BS ISO 28704:2011 pdf download
BS ISO 28704:2011 pdf download.Fine ceramics (advanced ceramics, advanced technical ceramics)—Test method for cyclic bending fatigue of porous ceramics at room temperature.
7.2 Number of cycles to failure
The number of cycles shall be counted by starting from when a load on a test piece reaches a specific testing stress. If the stress is adjusted dunng the test, the cycles fo adjustment shall be included In N. Represent the number of cycles of the test result by, for example, multiple of 10’ such as 2,34 * 106. and round off to three significant figures.
7.3 S.Nplot
Draw a S-N diagram by taking the maximum stress or its logarithmic value as the Ordinate, and the logarithmic value of the number of cycles to failure as the abscissa. When the life Is displayed In time, the number of cycles to failure is scaled on the underside of the abscissa, and the failure time is scaled on the upper side of the abscissa. A point expressing the test result for the test piece that is not broken is marked with a rlghtward arrow An example of the S-N diagram is given in Figure 2.
NOTE 1 In the S-N diagram, when at least two points are superimposed, the number of points is clearly described, or arrows are marked by the number of points as shown in Figiøe 2.
NOTE 2 When the arrow is superimposed on a marked line, the arrow is marked ctearly by drawing it upward or downward
8 Test report
The test report shall include the following infomiation:
a) name and class of material;
b) dimensions (mean values) of the test piece;
C) name of testing machine and its type;
d) test environment, including temperature and humidity;
e) loading conditions (loading method, loading waveform, loading frequency. rrwnimum to maximum stress ratio, and the number of cycles to the moment when a test is temporarily stopped midway and its stop time):
f) list of test results (the maximum stress and the fracture number of cycles);
g) S-N plot;
h) if appropriate, manufacturer’s name of the material and its date of manufacture;
I) it appropriate, name of the material, kinds of additive, and sintering method;
j) if appropriate, porosity and mean pore size of the material;
k) if appropriate, chemical composition of material;
I) if appropriate, sampling conditions of test piece made from the material and its machining conditions (when a test piece is heat treated, its conditions are included);
6.4 Reuse of test piece
Do not reuse a test piece which has been used once.
6.5 Recommended test procedure In fatigue test
When the maximum stress and the number of test pieces in a fatigue test are not previously agreed upon between the purchaser and the supplier, the test may be carried out according to the following procedure.
6.5.1 Measurement of flexural strength
In order to obtain the standard value ci the maximum stress In a fatigue test, measure the flexural strength of a test piece prior to the fatigue test. Use the test piece of the same shape as that of a fatigue test piece for measurement of flexural strength, and ob4ain It by the same loading method as that of the fatigue test. Allow the speed of a cross-head in the measurement of flexural strength to be 0.5 mm/mm, Calculate the flexur& strength from the measured maximum forces of respective test pieces.
6.5.2 Stress level in fatigue test
Determine the maximum stress in a fatigue test by relemng to the arithmetic mean value of the flexural strength obtained by the measurement In 6.5.1. Start the fatigue test fron’i a condition wherein the maximum stress Is high, and preferably measure the life of at least three test pieces by the same stress. When all the test pieces tested at the same stress are unfailed at the selected number of cycles for test termination, select a higher stress level for the next group of test pieces. Do not carry out tests at a lower stress level, It is preferred that the results of a test programme should contain at least three valid failures at each of al least three maximum stress levels.
6.6 Test environment
The moisture content In me test environment may have an Influence on the cyclIc fatigue behaviour. For tests ii air or other gaseous environments, the test temperature and humidity should be measured and reported at least at the beginning and the end of each test, or hour’y if the test duration is longer than 1 h.
