EN ISO 16808:2014

Metallic materials - Sheet and strip - Determination of biaxial stress-strain curve by means of bulge test with optical measuring systems (ISO 16808:2014)

ISO 16808:2014 specifies a method for determination of the biaxial stress-strain curve of metallic sheets having a thickness below 3 mm in pure stretch forming without significant friction influence. In comparison with tensile test results, higher strain values can be achieved.

Metallische Werkstoffe - Blech und Band - Bestimmung der biaxialen Spannung/Dehnung-Kurve durch einen hydraulischen Tiefungsversuch mit optischen Messsystemen (ISO 16808:2014)

Diese Internationale Norm legt ein Verfahren zur Ermittlung der biaxialen Spannung/Dehnung-Kurve von Metallblechen mit einer Dicke unter 3 mm bei reinem Streckziehen ohne signifikanten Reibungseinfluss fest. Im Vergleich zu den Ergebnissen der Zugprüfung können höhere Formänderungswerte erreicht werden.
ANMERKUNG   Der in der Norm verwendete Terminus „biaxialen Spannung/Dehnung-Kurve“ ist der Einfachheit halber verwendet. Prinzipiell wird in dem Versuch die biaxiale wahre Spannung über dem Umformgrad ermittelt.

Matériaux métalliques - Tôles et bandes - Détermination de la courbe contrainte-déformation biaxiale au moyen de l'essai de gonflement hydraulique avec systèmes de mesure optiques (ISO 16808:2014)

L'ISO 16808:2014 spécifie une méthode pour la détermination de la courbe contrainte-déformation biaxiale sur tôles métalliques d'épaisseur inférieure à 3 mm en formage en expansion pure sans influence significative des frottements. En comparaison à des résultats d'essais de traction, des valeurs plus élevées de la déformation peuvent être obtenues.

Kovinski materiali - Pločevina in trak - Ugotavljanje krivulje dvoosnega diagrama z izboklinskim preskusom optičnih merilnih sistemov (ISO 16808:2014)

Standard EN ISO 16808 določa metodo za ugotavljanje krivulje dvoosnega diagrama kovinskih pločevin z debelino, manjšo od 3 mm, pri oblikovanju popolnega raztezanja brez pomembnih vplivov trenja. V primerjavi z rezultati nateznega preskusa je ob tem mogoče doseči večje natezne vrednosti.

General Information

• Status: Withdrawn
• Publication Date: 15-Jul-2014
• Withdrawal Date: 24-May-2022
• ICS: 77.040.10 - Mechanical testing of metals
• Technical Committee: ECISS/TC 101 - Test methods for steel (other than chemical analysis)
• Drafting Committee: ECISS/TC 101 - Test methods for steel (other than chemical analysis)
• Current Stage: 9960 - Withdrawal effective - Withdrawal
• Completion Date: 25-May-2022
• Ref Project: SIST EN ISO 16808:2014 - Metallic materials - Sheet and strip - Determination of biaxial stress-strain curve by means of bulge test with optical measuring systems (ISO 16808:2014)

Relations

• Replaced By: EN ISO 16808:2022 - Metallic materials - Sheet and strip - Determination of biaxial stress-strain curve by means of bulge test with optical measuring systems (ISO 16808:2022)
• Effective Date: 08-Jun-2022

Standards Content (Sample)

SLOVENSKI STANDARD
01-oktober-2014
.RYLQVNLPDWHULDOL3ORþHYLQDLQWUDN8JRWDYOMDQMHNULYXOMHGYRRVQHJDGLDJUDPD]
L]ERNOLQVNLPSUHVNXVRPRSWLþQLKPHULOQLKVLVWHPRY,62
Metallic materials - Sheet and strip - Determination of biaxial stress-strain curve by
means of bulge test with optical measuring systems (ISO 16808:2014)
Metallische Werkstoffe - Bleche und Bänder - Bestimmung der biaxialen
Spannung/Dehnung-Kurve durch einen hydraulischen Tiefungsversuch mit optischen
Messsystemen (ISO 16808:2014)
Matériaux métalliques - Tôles et bandes - Détermination de la courbe contrainte-
déformation biaxiale par la méthode du renflement avec système de mesure optique
(ISO 16808:2014)
Ta slovenski standard je istoveten z: EN ISO 16808:2014
ICS:
77.040.10 Mehansko preskušanje kovin Mechanical testing of metals
77.140.50 3ORãþDWLMHNOHQLL]GHONLLQ Flat steel products and semi-
SROL]GHONL products
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN ISO 16808
NORME EUROPÉENNE
EUROPÄISCHE NORM
July 2014
ICS 77.040.10
English Version
Metallic materials - Sheet and strip - Determination of biaxial
stress-strain curve by means of bulge test with optical measuring
systems (ISO 16808:2014)
Matériaux métalliques - Tôles et bandes - Détermination de Metallische Werkstoffe - Bleche und Bänder - Bestimmung
la courbe contrainte-déformation biaxiale au moyen de der biaxialen Spannung/Dehnung-Kurve durch einen
l'essai de gonflement hydraulique avec systèmes de hydraulischen Tiefungsversuch mit optischen
mesure optiques (ISO 16808:2014) Messsystemen (ISO 16808:2014)
This European Standard was approved by CEN on 4 July 2014.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national
standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN member.

