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1、JIS JAPANESE I NDUSTRIAL STANDARD Translated and Published by Japanese Standards Association Verification of extensometers used in uniaxial testing ICs 77.040.10 Descriptors : metals, tensile testing, extensometers Reference number : JIS B 7741 : 1999 (E) PROTECTED BY COPYRIGHT Copyright Japanese St
2、andards Association Provided by IHS under license with JSALicensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/12/2007 08:07:05 MDTNo reproduction or networking permitted without license from IHS -,-,- B 7741 : 1999 Foreword This translation has been made based on the original Jap
3、anese Industrial Standard revised by the Minister of International Trade and Industry through deliberations at the Japanese Industrial Standards Committee in accordance with the Industrial Standardization Law. Consequently JIS 3 7741 :1991 is replaced with JIS B 7741 :1999. Date of Establishment: 19
4、91-03-01 Date of Revision: 1999-03-20 Date of Public Notice in Official Gazette: 1999-03-23 Investigated by: Japanese Industrial Standards Committee Divisional Council on Precision Machinery JIS B 7741: 1999, Second English edition published in 2003-12 Translated and published by: Japanese Standards
5、 Association 4-1-24, Akasaka, Minato-ku, Tokyo, 107-8440 JAPAN In the event of any doubts arising as to the contents, the original JIS is to be the final authority. O JSA 2003 Ail rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by
6、 any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the publisher. Printed in Japan PROTECTED BY COPYRIGHT Copyright Japanese Standards Association Provided by IHS under license with JSALicensee=IHS Employees/1111111001, User=Wing, Bernie No
7、t for Resale, 03/12/2007 08:07:05 MDTNo reproduction or networking permitted without license from IHS -,-,- JAPANESE INDUSTRIAL STANDARD JIS B 7741 : 1999 Le L Verification of extensometers used in uniaxial testing Nominal value of gauge length of extensometer Measured value of gauge length of exten
8、someter Introduction This Japanese Industrial Standard has been prepared based on ISODIS 9513 Metallic materials - Verification of extensometers used in uniaxial testing pub- lished in 1996 without modifying the technical contents. The portions underlined with dots in this Standard are the matters n
9、ot included in the original International Standard. Emax Emin 1 used in uniaxial testing. Scope This Standard specifies a method for the static calibration of extensometers The term “extensometer“ is understood to mean the displacement measuring device and the system for indicating or recording this
10、 displacement. Remarks : The International Standard corresgonding - to this Standard is as follows: ISO/DIS 9513 : 1996 Metallic materials - Verifkation of extensometers used in uniaxial testing Maximum limit of calibration range Minimum limit of calibration range 3 tions given in JIS G 0202 and JIS
11、 Z 8103 shall apply. Standard are given in Table 1 together with their designation. Symbols, designations and definitions For the purpose of this Standard, defini- Symbols used throughout this . li Table 1 Symbols and designations Displacement indicated by extensometer 1 Unit Symbol I Designation 4
12、qLe True displacement given by calibration apparatus () pm Relative gauge length error % 4 r Relative bias error of extensometer Resolution of extensometer PROTECTED BY COPYRIGHT Copyright Japanese Standards Association Provided by IHS under license with JSALicensee=IHS Employees/1111111001, User=Wi
13、ng, Bernie Not for Resale, 03/12/2007 08:07:05 MDTNo reproduction or networking permitted without license from IHS -,-,- 2 B 7741 : 1999 Note () It is given by a set value or a reading of calibration apparatus and does not mean “true value that is the term used in measurement. 4 Principle The calibr
14、ation of an extensometer involves a comparison of the readings given by the extensometer with known variations in length provided by a calibration apparatus. 5 The calibration apparatus which allows a known displace- ment It to be applied to the extensometer, may consist of a rigid frame with suitab
15、le co- axial spindles or other fixtures to which the extensometer can be attached. The cali- bration apparatus shall comprise a mechanism for moving at least one of the axial spin- dles and a device for accurately measuring the change in length produced. The varia- tions in length can be measured, f
16、or example, using an interferometer or gauge blocks and a comparator or a screw micrometer. The gauge blocks, comparator, micrometer used shall be calibrated by a method which is traceable to the international unit (SI) of length and their accuracy shall be known. The error of the calibration appara
