1、Designation: E 1736 05Standard Practice forAcousto-Ultrasonic Assessment of Filament-WoundPressure Vessels1This standard is issued under the fixed designation E 1736; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last
2、 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 covers a procedure for acousto-ultrasonic(AU) assessment of filament-wound pressure vessels. Guide-lines ar
3、e 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
4、 procedure 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 the
5、assessment 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 di
6、rec-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 E 1495, which givesthe rationale and basic technology for the AU method. Flawsand discontinuities such as large voids, disbonds, or ext
7、endedlack of contact of interfaces can be found by other nondestruc-tive examination (NDE) methods such as immersion pulse-echo ultrasonics.1.5 The values stated in SI units are to be regarded as thestandard.1.6 This standard does not purport to address all of thesafety concerns, if any, associated
8、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:3E 543 Practice for Agencies Performing NondestructiveTestingE 10
9、01 Practice for Detection and Evaluation of Disconti-nuities by the Immersed Pulse-Echo Ultrasonic MethodUsing Longitudinal WavesE 1067 Practice for Acoustic Emission Examination ofFiberglass Reinforced Plastic Resin (FRP) Tanks/VesselsE 1316 Terminology for Nondestructive TestingE 1495 Guide for Ac
10、ousto-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 Nondestructive Testing2.3 AIA Standard:5NAS-410 Certification
11、and Qualification of NondestructiveTest Personnel3. Terminology3.1 DefinitionsRelevant terminology and nomenclatureare defined in Terminology E 1316 and Guide E 1495.3.2 Definitions of Terms Specific to This Standard:3.2.1 composite shella multilayer filament-winding thatcomprises a second shell tha
12、t 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. 1. The number of layers, fiber1This practice is under the j
13、urisdiction 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, 2005. Published June 2005. Originallyapproved in 1995. Last previous edition approved in 2000 as E 1736 - 00.2Vary, A., “Ac
14、ousto-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, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at
15、 serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.4Available from TheAmerican Society for Nondestructive Testing (ASNT), P.O.Box 28518, 1711 Arlingate Ln., Columbus, OH 43228-0518.5Available from Aerospace Industrie
16、s 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.orientation, and composite shell thickness may vary from pointto point (Fig. 2). The examination and assessme
17、nt 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 a composite shell.The inner shell or liner may consist of an impervious metallicor nonmetallic material. The vessel may be cylindrical orsphero
18、idal and will have at least one penetration with valveattachments for introducing and holding pressurized liquids orgases.4. Significance and Use4.1 The AU method should be considered for vessels thatare proven to be free of major flaws or discontinuities asdetermined by conventional techniques. The
19、 AU method maybe used for detecting major flaws if other methods are deemedimpractical. It is important to use methods such as immersionpulse-echo ultrasonics (Practice E 1001) and acoustic emission(Practice E 1067) to ascertain the presence of major flawsbefore proceeding with AU.4.2 The AU method
20、is intended almost exclusively formaterials characterization by assessing the collective effects ofdispersed defects and subcritical flaw populations. These arematerial aberrations that influence AU measurements and alsounderlie mechanical property variations, dynamic load re-sponse, and impact and
21、fracture resistance.64.3 TheAU method can be used to evaluate laminate qualityusing access to only one surface, the usual constraint imposedby closed pressure vessels. For best results, the AU probesmust be fixtured to maintain the probe orientation at normalincidence to the curved surface of the ve
22、ssel. Given theseconstraints, this practice describes a procedure for automatedAU scanning using water squirters to assess the serviceabilityand reliability of filament-wound pressure vessels.75. Limitations5.1 TheAU method possesses the limitations common to allultrasonic methods that attempt to me
23、asure either absolute orrelative attenuation. When instrument settings and probe con-figurations are optimized for AU, they are unsuitable forconventional ultrasonic flaw detection because the objective ofAU is not the detection and imaging of individual micro- ormacro-flaws.5.2 The AU results may b
24、e affected adversely by thefollowing factors:(1) couplant (squirter or water jet) variations and bubbles,(2) vessel surface texture and roughness,(3) improper selection of probe characteristics (centerfrequency and bandwidth),(4) probe misalignment,(5) probe resonances and insufficient damping, and(
25、6) inadequate instrument (pulser-receiver) bandwidth.5.3 Misinterpretations of AU results can occur if there areintermittent disbonds or gaps in the composite shell or at theinterface between the composite and inner shell. Using con-ventional flaw detection methods, care should be taken toensure tha
26、t major delaminations, disbonds, or gaps are notpresent. Extensive gaps or disbonds will produce the sameeffect as low attenuation within the composite shell by causingmore energy to be reflected or channeled to the receivingprobe.6Vary, A., “Material Property Characterization,” Nondestructive Testi
