ASTM E2904-22

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it 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 version
of the standard as published by ASTM is to be considered the official document.
Designation: E2904 − 17 E2904 − 22
Standard Practice for
Characterization and Verification of Linear Phased Array
Ultrasonic Probes
This standard is issued under the fixed designation E2904; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope*
1.1 This standard practice covers measurement procedures for evaluating certain characteristics of phased-array ultrasonic probes
that are used with phased-array ultrasonic examination instrumentation.
1.2 This standard practice describes means for obtaining performance data that may be used to define the acoustic and electric
responses of phased-array ultrasonic probes including contact (with or without a wedge) and immersion linear phased-array probes
used for ultrasonic nondestructive testing with central frequencies ranging from 0.5 MHz to 10 MHz. Frequencies outside of this
range may use the same methods but the testing equipment may vary.
1.3 When ultrasonic values dependent on material are specified in this document,practice, they are based on carbon steel with an
ultrasonic wave propagation speed of 5920 m/s (650 m/s) for longitudinal wave modes and 3255 m/s (630 m/s) for transverse
or shear wave modes.
1.4 This documentpractice describes some of the characterization and verification procedures that can be carried out at the end
stage of the manufacturing process of linear phased array probes. This documentpractice does not describe the methods or
acceptance criteria used to verify the performance of the combined phased array ultrasonic instrument and probe system.
1.5 While this practice is intended to provide standardized procedures for evaluating linear phased-array ultrasonic probes, it may,
with suitable modifications, be used for evaluation of configurations other than linear; for example, 1.5D or 2D matrix array probes.
1.6 Units—The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information
only.after SI units are provided for information only and are not considered standard.
1.7 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of
regulatory limitations prior to use.
1.8 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
This practice/guidepractice is under the jurisdiction of ASTM Committee E07 on Nondestructive Testing and is the direct responsibility of Subcommittee E07.06 on
Ultrasonic Method.
Current edition approved Nov. 1, 2017Dec. 1, 2022. Published December 2017January 2023. Originally approved in 2012. Last previous edition approved in 20122017
as E2904E2904 – 17.–12. DOI: 10.1520/E2904-17.10.1520/E2904-22.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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2. Referenced Documents
2.1 ASTM Standards:
E1065 Practice for Evaluating Characteristics of Ultrasonic Search Units
E1316 Terminology for Nondestructive Examinations
3. Terminology
3.1 Definitions:
3.1.1 For definitions of terms used in this practice, see Terminology E1316.
3.1.2 Technical Specification of the Phased Array Probes:
3.1.2.1 datasheet—defined as specification. This is the document that defines the general geometry and expected performance
of a specific model or part number.
3.1.2.1 certification—certification, n—defined as measured performance of an individual probe. This is the document that
reports the measured performance of a specific probe (specific to a serial number).
3.1.2.2 probedatasheet, type—n—contact or immersion.defined as specification. This is the document that defines the general
geometry and expected performance of a specific model or part number.
3.1.2.3 probe shape and size—size, n—probe form and dimensions.
3.1.2.4 probe type, n—contact or immersion.
3.1.3 Terminology for Array Probes:
3.1.3.1 active aperture—aperture, n—pitch times the number of elements.
3.1.3.2 element width—in a rectangular element, the acoustic element’s short dimension.
3.1.3.2 element length—length, n—in a rectangular element, the acoustic element’s long dimension. See passive aperture (also
called element elevation) and Fig. 3.
3.1.3.3 element pitch (or pitch)—pitch), n—the distance between the centers of two adjacent array elements.
3.1.3.4 element width, n—in a rectangular element, the acoustic element’s short dimension.
3.1.3.5 passive aperture—aperture, n—the dimension of an array element’s length.
3.1.3.6 saw cut—cut, n—also called “kerf,” space or gap. The space between adjacent elements.
4. Summary of Practice
4.1 The physical, acoustic and electrical characteristics which can be described from the data obtained by procedures outlined in
this guide are described as follows.
4.2 Physical Aspects—Identification and physical dimension aspects of the probe should be noted. Details to be noted are
described in 7.1.
4.3 Center Frequency, Bandwidth And Time Response—Section 7.2 describes procedures for determining center frequency,
bandwidth, and time response of the individual elements of the linear array probe.
4.4 Sensitivity Range Of Elements—Section 7.3 describes a procedure to determine variation of sensitivity from one element to
the next based on a fixed input voltage.
4.5 Probe Sensitivity—The overall sensitivity performance of all the elements in the array is assessed in the procedure described
in 7.4.
