1、Designation: E 1065 08Standard Guide forEvaluating Characteristics of Ultrasonic Search Units1This standard is issued under the fixed designation E 1065; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A
2、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 covers measurement procedures for evaluat-ing certain characteristics of ultrasonic search units (alsoknown as “transducers”
3、) that are used with ultrasonic exami-nation instrumentation. This guide describes means for obtain-ing performance data that may be used to define the acousticand electric responses of ultrasonic search units.1.2 The procedures are designed to measure search units asindividual components (separate
4、from the ultrasonic test instru-ment) using commercial search unit characterization systemsor using laboratory instruments such as signal generators,pulsers, amplifiers, oscilloscopes, and waveform analyzers.1.3 The procedures are applicable to manufacturing accep-tance and incoming inspection of ne
5、w search units or toperiodic performance evaluation of search units throughouttheir service life.1.4 The procedures in Annex A1-Annex A6 are generallyapplicable to ultrasonic search units operating within the 0.4 to10 MHz range. Annex A7 is applicable to higher frequencyimmersion search unit evaluat
6、ion. Annex A8 describes a guidefor measuring sound beam profiles in metals from contactstraight-beam search units. Additional Annexes, such as soundbeam profiling for angle-beam search units in metal andalternate means for search unit characterization, will be addedwhen developed.1.5 The values stat
7、ed in inch-pound units are to be regardedas standard.1.6 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 and health practices and determine the applica-bility o
8、f regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2E 1316 Terminology for Nondestructive Examinations2.2 Other Document:Standard Methods for Testing Single Element Pulse-EchoUltrasonic Transducers33. Terminology3.1 DefinitionsFor definitions of terms used in this guide,
9、see Terminology E 1316.3.2 Definitions of Terms Specific to This Standard:3.2.1 aperturethe dimension(s) of the active area of thepiezoelectric element of the search unit as established byexperimentation.3.2.2 bandwidth (BW) that portion of the frequencyresponse that falls within given limits. In th
10、is text, the limitsused are the -6 dB level, as measured from the peak of thefrequency response. The equation used for BW is:BW 5 fu2 f1!/fc3 100 (1)where:fu= upper frequency,f1= lower frequency, andfc= center frequency.Bandwidth is expressed as a percentage.3.2.3 center frequency (fc)the frequency
11、value calculatedto be at the center of the bandwidth limits.3.2.4 depth of field (FD)as measured on the on-axis profileof a focused search unit, that portion of the sound beam thatfalls within given limits.3.2.5 focal length (FL)for focused search units, the dis-tance from the lens to the focal poin
12、t.3.2.6 focal point (Fp)for focused search units, the pointalong the acoustic axis of the beam in water at which the peak(maximum) pulse-echo amplitude response is recorded from aball target reflector.3.2.7 frequency responsethe pulse-echo response of thesearch unit measured as a function of frequen
13、cy. (This termalso referred to as frequency spectrum.)3.2.8 nominal frequency (fnom)the frequency stated on thelabel supplied by the manufacturer.3.2.9 on-axis profilea sequence of measurements madealong the acoustic axis of the beam of the search unit.3.2.10 peak frequency (fp)the frequency value a
14、t themaximum amplitude of the frequency response.1This guide is under the 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 July 2008. Originally approvedin 1985.
15、Last previous edition approved in 2003 as E 1065 99(2003).2For referenced 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.3Av
16、ailable from the American Institute of Ultrasonics in Medicine, 14750Sweitzer Lane, Suite 100, Laurel, MD 20707-5906.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.2.11 pulse durationthe length of the sinusoidal burstused to excit
17、e the search unit as expressed in time or numberof cycles (sometimes referred to as tone-burst).3.2.12 pulse echo sensitivitya measurement that comparesthe amplitude of the applied voltage with the amplitude of thepulse-echo voltage recorded from a specified target.3.2.13 shock excitationa short ele
18、ctrical impulse that isapplied to the search unit. The impulse is typically a negative-going voltage spike of fast rise time and short duration.3.2.14 transverse profilesequence of measurements madealong a line perpendicular to the acoustic axis of the beam ofthe search unit.3.2.15 waveform duration
19、the time interval or durationover which the unrectified signal or echo from a specifiedtarget exceeds a selected amplitude level as related to themaximum amplitude of the signal or echo (for example, 20or 40 dB).4. Summary of Guide4.1 The acoustic and electrical characteristics which can bedescribed
20、 from the data obtained by procedures outlined in thisguide are described as follows:4.1.1 Frequency ResponseThe frequency response maybe obtained from one of two procedures: (a) shock excitationand (b) sinusoidal burst. Annex A1 describes procedures forobtaining frequency response for immersion and
21、 zero-degreecontact search units. Annex A2 describes the procedure forobtaining bandwidth characteristics.4.1.2 Relative Pulse-Echo Sensitivity (Srel)The relativepulse-echo sensitivity may be obtained from the frequencyresponse data obtained using the sinusoidal burst proceduredescribed in Annex A1.