27、ngHandbookUltrasonic Testing, Vol 7, A. S. Birks, R. E. Green, Jr., and P. McIntire,eds., American Society for Nondestructive Testing, Columbus, OH, 1991, Section12, pp. 383431.7Sundaresan, M. J., Henneke, E. G., and Brosey, W. D., “Acousto-UltrasonicInvestigation of Filament-Wound Spherical Pressur
28、e Vessels,” Materials Evalua-tion, Vol 49, No. 5, 1991, pp. 6016012.FIG. 1 Kevlar-Epoxy Filament-Wound ShellFIG. 2 Representation of Filament-Wound Composite ShellLayers Showing Typical Thicknesses and Layering VariationsE17360526. Basis of Application6.1 The following items are subject to contractu
29、al agree-ment between the parties using or referencing the test method.6.2 Personnel Qualification6.2.1 If specified in the contractual agreement, personnelperforming examinations to this standard shall be qualified inaccordance with a nationally or internationally recognizedNDT personnel qualificat
30、ion 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. The practice or standard used and itsapplicable revision shall be identified in the contractual agree-ment between the using parties.6.2.2 P
31、ersonnel TrainingTraining in the following topicsis recommended for personnel who perform examinations.6.2.2.1 Failure mechanisms in fiber reinforced plastics6.2.2.2 Ultrasonic instrument and search unit checkout onfiber reinforced plastics.6.2.2.3 Technology of ultrasonic examination of fiber rein-
32、forced plastics.6.3 Qualification of Nondestructive AgenciesIf specifiedin the contractual agreement, NDT agencies shall be qualifiedand evaluated as described in Practice E 543. The applicableedition of Practice E 543 shall be specified in the contractualagreement.6.4 Timing of ExaminationExaminati
33、ons 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 9.1.1 unless otherwise specified.6.6 Reporting Criteria/Acceptance CriteriaReporting cri-teria for the examination results shall be in accorda
34、nce with 10unless otherwise specified. Since acceptance criteria are notspecified in this standard, they shall be specified in thecontractual agreement.6.7 Reexamination of Repaired/Reworked ItemsReexamination of repaired/reworked items is not addressed inthis standard and if required shall be speci
35、fied in the contrac-tual agreement.7. Apparatus7.1 The basic apparatus and instrumentation for performingautomatedAU scanning of filament-wound 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
36、 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 incidence angle relative to thevessel surface.7.1.2 Acousto-Ultrasonic ProbesA sender and a receiver,that is, two search units as defined i
37、n Terminology E 1316.7.1.2.1 The sender should produce wavelengths in thevessels composite filament-wound shell equal to or less thanits thickness. 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 MH
38、z 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 columns of water, that is, the “squirter” orwater jet method.7.1.2.3 Probe separation (distance between probes) shouldbe fixed at approximately
39、 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 of material between the sender and the receiver. Thelatter requirement is to ensure integrating the effects of diffuseflaw populations in
40、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-receiver. The need to strengthen the signal depends onthe sender-receiver probe spacing, water jet column length, andattenuation by the she
41、ll.7.1.3 Instrumentation, 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-receiv
42、er,digital display, 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 eachFIG. 3 Schematic Diagram of Scanning Apparatus and
43、SignalAcquisition, Image Processing, and Data AnalysisInstrumentationE1736053local volume or zone of the composite shell on AU stress wavepropagation are collected and evaluated.28.2 The objective is to measure the relative efficiency ofstress wave propagation in the composite shell. The dominantatt
44、ribute measured is stress wave attenuation, as represented bysignal strength or weakness. This measurement is quantified byan AU stress wave factor (SWF) defined in Guide E 1495.Lower attenuation corresponds to higher values of the AUSWF.8.3 At any given location, higher signal strength is a resulto
45、f better stress wave energy transmission within the compositeshell and, therefore, indicates better transmission and redistri-bution of dynamic strain energy. More efficient strain energytransfer and strain redistribution (for example, during loadingor impact) correspond to increased strength and fr
46、actureresistance in the composite shell.8.4 Regions that exhibit lower signal strength are those thatattenuate the probe-induced stress waves. These are regions inwhich the strain energy is likely to concentrate and result incrack growth and fracture upon experiencing impact or highloading.9. Proced
47、ure9.1 Before AU scanning commences, the sender and re-ceiver probes should be evaluated by comparing the signalswith standard waveforms established previously for a referencecomposite shell. This determines whether there are deficienciesin the instrumentation and probe response.9.1.1 Consider the f
48、ollowing 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
49、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 and set the gate thatacquires the signal of interest.9.1.2.1 The signal reaching the receiving probe shouldresemble that illustrated in Fig. 4. In
