1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationBS EN 843-7:2010Advanced technical ceramics Mechanical properties ofmonolithic ceramics at roomtemperaturePart 7: C-ring testsBS EN 843-7:2010 BRITISH STANDARDNational forewordTh
2、is British Standard is the UK implementation of EN 843-7:2010.The UK participation in its preparation was entrusted to TechnicalCommittee RPI/13, Advanced technical ceramics.A list of organizations represented on this committee can beobtained on request to its secretary.This publication does not pur
3、port to include all the necessaryprovisions of a contract. Users are responsible for its correctapplication. BSI 2010ISBN 978 0 580 68821 8ICS 81.060.30Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was published under the authority of theStanda
4、rds Policy and Strategy Committee on 31 July 2010Amendments issued since publicationDate Text affectedBS EN 843-7:2010EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 843-7 June 2010 ICS 81.060.30 English Version Advanced technical ceramics - Mechanical properties of monolithic ceramics at room
5、temperature - Part 7: C-ring tests Cramiques techniques avances - Proprits mcaniques des cramiques monolithiques temprature ambiante - Partie 7: Essais dchantillons en forme danneau en C Hochleistungskeramik - Mechanische Eigenschaften monolithischer Keramik bei Raumtemperatur - Teil 7: C-Ring-Prfun
6、gen 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 ref
7、erences 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 membe
8、r 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,
9、 Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Management Centre: Avenue Marnix 17, B
10、-1000 Brussels 2010 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 843-7:2010: EBS EN 843-7:2010EN 843-7:2010 (E) 2 Contents Page Foreword 31 Scope 42 Normative references 43 Definitions 44 Significance and use .45 Principle 55.1
11、Method A: C-ring compression 55.2 Method B: C-ring tension 56 Apparatus .66.1 Cutting machine .66.2 Vernier callipers .66.3 Micrometer callipers 66.4 Mechanical testing machine .76.5 Interface material .77 Test pieces .78 Test procedure .88.1 Test-piece dimensions 88.2 Mechanical testing .89 Calcula
12、tion 89.1 Method A: C-ring compression 89.2 Method B: C-ring tension test 99.3 Mean and standard deviation .99.4 Fractures away from the centre-line 910 Interferences 911 Report 10Annex A (informative) C-ring compliance 11Bibliography . 12BS EN 843-7:2010EN 843-7:2010 (E) 3 Foreword This document (E
13、N 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 2
14、010, 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 rig
15、hts. 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 Youngs modulus, shear modulus and Poissons ratio Part 3: Determination of subcritical c
16、rack 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,
17、 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 Standa
18、rd: 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 K
19、ingdom. BS EN 843-7:2010EN 843-7:2010 (E) 4 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 ref
20、erenced 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 o
21、f 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: Te
22、nsion/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
23、: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
24、-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
25、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 diametr
26、al 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
27、 in BS EN 843-7:2010EN 843-7:2010 (E) 5 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 t
28、he 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 t
29、o 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 pr
30、essurized 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
31、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 u
32、sed 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. BS EN 843-7:2010EN 843-7:2010 (E) 6 rirorcPPrirortPPa) C-ring te
33、st in compression b) C-ring test in tension Key angle between the mid-plane and the location of the crack developed during the test rcC-ring strength determined in compression mode rtC-ring strength determined in ring tension mode r0outside wall tube radius riinside wall tube radius P applied load F
34、igure 1 C-ring test in compression and in tension 6 Apparatus 6.1 Cutting machine A cutting machine equipped with a diamond saw blade suitable for preparing parallel faced slices from tube material. The saw blade may be selected to be appropriate for the material being cut, but the grit size should
