1、Designation: E2075/E2075M 10Standard 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. Scope1.1 This practice is used for routinely checking the sensi-tivity of acoustic emission (AE) sensors. It is int
3、ended 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 SI
4、 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 doe
5、s 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 Stan
6、dards:2E650 Guide for Mounting Piezoelectric Acoustic EmissionSensorsE750 Practice for Characterizing Acoustic Emission Instru-mentationE976 Guide for Determining the Reproducibility of Acous-tic Emission Sensor ResponseE2374 Guide for Acoustic Emission System PerformanceVerification3. Significance
7、and Use3.1 Degradation in sensor performance can occur due todropping, mechanical shock while mounted on the test struc-ture, temperature cycles, and so forth. It is necessary anddesirable to have a simple measurement procedure that willcheck the consistency of sensor response, while holding allothe
8、r variables 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
9、 the 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
10、 in 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
11、 to 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 degrad
12、ation 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
13、 system.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.3.6 All the above uses are recommended for consideration.The purpose of th
14、is 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 obtained will be accurate andreliable.1This practice is under the jurisdiction of ASTM Committee E07 on Nonde-structive Testing and is the direct responsibi
15、lity of Subcommittee E07.04 onAcoustic Emission Method.Current edition approved June 1, 2010. Published July 2010. Originally approvedin 2000. Last previous edition approved in 2005 as E2075 - 05. DOI: 10.1520/E2075_E2075M-10.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orco
16、ntact 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 Conshohocken, PA 19428-2959, United States.4. Apparatus4.1 Acry
17、lic Polymer Cylindrical Rod (Fig. 1), should beused. The actual material of the acrylic polymer rod ispolymethylmethacrylate.34.1.1 Dimensions of the rod should be 78.7 cm 31 in. longby 3.8 cm 1.5 in. in diameter, sensors end cut true and smoothwith a surface finish of 0.4 m RMS 0.16 in.4.1.2 Other
18、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.4.1.3 A permanent reference mark, for example an “X”, isplaced on the rod at a distance of 10.2 cm 4 in., or 30.5 cm12 in., or both
19、, 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 and 0.1mm 0.004 in. deep at these reference mark points, to rest thetip of the pencil lead to avoid slippage during the lead breakprocess.NO
20、TE 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 Lead Break Source, 0.3 or 0.5-mmHsu-Nielsen Pencil Lead Break Source, as described in GuideE976, wit
21、h 2H pencil lead.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 documented by theuser of this practice.5. Procedure5.1 Ensure
22、 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 referencemark(s) facing vertically up (12 oclock). The rod
23、may besecured with tape or other means no closer than 30.5 cm 12in. 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 systems performance.Verification may be accomplished on the
24、 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 tested on the flat end of the rodusing the prescribed coupla
25、nt 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 of the sensor during sensor verification. Ifthe sensor is a
26、 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 extension of 2.5 6 0.5 mm 0.1 6 0.02in. A Nielsen shoe may be use
27、d 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 and does not hit the sensor. Fingersmay be rested on the ro
28、d 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, use the 10.16 cm reference mark whenbreaking 0.3 mm penc
29、il lead and the 30.48 cm reference markwhen using 0.5 mm pencil lead. If using the 10.2 cm referencemark and the sensor amplitude response is 90 dB or greater,move to the 30.5 cm 12 in. reference mark instead to avoidpossible saturation effects, which might compromise the testresults.5.6 Make three
30、consistent lead breaks for 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
31、 toconducting this practice by the testing organization, should bedocumented, for example as shown in Appendix X1, andapplied to the sensor data recorded. Sensors failing the criteria3Some of the generic brand names of this material include, but are not limitedto, Lucite, PMMA, plexiglass, perspex,
32、and so forth.FIG. 1 Acrylic Rod DescriptionE2075/E2075M 102should not be used during the examination, and should bereturned for a more comprehensive analysis, repaired ordiscarded.6. Precision and Bias6.1 Temperature variations are known to affect the acousticabsorption properties of the acrylic rod
33、. 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 theexamination (environmental) temperature prior to application.6.2 Person-to-person variations
34、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 identified by the operator, even withoutreference to the results of the measurement.6.4 Bad breaks
35、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.7. Keywords7.1 acoustic emission sensors; AE; sensor check; sensorconsistency check; sensor respo
36、nse; sensor test; sensorverificationAPPENDIX(Nonmandatory Information)X1. Sensor Performance Verification FormSee Fig. X1.1.E2075/E2075M 103ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this
37、standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years
38、 andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committe
39、e, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-
40、2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).FIG. X1.1 Example of Sensor Performance Verification FormE2075/E2075M 104
