1、Designation: E2491 13Standard Guide forEvaluating Performance Characteristics of Phased-ArrayUltrasonic Testing Instruments and Systems1This standard is issued under the fixed designation E2491; the number immediately following the designation indicates the year oforiginal adoption or, in the case o
2、f 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*1.1 This guide describes procedures for evaluating someperformance characteristics of phased-arra
3、y ultrasonic exami-nation instruments and systems.1.2 Evaluation of these characteristics is intended to be usedfor comparing instruments and systems or, by periodicrepetition, for detecting long-term changes in the characteris-tics of a given instrument or system that may be indicative ofimpending
4、failure, and which, if beyond certain limits, willrequire corrective maintenance. Instrument characteristicsmeasured in accordance with this guide are expressed in termsthat relate to their potential usefulness for ultrasonic examina-tions. Other electronic instrument characteristics in phased-array
5、 units are similar to non-phased-array units and may bemeasured as described in Guide E1065 or E1324.1.3 Ultrasonic examination systems using pulsed-wavetrains and A-scan presentation (rf or video) may be evaluated.1.4 This guide establishes no performance limits for exami-nation systems; if such ac
6、ceptance criteria are required, thesemust be specified by the using parties. Where acceptancecriteria are implied herein they are for example only and aresubject to more or less restrictive limits imposed by customersand end users controlling documents.1.5 The specific parameters to be evaluated, co
7、nditions andfrequency of test, and report data required, must also bedetermined by the user.1.6 This guide may be used for the evaluation of a completeexamination system, including search unit, instrument,interconnections, scanner fixtures and connected alarm andauxiliary devices, primarily in cases
8、 where such a system isused repetitively without change or substitution. This guide isnot intended to be used as a substitute for calibration orstandardization of an instrument or system to inspect any givenmaterial.1.7 Required test apparatus includes selected test blocks andposition encoders in ad
9、dition to the instrument or system to beevaluated.1.8 Precautions relating to the applicability of the proce-dures and interpretation of the results are included.1.9 Alternate procedures, such as examples described in thisdocument, or others, may only be used with customer approval.1.10 The values s
10、tated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.11 This standard does not purport to 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
11、 and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2E317 Practice for Evaluating Performance Characteristics ofUltrasonic Pulse-Echo Testing Instruments and Systemswithout the Use of Electronic Measurement Instrumen
12、tsE494 Practice for Measuring Ultrasonic Velocity in Materi-alsE1065 Guide for Evaluating Characteristics of UltrasonicSearch UnitsE1316 Terminology for Nondestructive ExaminationsE1324 Guide for Measuring Some Electronic Characteristicsof Ultrasonic Testing Instruments3. Terminology3.1 Refer to Ter
13、minology E1316 for definitions of terms inthis guide.4. Summary of Guide4.1 Phased-array instruments and systems have similar in-dividual components as are found in traditional ultrasonic1This guide is under the jurisdiction of ASTM Committee E07 on Nondestruc-tive Testing and is the direct responsi
14、bility of Subcommittee E07.06 on UltrasonicMethod.Current edition approved June 1, 2013. Published June 2013. Originallyapproved in 2006. Last previous edition approved in 2008 as E2491 - 08. DOI:10.1520/E2491-13.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Cu
15、stomer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken
16、, PA 19428-2959. United States1systems that are based on single channel or multiplexedpulse-echo units. These include pulsers, receivers, probes andinterconnecting cables. The most significant difference is thatphased-array systems form the transmitted ultrasonic pulse byconstructive phase interfere
17、nce from the wavelets formed offthe individually pulsed elements of the phased-array probes.4.2 Each phased-array probe consists of a series of individu-ally wired elements that are activated separately using aprogrammable time delay pattern. Varying the number ofelements used and the delay time bet
18、ween the pulses to eachelement allows control of the beam. Depending on the probedesign, it is possible to electronically vary the angle (incidentor skew), or the focal distance, or the beam dimensions, or acombination of the three. In the receiving mode, acousticenergy is received by the elements a
