/www.asnt.org.5Available from Aerospace Industries Association of America, Inc. (AIA), 1000Wilson Blvd., Suite 1700,Arlington, VA22209-3928, http:/www.aia-aerospace.org.1Copyright ASTM Int
17、ernational, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.to point (Fig. 2). The examination and assessment of thecomposite shell are the objectives of this practice.3.2.2 filament-wound pressure vesselan inner shell over-wrapped with composite layers that form
18、a composite shell.The inner shell or liner may consist of an impervious metallicor nonmetallic material. The vessel may be cylindrical orspheroidal and will have at least one penetration with valveattachments for introducing and holding pressurized liquids orgases.4. Significance and Use4.1 The AU m
19、ethod should be considered for vessels thatare proven to be free of major flaws or discontinuities asdetermined by conventional techniques. The AU method maybe used for detecting major flaws if other methods are deemedimpractical. It is important to use methods such as immersionpulse-echo ultrasonic
20、s (Practice E1001) and acoustic emission(Practice E1067) to ascertain the presence of major flawsbefore proceeding with AU.4.2 The AU method is intended almost exclusively formaterials characterization by assessing the collective effects ofdispersed defects and subcritical flaw populations. These ar
21、ematerial aberrations that influence AU measurements and alsounderlie mechanical property variations, dynamic load re-sponse, and impact and fracture resistance.64.3 TheAU method can be used to evaluate laminate qualityusing access to only one surface, the usual constraint imposedby closed pressure
22、vessels. For best results, the AU probesmust be fixtured to maintain the probe orientation at normalincidence to the curved surface of the vessel. Given theseconstraints, this practice describes a procedure for automatedAU scanning using water squirters to assess the serviceabilityand reliability of
23、 filament-wound pressure vessels.75. Limitations5.1 TheAU method possesses the limitations common to allultrasonic methods that attempt to measure either absolute orrelative attenuation. When instrument settings and probe con-figurations are optimized for AU, they are unsuitable forconventional ultr
24、asonic flaw detection because the objective ofAU is not the detection and imaging of individual micro- ormacro-flaws.5.2 The AU results may be affected adversely by thefollowing factors:(1) couplant (squirter or water jet) variations and bubbles,(2) vessel surface texture and roughness,(3) improper
25、selection of probe characteristics (centerfrequency and bandwidth),(4) probe misalignment,(5) probe resonances and insufficient damping, and(6) inadequate instrument (pulser-receiver) bandwidth.5.3 Misinterpretations of AU results can occur if there areintermittent disbonds or gaps in the composite
26、shell or at theinterface between the composite and inner shell. Using con-ventional flaw detection methods, care should be taken toensure that major delaminations, disbonds, or gaps are notpresent. Extensive gaps or disbonds will produce the sameeffect as low attenuation within the composite shell b
27、y causingmore energy to be reflected or channeled to the receivingprobe.6Vary, A., “Material Property Characterization,” Nondestructive TestingHandbookUltrasonic Testing, Vol 7, A. S. Birks, R. E. Green, Jr., and P. McIntire,eds., American Society for Nondestructive Testing, Columbus, OH, 1991, Sect
28、ion12, pp. 383431.7Sundaresan, M. J., Henneke, E. G., and Brosey, W. D., “Acousto-UltrasonicInvestigation of Filament-Wound Spherical Pressure Vessels,” Materials Evalua-tion, Vol 49, No. 5, 1991, pp. 6016012.FIG. 1 Kevlar-Epoxy Filament-Wound ShellFIG. 2 Representation of Filament-Wound Composite S
29、hellLayers Showing Typical Thicknesses and Layering VariationsE1736 1026. Basis of Application6.1 The following items are subject to contractual agree-ment between the parties using or referencing the test method.6.2 Personnel Qualification6.2.1 If specified in the contractual agreement, personnelpe
30、rforming examinations to this standard shall be qualified inaccordance with a nationally or internationally recognizedNDT personnel qualification practice or standard such asANSI/ASNT-CP-189, ASNT SNT-TC-1A, NAS-410,orasimilar document and certified by the employer or certifyingagency, as applicable
31、. The practice or standard used and itsapplicable revision shall be identified in the contractual agree-ment between the using parties.6.2.2 Personnel TrainingTraining in the following topicsis recommended for personnel who perform examinations.6.2.2.1 Failure mechanisms in fiber reinforced plastics
32、6.2.2.2 Ultrasonic instrument and search unit checkout onfiber reinforced plastics.6.2.2.3 Technology of ultrasonic examination of fiber rein-forced plastics.6.3 Qualification of Nondestructive AgenciesIf specifiedin the contractual agreement, NDT agencies shall be qualifiedand evaluated as describe
33、d in Practice E543. The applicableedition of Practice E543 shall be specified in the contractualagreement.6.4 Timing of ExaminationExaminations shall be per-formed as desired during the manufacture and use of thevessels.6.5 Extent of ExaminationThe extent of examination shallbe in accordance with 9.
