1、Designation: E 2075 05Standard Practice forVerifying the Consistency of AE-Sensor Response Using anAcrylic Rod1This standard is issued under the fixed designation E 2075; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of
2、last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) 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 intended topro
3、vide 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 The values stated in SI units are to be
4、 regarded as thestandard. The values given in parentheses are provided forinformation only.1.4 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 practi
5、ces and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2E 650 Guide for Mounting Piezoelectric Acoustic EmissionSensorsE 750 Practice for CharacterizingAcoustic Emission Instru-mentationE 976 Guide for Determining the Reproducibility of
6、Acous-tic Emission Sensor ResponseE 2374 Guide for Acoustic Emission System PerformanceVerification3. Significance 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 anddesira
7、ble to have a simple measurement procedure that willcheck the consistency of sensor response, while holding allother 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 suitabl
8、e acousticproperties, practical convenience, ease of procurement and lowcost.3.3 Because the acoustic properties of 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 sensor
9、s.3.4 Attention should be paid to storage conditions for theacrylic polymer rod. For example, it should not be left 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
10、 in many ways. The user organization mustdetermine the context for its use, the acceptance standards andthe actions 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
11、 to high-riskconditions, such as dropping, overheating, and so forth.3.5.3 To get an early warning of sensor degradation 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
12、sensors, preamplifiers,instrumentation channels, or a combination thereof, for moreuniform performance of the total 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
13、channel does not pass aperformance check.1This practice is under the jurisdiction of ASTM Committee E07 on Nonde-structive Testing and is the direct responsibility of Subcommittee E07.04 onAcoustic Emission Method.Current edition approved June 1, 2005. Published June 2005. Originallyapproved in 2000
14、. Last previous edition approved in 2000 as E 2075 - 00.2For 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.1Copy
15、right ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.6 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 bepe
16、rformed so that the results 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 Dimensions of the rod should be 78.74 cm (31 in.)long by 3.81 cm (1.5 in.) in diam
17、eter, sensors end cut true andsmooth with a surface finish of 0.4 m RMS (0.16 in.).4.1.2 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.4.1.3 A permanent reference mark, fo
18、r example an “X”, isplaced on the rod at a distance of 10.16 cm (4 in.), or 30.48 cm(12 in.), or both, from one end; marking the spots where thelead is to be broken. It is convenient to provide a very smallspotface, for example, 0.8 mm (0.03 in.) diameter and 0.1 mm(0.004 in.) deep at these referenc
19、e mark points, to rest the tipof 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 Le
20、ad Break Source, 0.3 or 0.5-mmHsu-Nielsen Pencil Lead Break Source, as described in GuideE 976, with 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.
21、)4.5 Couplant, to be standardized and documented 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, fla
22、t surface, such as a benchtop, with the referencemark(s) facing vertically up (12 oclock). The rod may besecured with tape or other means no closer than 12 in. from thereference mark.5.3 Prepare and power-up the AE measurement systemincluding preamplifier (if used) and connecting cables; allowwarm u
23、p time as necessary. Verify the 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 E 750 or GuideE
24、 2374.5.4 Mount the sensor to be tested on the flat end of the rodusing the prescribed couplant and normal good applicationtechniques (refer to Guide E 650). Wipe off old couplant beforemounting. Mount the sensor in the six oclock position so thatit is resting on the same surface supporting the acry
25、lic rod. Thiswill prevent slipping 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
26、 0.5 mm(0.020 in.) with a lead extension of 2.5 6 0.5 mm (0.1 6 0.20in.). A Nielsen 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
27、, so thatthe lead flies off to one side and 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,3Some of the generic brand names of this
28、material include, but are not limitedto, Lucite, PMMA, plexiglass, perspex, and so forth.FIG. 1 Acrylic Rod DescriptionE2075052except 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 pencil lead and the 30.48 cm referenc
29、e markwhen using 0.5 mm pencil lead. If using the 10.16 cm referencemark and the sensor amplitude response is 90 dB or greater,move to the 30.48 cm reference mark instead to avoid possiblesaturation effects, which might compromise the test results.5.6 Make three consistent lead breaks for each senso
30、r,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 by the te
31、sting 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 Bias6.1 Temperat
32、ure 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 theexamin
33、ation (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 identified b
34、y 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.7. Keyword
35、s7.1 acoustic emission sensors; AE; sensor check; sensorconsistency check; sensor response; sensor test; sensorverificationAPPENDIX(Nonmandatory Information)X1. Sensor Performance Verification FormSee Fig. X1.1.E2075053ASTM International takes no position respecting the validity of any patent rights
36、 asserted in connection with any item mentionedin this standard. Users of this 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 ti
37、me by the responsible technical committee and must be reviewed every five years 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
38、receive careful consideration at a meeting of theresponsible technical committee, 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
39、International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,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).FIG. X1.1 Example of Sensor Performance Verification FormE2075054