This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management Centre has the same
status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United
Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2014 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 16808:2014 E
worldwide for CEN national Members.

Contents Page
Foreword .3

Foreword
This document (EN ISO 16808:2014) has been prepared by Technical Committee ISO/TC 164 “Mechanical
testing of metals” in collaboration with Technical Committee ECISS/TC 101 “Test methods for steel (other
than chemical analysis)” the secretariat of which is held by AFNOR.
This European Standard shall be given the status of a national standard, either by publication of an identical
text or by endorsement, at the latest by January 2015, and conflicting national standards shall be withdrawn at
the latest by January 2015.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the following
countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech
Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece,
Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,
Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom.
Endorsement notice
The text of ISO 16808:2014 has been approved by CEN as EN ISO 16808:2014 without any modification.
INTERNATIONAL ISO
STANDARD 16808
First edition
2014-08-01
Metallic materials — Sheet and strip
— Determination of biaxial stress-
strain curve by means of bulge test
with optical measuring systems
Matériaux métalliques — Tôles et bandes — Détermination de
la courbe contrainte-déformation biaxiale au moyen de l’essai de
gonflement hydraulique avec systèmes de mesure optiques
Reference number
ISO 16808:2014(E)
©
ISO 2014
ISO 16808:2014(E)
© ISO 2014
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior
written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of
the requester.
ISO copyright office
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Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail [e-mail]
Web www.iso.org
Published in Switzerland
ii © ISO 2014 – All rights reserved

ISO 16808:2014(E)
Contents Page
Foreword .iv
1 Scope . 1
2 Symbols and abbreviated terms . 1
3 Principle . 2
4 Test equipment. 2
5 Optical measurement system . 6
6 Test piece . 6
6.1 General . 6
6.2 Application of grid . 6
7 Procedure. 7
8 Evaluation methods for the determination of the curvature and strains at the pole .7
9 Calculation of biaxial stress-strain curves . 8
10 Test report . 9
Annex A (informative) International comparison of symbols used in the determination of the
bulge test flow curve .11
Annex B (normative) Test procedure for a quality check of the optical measurement system .13
Annex C (informative) Computation of the curvature on the basis of a response surface
........................16
Annex D (informative) Determination of the equi-biaxial stress point of the yield locus and the
hardening curve .18
Bibliography .26
ISO 16808:2014(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the meaning of ISO specific terms and expressions related to conformity
assessment, as well as information about ISO’s adherence to the WTO principles in the Technical Barriers
to Trade (TBT) see the following URL: Foreword - Supplementary information
The committee responsible for this document is ISO/TC 164, Mechanical testing of metals, Subcommittee
SC 2, Ductility testing.
iv © ISO 2014 – All rights reserved

INTERNATIONAL STANDARD ISO 16808:2014(E)
Metallic materials — Sheet and strip — Determination
of biaxial stress-strain curve by means of bulge test with
optical measuring systems
1 Scope
This International Standard specifies a method for determination of the biaxial stress-strain curve
of metallic sheets having a thickness below 3 mm in pure stretch forming without significant friction
influence. In comparison with tensile test results, higher strain values can be achieved.
NOTE In this document, the term “biaxial stress-strain curve” is used for simplification. In principle, in the
test the “biaxial true stress-true strain curve” is determined.
2 Symbols and abbreviated terms
The symbols and designations used are given in Table 1.
Table 1
Symbol Designation Unit
d Diameter of the die (inner) mm
die
d Diameter of the blank holder (inner) mm
BH
R Radius of the die (inner) mm
h Height of the drawn blank (outer surface) mm
t Initial thickness of the sheet (blank) mm
t Actual thickness of the sheet mm
p Pressure in the chamber MPa
rms Standard deviation (root mean square) -
ρ Radius of curvature mm
r Surface radius for determining curvature mm
r Surface radius for determining strain mm
r Surface radius to determine curvature with a die diam- mm
1_100
eter of 100 mm
a , b Coefficients for response surface -
i i
σ Biaxial stress MPa
Β
e Engineering strain -
ε Major true strain -
ε Minor true strain -
ε True thickness strain -
ε Equivalent true strain -
Ε
l Coordinate and length of a section mm
s
dz Displacement in the z-direction mm
dz Displacement after movement correction mm
mv
ISO 16808:2014(E)
3 Principle
A circular blank is completely clamped at the edge in a tool between die and blank holder. A bulge is
formed by pressing a fluid against the blank until final fracture occurs (Figure 1). During the test,
the pressure of the fluid is measured and the evolution of the deformation of the blank is recorded by
[1],[2],[3]
an optical measuring system. Based on the recorded deformation of the blank, the following
quantities near the centre of the blank are determined: the local curvature, the true strains at the
surface, and, by assuming incompressible deformation of the material, the actual thickness of the blank
...