1、Designation: E2075/E2075M 15Standard Practice forVerifying the Consistency of AE-Sensor Response Using anAcrylic Rod1This standard is issued under the fixed designation E2075/E2075M; the number immediately following the designation indicates the yearof original adoption or, in the case of revision,
2、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 practice is used for routinely checking the sensi-tivity of acoustic emission (AE) sensors. It is in
3、tended toprovide a reliable, precisely specified way of comparing a setof sensors, or telling whether an individual sensors sensitivityhas degraded during its service life, or both.1.2 This practice is not a “calibration” nor does it givefrequency response information.1.3 UnitsThe values stated in S
4、I units or inch-pound unitsare to be regarded separately as standard. The values stated ineach system may not be exact equivalents; therefore, eachsystem shall be used independently of the other. Combiningvalues from the two systems may result in non-conformancewith the standard.1.4 This standard do
5、es 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 of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Sta
6、ndards:2E650 Guide for Mounting Piezoelectric Acoustic EmissionSensorsE750 Practice for Characterizing Acoustic Emission Instru-mentationE976 Guide for Determining the Reproducibility ofAcousticEmission Sensor ResponseE2374 Guide for Acoustic Emission System PerformanceVerification3. Significance an
7、d Use3.1 Degradation in sensor performance can occur due todropping, mechanical shock while mounted on the teststructure, temperature cycles, and so forth. It is necessary anddesirable to have a simple measurement procedure that willcheck the consistency of sensor response, while holding allother va
8、riables constant.3.2 While test blocks of many different kinds have beenused for this purpose for many years, an acrylic polymer rodoffers the best all-around combination of suitable acousticproperties, practical convenience, ease of procurement and lowcost.3.3 Because the acoustic properties of the
9、 acrylic rod areknown to depend on temperature, this practice requires that therod, sensors, and couplant be stabilized at the same workingtemperature, prior to verifying the sensors.3.4 Attention should be paid to storage conditions for theacrylic polymer rod. For example, it should not be left in
10、afreezing or hot environment overnight, unless it is given timefor temperature stabilization before use.3.5 Properly applied and with proper record keeping, thispractice can be used in many ways. The user organization mustdetermine the context for its use, the acceptance standards andthe actions to
11、be taken based on the lead break results. Thefollowing uses are suggested:3.5.1 To determine when a sensor is no longer suitable foruse.3.5.2 To check sensors that have been exposed to high-riskconditions, such as dropping, overheating, and so forth.3.5.3 To get an early warning of sensor degradatio
12、n overtime. This can lead to identifying conditions of use, which aredamaging sensors, and thus, to better equipment care and lowerreplacement costs.3.5.4 To obtain matched sets of sensors, preamplifiers,instrumentation channels, or a combination thereof, for moreuniform performance of the total sys
13、tem.3.5.5 To save time and money, by eliminating the installa-tion of bad sensors.3.5.6 To verify sensors quickly but consistently in the fieldand to assist trouble-shooting when a channel does not pass aperformance check.1This practice is under the jurisdiction of ASTM Committee E07 on Nonde-struct
14、ive Testing and is the direct responsibility of Subcommittee E07.04 onAcoustic Emission Method.Current edition approved June 1, 2015. Published June 2015. Originallyapproved in 2000. Last previous edition approved in 2010 as E2075 - 10. DOI:10.1520/E2075_E2075M-15.2For referenced ASTM standards, vis
15、it 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.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 1
16、00 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.6 All the above uses are recommended for consideration.The purpose of this practice is not to call out how these uses areto be implemented, but only to state how the test itself is to beperformed so that the results
17、 obtained will be accurate andreliable.4. Apparatus4.1 Acrylic Polymer Cylindrical Rod (Fig. 1), should beused. The actual material of the acrylic polymer rod ispolymethylmethacrylate.34.1.1 The rod shall be cast, not extruded.4.1.2 Dimensions of the rod should be 78.7 cm 31 in. longby 3.8 cm 1.5 in
18、. in diameter, sensors end cut true and smoothwith a surface finish of 0.4 m RMS 0.16 in.4.1.3 Other lengths of rod are acceptable, provided thatthere is sufficient distance to attenuate and prevent reflectedsignals from the nonsensor end of the rod reaching the sensor.4.1.4 A permanent reference ma
19、rk, for example an “X”, isplaced on the rod at a distance of 10.2 cm 4 in., or 30.5 cm12 in., or both, from one end; marking the spots where thepencil lead is to be broken. It is convenient to provide a verysmall spotface, for example, 0.8 mm 0.03 in. diameter and0.1 mm 0.004 in. deep at these refer
20、ence mark points, to restthe tip of the pencil lead to avoid slippage during the lead breakprocess.NOTE 1The surface finish of the cylindrical rod section could producereflections that affect AE response. The surface finish should be main-tained in a clean, undamaged condition.4.2 Hsu-Nielsen Pencil
