ISO 17140:2013 pdf free
ISO 17140:2013 pdf free.Fine ceramics (advanced ceramics, advanced technical ceramics)
The total number of cycles is recorded. If strain is not determined, only the lifetime duration or the residual mechanical properties can be determined. If strain is determined, a number of stress-strain cycles are recorded at specified intervals to determine damage parameters, in addition to the lifetime duration and residual mechanical properties.
NOTE Residual properties can be determined on the test specimens which have not failed during the test using the methods described in the appropriate International Standards.
This International Standard enables characterization of the cyclic fatigue behaviour at constant amplitude of CMCs subjected to long duration loading. The simplest way to determine the fatigue properties of a material is to establish lifetime diagrams. In these diagrams, the time to failure (or the cyclic fatigue life) is plotted versus stress (or strain) amplitude.
The complete lifetime diagram requires the use of a great number of test specimens, which is expensive and time consuming. Hence, it is sufficient to know the cyclic-fatigue under specified stress (or strain) conditions, or to measure the fatigue limit. In any case, the typical fatigue test is defined by cyclic loading,constant amplitude, environment, temperature, and frequency.
To better characterize the mechanical behaviour during a fatigue test, it is possible to determine several mechanical parameters from stress-strain curves. These parameters can then be plotted versus time or versus number of cycles. This displays the damage evolution during the cyclic loading. The following parameters can be considered (see Figure 2):
一the residual strain at zero load;
一the secant elastic modulus, or the relative damage parameters;
一the area of the stress-strain hysteresis loop, or the internal friction;
一the maximum strain, the minimum strain, or the difference between them for a selected cycle;
一some specific tangent elastic moduli, for example, at the top or at the bottom of the stress-strain loop.ISO 17140 pdf download.
