1、Designation: E3045 16Standard Practice forCrack Detection Using Vibroacoustic Thermography1This standard is issued under the fixed designation E3045; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A numb
2、er in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 PurposeThis practice covers procedures required toconduct an examination of components using vibroacousticthermography.1.2 ApplicationThe v
3、ibroacoustic thermography processhas been used for component inspections in the aircraft, powergeneration, automotive, and other industries for testing newand serviced components, both coated and uncoated. Currentapplications are mostly targeting metallic components, butcomposite and ceramic compone
4、nt applications are underdevelopment.1.3 BackgroundVibroacoustic thermography is a newtechnique within the area of active thermography. The tech-nique was first published by Henneke, et al. in 1979 (1)2andhas been expanded on and popularized by Favro, et al. (2).During the test a defect thermal resp
5、onse resulting from a shortburst of ultrasonic energy typically in the range of 15 kHz to 40kHz is detected by an infrared camera. The ultrasound coupledinto the component being tested can activate a thermal re-sponse in defects with contact areas that can move against eachother, that is, cracks and
6、 delamination. There are differentenergizing and coupling techniques that are commonly useddepending on the needs and capabilities. These variations andthe down selection process are not included in the procedureand should be developed/optimized by experimentation foreach new component application.N
7、OTE 1Vibroacoustic thermography is typically sensitive to tightplanar defects (3). Volumetric defects such as porosity, inclusions, openruptures or cracks in wide-open areas, will not typically result in anindication. Therefore, an augmenting method should be conducted todetect volumetric defects.NO
8、TE 2Vibroacoustic thermography is a surface examination but hasdemonstrated detection sensitivity for subsurface defects including backwall defects for thin components (4), (5). Care should be taken whendeveloping vibroacoustic thermography for the detection of subsurfacedefects.1.4 WarningVibroacou
9、stic thermography requires theenergization of the test article with vibrational energy. Duringenergization, the complete component may be excited withvibroacoustic (vibration) energy for as long as several seconds.The development of this test for a new application requiresspecial measurements, preca
10、utions and attention to componentresponse. The component design engineer and the NDE engi-neering specialist, knowledgeable of this technique should besatisfied that the test will not cause damage or reduction ofservice life.1.5 This standard does not purport to address all of thesafety concerns, if
11、 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:E168 Practices for General Techniques of Infrare
12、d Quanti-tative Analysis (Withdrawn 2015)3E1213 Practice for Minimum Resolvable Temperature Dif-ference for Thermal Imaging SystemsE1252 Practice for General Techniques for Obtaining Infra-red Spectra for Qualitative AnalysisE1311 Practice for Minimum Detectable Temperature Dif-ference for Thermal I
13、maging SystemsE1316 Terminology for Nondestructive ExaminationsE1933 Practice for Measuring and Compensating for Emis-sivity Using Infrared Imaging RadiometersE2585 Practice for Thermal Diffusivity by the Flash Method2.2 ASNT Standards:4SNT-TC-1A Recommended Practice, Personnel Qualifica-tion and Ce
14、rtification in Nondestructive TestingANSI/ASNT CP-189-2001 Standard for Qualification andCertification of Nondestructive Testing Personnel2.3 ATA Standards:5ATA-105 Guidelines for Training and Qualifying Personnelin Nondestructive Testing1This test method is under the jurisdiction of ASTM Committee
15、E07 onNondestructive Testing and is the direct responsibility of Subcommittee E07.10 onSpecialized NDT Methods.Current edition approved April 1, 2016. Published April 2016. DOI: 10.1520/E3045-152The boldface numbers in parentheses refer to a list of references at the end ofthis standard.3The last ap
16、proved version of this historical standard is referenced onwww.astm.org.4Available fromAmerican Society for Nondestructive Testing (ASNT), P.O. Box28518, 1711 Arlingate Ln., Columbus, OH 43228-0518, http:/www.asnt.org.5Available from Air Transport Association, 1301 Pennsylvania Avenue, Suite1100, Wa
17、shington, DC 200041707.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States12.4 U.S. Publications:MIL-HDBK-1823A Department of Defense Handbook:Nondestructive Evaluation System Reliability Assessment3. Terminology3.1 Abbreviations:3.1.1 IR
18、Infrared3.1.2 MWIRMid-Wave Infrared3.1.3 LWIRLong-Wave Infrared3.1.4 NDENon-destructive Examination3.1.5 ROIRegion of Interest3.1.6 NETDNoise Equivalent Temperature Difference3.1.7 CCDCharge Couple Device3.1.8 MSDSMaterial Safety Data Sheets3.1.9 SPDSSafe Practice Data Sheets3.1.10 TBCThermal Barrie
