ASTM_E_1237_-_93_2014.pdf

Designation:E123793(Reapproved 2014)Standard Guide forInstalling Bonded Resistance Strain Gages1This standard is issued under the fixed designation E1237;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.This standard has been approved for use by agencies of the U.S.Department of Defense.1.Scope1.1 This guide provides guidelines for installing bondedresistance strain gages.It is not intended to be used for bulk ordiffused semiconductor gages.This document pertains only toadhesively bonded strain gages.1.2 The values stated in inch-pound units are to be regardedas standard.The values given in parentheses are mathematicalconversions to SI units that are provided for information onlyand are not considered standard.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:2E251 Test Methods for Performance Characteristics of Me-tallic Bonded Resistance Strain Gages2.2 Other Standards:ANSI/SEM 1-1984;Standard for Portable Strain-IndicatingInstrumentsDesignation of Strain Gage Bridge andColor Code of Terminal Connections;August 16,1984.33.Terminology3.1 Definitions:3.1.1 lead wirean electrical conductor used to connect asensor to its instrumentation.3.1.2 resistance strain gage bridgea commonWheatsone bridge made up of strain gages used for themeasurement of small changes of resistance produced by astrain gage,where the gages may be wired in the followingconfiguration(see also Fig.1 and Fig.2):Arm 1 between+excitation and signalArm 2 between excitation and signalArm 3 between+signal and excitationArm 4 between+signal and+excitation3.2 Definitions of Terms Specific to This Standard:3.2.1 bonded resistance strain gagea resistive elementwith a carrier that is attached by bonding to the base materialso that the resistance of the element will vary as the surface ofthe base material to which it is attached is deformed.3.2.1.1 DiscussionFor a complete explanation of this termsee Test Methods E251.4.Significance and Use4.1 Methods and procedures used in installing bondedresistance strain gages can have significant effects upon theperformance of those sensors.Optimum and reproducibledetection of surface deformation requires appropriate andconsistent surface preparation,mounting procedures,and veri-fication techniques.5.Gage Selection5.1 Careful consideration must be given to the intended usewhen selecting an appropriate gage.Installation and operatingcharacteristics of a gage are affected by many factors such asresistive element alloy,carrier material,gage length,gage andresistive element pattern,solder tab type and configuration,temperature compensation characteristics,resistance of activeelements,gage factor,and options desired.5.2 Factors that should also be considered include type oftest or application,operating temperature range,environmentalconditions,accuracy requirements,stability,maximumelongation,test conditions(static or dynamic)and duration,and simplicity and ease of installation.Dissipation of self-generated heat to the carrier should be considered in selectinggage resistance and size of grid.5.3 To minimize errors due to strain gradients over the gagearea,gage size should normally be small with respect to thedimensions of an immediately adjacent geometric irregularity(hole,fillet,etc.).However,the gage size should generally be1This guide is under the jurisdiction of ASTM Committee E28 on MechanicalTesting and is the direct responsibility of Subcommittee E28.01 on Calibration ofMechanical Testing Machines and Apparatus.Current edition approved April 15,2014.Published August 2014.Originallyapproved in 1993.Last previous edition approved in 2009 as E1237 93(2009).DOI:10.1520/E1237-93R14.2For 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.3Available from American National Standards Institute(ANSI),25 W.43rd St.,4th Floor,New York,NY 10036,http:/www.ansi.org.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 large relative to the underlying material structure(grain size,fabric-reinforced composite weave pattern,etc.).5.4 A two-or three-element rosette gage should be usedunless the strain state is unquestionably uniaxial.A single-element gage may be selected to measure the strain due to auniaxial strain state if the principal directions are known.5.5 Temperature compensation of t