1、Designation: C1331 01 (Reapproved 2012)C1331 18Standard Test Method Practice forMeasuring Ultrasonic Velocity in Advanced Ceramics withBroadband Pulse-Echo Cross-Correlation Method1This standard is issued under the fixed designation C1331; the number immediately following the designation indicates t
2、he year oforiginal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope Scope*1.1 This test method practice describes a proc
3、edure for measurement of ultrasonic velocity in structural engineering solids suchas monolithic ceramics, toughened ceramics, and ceramic matrix composites.1.2 This test method practice is based on the broadband pulse-echo contact ultrasonic method. The procedure involves acomputer-implemented, freq
4、uency-domain method for precise measurement of time delays between pairs of echoes returned bythe back surface of a test sample or part.1.3 This test method practice describes a procedure for using a digital cross-correlation algorithm for velocity measurement.Thecross-correlation function yields a
5、time delay between any two echo waveforms (1).21.4 This international standard was developed in accordance with internationally recognized principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations issuedby the Wo
6、rld Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:3B311 Test Method for Density of Powder Metallurgy (PM) Materials Containing Less Than Two Percent PorosityC373 Test Methods for Determination of Water Absorption and Associated Properties by
7、 Vacuum Method for Pressed CeramicTiles and Glass Tiles and Boil Method for Extruded Ceramic Tiles and Non-tile Fired Ceramic Whiteware ProductsE494 Practice for Measuring Ultrasonic Velocity in MaterialsE543 Specification for Agencies Performing Nondestructive TestingE1316 Terminology for Nondestru
8、ctive Examinations2.2 ASNT Document:Documents:4Recommended Practice SNT-TC-1A for Nondestructive Testing Personnel Qualification and CertificationANSI/ASNT CP-189 Standard for Qualification and Certification of Nondestructive Testing Personnel2.3 Military Standard:ISO Document:MIL-STD-410ISO 9712 No
9、ndestructive Testing Personnel Qualification Non-destrtuctive Testing Qualification and Certifi-cation of NDT Personnel52.4 Aerospace Industries Association Document:NAS 410 Certification and Qualification of Nondestructive Testing Personnel62.5 Additional references are cited in the text and at end
10、 of this document.1 This test method practice is under the jurisdiction of ASTM Committee E07 on Nondestructive Testing and is the direct responsibility of Subcommittee E07.06 onUltrasonic Method.Current edition approved Aug. 1, 2012Feb. 1, 2018. Published November 2012February 2018. Originally appr
11、oved in 1996. Last previous edition approved in 20072012as C1331 01 (2007).(2012). DOI: 10.1520/C1331-01R12.10.1520/C1331-18.2 The boldface numbers in parentheses refer to the list of references at the end of this test method.practice.3 For referencedASTM standards, visit theASTM website, www.astm.o
12、rg, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.4 Available from American Society for Nondestructive Testing (ASNT), P.O. Box 28518, 1711 Arlingate Ln., Columbus, OH 43228-05
13、18, http:/www.asnt.org.5 Available from Standardization Documents Order Desk, DODSSP, Bldg. 4, Section D, 700 Robbins Ave., Philadelphia, PA 19111-5098, http:/www.dodssp.daps.mil.International Organization for Standardization (ISO), ISO Central Secretariat, BIBC II, Chemin de Blandonnet 8, CP 401, 1
14、214 Vernier, Geneva,Switzerland, http:/www.iso.org.6 Available from Aerospace Industries Association of America, Inc., 1250 Eye St. NW, Washington, DC, 2005.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
15、 to the previous version. Becauseit may not 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 Su
16、mmary 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. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 back surfacethe surface of a test sample which is oppos
17、ite to the front surface and from which back surface echoes arereturned at normal incidence directly to the transducer.3.1.2 bandwidththe frequency range of an ultrasonic probe, defined by convention as the difference between the lower andupper frequencies at which the signal amplitude is 6 dB down
18、from the frequency at which maximum signal amplitude occurs.3.1.3 broadband transduceran ultrasonic transducer capable of sending and receiving undistorted signals over a broadbandwidth, consisting of a thin damped piezocrystal in a buffered probe (search unit).3.1.4 buffered probean ultrasonic sear
19、ch unit as defined in Terminology E1316 but containing a delay line, or buffer rod, towhich the piezocrystal is affixed within the search unit housing and which separates the piezocrystal from the test sample (Fig. 1).3.1.5 buffer rodan integral part of a buffered probe, usually a quartz or fused si
20、lica cylinder that provides a time delay betweenthe excitation pulse from the piezocrystal and echoes returning from a sample coupled to the free end of the buffer rod.3.1.6 cross-correlation functionthe cross-correlation function, implemented by a digital algorithm, yields a time delaybetween any t
