1、Designation: E1012 12 E1012 12 1 Standard Practice for Verication of Testing Frame and Specimen Alignment Under Tensile and Compressive Axial Force Application 1 This standard is issued under the xed designation E1012; the number immediately following the designation indicates the year of original a
2、doption or, in the case of revision, 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 NOTENote 13, 10.2.1, and Eq 14 were editorially corrected in September 2012.
3、1. Scope* 1.1 Included in this practice are methods covering the determination of the amount of bending that occurs during the application of tensile and compressive forces to notched and unnotched test specimens during routine testing in the elastic range. These methods are particularly applicable
4、to the force levels normally used for tension testing, creep testing, and uniaxial fatigue testing. The principal objective of this practice is to assess the amount of bending exerted upon a test specimen by the ordinary components assembled into a materials testing machine, during routine tests. 2.
5、 Referenced Documents 2.1 ASTM Standards: 2 E6 Terminology Relating to Methods of Mechanical Testing E8 Test Methods for Tension Testing of Metallic Materials E9 Test Methods of Compression Testing of Metallic Materials at Room Temperature E21 Test Methods for Elevated Temperature Tension Tests of M
6、etallic Materials E83 Practice for Verication and Classication of Extensometer Systems E251 Test Methods for Performance Characteristics of Metallic Bonded Resistance Strain Gauges E466 Practice for Conducting Force Controlled Constant Amplitude Axial Fatigue Tests of Metallic Materials E606 Practic
7、e for Strain-Controlled Fatigue Testing E1237 Guide for Installing Bonded Resistance Strain Gages 2.2 Other Documents: V AMAS Guide 42 A Procedure for the Measurement of Machine Alignment in Axial Testing 3. Terminology 3.1 Denitions of Terms Common to Mechanical Testing: 3.1.1 For denitions of term
8、s used in this practice that are common to mechanical testing of materials, see Terminology E6. 3.1.2 alignment, nthe condition of a testing machine that inuences the introduction of bending moments into a specimen (or alignment transducer) during the application of tensile or compressive forces. 3.
9、1.3 eccentricity L, nthe distance between the line of action of the applied force and the axis of symmetry of the specimen in a plane perpendicular to the longitudinal axis of the specimen. 3.1.4 reduced section L, nsection in the central portion of the specimen which has a cross section smaller tha
10、n the gripped ends. 3.2 Denitions of Terms Specic to This Standard: 3.2.1 axial strain, a, nthe average of the longitudinal strains measured by strain gages at the surface on opposite sides of the longitudinal axis of symmetry of the alignment transducer by multiple strain-sensing devices located at
11、 the same longitudinal position. 1 This practice is under the jurisdiction of ASTM Committee E28 on Mechanical Testing and is the direct responsibility of Subcommittee E28.01 on Calibration of Mechanical Testing Machines and Apparatus. Current edition approved June 1, 2012. Published June 2010 June
12、2012. Originally approved in 1989. Last previous edition approved in 2005 as E1012 05. DOI: 10.1520/E1012-12.10.1520/E1012-12E01. 2 For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standards volume infor
13、mation, refer to the standards Document Summary page on the ASTM website. This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because it may not be technically possible to adequately
14、depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version of the standard as published by ASTM is to be considered the official document. *A Summary of Changes section appears at the end of this standard Copyright ASTM Inte
15、rnational, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States 13.2.1.1 Discussion This denition is only applicable to this standard. The term is used in other contexts elsewhere in mechanical testing. 3.2.2 bending strain, b, nthe difference between the strain at the
16、 surface and the axial strain (see Fig. 1). 3.2.2.1 Discussion in general, the bending strain varies from point to point around and along the reduced section of the specimen. Bending strain is calculated as shown in Section 10. 3.2.3 component (also known as force application component), nany of the
17、 parts used in the attachment of the load cell or grips to the testing frame, as well as any part, including the grips used in the application of force to the strain-gaged alignment transducer or the test specimen. 3.2.4 grips, nthat part of the force application components that directly attach to t
18、he strain-gage alignment transducer or the test specimen. 3.2.5 microstrain, nstrain expressed in micro-units per unit, such as micrometers/meter or microinches/in. 3.2.6 notched section L, nthe section perpendicular to the longitudinal axis of symmetry of the specimen where the cross-sectional area
