1、Designation: E1495/E1495M 12E1495/E1495M 17Standard Guide forAcousto-Ultrasonic Assessment of Composites, Laminates,and Bonded Joints1This standard is issued under the fixed designation E1495/E1495M; the number immediately following the designation indicates the yearof original adoption or, in the c
2、ase of 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 guide explains the rationale and basic technology for the acousto-ultrasonic (AU) m
3、ethod. Guidelines are given fornondestructive evaluation (NDE) of flaws and physical characteristics that influence the mechanical properties and relative strengthof composite structures (for example, filament-wound pressure vessels), adhesive bonds (for example, joints between metal plates),and int
4、erlaminar and fiber/matrix bonds in man-made composites and natural composites (for example, wood products).1.2 This guide covers technical details and rules that must be observed to ensure reliable and reproducible quantitative AUassessments of laminates, composites, and bonded structures. The unde
5、rlying principles, prototype apparatus, instrumentation,standardization, examination methods, and data analysis for such assessments are covered. Limitations of the AU method andguidelines for taking advantage of its capabilities are cited.1.3 The objective of AU is to assess subtle flaws and associ
6、ated strength variations in composite structures and bonded joints.Discontinuities such as large voids, disbonds, or extended lack of contact at interfaces can be assessed by other NDE methods suchas conventional ultrasonics.1.4 Additional information may be found in the publications cited in the li
7、st of references at the end of this guide.The referencedworks provide background on research, applications, and various aspects of signal acquisition, processing, and interpretation.1.5 UnitsThe values stated in either SI units or inch-pound units are to be regarded as standard. The values stated in
8、 eachsystem may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from thetwo systems may result in non-conformance with the standards.1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use.
9、It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.1.7 This international standard was developed in accordance with internationally recognized principles on standardizationest
10、ablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2E543 Specification for Agencies Performing Nondestructive Tes
11、tingE1316 Terminology for Nondestructive Examinations2.2 ASNT Standard:3ANSI/ASNT CP-189 Standard for Qualification and Certification of Nondestructive Testing PersonnelSNT-TC-1A Recommended PracticemPractice for Personnel Qualifications and Certification in Nondestructive Testing2.3 AIA Document:4N
12、AS-410 Certification and Qualification of Nondestructive Testing Personnel1 This guide is under the jurisdiction of ASTM Committee E07 on Nondestructive Testing and is the direct responsibility of Subcommittee E07.04 on Acoustic EmissionMethod.Current edition approved June 15, 2012June 1, 2017. Publ
13、ished July 2012June 2017. Originally approved in 1992. Last previous edition approved in 20072012 asE1495 - 02 (2007).E1495 - 12. DOI: 10.1520/E1495-12.10.1520/E1495-17.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual
14、 Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.3 Available from American Society for Nondestructive Testing (ASNT), P.O. Box 28518, 1711 Arlingate Ln., Columbus, OH 43228-0518, http:/www.asnt.org.4 Available from Aerospace Industries Assoc
15、iation of America, Inc. (AIA), 1000 Wilson Blvd., Suite 1700, Arlington, VA 22209-3928, http:/www.aia-aerospace.org.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may n
16、ot be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.*A Summary of Changes section appears at the e
17、nd of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States12.4 ISO Standard:5ISO 9712 Non-Destructive Testing: Qualification and Certification of NDT Personnel3. Terminology3.1 Definitions:3.1.1 acousto-ultrasonics (AU)a nonde
18、structive examination method that uses induced stress waves to detect and assess thediffuse defect states, damage conditions, and variations of mechanical properties of an examination structure. The AU methodcombines aspects of acoustic emission (AE) signal analysis with ultrasonic materials charact
19、erization methods (TerminologyE1316).3.1.2 Additional related definitions may be found in Terminology E1316.3.2 Definitions of Terms Specific to This Standard:3.2.1 stress wave factor (SWF)a generic measure of the relative energy loss (attenuation) or propagation efficiency of stresswaves generated
