1、 Reference number ISO 22214:2006(E) ISO 2006INTERNATIONAL STANDARD ISO 22214 First edition 2006-02-01 Fine ceramics (advanced ceramics, advanced technical ceramics) Test method for cyclic bending fatigue of monolithic ceramics at room temperature Cramiques techniques Mthode dessai pour la fatigue de
2、 courbure cyclique de cramiques monolithiques temprature ambiante ISO 22214:2006(E) PDF disclaimer This PDF file may contain embedded typefaces. In accordance with Adobes licensing policy, this file may be printed or viewed but shall not be edited unless the typefaces which are embedded are licensed
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5、t is found, please inform the Central Secretariat at the address given below. ISO 2006 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permi
6、ssion in writing from either ISO at the address below or ISOs member body in the country of the requester. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ii ISO 2006 All rights reser
7、vedISO 22214:2006(E) ISO 2006 All rights reserved iii Contents Page Foreword iv 1 Scope . 1 2 Normative references . 1 3 Terms and definitions. 1 4 Test specimens . 4 5 Testing machine 4 6 Testing method . 6 7 Treatment of test result 7 8 Test report . 8 Bibliography . 9 ISO 22214:2006(E) iv ISO 200
8、6 All rights reservedForeword 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
9、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
10、 (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical com
11、mittees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not
12、 be held responsible for identifying any or all such patent rights. ISO 22214 was prepared by Technical Committee ISO/TC 206, Fine ceramics. INTERNATIONAL STANDARD ISO 22214:2006(E) ISO 2006 All rights reserved 1 Fine ceramics (advanced ceramics, advanced technical ceramics) Test method for cyclic b
13、ending fatigue of monolithic ceramics at room temperature 1 Scope This International Standard specifies a test method for four-point cyclic bending fatigue of fine ceramics that are carried out in the air at room temperature. This test may be used as a pass/fail test for material qualification purpo
14、ses, or for determination of the overall fatigue behaviour at several different stress levels. 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 ed
15、ition of the referenced document (including any amendments) applies. ISO 31-0:1992, Quantities and units Part 0: General principles ISO 14704:2000, Fine ceramics (advanced ceramics, advanced technical ceramics) Test method for flexural strength of monolithic ceramics at room temperature ISO/IEC 1702
16、5:2005, General requirements for the competence of testing and calibration laboratories 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 fatigue test test where repeated stress is applied to a test specimen, and the number of cycles to fractur
17、e is measured 3.2 fatigue failure fracture due to cyclic loading well below the strength under monotonic loading 3.3 suspending time time at which test is intentionally interrupted without fracture 3.4 four-point bending stress maximum value of stress generated in a test specimen when a test specime
18、n is loaded equally by two bearings symmetrically located between two support bearings 3.5 cyclic stress stress which is simply and cyclically varied between a specific maximum value and a specific minimum value See Figure 1. ISO 22214:2006(E) 2 ISO 2006 All rights reserved3.6 maximum stress maxalge
19、braic maximum value of cyclic stress See Figure 1. 3.7 minimum stress minalgebraic minimum value of cyclic stress See Figure 1. NOTE For maximum stress or minimum stress, the sign is considered. A tensile stress is taken as positive, and a compressive stress is taken as negative. 3.8 stress cycle on
20、e period of the cyclic stress See Figure 1. Key X Time Y Stress 1 min2 max3 One stress cycle Figure 1 Cyclic stress ISO 22214:2006(E) ISO 2006 All rights reserved 3 3.9 minimum to maximum stress ratio R algebraic ratio of minimum stress to maximum stress min max R = 3.10 number of cycles number of c
21、ycles of stress in fatigue test 3.11 number of cycles to failure N number of cycles of stress until fatigue failure occurs 3.12 time to failure T loading time until fatigue failure occurs 3.13 S-N plot diagram where maximum stress is taken as the ordinate and the number of cycles to failure as the a
22、bscissa See Figure 2. NOTE When the test is interrupted, the result is plotted as the maximum stress and the number of cycles at the suspending time. Key X 1Number of cycles to failure (N) Y Maximum stress (MPa) X 2Time to failure (s) 5 Number of superimposed points Figure 2 Example of S-N plot ISO
23、22214:2006(E) 4 ISO 2006 All rights reserved4 Test specimens 4.1 Test specimen size The test specimen dimensions and tolerances, which are shown in Figure 3, shall be in accordance with ISO 14704. Cross-sectional tolerances shall be 0,2 mm. The use of test specimens having twisting or warpage, which
24、 may lead to uneven contact, is not permitted. Dimensions in millimetres Edge chamfers at (0,12 0,03) mm 45 5 or rounded at (0,15 0,05) mm The parallelism tolerance on opposite longitudinal faces is 0,015 mm Key L Specimen length (W 35 mm for 30 mm test fixture but W 45 mm for 40 mm test fixture). F
25、igure 3 Test specimen 4.2 Specimen preparation Machining for surface preparation of test specimens shall be based on the procedure described in ISO 14704. The surface roughness should be 0,20 m Ra or smaller, as defined in ISO 4287, and be reported. The width and thickness of the test specimen shall
26、 be measured according to ISO 14704. 4.3 Number of test specimens The number of identical test specimens that should be prepared depends on the purpose of the fatigue tests. If test conditions for a pass/fail test are set, it is recommended that at least three test specimens be prepared. If the dete
27、rmination of an S-N plot is required, at least 15 test specimens should be prepared, of which three to five are used to determine the flexural strength under monotonic loading based on the testing procedure described in ISO 14704 and the remainder are used to determine the number of cycles to failur
28、e for at least three different stress levels. 5 Testing machine 5.1 Structure of testing machine A testing machine shall be configured so that cyclic bending stress can be applied to a test specimen and forces or moments other than that related to the cyclic bending stress are not applied. The testi