19、 is intentionally at a minimum value in order to serve as a stress raiser. 3.2.7 percent bending, PB, (also known as percent bending strain), nthe ratio of the bending strain to the axial strain expressed as a percentage. 3.2.8 strain-gaged alignment transducer, nthe transducer used to determine the
20、 state of bending and the percent bending of a testing frame. 3.2.9 Type 1 alignment, nthe condition of a testing machine typically used for static or quasi-static testing including the non-rigid components and the positioning of the specimen within the grips which can introduce bending moments into
21、 the strain-gaged alignment transducer or test specimen during force application. 3.2.10 Type 2 alignment, nthe condition of a testing machine typically used for dynamic testing and all rigid parts of the load train which can introduce bending moments into the strain-gaged alignment transducer or te
22、st specimen force application. NOTE 1A bending strain,6B, is superimposed on the axial strain, a, for low-axial strain (or stress) in (a) and high-axial strain (or stress) in (b). For the same bending strain 6B, a high-percent bending is indicated in (a) and a low-percent bending is indicated in (b)
23、. FIG. 1 Schematic Representations of Bending Strains (or Stresses) That May Accompany Uniaxial Loading E1012 12 1 24. Signicance and Use 4.1 It has been shown that bending stresses that inadvertently occur due to misalignment between the applied force and the specimen axes during the application of
24、 tensile and compressive forces can affect the test results. In recognition of this effect, some test methods include a statement limiting the misalignment that is permitted. The purpose of this practice is to provide a reference for test methods and practices that require the application of tensile
25、 or compressive forces under conditions where alignment is important. The objective is to implement the use of common terminology and methods for verication of alignment of testing machines, associated components and test specimens. 4.2 Alignment verication intervals when required are specied in the
26、 methods or practices that require the alignment verication. Certain types of testing can provide an indication of the current alignment condition of a testing frame with each specimen tested. If a test method requires alignment verication, the frequency of the alignment verication should capture al
27、l the considerations i.e. time interval, changes to the testing frame and when applicable, current indicators of the alignment condition through test results. 4.3 Whether or not to improve axiality should be a matter of negotiation between the material producer and the user. 5. Verication of Alignme
28、nt 5.1 A numerical requirement for alignment should specify the force, strain-gaged alignment transducer dimensions, and temperature at which the measurement is to be made. Alternate methods employed when strain levels are of particular importance may be used as described in Practices E466 or E606.
29、When these methods are used, the numerical requirement should specify the strain levels, strain-gaged alignment transducer dimensions and temperature at which the measurement is to be made. NOTE 1For a misaligned load train, the percent bending usually decreases with increasing applied force. (See C
30、urves A, B, and C in Fig. 2.) However, in some severe instances, percent bending may increase with increasing applied force. (See Curve D in Fig. 2.) 5.2 For a verication of alignment to be reported in compliance with the current revision of E1012 a strain-gaged alignment transducer shall be used. T
31、his applies to both Type 1 and Type 2 levels of alignment verication. 5.2.1 This standard denes two types of classied testing machine alignment per the classication criteria. The type of alignment shall be noted on the report. 5.2.2 When performing an alignment of a testing machine for the rst time
32、or if normally xed components have been adjusted or repaired, a mechanical alignment of the testing machine should be performed. For tensile and fatigue equipment, this step can be accomplished by means of a dial indicator for concentricity alignment adjustment and with precision shims or feeler gau
33、ges with the components brought together for angularity alignment adjustment. For creep and stress-rupture machines incorporating lever arms, this step may be accomplished by means of precision shims or feeler gauges, and/or double knife-edge couplings, and/or suitable components below the lower cro
34、sshead of the testing machine. Severe damage may occur to a strain-gaged alignment transducer if this step is omitted. A Mechanical Alignment is a preliminary step, but is not a substitute for a verication of alignment using a strain-gaged alignment transducer. 5.3 Testing Machine Alignment Type 1A