17、tus shall not be greater than one-third of the permissible error of the extensometer (see Table 2). The resolution of the calibration apparatus shall be in accordance with Table 2. Calibration apparatus 6 Procedure 6 . 1 Position of the extensometer The extensometer shall be placed in the calibratio
18、n apparatus in the same position and orientation in which it is used during uniaxial testing so as to avoid errors due to loss of equilibrium or deformation of any part of the extensometer. The extensometer shall be attached in the same way as during uniaxial testing. 6.2 Temperature at which the ca
19、libration is made In general, the calibration of the extensometer shall be carried out at a temperature stable to within t2”C; this tem- perature shall be within the range 18C to 28C. For extensometers used for uniaxial testing at temperatures within the range 10C to 35”C, it is recommended that the
20、 calibration be carried out at or near the test tem- perature, if facilities exist. The extensometer shall be placed near the calibration apparatus or mounted on it for a sufficient length of time prior to its calibration so that the parts of the extensome- ter and of the calibration apparatus which
21、 are in contact shall attain the calibration temperature. 6.3 Accuracy of gauge length of the extensometer The gauge length of the exten- someter can be measured directly or indirectly. The following indirect method is given as an example. The extensometer is placed on a soft metal test piece in suc
22、h a way that the blades Once the extensometer is removed, or points of the extensometer leave their marks. the distance between the marks on the test piece is measured. PROTECTED BY COPYRIGHT Copyright Japanese Standards Association Provided by IHS under license with JSALicensee=IHS Employees/111111
23、1001, User=Wing, Bernie Not for Resale, 03/12/2007 08:07:05 MDTNo reproduction or networking permitted without license from IHS -,-,- 3 B7741 : 1999 The relative error on the gauge length, qLe, calculated from the following formula shall not exceed the values given in Table 2. In the case of an exte
24、nsometer having several gauge lengths, the calibration shall be carried out for each of the gauge lengths required by the user. 6.4 Range of calibration The calibration range shall be defined by the user to cover the measuring range required to determine a given material property. The maximum and mi
25、nimum limits E, and E, of the calibration range shall be such that: (2) Emax 510 s . . . . . . * . . . . . . . . . . . . . f . * . . * . . . . . . . . . 51- E,? If several calibration ranges are specified by the user, each one shall be calibrated. The ranges of calibration shall An example of calibr
26、ation ranges is given in annex A. be noted in the calibration report. 6.5 Calibration procedure 6.5.1 When the temperature has stabilized, it is recommended that, before calibration and by means of the calibration apparatus, the extensometer be tried for at least two lengths over the calibration ran
27、ge of the extensometer. If possible, the displacement is taken to a slightly negative value and returned to zero. Where appropriate, the exten- someter is reset to zero. 6 . 5 . 2 Depending on the expected use of the extensometer, the two series of measure- ments are made for increases in length or
28、for decreases in length or for both. The Cali- bration consists first of one series of at least 10 measurements, l, distributed approxi- mately evenly over the calibration range of the extensometer. The extensometer is removed and then placed back on the calibration apparatus. A second series of mea
29、s- urements is then made in the same manner as the first. The calibration shall be made without cleaning or lubricating any part of the exten- After the extensometer complies with class requirements for its intended use someter. on the first calibration, second calibration shall be conducted. If the
30、 extensometer meets the requirements of the same conditions on the second calibration, the results shall be noted ?accepted on the calibration certificate. When adjustments are needed for the extensometer after completing first calibration, the re- sults shall be noted ?rejected? on the calibration
31、certificate. For each measurement point, calculate the relative bias error (see 6.6.2). 6.6 Determination of the characteristics of the extensometer 6.6.1 instrument. Resolution The resolution, Y, is the smallest quantity which can be read OE the The values of the resolution of the extensometer shal
32、l be in accordance PROTECTED BY COPYRIGHT Copyright Japanese Standards Association Provided by IHS under license with JSALicensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/12/2007 08:07:05 MDTNo reproduction or networking permitted without license from IHS -,-,- 4 B 7741 : 1999
33、Relative I Resolution* error on Percent- Absolute the gauge age of value 4 L . e r/l, r length readings % % Pm ir0.2 0.1 0.2 L0.5 0.25 0.5 with the values given in Table 2. Bias error* Resolution* Bias error* Relative Absolute Relative Absolute Relative Absolute error value error value error value 9
