ASTM_E_1106_-_12.pdf

Designation:E110612Standard Test Method forPrimary Calibration of Acoustic Emission Sensors1This standard is issued under the fixed designation E1106;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope*1.1 This test method covers the requirements for the abso-lute calibration of acoustic emission(AE)sensors.The cali-bration yields the frequency response of a transducer to waves,at a surface,of the type normally encountered in acousticemission work.The transducer voltage response is determinedat discrete frequency intervals of approximately 10 kHz up to1 MHz.The input is a given well-established dynamic dis-placement normal to the mounting surface.The units of thecalibration are output voltage per unit mechanical input(displacement,velocity,or acceleration).1.2 UnitsThe values stated in SI units are to be regardedas standard.No other units of measurement are included in thisstandard.1.3 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 of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2E114 Practice for Ultrasonic Pulse-Echo Straight-BeamContact TestingE494 Practice for Measuring Ultrasonic Velocity in Materi-alsE650 Guide for Mounting Piezoelectric Acoustic EmissionSensorsE1316 Terminology for Nondestructive Examinations3.Terminology3.1 Refer to Terminology E1316 for terminology used inthis test method.4.Significance and Use4.1 Transfer StandardsOne purpose of this test method isfor the direct calibration of displacement transducers for use assecondary standards for the calibration ofAE sensors for use innondestructive evaluation.For this purpose,the transfer stan-dard should be high fidelity and very well behaved andunderstood.If this can be established,the stated accuracyshould apply over the full frequency range up to 1 MHz.NOTE1The stated accuracy applies only if the transfer standardreturns to quiescence,following the transient input,before any wavereflected from the boundary of the calibration block returns to the transferstandard(;100 s).For low frequencies with periods on the order of thetime window,this condition is problematical to prove.4.2 Applications SensorsThis test method may also beused for the calibration ofAE sensors for use in nondestructiveevaluation.Some of these sensors are less well behaved thandevices suitable for a transfer standard.The stated accuracy forsuch devices applies in the range of 100 kHz to 1 MHz andwith less accuracy below 100 kHz.5.General Requirements5.1 A primary difficulty in any calibration of a mechanical/electrical transduction device is the determination of themechanical-motion input to the device.To address thisdifficulty,this calibration procedure uses(i)a standard trans-ducer whose absolute sensitivity is known from its design andphysical characteristics;and also(ii)a source that producesmotion that approximates a waveform calculable from theory.The use of two independent sources of information confers adegree of redundancy that is employed to confirm the validityof the measurements and quantify the experimental errors.Briefly stated,the sensitivity of the transfer standard(or othersensor under test)is determined by comparison with thestandard transducer,while knowledge of a part of the theoreti-cal waveform is used as a check.5.2 Test Block and Mechanical InputThe mechanicalinput to the sensors is obtained by pressing a glass capillarydown onto the surface of a large test block until it breaks.Thereasons for selecting this approach are:(a)capillary breaks arelocalized and short in duration,like natural acoustic emissionevents;and(b)use of a large block simplifies wave propaga-tion and makes sensor output less dependent on arbitraryfeatures of block geometry.1This test method is under the jurisdiction of ASTM Committee E07 onNondestructive Testing and is the direct responsibility of Subcommittee E07.04 onAcoustic Emission Method.Current edition approved June 15,2012.Published September 2012.Originallyapproved in 1986.Last previous edition approved in 2007 as E1106-07.DOI:10.1520/E1106-12.2For 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.*A Summary of Changes section appears at the end of this standardCopyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 5.2.1 Prior to the fracture of the glass capillary,the force itexerts on the surface is distributed over an area