21、wo (ultrasonic) echo waveforms. This time is used to determine velocity (1).3.1.7 dispersionvariation of ultrasonic velocity as a function of wavelength, that is, frequency dependence of velocity.3.1.8 front surfacethe surface of a test sample to which the buffer rod is coupled at normal incidence (
22、designated as testsurface in Terminology E1316.3.1.9 group velocityvelocity of a broadband ultrasonic pulse consisting of many different component wavelengths.3.1.10 test samplea solid coupon or material part that meets the constraints needed to make the ultrasonic velocitymeasurements described her
23、ein, that is, a test sample or part having flat, parallel, smooth, preferably ground or polished opposing(front and back) surfaces, and having no discrete flaws or anomalies unrepresentative of the inherent properties of the material.3.1.11 wavelength ()distance that sound (of a particular frequency
24、) travels during one period (during one oscillation), = v/f,where v is the velocity of sound in the material and where velocity is measured in cm/s, frequency in MHz, and wavelength incm, herein.3.2 Other terms or nomenclature used in this test method practice are defined in Terminology E1316.4. Sig
25、nificance and Use4.1 The velocity measurements described in this test method practice may be used to characterize material variations that affectmechanical or physical properties. This procedure is useful for measuring variations in microstructural features such as grainstructure, pore fractions, an
26、d density variations in monolithic ceramics.4.2 Velocity measurements described herein can assess subtle variations in porosity within a given material or component, as,for example, in ceramic superconductors and structural ceramic specimens (2, 3).4.3 In addition to ceramics and ceramic composites,
27、 the velocity measurements described herein may be applied topolycrystalline and single crystal metals, metal matrix composites, and polymer matrix composites.4.4 An alternative technique for velocity measurement is given in Practice E494.NOTE 1B1 and B2 are first and second back surface echoes, res
28、pectively, and T is time interval between the echoes.FIG. 1 Cross Section of Buffered Ultrasonic Probe (a) and Principle Echoes (b) for Velocity MeasurementC1331 1825. Personnel Qualifications5.1 It is recommended that nondestructive evaluation/examination personnel applying this test methodIf speci
29、fied in thecontractual agreement, personnel performing examinations to this practice shall be qualified in accordance with a nationally-recognized nationally or internationally recognized NDT personnel qualification practice or standard such as ASNTANSI/ASNT-CP-189, SNT-TC-1A, MIL STD 410, NAS 410,
30、ISO 9712, or a similar document. The qualification document and certified by theemployer or certifying agency, as applicable. The practice or standard used and its applicable revision(s) shouldrevision shall bespecifiedidentified in a contractual agreement.the contractual agreement between the using
31、 parties.5.2 Knowledge of the principles of ultrasonic testing is required. Personnel applying this test method practice should beexperienced practitioners of ultrasonic examinations and associated methods for signal acquisition, processing, and interpretation.5.3 Personnel should have proficiency i
32、n computer signal processing and the use of digital methods for time and frequencydomain signal analysis. Familiarity with Fourier and associated transforms for ultrasonic spectrum analysis is required.6. Qualification of Nondestructive Agencies6.1 If specified in the contractual agreement, NDT agen
33、cies shall be qualified and evaluated as described in Specification E543.The applicable edition of Specification E543 shall be specified in the contractual agreement.7. Apparatus and Test Sample7.1 Instrumentation (Fig. 1 and Fig. 2) for broadband cross-correlation pulse-echo ultrasonic velocity mea
34、surement shouldinclude the following:7.1.1 Buffered Probe:7.1.1.1 The buffer rod, which is an integral part of the probe (search unit), should be a right cylinder with smooth flat endsnormal to the axis of the probe.7.1.1.2 The center frequency of the buffered probe should produce a wavelength withi
35、n the sample that is less than one fifthof the thickness of the sample.7.1.1.3 The buffer rod length, that is, time delay should be three times the interval between two successive back surface echoes.7.1.1.4 The wave mode may be either longitudinal or shear.7.1.2 Pulser-Receiver, with a bandwidth th
36、at is at least twice that of the buffered probe. The bandwidth should includefrequencies in the range from 100 kHz to over 100 MHz.7.1.2.1 The pulser-receiver should have provisions for controlling the pulse repetition rate, pulse energy level, pulse damping,and received signal gain.7.1.2.2 The puls
37、er-receiver should provide a synchronization pulse and signal output connector.7.1.3 Waveform Digitizing Oscilloscope (A/D Board), bus programmable, to window and digitize the echo waveforms.7.1.3.1 Aminimum 512-element waveform array with a maximum data sampling interval of 1.95 ns is recommended.