34、 18-4 1 % Pm % Pm % Pm t0.2 i0.6 0.05 0.1 -+ 0.06 20.2 t0.5 51.5 0.12 0.25 50.15 0 . 5 6.6.2 Relative bias error culated from the formula: The relative bias error, q, for a given displacement, It, is cal- (3) xloo . I . . . . . . . . . . . . . . . . . * . . . . . . . . . . * q=- li - 1, 1, 7 for the
35、 relative gauge length error, the resolution and the relative bias error. Classification of the extensometer Table 2 gives the maximum permissible values Table 2 Classification of extensometers Class of exten- someter 0.2 0.5 1 Extensometer (maximum values) I Calibration amaratus (maximurn values) I
36、 * Whichever value is the greater. NOTE : For small gauge lengths (I: 25 mm) and for small strains, the user should consider one of the better classes of extensometer. 8 Frequency of calibration The time between two calibrations depends on the type of extensometer, the maintenance standard and the n
37、umber of times the extensometer has been used. Under normal conditions, it is recommended that calibration be carried out at intervals of approximately 12 months. This interval shall not exceed 18 months unless the test is expected to last more than 18 months; in such case the extensometer shall be
38、calibrated before and after the test. The extensometer shall be calibrated after each repair or adjustment of its con- stituent elements which could affect the accuracy of measurements. 9 formation: Calibration report The calibration report shall contain at least the following in- a) general informa
39、tion: 1) 2) reference to this Standard, i.e. JIS B 7741; identification of the extensometer (type, gauge length, mark, name of the manu- facturer, serial number and mounting position); type and reference number of calibration apparatus; temperature at which the calibration was carried out; 3) 4) PRO
40、TECTED BY COPYRIGHT Copyright Japanese Standards Association Provided by IHS under license with JSALicensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/12/2007 08:07:05 MDTNo reproduction or networking permitted without license from IHS -,-,- 5 B7741 : 1999 5) nature of variations
41、 of length for which the calibration was carried out, i.e. either for increases and/or for decreases in length; 6) date of calibration; 7) 8) name or mark of the organization which carried out the calibration; date of expiry of the calibration report. b) results of the calibration: i) 2) class of ea
42、ch range of the extensometer; the individual values of the bias errors, if requested. PROTECTED BY COPYRIGHT Copyright Japanese Standards Association Provided by IHS under license with JSALicensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/12/2007 08:07:05 MDTNo reproduction or n
43、etworking permitted without license from IHS -,-,- 6 B 7741 : 1999 Annex A (informative) Example of calibration ranges of an extensometer This annex (informative) is to supplement the matters in the main text and is not part of the provisions. 5% 50 % 0.5 % I 0.05 % of the nominal value of the exten
44、someter travel First calibration range: Second calibration range: Third calibration range: 0.05% to 0.5% 0.5% to 5% 5% to 50% Figure A.l Example of calibration ranges of an extensometer PROTECTED BY COPYRIGHT Copyright Japanese Standards Association Provided by IHS under license with JSALicensee=IHS
45、 Employees/1111111001, User=Wing, Bernie Not for Resale, 03/12/2007 08:07:05 MDTNo reproduction or networking permitted without license from IHS -,-,- 7 B7741 : 1999 Extensometer gauge length Le mm 50 100 100 Annex B (informative) Parameters for classification of an extensometer True value Measured
46、value Absolute bias error Displace- Strain Displace- Strain Displace- Strain ment ment ment i, It I Le = E t I, lilLe=E; li-lt E; -Et P Pm Fm 100 , 2x104 101 2.02x10- I 0.02 x 10-3 100 1x10-3 101 1.01x10- i 0.01 x 10-3 200 2x10-3 201 2.01x10- i 0.01 x 10-3 This annex (informative) is to supplement t
47、he matters in the main text and is not part of the provisions. In order to clarify the parameters used for the classification of extensometers (see clause 6): a b) Table B.l gives three examples of calculation of these parameters; the diagrams in Figures B.l and B.2 illustrate clearly, for class 1 e
48、xtensometers, how to decide which of the two limits, “relative” or “absolute”, should be chosen. o Table B.l Examples of calculation of parameters for the classification of extensometers I l L I Relative bias error* 4 % Displace- Strain ment 111 1 1 0.5 i 0.5 * For a given displacement error, the relative error, q, is independent of the gauge length of the exten- someter, Le, but is dependent on the displacement value, 1,. Y; /c I Use the resolution expressed as percentage of reading, Use the absolute value, ,-/I i=n 6%) Figur