22、 The value is obtained from therelationship of the amplitude of the voltage applied to thesearch unit and the amplitude of the pulse-echo signal receivedfrom a specified target. Annex A3 describes the procedure forobtaining pulse-echo sensitivity.NOTE 1Values for applied and received power, from whi
23、ch insertionloss might be determined are not covered with procedures described in thisguide.4.1.3 Time ResponseThe time response provides a meansfor describing the radio frequency (rf) response of the wave-form. A shock excitation, pulse-echo procedure is used toobtain the response. The time or wave
24、form responses arerecorded from specific targets that are chosen for the type ofsearch unit under evaluation (for example, immersion, contactstraight beam, or contact angle beam). Annex A4 describes theprocedures for measuring time response.4.1.4 Electrical Impedance:4.1.4.1 Complex Electrical Imped
25、anceThe complex elec-trical impedance may be obtained with commercial impedancemeasuring instrumentation, and these measurements may beused to provide the magnitude and phase of the impedance ofthe search unit over the operating frequency range of the unit.These measurements are generally made under
26、 laboratoryconditions with minimum cable lengths or external accessoriesand in accordance with the instructions of the instrumentmanufacturer. The value of the magnitude of the complexelectrical impedance may also be obtained using values re-corded from the sinusoidal burst techniques as outlined in
27、Annex A5.4.1.4.2 d-c ResistanceThe d-c resistance of the searchunit may provide information regarding the electrical tuningelements. Measurements are made across the terminals of theunit.4.1.5 Sound Field MeasurementsThe objective of thesemeasurements is to establish parameters such as the on-axisan
28、d transverse sound beam profiles for immersion flat andfocused search units.4.1.5.1 Annexes A6 and A8 of this guide describe ways formaking sound field measurements for both immersion flat andfocused search units in water and contact straight-beam searchunits in metal. The literature discusses sever
29、al ways for makingthese measurements, but the techniques described are relativelysimple and easily performed.4.1.5.2 Means are recommended for making measurementsin an immersion tank, thereby allowing either pulse-echo (balltarget) or hydrophone receiver techniques to be followed. Thegoal is to prov
30、ide measurements to evaluate the characteristicsof search units or to identify changes that may occur as afunction of time or use, or both.4.1.5.3 None of the measurements of sound beam patternsare intended to define limits of performance. They are designedto provide a common means for making measur
31、ements thatmay be used to define the initial and inservice performance.NOTE 2No procedure is given for measuring sound beam profilecharacteristics for angle-beam search units. Several potential approachesare being considered, but have not yet gained subcommittee agreement(1).4NOTE 3Frequency Respons
32、e Displays. The frequency responses inFig. 1 and Fig. 2 and throughout the text are displayed as a linearamplitude (not logarithmic) response as a function of frequency. Therecording or line drawing shows only the positive component or envelopeof the responses. While this is the normal display for a
33、 spectrum analyzer,the sinusoidal burst response is shown as only one-half of the actualsinusoidal wave.5. Significance and Use5.1 This guide is intended to provide standardized proce-dures for evaluating ultrasonic search units. It is not intended todefine performance and acceptance criteria, but r
34、ather toprovide data from which such criteria may be established.5.2 These procedures are intended to evaluate the charac-teristics of single-element piezoelectric search units.5.3 Implementation may require more detailed proceduralinstructions in a format of the using facility.5.4 The measurement d
35、ata obtained may be employed byusers of this guide to specify, describe, or provide a perfor-mance criteria for procurement and quality assurance, orservice evaluation of the operating characteristics of ultrasonicsearch units. All or portions of the guide may be used asdetermined by the user.4The b