4.6 Element Crosstalk—A procedure for assessment of damping between elements to eliminate crosstalk is provided in 7.5.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
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FIG. 1 Schematic Showing Digitization Rate
5. Significance and Use
5.1 This standard practice is intended to provide standardized procedures for evaluating linear phased-array ultrasonic probes. It
is not intended to define performance and acceptance criteria, but rather to provide data from which such criteria may be
established.
5.2 Implementation may require more detailed procedural instructions in a format of the using facility.
5.3 The measurement data obtained may be employed by users of this guide to specify, describe, or provide performance criteria
for procurement and quality assurance, or service evaluation of the operating characteristics of linear phased-array ultrasonic
probes. All or portions of the standard practice may be used as determined by the user.
5.4 The measurements are made primarily under pulse-echo conditions. To determine the relative performance of a probe element
as either a transmitter or a receiver may require additional tests.
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FIG. 2 Two-Channel Schematic Showing Measurement Technique for Crosstalk
Legend:
A = active aperture (number of active elements x element pitch)
H = passive aperture
e = element width
p = element pitch
g = saw cut between elements (also called kerf or gap)
FIG. 3 Schematic of Key Parameters for Linear Arrays
5.5 While these procedures relate to many of the significant parameters, others that may be important in specific applications may
not be treated. These might include power handling capability, breakdown voltage, wear properties of contact units,
radio-frequency interference, and the like.
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5.6 Care must be taken to ensure that comparable measurements are made and that users of the standard practice follow similar
procedures. The conditions specified or selected (if optional) may affect the test results and lead to apparent differences.
5.7 Interpretation of some test results, such as the shape of the frequency response curve, may be subjective. Small irregularities
may be significant. Interpretation of the test results is beyond the scope of this standard practice.
5.8 Certain results obtained using the procedures outlined may differ from measurements made with phased-array ultrasonic test
instruments. These differences may be attributed to differences in the nature of the experiment or the electrical characteristics of
the instrumentation.
5.9 The pulse generator used to obtain the frequency response and time response of the probe must have a rise time, duration, and
spectral content sufficient to excite the probe over its full bandwidth, otherwise time distortion and erroneous results may result.
5.10 While this standard practice is intended to provide standardized procedures for evaluating linear phased-array ultrasonic
probes, it may, with suitable modifications, be used for evaluation of configurations other than linear; e.g. 1.5D or 2D matrix array
probes.
6. Instrumentation
6.1 Electronic Instruments:
6.1.1 The type of instrument(s) used for the tests specified in Section 7 shall be the same as that indicated on the Certification
report and Table 2. They shall also be compliant with the applicable verification standard for the inspection unit.
6.1.2 The following equipment is required in order to evaluate the probes in compliance with this standard:practice:
6.1.2.1 A pulser/receiver with a minimum bandwidth of 20 MHz, digitizing to 100 MHz, or better, and an oscilloscope (or
equivalent) with a minimum bandwidth of 100 MHz. A phased-array instrument which contains the equivalent combination may
be used.
6.1.2.2 Digitizing should be able to get 10 samples in maximum slope of waveform, as illustrated in Fig. 1.
TABLE 1 List of Variables for Probe Manufacture and Testing
Information Type Optional or
Information Needed Observations
A
(C, I, M) Required
Name of Manufacturer I Required
Probe type I Required
Instruments and settings used in the test process I Required See Table 2
Test conditions I Required Coupling medium, sound path, target, fixturing
See Table 2
Probe Dimensions or shape M or I Optional Casing dimensions
Element shape and size (active and passive I Optional Arrangement of the array(s)
apertures) Dimensions and geometry of the array(s)
Relative position of array in housing I Optional Location of first or last element in relation to the
housing
Pitch, gap between elements, element width, I Required Pitch, gap between elements (saw cut), and
length and dimensions element dimensions (length and width)
Connector type I Required
Dimensions and material of integrated wedge I Optional Applicable to contact probes
Dimensions and geometry of integrated wedge(s)
Wiring I Optional Cable length and external diameter
Center frequency, bandwidth, and time response M Required
Relative Sensitivity Range of the Elements M or C in dB Required Basic voltage indication of each element
Probe sensitivity M Required
Probe crosstalk I or C in dB Optional Must state medium if crosstalk reported
A
Legend:
C = Calculations
I = Information
M = Measurement
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TABLE 2 Instrumentation and Target Requirements
NOTE 1—Table 2 gives a list of the instrumentation requirements to
evaluate arrays.
Optional or
Instrument and Target Comments
Required
Inst
...