34、1.1 unless otherwise specified.6.6 Reporting Criteria/Acceptance CriteriaReporting cri-teria for the examination results shall be in accordance with 10unless otherwise specified. Since acceptance criteria are notspecified in this standard, they shall be specified in thecontractual agreement.6.7 Reex
35、amination of Repaired/Reworked ItemsReexamination of repaired/reworked items is not addressed inthis standard and if required shall be specified in the contrac-tual agreement.7. Apparatus7.1 The basic apparatus and instrumentation for performingautomatedAU scanning of filament-wound pressure vessels
36、 areshown schematically in Fig. 3.7.1.1 Scanning Apparatus, consisting of a device capable ofholding a pressure vessel and rotating it about an axis. The AUprobe assembly is mounted in a holder capable of beingarticulated and indexed in a manner that maintains the probespacing and probes at a normal
37、 incidence angle relative to thevessel surface.7.1.2 Acousto-Ultrasonic ProbesA sender and a receiver,that is, two search units as defined in Terminology E1316.7.1.2.1 The sender should produce wavelengths in thevessels composite filament-wound shell equal to or less thanits thickness. For example,
38、for composite shells up to 1 cmthick, the center frequency of the probes should be in the rangefrom 1 to 5 MHz. Probes operating at 2.25 MHz are recom-mended for general use on polymer or organic matrix compos-ites.7.1.2.2 The probes should be acoustically coupled individu-ally to the vessel by colu
39、mns of water, that is, the “squirter” orwater jet method.7.1.2.3 Probe separation (distance between probes) shouldbe fixed at approximately 2 to 5 cm, depending on consider-ations such as avoiding “cross-talk” reflections, signal attenu-ation, and the need to include an adequate representativevolume
40、 of material between the sender and the receiver. Thelatter requirement is to ensure integrating the effects of diffuseflaw populations in the region being examined currently.7.1.2.4 Apreamplifier is recommended in close proximity tothe receiving probe to strengthen the signal it sends to thepulser-
41、receiver. The need to strengthen the signal depends onthe sender-receiver probe spacing, water jet column length, andattenuation by the shell.7.1.3 Instrumentation, for automated scanning and dataacquisition and presentation. Essential components consist of aprogrammable scan drive module, signal di
42、gitizing oscillo-scope with time base and vertical (voltage) amplifier, computerwith an appropriate bus interface, ultrasonic pulser-receiver,digital display, and printer/plotter.8. Principles of Practice8.1 The sending probe introduces simulated stress waves inthe composite shell. The receiving pro
43、be collects the resultantmultiple reverberations that are generated. The effects of eachFIG. 3 Schematic Diagram of Scanning Apparatus and SignalAcquisition, Image Processing, and Data AnalysisInstrumentationE1736 103local volume or zone of the composite shell on AU stress wavepropagation are collec
44、ted and evaluated.28.2 The objective is to measure the relative efficiency ofstress wave propagation in the composite shell. The dominantattribute measured is stress wave attenuation, as represented bysignal strength or weakness. This measurement is quantified byan AU stress wave factor (SWF) define
45、d in Guide E1495.Lower attenuation corresponds to higher values of the AUSWF.8.3 At any given location, higher signal strength is a resultof better stress wave energy transmission within the compositeshell and, therefore, indicates better transmission and redistri-bution of dynamic strain energy. Mo
46、re efficient strain energytransfer and strain redistribution (for example, during loadingor impact) correspond to increased strength and fractureresistance in the composite shell.8.4 Regions that exhibit lower signal strength are those thatattenuate the probe-induced stress waves. These are regions
47、inwhich the strain energy is likely to concentrate and result incrack growth and fracture upon experiencing impact or highloading.9. Procedure9.1 Before AU scanning commences, the sender and re-ceiver probes should be evaluated by comparing the signalswith standard waveforms established previously f
48、or a referencecomposite shell. This determines whether there are deficienciesin the instrumentation and probe response.9.1.1 Consider the following two options before proceed-ing:9.1.1.1 Option 1Refer all AU readings on the compositeshell being examined to measurements at the same locations ona refe
49、rence shell that is known to be free of flaws andrepresents the optimum or most acceptable condition. In thiscase, AU readings on the test shell are “normalized” againstpreviously recorded AU readings for the same locations on thereference shell.9.1.1.2 Option 2Refer all AU readings on the compositeshell being examined to the highest reading on the same shell.In this case,AU readings on the test shell will demonstrate onlynonuniformities in and peculiar to that shell.9.1.2 Using an optimized reference composite shell, adjustthe probes with respect to each other an
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