1、Designation:E608aStandard Terminology Relating toMethods of Mechanical Testing1This standard is issued under the fixed designation E 6; the number immediately following the designation indicates the year of originaladoption or, in the case of revision, the year of last revision.Anumber in parenthese
2、s indicates the year of last reapproval.Asuperscriptepsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1. Scope1.1 This terminology covers the principal terms relating tomethods of mechanical
3、 testing of solids. The general defini-tions are restricted and interpreted, when necessary, to makethem particularly applicable and practicable for use in stan-dards requiring or relating to mechanical tests. These defini-tions are published to encourage uniformity of terminology inproduct specific
4、ations.1.2 Terms relating to fatigue and fracture testing are definedin Terminology E 1823.2. Referenced Documents2.1 ASTM Standards:2E 8/E 8M Test Methods for Tension Testing of MetallicMaterialsE 796 Test Method for Ductility Testing of Metallic FoilE 1823 Terminology Relating to Fatigue and Fract
5、ure Test-ing2.2 ISO Standard:3ISO/IEC Guide 99:2007 International Vocabulary ofmetrologyBasic and general concepts and terms (VIM)3. Index of Cross-References and Associated Definitions3.1 The terms listed below are associated with terminologythat is fundamental or commonly used. The definition for
6、theterm of interest is related to or is given below the definition forthe fundamental term cited.Termangular strain see strainaxial strain see strainbending strain see strainchord modulus see modulus of elasticitydirect verification see verificationcompressive stress see stresselastic constants see
7、modulus of elasticity and Poissonsratioelastic modulus see modulus of elasticityengineering strain see strainengineering stress see stressfracture stress see stressindirect verification see verificationlinear (tensile or compressive) strain see strainmacrostrain see strainmalleability see ductilitym
8、icrostrain see strainmodulus of rigidity see modulus of elasticitynominal stress see stressnormal stress see stressphysical properties see mechanical propertiespin see mandrel (in bend testing)plunger see mandrel (in bend testing)principal stress see stressresidual strain see strainresidual stress s
9、ee stressRockwell superficialhardness numbersee Rockwell hardness numbersecant modulus see modulus of elasticityshear strain see strainshear stress see stressstatic fatigue strength see creep rupture strengthstrain gauge fatigue life see fatigue lifestress-rupture strength see creep rupture strength
10、tangent modulus see modulus of elasticitytensile stress see stresstorsional modulus see modulus of elasticitytorsional stress see stresstransverse strain see straintrue strain see straintrue stress see stressultimate tensile strength (UTS) see tensile strengthyield strength see also upper yield stre
11、ngth and loweryield strength4. Terminology4.1 Terms and Definitions:accuracy, nthe permissible variation from the correct value.(E28.01)1This terminology is under the jurisdiction of ASTM Committee E28 onMechanical Testing and is the direct responsibility of Subcommittee E28.91 onTerminology except
12、where designated otherwise. A subcommittee designation inparentheses following a definition indicates the subcommittee with responsibility forthat definition.Current edition approved Oct. 1, 2008. Published December 2008. Originallyapproved in 1923. Last previous edition approved in 2008 as E608.2Fo
13、r 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 International Organization for Standardization (
14、ISO), 1 rue deVaremb, Case postale 56, CH-1211, Geneva 20, Switzerland, http:/www.iso.ch.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.alignment, nthe condition of a testing machine and loadtrain (including the test specimen) that
15、influences the intro-duction of bending moments into a specimen during tensileloading. (E28.04)angle of bend, nthe change in the angle between the twolegs of the specimen during a bend test, measured beforerelease of the bending forces.DISCUSSIONThe angle of bend is measured before release of theben
16、ding force, unless otherwise specified. (E28.02)angle of twist (torsion test), nthe angle of relative rotationmeasured in a plane normal to the torsion specimenslongitudinal axis over the gauge length. (E28.04)bearing area L2, nthe product of the pin diameter andspecimen thickness. (E28.04)bearing f
17、orce F, na compressive force on an interface.(E28.04)bearing strain, nthe ratio of the bearing deformation of thebearing hole, in the direction of the applied force, to the pindiameter. (E28.04)bearing strength FL2, nthe maximum bearing stresswhich a material is capable of sustaining. (E28.04)bearin
