1、Designation: E 2491 08Standard Guide forEvaluating Performance Characteristics of Phased-ArrayUltrasonic Testing Instruments and Systems1This standard is issued under the fixed designation E 2491; the number immediately following the designation indicates the year oforiginal adoption or, in the case
2、 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. Scope1.1 This guide describes procedures for evaluating someperformance characteristics of phased-arr
3、ay ultrasonic exami-nation instruments and systems.1.2 Evaluation of these characteristics is intended to be usedfor comparing instruments and systems or, by periodic repeti-tion, for detecting long-term changes in the characteristics of agiven instrument or system that may be indicative of impend-i
4、ng failure, and which, if beyond certain limits, will requirecorrective maintenance. Instrument characteristics measured inaccordance with this guide are expressed in terms that relate totheir potential usefulness for ultrasonic examinations. Otherelectronic instrument characteristics in phased-arra
5、y units aresimilar to non-phased-array units and may be measured asdescribed in E 1065 or E 1324.1.3 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 accept
6、ance 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, condit
7、ions 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, inter-connections, scanner fixtures and connected alarm and auxil-iary devices, primarily in cases
8、 where such a system is usedrepetitively without change or substitution. This guide is notintended to be used as a substitute for calibration or standard-ization of an instrument or system to inspect any givenmaterial.1.7 Required test apparatus includes selected test blocks andposition encoders in
9、addition 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
10、 stated 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 safe
11、ty and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2E 317 Practice for Evaluating Performance Characteristicsof Ultrasonic Pulse-Echo Testing Instruments and Systemswithout the Use of Electronic Measurement Instru
12、mentsE 494 Practice for Measuring Ultrasonic Velocity in Mate-rialsE 1065 Guide for Evaluating Characteristics of UltrasonicSearch UnitsE 1316 Terminology for Nondestructive ExaminationsE 1324 Guide for Measuring Some Electronic Characteris-tics of Ultrasonic Examination Instruments3. Terminology3.1
13、 Refer to Terminology E 1316 for definitions of terms inthis guide3.2 Definitions:3.2.1 angle corrected gainalso called ACG. Is compensa-tion applied to focal laws in an S-scan to correct for the effectsof echo-transmittance variation at different angles. This may beaccomplished by equalizing the am
14、plitude response in the farfield from a uniform reflector at a constant sound path throughthe range of angles used in the S-scan.An “infinite radius” suchas that provided by the 100 mm radius of the IIW block is aconvenient target for this function.Aseries of side drilled holes1This guide is under t
15、he jurisdiction of ASTM Committee E07 on Nondestruc-tive Testing and is the direct responsibility of Subcommittee E07.06 on UltrasonicMethod.Current edition approved July 1, 2008. Published August 2008. Originallyapproved in 2006. Last previous edition approved in 2006 as E 2491 - 06.2For referenced
16、 ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Cons
17、hohocken, PA 19428-2959, United States.arranged in a radiused pattern may also present uniformreflectors at a constant sound path but the corrections are thenin angular increments. Note that there are technical limits toACG, that is, beyond a certain angular range, compensation isnot possible.3.2.2
18、annular array probesphased-array probes that havethe transducers configured as a set of concentric rings. Theyallow the beam to be focused to different depths along an axis.The surface area of the rings is in most cases constant, whichimplies a different width for each ring.3.2.3 array (phased)a pat
19、terned arrangement of elements.Typical arrangements include linear, annular, two dimensionalmatrix, and “rho-theta”.3.2.4 electronic scanalso termed an E-scan. The samefocal law is multiplexed across a group of active elements;electronic raster scanning is performed at a constant angle andalong the
20、phased-array probe length. This is equivalent to aconventional ultrasonic probe performing a raster scan. Alsocalled electronic scanning.3.2.5 focal lawthe entire set of hardware and softwareparameters affecting the acoustic sensitivity field of a phasedarray search unit, whether a pulse-echo or a p
21、itch-catchconfiguration. Within focal laws, there are included delay lawsin transmitter and delay laws in receiver, as well as apodizationlaws, and element activation laws.3.2.6 linear array probesprobes made using a set ofelements juxtaposed and aligned along a linear axis. Theyenable a beam to be
22、moved, focused, and deflected along asingle azimuthal plane.3.2.7 matrix array probesthese probes have an active areadivided in two dimensions in different elements. This divisioncan, for example, be in the form of a checkerboard, or sectoredrings. These probes allow the ultrasonic beam steering in
23、morethan one plane.3.2.8 sectorial scanalso termed an S-scan or azimuthalscan. This may refer to either the beam movement or the datadisplay. As a data display it is a 2D view of all A-scans froma specific set of elements corrected for delay and refractedangle. When used to refer to the beam movemen
24、t it refers to theset of focal laws that sweeps a defined range of angles using thesame set of elements.3.2.9 S-scan (q.v. sectorial scan)4. Summary of Guide4.1 Phased-array instruments and systems have similar in-dividual components as are found in traditional ultrasonicsystems that are based on si
25、ngle 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 interference from the wavelets formed offthe individually pulsed ele
26、ments 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 between the pulses to eachelement allows control of the beam.
27、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 and the signals undergo asummation process utilizing the sam
28、e 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,resonant frequency of the elements, the material into which theb
29、eam 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 signals aretypically displayed on computer monitors via com
30、puter 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-arrayinstrumentation.4.6 Most phased array systems can use encod
31、ers 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 signals. This will typically be accomplishedwhen the hole diame
32、ter 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 performance and acceptance criteria,but rather to provide data
33、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 phased-array test system itself. It isintended for phased-array
34、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 service calibration, ormaintenance of circuitry for which the m
35、anufacturers 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 specify, describe, or provide a perfor-mance criteria for p
36、rocurement 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 determined by the user.E24910826. Procedure6.1 Procedures for ass
37、essment 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 of received signals),compensation for wedge attenuat
38、ion, 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 PROFILEA1.1 IntroductionA1.1.1 This annex describes procedures to determine beamprofiles of p
39、hased-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 precautions are not taken to ensureconstant coupling condit
40、ions.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 E 1065 may be used. Forphased array probes used in a dynamic fashion where
41、 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 amplitude to distancemoved. Encoder accuracy shall be verified t
42、o 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 may bereplaced with rods or balls as appropriate.A1.2.2 Li
43、near-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 electronically advance the beam past the targets ofinterest. For ph
44、ased 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 encoded mechanical motion and assess each focal lawalong the
45、 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 is passed over the targetsat the various depths of interest.
46、 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 the test material shall be presented along one axis anddist
47、ance 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 time versus displacementor it can be angle corrected as ill
48、ustrated 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 sampling.A1.2.7 Resolution along the beam axis will be a f
49、unction 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 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.A1.2.9 Waveform collection of signals using a combinationof electronic scanning in the active pl
