1、Designation: E1736 15Standard 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. Scope*1.1 This practice covers a procedure for acousto-ultrasonic(AU) assessment of filament-wound pressure vessels. Guide-lines are
3、given 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 p
4、rocedure 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 theas
5、sessment 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 dire
6、c-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 extend
7、ed 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 Spec
9、ification for Agencies Performing NondestructiveTestingE1001 Practice for Detection and Evaluation of Discontinui-ties by the Immersed Pulse-Echo Ultrasonic MethodUsing Longitudinal WavesE1067 Practice forAcoustic Emission Examination of Fiber-glass Reinforced Plastic Resin (FRP) Tanks/VesselsE1316
10、Terminology for Nondestructive ExaminationsE1495 Guide for Acousto-Ultrasonic Assessment ofComposites, 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 Non
11、destructive Testing2.3 AIA Standard:5NAS-410 Certification and Qualification of NondestructiveTest Personnel2.4 ISO Standard:6ISO 9712 Non-destructive TestingQualification and Cer-tification of NDT Personnel3. Terminology3.1 DefinitionsRelevant terminology and nomenclatureare defined in Terminology
12、E1316 and Guide E1495.1This 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 June 1, 2015. Published June 2015. Originallyapproved in 1995. Last previous edi
13、tion approved in 2010 as E1736-10. DOI:10.1520/E1736-15.2Vary, A., “Acousto-Ultrasonics,” Nondestructive Testing of Fibre-ReinforcedPlastics Composites, Vol 2, J. Summerscales, ed., Elsevier Science Publishers Ltd.,Barking, Essex, England, 1990, Chapter 1, pp. 1-54.3For referenced ASTM standards, vi
14、sit 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 fromAmerican Society for Nondestructive Testing (ASNT), P.O. Box28518, 1711 Arlingat
15、e 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.6Available from International Organization for Standardization (ISO), 1, ch. dela Voie-Creuse,
16、 CP 56, CH-1211 Geneva 20, Switzerland, http:/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 States13.2 Definitions of Terms Specific to This Standard:3.2.1 compos
17、ite shella 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 sh
18、own in Fig. 1. The number of layers, fiberorientation, and composite shell thickness may vary from pointto 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 th
19、at form 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
20、The AU method 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 ul
21、trasonics (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.
22、These arematerial aberrations that influence AU measurements and alsounderlie mechanical property variations, dynamic loadresponse, and impact and fracture resistance.74.3 TheAU method can be used to evaluate laminate qualityusing access to only one surface, the usual constraint imposedby closed pre
23、ssure 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 reliabil
24、ity of filament-wound pressure vessels.85. 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 forconventiona
25、l ultrasonic 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) imp
26、roper selection of probe characteristics (center fre-quency and bandwidth),7Vary, 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, S
27、ection12, pp. 383431.8Sundaresan, M. J., Henneke, E. G., and Brosey, W. D., “Acousto-UltrasonicInvestigation of Filament-Wound Spherical Pressure Vessels,” MaterialsEvaluation, Vol 49, No. 5, 1991, pp. 6016012.FIG. 1 Kevlar-Epoxy Filament-Wound ShellFIG. 2 Representation of Filament-Wound Composite
28、Shell Lay-ers Showing Typical Thicknesses and Layering VariationsE1736 152(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 com
29、posite 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
30、shell by causingmore energy to be reflected or channeled to the receivingprobe.6. 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, per
31、sonnelperforming 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, ISO9712, or a similar document and certified by the employer orcertifying a
32、gency, as applicable. The practice or standard usedand its applicable revision shall be identified in the contractualagreement 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 r
33、einforced plastics6.2.2.2 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 eva
34、luated as described 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
35、accordance with 9.1.1 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
36、agreement.6.7 Reexamination 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-woun
37、d pressure vessels 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
38、probes at a normal 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 thickn
39、ess. For example, 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
40、the vessel by columns 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, signalattenuation, and the need to include an adequate repr
41、esentativevolume 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 sen
42、ds to thepulser-receiver. The need to strengthen the signal depends onFIG. 3 Schematic Diagram of Scanning Apparatus and SignalAcquisition, Image Processing, and Data Analysis Instrumenta-tionE1736 153the sender-receiver probe spacing, water jet column length, andattenuation by the shell.7.1.3 Instr
43、umentation, for automated scanning and dataacquisition and presentation. Essential components consist of aprogrammable scan drive module, signal digitizing oscillo-scope with time base and vertical (voltage) amplifier, computerwith an appropriate bus interface, ultrasonic pulser-receiver,digital dis
44、play, and printer/plotter.8. Principles of Practice8.1 The sending probe introduces simulated stress waves inthe composite shell. The receiving probe collects the resultantmultiple reverberations that are generated. The effects of eachlocal volume or zone of the composite shell on AU stress waveprop
45、agation are collected 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 f
46、actor (SWF) defined 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
47、 strain energy. More 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.
48、These are regions 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 establ
49、ished previously for 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 reference 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
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