19、nd the signals undergo asummation process utilizing the same type of time delayprocess as was used during transmission.4.3 The degree of beam steering available is dependent onseveral parameters including; number of elements, pitch of theelement spacing, element dimensions, element array shape,reson
20、ant frequency of the elements, the material into which thebeam is directed, the minimum delay possible between firing ofadjacent pulsers and receivers and the pulser voltage charac-teristics.4.4 Pulser and receiver parameters in phased-array systemsare generally computer controlled and the received
21、signals aretypically displayed on computer monitors via computer dataacquisition systems and may be stored to computer files.4.5 Although most systems use piezo-electric materials forthe elements, electro-magnetic acoustic transducer (EMAT)devices have also been designed and built using phased-array
22、instrumentation.4.6 Most phased array systems can use encoders for auto-mated and semi-automated scanning.4.7 Side Drilled Holes used as targets in this documentshould have diameters less than the wavelength of the pulsebeing assessed and long enough to avoid end effects fromcausing interfering sign
23、als. This will typically be accomplishedwhen the hole diameter is between about 1.5 mm and 2.5 mmand 20 mm to 25 mm in length.5. Significance and Use5.1 This guide is intended to evaluate performance assess-ment of combinations of phased-array probes and instruments.It is not intended to define perf
24、ormance and acceptance criteria,but rather to provide data from which such criteria may beestablished.5.2 Recommended procedures described in this guide areintended to provide performance-related measurements thatcan be reproduced under the specified test conditions usingsimple targets and the phase
25、d-array test system itself. It isintended for phased-array flaw detection instruments operatingin the nominal frequency range of 1 MHz to 20 MHz, but theprocedures are applicable to measurements on instrumentsutilizing significantly higher frequency components.5.3 This guide is not intended for serv
26、ice calibration, ormaintenance of circuitry for which the manufacturers instruc-tions are available.5.4 Implementation of specific assessments may requiremore detailed procedural instructions in a format of the usingfacility.5.5 The measurement data obtained may be employed byusers of this guide to
27、specify, describe, or provide a perfor-mance criteria for procurement and quality assurance, orservice evaluation of the operating characteristics of phased-array systems.5.6 Not all assessments described in this guide are appli-cable to all systems. All or portions of the guide may be usedas determ
28、ined by the user.6. Procedure6.1 Procedures for assessment of several parameters inphased-array systems are described in Annexes A1 to A7.6.1.1 These include; determination of beam profile, beamsteering capability, element activity, focusing capability, soft-ware calculations (controls and display o
29、f received signals),compensation for wedge attenuation, receiver gain linearity.7. Keywords7.1 characterization; focal point; phased-array; phased-arrayprobe; sound beam profile; ultrasoundANNEXES(Mandatory Information)A1. DETERMINATION OF PHASED-ARRAY BEAM PROFILEE2491 132A1.1 IntroductionA1.1.1 Th
30、is annex describes procedures to determine beamprofiles of phased-array probes. Either immersion or contactprobe applications can be addressed using these procedures.However, it should be cautioned that assessments of contactprobes may suffer from variability greater than imposedtolerances if proper
31、 precautions are not taken to ensureconstant coupling conditions.A1.2 Test SetupA1.2.1 For single focal laws where the beam is fixed (thatis, not used in an electronic or sectorial scan mode) and theprobe is used in an immersion setup, the ball-target orhydrophone options described in E1065 may be u
32、sed. Forphased array probes used in a dynamic fashion where severalfocal laws are used to produce sectorial or electronic scanningit may be possible to make beam-profile assessments with no orlittle mechanical motion. Where mechanical motion is used itshall be encoded to relate signal time and ampli
33、tude to distancemoved. Encoder accuracy shall be verified to be withintolerances appropriate for the measurements made. Descrip-tions made for electronic scan and sectorial scan beam profileassessments will be made for contact probes; however, whenassessment in water is required the machined targets
34、 may bereplaced with rods or balls as appropriate.A1.2.2 Linear-Array ProbesLinear-array probes have anactive plane and an inactive or passive plane. Assessment ofthe beam in the active plane should be made by use of anelectronic scan sequence for probes with sufficient number ofelements to electron