20、by the AU method. There are many ways to define and calculate the SWF. Several of these are described inSection 11 of this guide.4. Summary of Guide4.1 GeneralTwo probes are attached to a sample in a send-receive configuration. One (a pulsed sending probe) is optimizedfor wave generation, while the
21、other (a receiving probe) is optimized for signal sensing. The probes are attached to the samplesurface at normal incidence. The usual, and often most practical, configuration has piezoelectric probes, a sender and receiver, onthe same side of the examination part (1).6 Measurements are performed by
22、 allowing ultrasonic stress waves to interact with avolume of material between the probes. The waves are modified by the material microstructure and morphology (2).4.2 PrincipleTheAU method measures the relative efficiency of stress wave propagation in a material. The dominant attributemeasured is s
23、tress wave attenuation. Lower attenuation, a high SWF value, means better stress wave energy transmission for manycomposites and, therefore, better transmission and redistribution of dynamic strain energy. More efficient strain energy transfer andstrain redistribution during loading or impact corres
24、ponds to increased strength and fracture resistance in composite structures andadhesive bonds. A lower SWF usually indicates regions in which strain energy is likely to concentrate and result in crack growthand fracture (3).4.3 Structure Configuration EffectsIn monolithic plates and homogeneous comp
25、osite slabs, the SWF will exhibit signalattenuation effects due to variations in microstructure, morphology, porosity, cure state, microcrack populations, etc. (4). A lowerSWF typically corresponds to regions of higher attenuation. In laminated structures or bonded joints, however, interfaces andbon
26、dlines can produce either lower or higher SWF values, depending on the bond quality (5). Delaminated regions can producehigher SWF values because more energy is reflected or channeled to the receiving probe.4.4 In-Plane MeasurementsOffsetting probes enables the collection of stress wave reverberatio
27、ns that have traveled in-planefrom sender to receiver. It is therefore possible to measure in-plane, mechanical property variations in principal load directions infiber-reinforced laminates or adhesively bonded joints (that is, properties such as interlaminar shear strength and adhesive bondstrength
28、).4.5 Signal Collection CriterionWith theAU method, instead of singling out specific echoes, all of the multiple reverberations,including signals from internal reflectors and scatterers, are collected and analyzed together. Even with pulse-echo orthrough-transmission configurations, all stress wave
29、reflections and reverberations in a local volume of material are collected andevaluated, as in backscatter, forward-scatter, and diffuse field analysis.4.6 Wavelength CriterionIn composite panels or bonded plates, the sender should produce wavelengths that are comparableto or less than the panel or
30、plate thickness. Suitable wavelengths are those passed by the examination piece at frequencies equalto or greater than the sending probe center frequencies.5. Significance and Use5.1 GeneralConventional ultrasonics should be considered first for the detection of overt flaws such as delaminations inc
31、omposites. Thereafter, AU should be considered for composites that are proved to be free of major flaws or discontinuities. TheAU method is intended almost exclusively for assessing the collective effects of dispersed defects and subcritical flaw populations.These are material aberrations that influ
32、ence AU measurements and also underlie mechanical property variations, dynamic loadresponse, and impact and fracture resistance.5.2 Specific AdvantagesThe AU method can be used to evaluate composite laminate and bond quality using access to onlyone surface as, for example, the exterior surface of pr
33、essure vessels. It is unnecessary to utilize angle beam fixtures because the5 Available from International Organization for Standardization (ISO), ISO Central Secretariat, BIBC II, Chemin de Blandonnet 8, CP 401, 1214 Vernier, Geneva,Switzerland, http:/www.iso.org.6 The boldface numbers in parenthes
34、es refer to the list of references at the end of this guide.E1495/E1495M 172method can always be applied with probes at normal incidence. The method can be applied using dry coupling with elastomer padsattached to the probes, and there is no need to immerse the examination object in water.5.3 Genera
35、l ApplicationsTheAU method was devised to assess diffuse discontinuity populations and any associated changesof the mechanical properties of composites and composite-like materials. The AU method has been used to evaluatefiber-reinforced composites (6), composite laminates (7), filament-wound pressu