35、be minimised, and the cutting process adjusted to minimise edge chipping and other damage. If the available machine does not cut adequately dimensioned test-pieces (see Clause 7), test-pieces may be subsequently ground or lapped flat and parallel faced using other appropriate machines. 6.2 Vernier c
36、allipers Vernier callipers reading to 0,02 mm in accordance with ISO 6906:1984, but additionally equipped with the ability to measure internal diameters of test pieces, or other suitable measurement device of equivalent accuracy. 6.3 Micrometer callipers Micrometer callipers reading to 0,01 mm or be
37、tter in accordance with ISO 3611:1978, or other suitable measurement device of equivalent accuracy. BS EN 843-7:2010EN 843-7:2010 (E) 7 NOTE Micrometer callipers with flat anvils are normally recommended for making measurements on ceramic materials to avoid risks of indentation associated with round
38、ed anvils. However, rounded anvils will be required for measuring wall thickness, and should be used with considerable caution. 6.4 Mechanical testing machine A mechanical testing machine capable of applying a force to the test jig at a constant displacement rate or at constant loading rate. The tes
39、ting machine shall be equipped for recording the load applied to the test jig at any point in time. The accuracy and calibration of the testing machine shall be in accordance with EN ISO 7500-1:2004, Grade 1 (1 % of indicated load). For Method A, the testing machine shall be equipped with hard flat
40、anvils with faces either fixed parallel to within 0,05 mm over the area to be used for testing, or self-aligning during testing. For Method B, the testing machine shall be equipped with a device for permitting two hard steel rollers to be inserted through the ring and supported at each end by yokes
41、connected to the testing machine which permit a tensile force to be applied. Universal joints shall be incorporated into the load train to permit alignment and to minimise stress concentrations towards one face or other of the ring. NOTE Any suitable alternative arrangement may be used in which the
42、load can be applied in compression mode using a lever system containing the loading rollers. Precautions shall be taken to avoid flying fragments from the test-piece during fracture. 6.5 Interface material Thin, compliant materials such as cardboard, metal foil or rubber sheet, to be placed between
43、the test piece and the compression anvils (Method A) or steel rollers (Method B). 7 Test pieces Test pieces or test material shall be selected in accordance with the guidelines in EN 1006. If the test rings are to be cut from tube stock, select stock which is acceptably round and straight. This stan
44、dard does not prescribe any particular dimensions for test pieces, but the following size ratios are recommended to avoid problems with alignment or validity of the calculation equations: a) 0,05 (wall thickness/outer ring radius) 0,5; b) 0,2 (axial length/outer ring radius) 1,0; c) 1,0 (axial lengt
45、h/wall thickness) 4,0. Cut or otherwise machine the side faces of the test pieces to a parallelism of better than 0,015 mm using a diamond saw with or without additional machining by lapping or surface grinding. This process shall introduce a minimum of damage such that failure does not occur from t
46、he cut face. NOTE 1 Guidance on machining processes may be found in EN 843-1 6 and ASTM C1495 1. Make an axial cut through the wall of the ring using a diamond saw. For Method A the slot width shall be sufficiently large that the sides of the slot do not close during the test before failure of the t
47、est-piece. For thick-walled test-pieces, a slot of 1 mm to 2 mm is adequate, but for thinner walled test-pieces, the slot shall be rather wider. All edges shall be chamfered at 45 to a distance of at least (0,15 0,05) mm or rounded to a radius of at least (0,15 0,05) mm to avoid edge dominated failu
48、res. BS EN 843-7:2010EN 843-7:2010 (E) 8 NOTE 2 It is necessary only to make the chamfer over an arc length of at least 90 of the tube wall adjacent to region of maximum tensile stress. NOTE 3 Chamfering may be done by machine or by hand. The size of chamfer may need to be increased above the minimu
49、m values above for high-strength materials if it is found by fractography that chamfer dominated failure rather than surface dominated failures result. See 4 and 5. At least ten test pieces shall be tested for determination of a mean strength, or at least 30 test pieces if a Weibull statistical analysis in accordance with EN 843-5:2006 is to be performed. 8 Test procedure 8.1 Test-piece dimensions Measure the axial length of the each test piece to
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