36、oldface numbers in parentheses refer to a list of references at the end ofthis test method.E10650825.5 The measurements are made primarily under pulse-echoconditions. To determine the relative performance of a searchunit as either a transmitter or a receiver may require additionaltests.5.6 While the
37、se procedures relate to many of the significantparameters, others that may be important in specific applica-tions may not be treated. These might include power handlingcapability, breakdown voltage, wear properties of contact units,radio-frequency interference, and the like.5.7 Care must be taken to
38、 ensure that comparable measure-ments are made and that users of the guide follow similarprocedures. The conditions specified or selected (if optional)may affect the test results and lead to apparent differences.FIG. 1 Test Data Available from Shock Excitation ProcedureFIG. 2 Test Data Available fro
39、m Sinusoidal Burst TechniqueE10650835.8 Interpretation of some test results, such as the shape ofthe frequency response curve, may be subjective. Small irregu-larities may be significant. Interpretation of the test results isbeyond the scope of this guide.5.9 Certain results obtained using the proce
40、dures outlinedmay differ from measurements made with ultrasonic testinstruments. These differences may be attributed to differencesin the nature of the experiment or the electrical characteristicsof the instrumentation.5.10 The pulse generator used to obtain the frequencyresponse and time response o
41、f the search unit must have a risetime, duration, and spectral content sufficient to excite thesearch unit over its full bandwidth, otherwise time distortionand erroneous results may result.6. Typical Results Obtainable from Tests Described inAnnex A1-Annex A56.1 Fig. 1 illustrates some of the typic
42、al results that may beobtained using shock excitation techniques. Values for fre-quency response, peak frequency, bandwidth, bandwidth centerfrequency, and time response may be obtained.6.2 Fig. 2 illustrates the typical results obtained using thesinusoidal burst technique. Values may be obtained fo
43、r fre-quency response, peak frequency, bandwidth, bandwidth centerfrequency, relative pulse-echo sensitivity, and magnitude of theelectrical impedance from the data recorded with this tech-nique.7. Keywords7.1 aperture; bandwidth; characterization; contact testing;depth of field; focal point; freque
44、ncy response; immersiontesting; peak frequency; search unit; sound beam profile; timeresponse; ultrasoundANNEXES(Mandatory Information)A1. MEASUREMENT OF FREQUENCY RESPONSEA1.1 IntroductionThe frequency response (also knownas frequency spectrum) is a measure of the amplitude of thepulse-echo respons
45、e from a given target as a function offrequency. This response is used as the basis for establishingother operating parameters of the search unit including peakfrequency, center frequency (see Annex A1), bandwidth (seeAnnex A2) and sensitivity (see Annex A3). Sketches of typicalresponse curves are s
46、hown in Fig. A1.1. These sketches areused to describe two conditions: (a) a response that is sym-metrical about a center frequency, and (b) a condition in whichthe frequency response is asymmetrical.A1.1.1 Two means are described for obtaining the fre-quency response: (a) shock excitation, and (b) s
47、inusoidal burst.The responses obtained using these procedures provide similarresults; however, reproducibility is dependent on factors suchas generator driving impedance, search unit impedance, pulseshape, and measurement systems. The measurement system tobe used for search unit evaluation should be
48、 established byusers of the guide.A1.2 Shock Excitation TechniqueThe shock excitationtechnique for obtaining frequency response is based on theprinciple that a shock pulse applied to the search unit producesa broad spectrum of energies and that the echo from a giventarget reflects the frequency dist
49、ribution that is characteristic ofthat search unit. Measurements may be made using either theanalog or digitized rf waveform. Fig. A1.2 describes typicalcomponents used to measure frequency response of an rfanalog waveform. The system consists of a search unit, shockpulse generator (pulser), preamplifier (receiver), electronic gatethat can be adjusted to capture the echo waveform, displayoscilloscope, and spectrum analyzer. Fig. A1.3 describes typi-cal components used to measure the frequency response of adigitized rf waveform. The system consists of a