21、 Lead Break Source, with 2H pencillead, as described in 4.3.3 of Guide E976.4.3 Sensor(s), to be tested.4.4 Acoustic Emission Equipment, with amplitude measure-ment capability, for recording sensor response. (Operatingfamiliarity with the apparatus is assumed.)4.5 Couplant, to be standardized and do
22、cumented by theuser of this practice.5. Procedure5.1 Ensure that the acrylic rod, sensors and couplant havebeen allowed to stabilize to the ambient temperature of theexamination environment.5.2 Place the prepared acrylic rod horizontally on a suitablehard, flat surface, such as a benchtop, with the
23、referencemark(s) facing vertically up (12 oclock). The rod may besecured with tape or other means no closer than 30.5 cm12 in. from the reference mark.5.3 Prepare and power-up the AE measurement systemincluding preamplifier (if used) and connecting cables; allowwarm up time as necessary. Verify the
24、systems performance.Verification may be accomplished on the rod using a referencesensor that is dedicated to this purpose and not exposed to thehazards of field use; or, it may be accomplished by electronicprocedures such as those described in Practice E750 or GuideE2374.5.4 Mount the sensor to be t
25、ested on the flat end of the rodusing the prescribed couplant and normal good applicationtechniques (refer to Guide E650). Wipe off old couplant beforemounting. Mount the sensor in the six oclock position so thatit is resting on the same surface supporting the acrylic rod. Thiswill prevent slipping
26、of the sensor during sensor verification. Ifthe sensor is a side connector type, have the connector pointingin the 3 oclock direction as shown in Fig. 1.5.5 Using the pencil lead source, break lead with the end ofthe lead in the center of the reference mark, within 0.5 mm0.020 in. with a lead extens
27、ion of 2.5 6 0.5 mm 0.1 60.02 in.ANielsen shoe may be used to obtain a consistent 30angle between the lead and the surface. Hold the pencilpointing towards the sensor but with its axis approximately 22(a quarter of a right angle) off from the axis of the rod, so thatthe lead flies off to one side an
28、d does not hit the sensor. Fingersmay be rested on the rod on the side away from the sensor tosteady the pencil, but there must be no finger contact or othermaterials in contact with the rod between pencil and sensor,except for the hard surface on which the acrylic rod is resting.As a general guide,
29、 use the 10.2 cm 4 in. reference markwhen breaking 0.3 mm 0.012 in. pencil lead and the 30.5 cm12.0 in. reference mark when using 0.5 mm 0.02 in. pencil3Some of the generic brand names of this material include, but are not limitedto: Lucite, PMMA, plexiglass, perspex, and so forth.FIG. 1 Acrylic Rod
30、 DescriptionE2075/E2075M 152lead. If using the 10.2 cm 4.0 in. reference mark and thesensor amplitude response is 90 dB or greater, move to the30.5 cm 12 in. reference mark instead to avoid possiblesaturation effects, which might compromise the test results.5.6 Make three consistent lead breaks for
31、each sensor,recording amplitude responses on a sensor performance veri-fication form, similar to that shown in Appendix X1.Asageneral rule, determine the average sensor amplitude responseand proceed to the next sensor.5.7 Acceptance criteria, which should be assigned prior toconducting this practice
32、 by the testing organization, should bedocumented, for example as shown in Appendix X1, andapplied to the sensor data recorded. Sensors failing the criteriashould not be used during the examination, and should bereturned for a more comprehensive analysis, repaired ordiscarded.6. Precision and Bias6.
33、1 Temperature variations are known to affect the acousticabsorption properties of the acrylic rod. However, since this isa comparative technique rather than an absolute one, thispractice can be carried out with good results if all componentparts used in the practice have been allowed to stabilize to
34、 theexamination (environmental) temperature prior to application.6.2 Person-to-person variations can be reduced to a range of1 dB by proper technique and training.6.3 Variations in fracture performance within a lead andbetween leads are possible. With experience, occasional badbreaks often can be id
35、entified by the operator, even withoutreference to the results of the measurement.6.4 Bad breaks are relatively common as the pencil is aboutto run out of lead.6.5 While uniformity of material is a major quality goal ofthe lead manufacturer, runs of bad lead can occur due tomanufacturing variations.
36、7. Keywords7.1 acoustic emission sensors; AE; sensor check; sensorconsistency check; sensor response; sensor test; sensor verifi-cationAPPENDIX(Nonmandatory Information)X1. Sensor Performance Verification FormSee Fig. X1.1.E2075/E2075M 153SUMMARY OF CHANGESCommittee E07 has identified the location o
37、f selected changes to this standard since the last issue(E2075/E2075M10) that may impact the use of this standard.(1) Added a new section, 4.1.1, to describe that the rod was a“cast” part, not extruded.(2) Rearranged paragraph 4.2.(3) Added inch-pound units conversions to Section 5.(4) Updated Fig.
38、X1.1.(5) Added “Summary of Changes.”FIG. X1.1 Example of Sensor Performance Verification FormE2075/E2075M 154ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised
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