18、g stress FL2, nthe force per unit of bearing area.(E28.04)bearing yield strength FL2, nthe bearing stress at whicha material exhibits a specified limiting deviation from theproportionality of bearing stress to bearing strain. (E28.04)bend test, na test for ductility performed by bending orfolding a
19、specimen, usually by steadily applied forces but insome instances by blows. The bending may be interrupted toexamine the bent surface for cracks.DISCUSSIONThe ductility is usually judged by whether or not thespecimen cracks under the specified conditions of the test.DISCUSSIONThere are four general
20、types of bend tests according tothe manner in which the forces are applied to the specimen to make thebend. These are as follows:1. Free Bend2. Guided Bend3. Semi-Guided Bend4. Wrap-Around BendDISCUSSIONThe specimen has a substantially uniform cross-sectionand a length several times as great as the
21、largest dimension of thecross-section. (E28.02)bias, statistical, na constant or systematic error in testresults. (E28.04)biaxial stretching, va mode of sheet metal forming in whichpositive strains are observed in all directions at a givenlocation. (E28.02)breaking forceF, nthe force at which fractu
22、re occurs.DISCUSSIONWhen used in connection with tension tests of thinmaterials or materials of small diameter for which it is often difficult todistinguish between the breaking force and the maximum forcedeveloped, the latter is considered to be the breaking force.(E28.04)Brinell hardness number, H
23、B , nindentation hardness testin which a number proportional to the quotient obtained bydividing the test force by the curved surface area of theindentation which is assumed to be sphereical and of thediameter of the ball.HBW 5 0.10232F/pDD D2 d2!1/2(1)where:F = test force, N,D = diameter of ball, m
24、m, andd = mean diameter of the indentation, mm.DISCUSSIONIn former standards, a steel ball was allowed forhardness values below 450. In cases where a steel ball was used theBrinell hardness was denoted by HB or HBS.DISCUSSIONThe symbol HBW is preceded by the hardness valuewhen the test is carried ou
25、t under the following conditions:Ball diameter 10 mmForce 3000 kgfDuration of loading 10 to 15 sWhen other conditions are used, the hardness value and symbol aresupplemented by numbers indicating the test conditions in the follow-ing order: diameter of ball, force, and duration of loading. (E28.06)B
26、rinell hardness test, nan indenter (tungsten carbide ball) isforced into the surface of a test piece and the diameter of theindentation left in the surface after removal of the test forceis measured.DISCUSSIONThe tungsten carbide ball may be used for materialswith Brinell hardness not exceeding 650.
27、 (E28.06)calibration, na process that establishes, under specificconditions, the relationship between values indicated by ameasuring system and the corresponding values indicated byone or more standards.DISCUSSIONThis definition is intended to meet the principles of thedefinition of calibration prov
28、ided by the ISO/IEC Guide 99:2007International Vocabulary of Basic and General Terms in Metrology(VIM). (E28.91)calibration, ndetermination of the values of significantparameters by comparison with values indicated by a refer-ence instrument or by reference standards. (E28.06)calibration factor, nth
29、e factor by which the change inextensometer reading must be multiplied to obtain theequivalent strain.DISCUSSIONFor any extensometer, the calibration factor is equal tothe ratio of change in length to the product of the gauge length and thechange in extensometer reading. For direct-reading extensome
30、ters thecalibration factor is unity. (E28.01)compressive strength FL2, nthe maximum compressivestress that a material is capable of sustaining. Compressivestrength is calculated by dividing the maximum force duringa compression test by the original cross-sectional area of thespecimen.DISCUSSIONIn th
31、e case of a material which fails in compression bya shattering fracture, the compressive strength has a very definite value.In the case of materials which do not fail in compression by a shatteringfracture, the value obtained for compressive strength is an arbitraryvalue depending upon the degree of
32、 distortion which is regarded asindicating complete failure of the material. (E28.04)E608a2compressometer, na specialized extensometer used forsensing negative or compressive strain. (E28.01)constraint, nany restriction to the deformation of a body.(E28.11)creep, nthe time-dependent increase in stra
33、in in a solidresulting from force.DISCUSSIONCreep tests are usually made at constant load and atconstant temperature. For tests on plastics the initial strain, howeverdefined, is included and for metals it is not.DISCUSSIONThis change in strain is sometimes referred to as creepstrain. (E28.10)creep
