IEC 61788-18:2013

IEC 61788-18 ®
Edition 1.0 2013-09
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Superconductivity –
Part 18: Mechanical properties measurement – Room temperature tensile test of
Ag- and/or Ag alloy-sheathed Bi-2223 and Bi-2212 composite superconductors

Supraconductivité –
Partie 18: Mesure des propriétés mécaniques – Essai de traction à température
ambiante des supraconducteurs composites Bi-2223 et Bi-2212 avec gaine Ag
et/ou en alliage d'Ag
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IEC 61788-18 ®
Edition 1.0 2013-09
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Superconductivity –
Part 18: Mechanical properties measurement – Room temperature tensile test of

Ag- and/or Ag alloy-sheathed Bi-2223 and Bi-2212 composite superconductors

Supraconductivité –
Partie 18: Mesure des propriétés mécaniques – Essai de traction à température

ambiante des supraconducteurs composites Bi-2223 et Bi-2212 avec gaine Ag

et/ou en alliage d'Ag
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX W
ICS 29.050 ISBN 978-2-8322-1051-2

– 2 – 61788-18 © IEC:2013
CONTENTS
1 Scope . 7
2 Normative references . 7
3 Terms and definitions . 7
4 Principle . 9
5 Apparatus . 9
5.1 General . 9
5.2 Testing machine . 9
5.3 Extensometer . 9
6 Specimen preparation . 9
6.1 General . 9
6.2 Length of specimen . 10
6.3 Removing insulation . 10
6.4 Determination of cross-sectional area (S ) . 10
7 Testing conditions . 10
7.1 Specimen gripping . 10
7.2 Setting of extensometer . 10
7.3 Testing speed . 10
7.4 Test . 10
8 Calculation of results . 12
8.1 Modulus of elasticity (E) . 12
8.2 0,2 % proof strength (R ) . 13
p 0,2
8.3 Tensile stress at specified strains (R ) . 13
A
8.4 Fracture strength (R ) . 14
f
9 Uncertainty of measurement . 14
10 Test report . 14
10.1 Specimen . 14
10.2 Results . 15
10.3 Test conditions . 15
Annex A (informative) Additional information relating to Clauses 1 to 14 . 16
Annex B (informative) Uncertainty considerations . 26
Annex C (informative) Specific examples related to evaluation of uncertainties for
Ag/Bi-2223 and Ag/Bi-2212 wires . 30

Figure 1 – Typical stress-strain curve and definition of modulus of elasticity and 0,2 %
proof strengths of an externally laminated Ag/Bi-2223 wire by brass foil . 11
Figure 2 – Typical stress-strain curve of an Ag/Bi-2223 wire where the 0,2 % proof
strengths could not be determined and definition of tensile stresses at specified strains . 12
Figure A.1 – Low mass Siam twin type extensometer with a gauge length of ~ 12,3 mm
(total mass ~ 0,5 g) . 16
Figure A.2 – Low mass double extensometer with a gauge length of ~ 25,6 mm (total
mass ~ 3 g) . 17
Figure A.3 – An example of the extensometer provided with balance weight and vertical
specimen axis . 18
Figure A.4 – Original raw data of an Ag/Bi-2223 wire measurement in form of load and
displacement graph . 19

61788-18 © IEC:2013 – 3 –
Figure A.5 – Typical stress versus strain of an Ag/Bi-2223 wire up to the elastic limit
corresponding to the transition region from elastic to plastic deformation (point G) . 20
Figure C.1 – Measured stress versus strain curve for Bi-2223 wire . 31

Table A.1 – Results of relative standard uncertainty values achieved on different
Ag/Bi-2223 wires during the international round robin tests . 23
Table A.2 – Selected data for F test for E of Sample E bare wire . 24
Table A.3 – Results of F-test for the variations of E of four kinds of Bi-2223 wires . 24
Table B.1 – Output signals from two nominally identical extensometers . 27
Table B.2 – Mean values of two output signals . 27
Table B.3 – Experimental standard deviations of two output signals . 27
Table B.4 – Standard uncertainties of two output signals . 27
Table B.5 – Coefficient of variations of two output signals . 28
Table C.1. – Load cell specifications according to manufacturer’s data sheet. 32
Table C.2 – Uncertainties from various factors for stress measurement . 33
Table C.3 – Uncertainties with respect to measurement of strain measurement . 35
Table C.4 – Summary of evaluated uncertainties caused by various factors . 35
Table C.5 – Results of uncertainty evaluation for the modulus of elasticity (E = 86,1
GPa) as a function of initial cross head rate . 36
Table C.6 – Uncertainties from various factors for stress measurement . 37
Table C.7 – Results of uncertainty evaluation for the stress (R = 42,5 MPa) as a function
of initial strain rate . 37

– 4 – 61788-18 © IEC:2013
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
SUPERCONDUCTIVITY –
Part 18: Mechanical properties measurement –
Room temperature tensile test of Ag- and/or Ag alloy-sheathed
Bi-2223 and Bi-2212 composite superconductors

FOREWORD
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Standardiza
...