19、r Coating3.1.11 ASNTAmerican Society for Nondestructive Testing3.1.12 ANSIAmerican National Standards Institute3.1.13 ATAAir Transport Association3.1.14 FOVField of View3.1.15 PODProbability of Detection4. Summary of Practice4.1 Personnel Qualification/CertificationVibroacousticthermography is a new
20、 active thermography technique withinthe method of infrared and thermal testing. As the techniquedevelops, it is expected that several sub-techniques for ener-gizing will be developed, refined, and documented. The currentenergizing variations require competence in areas of materials,mechanics, and h
21、eat transfer. Therefore, early users are ex-pected to be well versed in these areas to ensure conservativeapplications. Because there is no existing single NDE methodthat matches all of the necessary skills, this first procedurerequires the responsible control of a certified Level III in themethod o
22、f infrared and thermal testing in accordance withANSI/ASNT CP-189 or ASNT, SNTTC-1A. It is recom-mended that the Level III, under consultation with the respon-sible component engineer, develop the necessary supplementaltraining requirements for Level I and Level II personnel.Inspections shall be con
23、ducted by NDE Level I or Level IIinspection personnel certified in accordance with ANSI/ASNTCP-189 or ASNT, SNTTC-1A. The NDE Level I should bequalified to properly perform specific calibrations, specificNDE, specific evaluations and record results according towritten instructions. The NDE Level II
24、should be qualified toset up and calibrate equipment, to interpret and evaluate resultswith respect to applicable codes, standards and specificationsand to organize and report the results of NDE.4.2 Vibroacoustic Thermography Test SystemThe systemconsists of an ultrasonic exciter, an infrared camera
25、, andoperating software to sequence the test and capture the result.The exciter is an ultrasonic piezoelectric transducer stack thatmay commonly be used for ultrasonic welding (plastics indus-try) or vibrations testing. Depending on the specific method ofenergization, a booster (amplifier) or a horn
26、 may also be usedto augment, phase, couple or focus the ultrasonic energy.Energization occurs for the first0-8seconds of test againdepending on the energization method. During this time, the IRcamera is triggered to capture resulting active heating of thecomponent defects. The images are labeled and
27、 stored for slowmotion play back of the simple vibroacoustic thermographymovie, or for further analysis.4.2.1 Ultrasonic SystemIncludes power supply and com-ponent fixture. Examples of these systems include a piezoelet-ric shaker, or ultrasonic welder system. Specific power ratings(watts) and freque
28、ncy (kHz) for the power supply and theconverter are essential to the vibroacoustic thermographyinspection process and shall not be changed or modifiedwithout contacting system manufacturer. Typical power ratingsfor a piezoeletric shaker system range from 800W - 4000Wwith typical frequencies ranging
29、from 14,000 Hz - 100,000 Hz.For ultrasonic welder systems, booster gain ratio, horn shapeand horn material also are essential to the vibroacousticthermography inspection process and shall not be changed ormodified without contacting system manufacturer.4.2.2 Infrared Thermal CameraThermal camera mus
30、thave the sensitivity to achieve the required defect Probabilityof Detection (POD) (6), (7), (8). Cooled MWIR (InSb) thermalcameras usually provide the best sensitivity (around 20 mK orbetter), whereas LWIR microbolometer are generally lesssensitive but may be adequate in many applications. Framerat
31、es 30 Hz are generally sufficient for vibroacoustic thermog-raphy measurements. Any resolution is adequate so long as thecamera is close enough to the specimen to resolve defectindications as in Practice E2585, subsection 6.1. This can bedetermined prior to test by use of a setup specimen having ade
32、fect in it of similar thermal signal to that of the defects ofinterest in the inspected parts.4.2.3 Minimum Software RequirementsThe softwareshould provide a method for triggering the excitation of thepart and recording the part response. The software should alsoprovide a method for reviewing and an
33、alyzing the results.4.3 System Calibration:4.3.1 If detection of certain critical defects is an engineeringrequirement, then a rigorous evaluation of capability andreliability is required, including a proper POD study. Such anevaluation would consider process variability due to excitation,vibration,
34、 crack location and orientation, crack closure, crackthermal response variability, non-uniformity of thermal camerafield, and infrared detection. General principles and guidelinesfor POD evaluation can be found in MIL-HDBK-1823A.4.3.2 If there is no engineering requirement on defectdetection, system