34、recovery, nthe time-dependent decrease in strain in asolid, following the removal of force.DISCUSSIONRecovery is usually determined at constant tempera-ture.DISCUSSIONIn tests of plastics, the initial recovery is generallyincluded; for metals it is not. Thermal expansion is excluded.(E28.04)creep ru
35、pture strength FL2, nthe stress that will causefracture in a creep test at a given time, in a specified constantenvironment. (E28.10)DISCUSSIONThis is sometimes referred to as the stress-rupturestrength. In glass technology this is termed the “static fatigue strength.”creep strength FL2, nthe stress
36、 that causes a given creepin a creep test at a given time in a specified constantenvironment. (E28.04)deep drawing, va metal sheet forming operation in whichstrains on the sheet surface are positive in the direction of thepunch travel and negative at 90 to that direction.(E28.02)deflectometer, na sp
37、ecialized extensometer used for sensingof extension or motion, usually without reference to aspecific gauge length. (E28.01)Demeri split-ring test, na test the measures the springbackbehavior of sheet metal by comparing the diameter of a ringextracted from the wall of a flat bottom cup to the diamet
38、erof the same ring, split to release residual stresses.(E28.02)discontinuous yielding, na hesitation or fluctuation of forceobserved at the onset of plastic deformation, due to localizedyielding.DISCUSSIONThe stress-strain curve need not appear to be discon-tinuous. (E28.04)discontinuous yielding st
39、ress, nthe peak stress at theinitiation of the first measurable serration on the curve ofstress-versus strain. (E28.04)ductility, nthe ability of a material to deform plasticallybefore fracturing.DISCUSSIONDuctility is usually evaluated by measuring (1) theelongation or reduction of area from a tens
40、ion test, (2) the depth of cupfrom a cupping test, (3) the radius or angle of bend from the bend test,or (4) the fatigue ductility from the fatigue ductility test (see TestMethod E 796).DISCUSSIONMalleability is the ability to deform plastically underrepetitive compressive forces. (E28.02)dynamic me
41、chanical measurement, na technique in whicheither the modulus or damping, or both, of a substance underoscillatory applied force or displacement is measured as afunction of temperature, frequency, or time, or a combina-tion thereof. (E28.04)eccentricity, nthe distance between the line of action of t
42、heapplied force and the axis of symmetry of the specimen in aplane perpendicular to the longitudinal axis of the specimen.(E28.04)edge distance L, nthe distance from the edge of a bearingspecimen to the center of the hole in the direction of appliedforce. (E28.04)edge distance ratio, nthe ratio of t
43、he edge distance to thepin diameter. (E28.04)elastic calibration device, na device used in verifying theforce readings of a testing machine consisting of an elasticmember(s) to which forces may be applied, combined with amechanism or device for indicating the magnitude (or aquantity proportional to
44、the magnitude) of deformation ofthe member under an applied force. (E28.01)elastic force measuring device, na device or system con-sisting of an elastic member combined with a device forindicating the magnitude (or a quantity proportional to themagnitude) of deformation of the member under an applie
45、dforce. (E28.01)elastic limit FL2, nthe greatest stress which a material iscapable of sustaining without any permanent strain remain-ing upon complete release of the stress.DISCUSSIONDue to practical considerations in determining theelastic limit, measurements of strain, using a small force rather t
46、hanzero force, are usually taken as the initial and final reference.elongation, El, nthe increase in gauge length of a bodysubjected to a tension force, referenced to a gauge length onthe body. Usually elongation is expressed as a percentage ofthe original gauge length.DISCUSSIONThe increase in gaug
47、e length may be determined eitherat or after fracture, as specified for the material under test.DISCUSSIONThe term elongation, when applied to metals, generallymeans measurement after fracture; when applied to plastics andelastomers, measurement at fracture. Such interpretation is usuallyapplicable
48、to values of elongation reported in the literature when nofurther qualification is given.DISCUSSIONIn reporting values of elongation the gauge length shallbe stated.DISCUSSIONElongation is affected by specimen geometry (area andshape of cross section, parallel length, parallelism, fillet radii, etc.
49、),preparation (degree to which surfaces within the reduced section aresmooth and free of cold work), and test procedure (alignment and testspeed, for example). (E28.04)error, nfor a measurement or reading, the amount it deviatesfrom a known or reference value, represented by a measure-ment standard. Mathematically, the error is calculated bysubtracting the accepted value from the measurement orreading. (See also percent error.) (E28.91)extensometer, na device for sensing strain. (