38、For betterwaveform resolution, a 1024-element array with a data sampling interval of 0.97 ns may be needed.7.1.3.2 Vertical Amplifier, bus programmable module.7.1.3.3 Time Base, bus programmable module with a resolution of at least 5 ns per division and several time base rangesincluding a fundamenta
39、l time base of at least 200 ns.FIG. 2 Instrumentation Diagram for Acquiring and Separately Windowing Two Successive Back Surface Echoes, B1 and B2, for Cross-Correlation Velocity MeasurementC1331 1837.1.4 Digital Time Delay Module, bus programmable, to introduce a known time delay between the start
40、of two separate timegates, that is, windows each of which containing one of two successive back surface echoes.7.1.4.1 Separate windows are preferred for waveform digitization. Each waveform should occupy from 60 to 80 % of thewindow.7.1.4.2 The time synthesizer should have an accuracy of 61 ns with
41、 a precision of 60.1 ns.7.1.5 Video Monitors, (optional) one analog, one digital for real-time visual inspection of echo waveforms and for makinginteractive manual adjustments to the data acquisition controls.7.1.6 Computer, with adequate speed and storage capacity to provide needed software control
42、, data storage, and graphicscapability. The software should include a fast Fourier transform (FFT) algorithm package containing the cross-correlationalgorithm.7.1.7 Couplant Layer, to establish good signal transfer between the buffer rod and test sample. The layer should be as thin aspossible to min
43、imize couplant resonances and distortion of the echo waveforms.7.1.7.1 The couplant should not be absorbed by or be otherwise deleterious to the test sample.7.1.7.2 Dry coupling with a thin polymer may be used where liquid contamination by or absorption of liquids by the test sampleor part must be a
44、voided.7.2 The test sample or part should have flat parallel opposing surfaces in the region where the velocity measurements are made.This will assure good coupling between the transducer and sample and also produce valid echoes for velocity measurements.7.2.1 Lack of precision in the measurement of
45、 the test sample thickness can undermine the nanosecond precision with whichpulse-echo travel times can be measured.Therefore, the sample thickness should be measurable to an accuracy of60.1 % or better.7.2.2 For most engineering solids, the sample thickness should be at least 2.5 mm. There is a pra
46、ctical upper bound on samplethickness, for example, if the sample is too thick, there may be considerable signal attenuation, beam spreading, and dispersionthat render the signal useless.8. Procedure8.1 Use instrument control software routines to start and control the interface bus; perform procedur
47、es such as optimizingintensity, voltage, and time on the waveform digitizing oscilloscope; control the digital time delay module; and acquire, store, andprocess data.8.1.1 A cross-correlation algorithm should be part of the FFT software.8.1.2 The arguments needed to implement the cross-correlation a
48、lgorithm are the time domain waveform arrays, that is,digitized echoes B1 and B2 (Fig. 1).8.2 Prepare samples with front and back surfaces that are sufficiently smooth, flat, and parallel to allow measurement of the testsample thickness to an accuracy of 0.1 % or better.8.3 Couple the sample to the
49、transducer to obtain two strong back surface echoes.8.3.1 Apply pressure to minimize the couplant layer thickness. A backing fixture may be necessary to apply pressure.8.3.2 Care shall be taken to avoid coupling the sample to the backing fixture and thereby losing echo signal strength by leakage.8.3.3 A dry, hard rubber or composite material with a rough-machined or sawtooth surface is recommended for the backingfixture.NOTE 1Time delay, W, between the two window start times is predetermined. Time interval, T, between echoes B1 and B2 is calculated from T