35、ically advance the beam past the targets ofinterest. For phased array probes using a large portion of theavailable elements to form the beam the number of remainingelements for the electronic raster may be too small to allow thebeam to pass over the target. In this case it will be necessary tohave e
36、ncoded mechanical motion and assess each focal lawalong the active plane separately.A1.2.3 Side-drilled holes should be arranged at variousdepths in a flaw-free sample of the test material in which focallaws have been programmed for. Using the linear scan featureof the phased-array system the beam i
37、s passed over the targetsat the various depths of interest. The electronic scan isillustrated schematically in Fig. A1.1.A1.2.4 Data collection of the entire waveform over therange of interest shall be made. The display shall representamplitude as a color or grayscale. Time or equivalent distancein
38、the test material shall be presented along one axis anddistance displaced along the other axis. This is a typical B-scanas illustrated in Fig. A1.2.A1.2.5 Data display for an electronic scan using a phased-array probe mounted on a wedge can be similarly made usingsimple orthogonal representation of
39、time versus displacementor it can be angle corrected as illustrated in Fig. A1.3.A1.2.6 Resolution along the displacement axis will be afunction of the step size of the electronic scan or, if the scanuses an encoded mechanical fixture the resolution will bedependent on the encoder step-size used for
40、 sampling.A1.2.7 Resolution along the beam axis will be a function ofthe intervals between the target paths. For highly focusedbeams it may be desirable to have small differences betweenthe sound paths to the target paths (for example, 1 mm or 2mm).A1.2.8 Beam profiling in the passive plane can also
41、 bemade. The passive plane in a linear-array probe is perpendicu-lar to the active plane and refers to the plane in which no beamsteering is possible by phasing effects. Beam profiling in thepassive direction will require mechanical scanning.FIG. A1.1 Electronic Scan of Side Drilled HolesE2491 133A1
42、.2.9 Waveform collection of signals using a combinationof electronic scanning in the active plane and encoded me-chanical motion in the passive plane provides data that can beprojection-corrected to provide beam dimensions in the passiveplane. Fig. A1.4 illustrates a method for beam assessment inFIG
43、. A1.2 B-Scan Display of Electronic Scan Represented in Fig. A1.1 (Depth is in the vertical axis and electronic-scan distance is rep-resented along the horizontal axis.)FIG. A1.3 Angle-Corrected B-Scan of a Phased-Array Beam (in Shear Wave Mode) from a Side Drilled Hole (Off-axis lobe effects can be
44、seen in the display.)FIG. A1.4 Scanning End-Drilled Holes to Obtain Beam Dimensions in Passive PlaneE2491 134the passive plane. This technique uses a corner reflection froman end-drilled hole at depths established by a series of steps.A1.2.10 Fig. A1.5 illustrates an alternative to the steppedinterv
45、als shown in Fig. A1.4. A through hole may be arrangedperpendicular to the required refracted angle to provide acontinuous transition of path length to the target.A1.2.11 A projected C-scan can be used to size the beambased on either color or grayscale indicating amplitude drop ora computer display
46、that plots amplitude with respect todisplacement. The projected C-scan option is schematicallyrepresented in Fig. A1.6.FIG. A1.5 Representation of an Inclined Hole for Beam Characterization in the Passive PlaneE2491 135A2. DETERMINATION OF PHASED-ARRAY BEAM STEERING LIMITSA2.1 IntroductionA2.1.1 Thi
47、s annex describes procedures to determine prac-tical limits for beam steering capabilities of a phased-arrayprobe and as such applies to the active plane(s) only. Eitherimmersion or contact probe applications can be addressedusing these procedures. However, it should be cautioned thatassessments of
48、contact probes may suffer from variabilitygreater than imposed tolerances if proper precautions are nottaken to ensure constant coupling conditions.A2.1.2 Recommended limits to establish the working rangeof angular sweep of a phased-array probe relate to thedivergence of the beam of each element in
49、the probe array.When used in pulse-echo mode the steering limit is consideredto be within the 6-dB divergence envelope of the individualelements. It is therefore possible to calculate a theoretical limitbased on nominal frequency and manufacturer provided infor-mation on the element dimensions. However, several param-eters can affect the theoretical calculations. These are primarilyrelated to the nominal frequency of the probe. Some param-eters affecting actual frequency include; pulse length, damping,use of a delay-line or refracting wedge and variations inmanufacturing pro
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