29、ng machine shall be equipped with an apparatus for measuring or indicating the maximum or minimum force, an apparatus capable of obtaining the number of cycles until the test specimen fractures, and a mechanism where automatic reactivation is prevented when the testing machine is stopped for reasons
30、 other than test specimen fracture (e.g. power failure, etc.). ISO 22214:2006(E) ISO 2006 All rights reserved 5 5.2 Loading precision The fluctuation of the maximum stress shall be within 1 % of the chosen value and that of the minimum to maximum stress ratio shall be within 5 % thereof. NOTE The sc
31、ope of ISO 7500-1 does not include dynamic-fatigue machine calibration, but in the absence of a directly applicable standard, the procedure in ISO 7500-1 may be used within this International Standard with the risk of only a small error. 5.3 Test fixture The four-point flexure fixture specified in I
32、SO 14704 (see Figure 4) shall be used. A fixture other than one which is semi-articulating or fully articulating (e.g., one not equipped with free-to-roll bearings) may be used if an articulating fixture is not available. Deviations from the specification described in ISO 14704 shall be reported. NO
33、TE The influence of friction at the contact between the bearing and test specimen on cyclic-fatigue behaviour is not clear at this time and this International Standard provides some latitude in the use of non-articulating fixtures. L = 40 mm 0,1 mm a) Four-point-1/4 point flexure L = 30 mm 0,1 mm b)
34、 Four-point 1/3-point flexure Key 1 loading bearing 2 supporting bearing b width of specimen (mm) d thickness of specimen (mm) All bearings shall be free to roll. Figure 4 Four-point flexure fixture ISO 22214:2006(E) 6 ISO 2006 All rights reserved6 Testing method 6.1 Waveform of loading stress The r
35、ecommended stress waveform is a sinusoidal wave of 20 Hz frequency and a stress ratio, R = 0,1. If other waveforms are employed, the specifics shall be stated in the test report. Regardless of waveform specifics, all tests in a series of fatigue tests shall be conducted using the same waveform. 6.2
36、Loading method 6.2.1 Either the four-point-1/4 point or the four-point-1/3 point loading configuration specified in ISO 14704 shall be used (see Figure 4). The ratio of difference between the outer and the inner spans to the test specimen thickness should not be less than 5. 6.2.2 Because the force
37、to achieve the maximum stress is typically not applied upon the first load cycle, it must be slowly increased during subsequent cyclic loading. However, the number of cycles from the start of cycling to that which the final maximum stress is reached should be as few as possible. The peak stress that
38、 occurs during this adjustment period shall not exceed the required or specified maximum stress. 6.2.3 The test shall be carried out without a pause of the cyclic loading on the same test specimen from start to end. However, when a test is temporarily stopped during a test for any reason, the number
39、 of cycles applied up to the stop, as well as the time duration of the stop, shall be recorded. 6.2.4 Unless the test is being employed for pass/fail purposes, the fatigue test should be carried out on three or more test specimens at each of three or more different stress levels. NOTE To have meanin
40、gful data trends, more than 3 stress levels are preferable. However, there is a tradeoff between testing time and data obtained. 6.3 Number of cycles for suspension Unless otherwise specified when the test specimen has not fractured after 10 7cycles, the test may be suspended. NOTE When 20 Hz freque
41、ncy is chosen for the loading condition, the 10 7cycles is equivalent to 5,8 days, approximately. 6.4 Reuse of test specimen Reuse of a test specimen that has been previously fatigue tested shall be prohibited. 6.5 Recommended test procedure in fatigue test When the maximum stress and the number of
42、test specimens in a fatigue test are not previously agreed on between the tester and the requester, the test may be carried out according to the procedure described in 6.5.1 and 6.5.2. 6.5.1 Measurement of flexural strength To obtain a baseline for the maximum stress in a fatigue test, the monotonic
43、 flexural strength should be measured in advance. Use flexural strength of test specimens of the same shape and preparation as that of fatigue test specimens. The flexural strength tests shall be conducted using the same fixture as the fatigue test and the testing procedure in accordance with ISO 14
44、704. The mean of the monotonic flexural strength shall be calculated by the standard formulae specified in ISO 14704. ISO 22214:2006(E) ISO 2006 All rights reserved 7 6.5.2 Stress level in fatigue test For a series of fatigue tests, the first maximum stress level should be chosen such that the maxim
45、um stress is less than, but close to, the mean of the monotonic flexural strength. Determine the cycles to failure of at least three fatigue test specimens under this same maximum stress. If none of the fatigue test specimens cycled at this maximum stress level has fractured before the agreed number
46、 of cycles for suspending a test, then additional fatigue tests shall be conducted at maximum stress levels greater than the first maximum stress level. When a relation between the maximum cyclic stress and the number of cycles is required, then test specimen fractures at at least three maximum stre
47、ss levels should be obtained. 6.6 Test environment Moisture content in the test environment may have an influence on the cyclic fatigue behaviour. For tests in air or another gaseous environment, the test temperature and humidity should be measured and reported at least at the beginning and the end
48、of each test, or hourly if the test duration is longer than 1 h. 7 Treatment of test result 7.1 Maximum stress Calculate the maximum stress according to the following formulae from measuring values of respective test specimens, and round off to three significant figures in accordance with ISO 31-0.
49、For four-point flexural test max max 2 3() 2 PLl bd = where maxis the maximum stress (MPa); P maxis the maximum force (N); lis the span of inner bearings (mm); Lis the span of outer bearings (mm); bis the width of specimen (mm); dis the thickness of specimen (mm). 7.2 Number of cycles to failure The number of cycles shall be counted by starting from the time when a force on the test specimen reaches the force necessary to achieve the required maximum stress level. If the stress is adj