35、general alignment verication of the dened load train components. It is understood that some parts of the testing machine (i.e. the crosshead, actuator or grip faces) may be moved or exchanged in normal day to day testing. This alignment verication should be conducted for the various changes to the s
36、ystem (i.e. adjusting the crosshead and actuator position) to demonstrate reproducibility between changing conditions. Whenever possible the alignment verication should be conducted with the testing system components at a physical position that would simulate the position in which a test specimen wo
37、uld be installed. The strain-gaged alignment transducer geometry and material shall be adequately referenced in the verication report. NOTE 2Type 1 typically refers to static test equipment, such as tensile, stress rupture, or creep machines. NOTE 3For creep and stress rupture machines, the lever ar
38、m should be in a level position when performing alignment verication. 5.3.1 For some material testing, it is not possible or feasible to use all parts of the force application components when verifying alignment. In such cases alternative components may be used. The use of alternative components sha
39、ll be adequately referenced in the verication report. 5.4 Testing Machine Alignment Type 2Grip-to-grip alignment verication, where the testing machine mechanical congura- tion is xed and will not be changed or adjusted during the testing period. However, when testing some specimen geometries, it may
40、 be necessary to move the actuator or crosshead to install the strain-gaged alignment transducer and/or test specimens. This should be avoided if possible, but if it is necessary, care should be taken to reposition the actuator and or crosshead in the position used during the alignment. Any removabl
41、e components specic to the test specimen should be assembled within the aligned grip set and a strain-gaged alignment transducer used for verication of compliance to E1012. 5.4.1 Precision machined grip housings with hydraulic or pneumatically actuated wedge inserts are commonly used in laboratory t
42、esting. These devices are specically designed to allow for interchangeability of wedge inserts without adversely affecting the alignment of the loading train. For testing systems using these gripping congurations, grip wedge inserts may be replaced with smooth wedge inserts to assess the alignment o
43、f the testing machine under a Type 2 alignment assessment. NOTE 4Type 2 typically refers to dynamic test equipment, such as fatigue testing machines. E1012 12 1 3NOTE 5Type 2 alignment requires as many of the adjustable components of the testing machine as possible to be positioned in the nal veried
44、 position. This could include adjustable reaction components (i.e. crosshead) and actuators, which may otherwise be free to rotate about the loading axis. 5.5 Strain-gaged alignment transducers shall be manufactured per Section 7 of this standard. The strain-gaged alignment transducer is to be manuf
45、actured per section 7.4 as closely as possible, except that any notches may be eliminated. The same strain-gaged alignment transducer may be used for successive verications. The materials and design should be such that only elastic strains occur at the applied forces. 5.5.1 Strain-gaged alignment tr
46、ansducers shall be used for both Type 1 and Type 2 Testing Machine Alignment. 6. Apparatus 6.1 This standard requires the use of a strain-gaged alignment transducer. In some cases it may be helpful to make an assessment using extensometers or alignment components employing mechanical linkages (see A
47、ppendix X2), however these types of strain sensors do not meet the reporting requirements in Section 11. 6.2 In general, repeated force applications to strain levels approaching yielding are not good laboratory practice because they may affect the subsequently measured results by deforming or fatigu
48、ing the strain-gaged alignment transducer. 6.3 Additional Testing Machine and Force Application Component Considerations: NOTE 1Curve A: Machine 1, threaded grip ends (11) NOTE 2Curve B: Machine 2, buttonhead grip ends (11) NOTE 3Curve C: Machine 3, grips with universal couplings (7) NOTE 4Curve D:
49、schematic representation of a possible response from a concentrically misaligned load train (16) FIG. 2 Effects of Applied Force on Percent Bending for Different Testing Machines and Gripping Methods E1012 12 1 46.3.1 Poorly made components and multiple interfaces in a load train can cause major difficulty in attempting to align a test system. All components in the load train should be machined within precision machining practices with attention paid to perpendicularity, concentricity, atness a
