EN 843-7:2010

SLOVENSKI STANDARD
01-september-2010
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Advanced technical ceramics - Mechanical properties of monolithic ceramics at room
temperature - Part 7: C-ring tests
Hochleistungskeramik - Mechanische Eigenschaften monolithischer Keramik bei
Raumtemperatur - Teil 7: C-Ring-Prüfungen
Céramiques techniques avancées - Propriétés mécaniques des céramiques
monolithiques à température ambiante - Partie 7: Essais d'échantillons en forme
d'anneau en C
Ta slovenski standard je istoveten z: EN 843-7:2010
ICS:
81.060.30 Sodobna keramika Advanced ceramics
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN 843-7
NORME EUROPÉENNE
EUROPÄISCHE NORM
June 2010
ICS 81.060.30
English Version
Advanced technical ceramics - Mechanical properties of
monolithic ceramics at room temperature - Part 7: C-ring tests
Céramiques techniques avancées - Propriétés mécaniques Hochleistungskeramik - Mechanische Eigenschaften
des céramiques monolithiques à température ambiante - monolithischer Keramik bei Raumtemperatur - Teil 7: C-
Partie 7: Essais d'échantillons en forme d'anneau en C Ring-Prüfungen
This European Standard was approved by CEN on 13 May 2010.

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 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 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, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland,
Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.

EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2010 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 843-7:2010: E
worldwide for CEN national Members.

Contents Page
Foreword .3
1 Scope .4
2 Normative references .4
3 Definitions .4
4 Significance and use .4
5 Principle .5
5.1 Method A: C-ring compression .5
5.2 Method B: C-ring tension .5
6 Apparatus .6
6.1 Cutting machine .6
6.2 Vernier callipers .6
6.3 Micrometer callipers .6
6.4 Mechanical testing machine .7
6.5 Interface material .7
7 Test pieces .7
8 Test procedure .8
8.1 Test-piece dimensions .8
8.2 Mechanical testing .8
9 Calculation .8
9.1 Method A: C-ring compression .8
9.2 Method B: C-ring tension test .9
9.3 Mean and standard deviation .9
9.4 Fractures away from the centre-line .9
10 Interferences .9
11 Report . 10
Annex A (informative) C-ring compliance . 11
Bibliography . 12

Foreword
This document (EN 843-7:2010) has been prepared by Technical Committee CEN/TC 184 “Advanced
technical ceramics”, the secretariat of which is held by BSI.
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 December 2010, and conflicting national standards shall be withdrawn
at the latest by December 2010.
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.
EN 843, Advanced technical ceramics ― Mechanical properties of monolithic ceramics at room temperature,
consists of the following nine parts:
 Part 1: Determination of flexural strength
 Part 2: Determination of Young's modulus, shear modulus and Poisson's ratio
 Part 3: Determination of subcritical crack growth parameters from constant stressing rate flexural strength
tests
 Part 4: Vickers, Knoop and Rockwell superficial hardness tests
 Part 5: Statistical analysis
 Part 6: Guidance for fractographic investigation
 Part 7: C-ring tests
 Part 8: Guidelines for conducting proof tests
 FprCEN/TS 843-9, Advanced technical ceramics ― Mechanical properties of monolithic ceramics at room
temperature ― Part 9: Method of test for edge-chip resistance
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, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain,
Sweden, Switzerland and the United Kingdom.

1 Scope
This European Standard describes a method for undertaking ultimate strength tests on slotted rings (C-rings)
in order to determine the strength of ring or tube-shaped components in the manufactured geometry.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references,
only the edition cited applies. For undated references, the latest edition of the referenced document (including any
amendments) applies.
EN 843-5:2006, Advanced technical ceramics ― Mechanical properties of monolithic ceramics at room
temperature ― Part 5: Statistical analysis
EN 1006, Advanced technical ceramics — Monolithic ceramics — Guidance on the selection of test pieces for
the evaluation of properties
EN ISO 7500-1:2004, Metallic materials — Verification of static uniaxial testing machines — Part 1:
Tension/compression testing machines — Verification and calibration of the force-measuring system
(ISO 7500-1:2004)
EN ISO/IEC 17025, General requirements for the competence of testing and calibration laboratories
(ISO/IEC 17025:2005)
ISO 3611:1978, Micrometer callipers for external measurement
ISO 6906:1984, Vernier callipers reading to 0,02 mm
3 Definitions
For the purposes of this document, the following terms and definitions apply.
3.1
C-ring test piece
ring-shaped test piece in which a radial slot has been cut to convert it into an incomplete ring
3.2
C-ring compression test
test in which a C-ring test piece is compressed across a diameter away from the slot, and which imposes the
maximum tensile stress on the outside surface of the ring remote from the points of compression load
application
3.3
C-ring tension test
test in which a C-ring test piece is pulled across a diameter away from the slot, and which imposes the
maximum tensile stress on the inside surface of the ring remote from the point of tensile load application
4 Significance and use
This method of test permits the strength of circular symmetry test pieces such as thin-walled rings or tubes to
be determined. The diametral loading of a short length of slotted tube or a slotted ring produces a tensile
stress in the mid-section of the tube wall, either in the outside region of the wall thickness if the ring is
compressed, or in the inside region if the ring is pulled in tension. In both cases the maximum stresses are in
the tube surface, and are remote from the points of load application, and thus only weakly influenced by the
precise geometry of load application. In contrast, diametral compression of a ring without a slot leads to high
tensile stresses immediately opposite the points of load application, with much poorer calibration and greater
sensitivity to the precise geometry of loading.
The result of a C-ring test is sensitive to the surface finish applied to the cylindrical surfaces of the ring, for
example by the method of shaping the article, and additionally to the planar ring faces. Thus if a ring is cut
from a tube, the cutting shall be done in such a manner as not to influence the result of the test if the purpose
of the test is to determine the as manufactured tube strength.
The results obtained from this test are representative of the strength of pressurized tubes and other cylindrical
shapes.
5 Principle
5.1 Method A: C-ring compression
A slotted ring test-piece is placed on its cylindrical surface on a flat anvil of a mechanical testing machine with
the slot remote from anvil (Figure 1a)). The second anvil of the test machine is brought into contact with the
top surface of the ring, and the load is increased until failure occurs by closing the C-ring. The strength is
computed from the ring geometry and the maximum force applied.
5.2 Method B: C-ring tension
Two opposed horizontal pull bars connected to a mechanical testing machine are used to contact the slotted
ring at diametrally opposed positions remote from the slot (Figure 1b)). The force is increased until failure by
opening the ring. The strength is computed from the ring geometry and the maximum force applied.
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