ISO 12111-2011 pdf free download

ISO 12111-2011 pdf free download.Metallic materials Fatigue testing Strain-controlled thermomechanical fatigue testing method
Matériaux metalliques — Essais de fatigue — Méthode d’essai de fatigue thermo-mecanique avec deformation contrOlée.
The test is terminated when the conditions for the selected end of test criterion are fulfilled. The specimen- heating device should be switched off as soon as the test terminates in order to limit the corrosion/oxidation of the specimen and cracked surfaces with a view to carrying out post mortem examinations. If the failure criterion is other than specimen separation, every effort should be taken to ensure that the specimen is not over-loaded during test termination.
It is recommended that post mortem examinations (metallographic and fractographic analysis) be conducted on the failed specimens. These will provide insight into various failure mechanics and also serve to make known any unusual phenomena that might stand to invalidate the test results.
7.13 Test interruption sequence
If a test is interrupted, then care shall be taken to ensure that upon restart there is no significant overshoot in temperature, axial force or mechanical strain. An example of a suitable technique is given below.
Prior to interrupting a strain-controlled TMF test, record the maximum and minimum forces of the final 3 cycles. After the test has been discontinued, record several free thermal cycles (at zero force control) prior to cooling the specimen to room temperature and note the maximum and minimum strain values. The thermal strain range should not have changed but may have shifted due to gauge section changes. Prior to removing the extensometer, a room temperature strain value should be recorded and the extensometer’s position marked on the specimen. After specimen replication and its careful re-mounting, the extensometer should be placed at the markings and manually adjusted to the same strain value as when removed. Thermal cycling should then be initiated and the thermal strains should match the post shutdown strains previously recorded. Adjust the extensometer until the thermal strains are matched. Upon restart, the forces recorded prior to shut down shall be matched. Some small amount of extensometer tare may be used to aid in matching the previous force level.
8 Expression of results
8.1 Preliminary data
The elastic modulus, measured as a function of temperature, E(7) (see Annex B), may be plotted for each specimen.
The thermal strain as a function of temperature, shall be plotted and tabulated for each specimen.
8.2 Reduction of recorded data
As a minimum, plots of stress, mechanical strain, and temperature as a function of time, mechanical strain as a function of stress and temperature shall be generated for representative cycles.ISO 12111-2011 pdf free download.