35、 capability can be estimated from sampleswith relevant defects or samples with similar simulated defects,called reference standards or reference components. Use ofthese samples can help confirm that the relevant defects arewithin the usual resolution and sensitivity limits of the IR NDEsystem.4.3.3
36、Once reference standards or reference componentshave been established, the same sample(s) can be retested laterto help confirm proper system operation. Although it is notpossible to define a universal reference standard, the followingE3045 162guidelines for development of reference and calibration s
37、tan-dards will apply to most commonly encountered NDE situa-tions:4.3.3.1 The reference sample should be constructed ofsimilar material as the actual part.4.3.3.2 The reference sample should have similar surfacepreparation as the actual part.4.3.3.3 The reference sample should contain real or simu-l
38、ated defects which correspond to worst and best case defectscenarios, with a reasonable range of severity, depth, and/orsize between these limits.4.4 Development of Evaluation CriteriaA basis foraccept/reject decisions must be developed. Procedures shouldbe developed by various engineering departmen
39、t representa-tives in harmony with certified Level III personnel, who arefamiliar with the thermographic inspection equipment to beused, as well as the part to be inspected, its function,composition, and defect and failure modes.5. Specific Practices5.1 Cleaning and Surface Preparation:5.1.1 The cle
40、aning and surfaces preparation process shouldbe determined in conjunction with the creation of the inspec-tion process specification for the specific part and should beused to remove or limit the false indications that may arisefrom foreign objects or contamination. The following is adescription of
41、the minimum recommended cleaning and sur-face preparation requirements.5.1.2 Visually inspect the examination area for defects thatvibroacoustic thermography is not specifically designed todetect. This may include dents, gouges, and other openindications where vibro-acoustically excited features wil
42、l notinteract to generate heat. Remove foreign objects, or contami-nation that could interfere with the inspection. This includesany loose debris that may move on the surface. Excess greaseor oil should be wiped away.5.1.3 In rare cases the emissivity of the surface may be lowenough to reduce therma
43、l emission from relevant indications.In this case the surface emissivity may be increased byapplication of a suitable coating. An example process forapplying a coating to improve surface emissivity of a part isdescribed in Appendix X1.5.2 Reference Standards:5.2.1 There are two types of reference st
44、andards currentlyused for vibroacoustic thermography: cracked standards andthermoelastic standards. Cracked standards require real cracksto cause a repeatable indication for standardization or refer-ence. Thermoelastic standards are typically attached polymersthat heat up characteristically upon ene
45、rgization. Any of thefollowing standards may be used for the purpose of assuring aproper energization/ imaging process as well as establishing alevel of confidence for defect detection.5.3 Reference ComponentA component(s) having aknown natural or fabricated defect in it may be used for areference s
46、tandard. The reference standard should contain atleast one defect of current and specific concern. A permanentrecord of a detailed defect map of the reference componentshall be maintained. This record shall include defect location,length and orientation. The original indication response shallbe stor
47、ed for reference.Additionally, an indication response forthe reference component shall be included in the inspectionreport for each heat or batch of components and for every shiftor work per inspection station.5.4 Quality IndicatorA quality indicator is a simple andcost effective polymer tape consis
48、ting of an adhesive posterstrip attached to the test article (that is, 3M Command PosterStrips). The reference standard should always be used with anattached quality indicator in the ROI. Quality indicators heatup upon energization of the test article to verify systemoperation. It is recommended tha
49、t quality indicators be used onevery component of the testing cycle.5.5 Examination CoverageAs with all image based NDE,the detection capability is limited by the spatial resolution ofthe acquired image. In cases where the instantaneous field ofview is insufficient to resolve the indication (that is, measuredmillimetres per pixel times 2-5 pixel safety factor is less thanthe indication size), a special qualification should be conductedto demonstrate adequate detection of relevant indications. Thenature of the examination allows for repeat magnified exami
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