36、re vessels (8), adhesive bonds (9), paper and woodproducts (10), and cable and rope (11). The method has been shown to be particularly practical for assessing the strength ofadhesively bonded joints. It has also been shown to be useful for assessing microporosity (12), micro-cracking (13), hydrother
37、malaging (14), and damage produced by impacts (15) and fatigue (16).6. Basis of Application6.1 Personnel Qualification6.1.1 If specified in the contractual agreement, personnel performing examinations to this standard shall be qualified inaccordance with a nationally recognized NDT personnel qualifi
38、cation practice or standard such as ANSI/ASNT CP-189,SNT-TC-1A, NAS-410, ISO 9712 , or a similar document and certified by the employer or certifying agency, as applicable. Thepractice or standard used and its applicable revision shall be identified in the contractual agreement between the using par
39、ties.6.2 Qualification of Nondestructive Agencies6.2.1 If specified in the contractual agreement, NDT agencies shall be qualified and evaluated as described in Practice E543.The applicable edition of Practice E543 shall be specified in the contractual agreement.6.3 Proper application of the AU metho
40、d requires the involvement of an NDE specialist to plan and guide the examinationprocedure. Knowledge of the principles of ultrasonic examination is required. Personnel applying AU should be experiencedpractitioners of conventional ultrasonic and acoustic emission examination and associated methods
41、for signal acquisition,processing, and interpretation.6.4 Particular emphasis should be placed on personnel having proficiency in computer signal processing and the use of digitalmethods for time and frequency domain signal analysis. Familiarity with ultrasonic spectrum analysis using digital Fourie
42、rtransforms is mandatory. Spectral distribution, multiple regression, and pattern recognition analyses and adaptive learningprocedures are important.6.5 Application of the AU method also requires proficiency in developing and designing reference standards. The developmentof reference standards is ne
43、eded for each type of material and configuration to be examined. BecauseAU measurements are relativeand comparative, experimental examinations confirmed by destructive testing are needed to avoid ambiguities in the interpretationof results.7. Limitations7.1 GeneralThe AU method possesses the limitat
44、ions common to all ultrasonic methods that attempt to measure eitherabsolute or relative attenuation. When instrument settings and probe configurations are optimized for AU, they are unsuitable forconventional ultrasonic flaw detection.7.2 Signal Reproducibility FactorsThe AU results may be affected
45、 adversely by the following factors: (1) improper selectionof type and amount of couplant, (2) couplant thickness variations and bubbles, (3) specimen surface roughness and texture, (4)probe misalignment and insufficient pressure, (5) probe resonances and insufficient damping, and (6) insufficient i
46、nstrumentbandwidth.8. Standardization8.1 Self-StandardizationThe sender and receiver probes can be used to verify each other. Deficiencies in the instrumentationand probe response become evident by comparing the results with the standard waveforms established previously for a referenceitem. Commerci
47、al ultrasonic probes andAE sensors respond to deformation (stress) waves in a complex fashion that involves bothnormal and in-plane displacements of the examination sample surface. Although it is possible to standardize such probes in anabsolute sense, even sensors of the same design and specificati
48、on should be treated as unique and definitely noninterchangeable.8.2 Stress Wave Factor NormalizationRegardless of how the SWF is defined, it is practical to normalize it relative to somestandard value, for example, the maximum value found for the optimum condition of a representative material sampl
49、e or structure.This is appropriate where many nominally identical articles will be examined.8.3 Reference StandardsNormalization of the SWF is the first step toward establishing a reference standard. The second stepis to fabricate a set of samples exhibiting the full range of expected material conditions and flaw states. One of these samples shouldrepresent the optimum condition of the material. This procedure should be followed by the development of benchmark structuresthat can be used as comparative standards.E1495/E1495M 1739. System Configuration9.1 Standar
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