ISO 22214:2006

INTERNATIONAL ISO
STANDARD 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
Céramiques techniques — Méthode d'essai pour la fatigue de courbure
cyclique de céramiques monolithiques à température ambiante

Reference number
©
ISO 2006
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ii © ISO 2006 – All rights reserved

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

Foreword
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(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
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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
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rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 22214 was prepared by Technical Committee ISO/TC 206, Fine ceramics.

iv © ISO 2006 – All rights reserved

INTERNATIONAL STANDARD ISO 22214:2006(E)

Fine ceramics (advanced ceramics, advanced technical
ceramics) — Test method for cyclic bending 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 purposes, 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 edition 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 17025:2005, 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 fracture 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 specimen 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.
3.6
maximum stress
σ
max
algebraic maximum value of cyclic stress
See Figure 1.
3.7
minimum stress
σ
min
algebraic 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
one period of the cyclic stress
See Figure 1.
Key
X Time
Y Stress
1 σ
min
2 σ
max
3 One stress cycle
Figure 1 — Cyclic stress
2 © ISO 2006 – All rights reserved

3.9
minimum to maximum stress ratio
R
algebraic ratio of minimum stress to maximum stress
σ
min
R =
σ
max
3.10
number of cycles
number of cycles 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 abscissa
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 Number of cycles to failure (N)
Y Maximum stress (MPa)
X Time to failure (s)
5 Number of superimposed points
Figure 2 — Example of S-N plot
4 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 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).
Figure 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 µm Ra or smaller, as defined in ISO 4287, and be reported. The width
and thickness of the test specimen shall 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 determination 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 failure 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 stre
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