Let's say I have the values of my material properties (e.g. UTS, Yield Strength, Young's modulus) after conducting a tensile test, and then I would proceed to conduct a fatigue test to investigate on the fatigue strength.
Hence, I wonder what stress should I start with to conduct the fatigue test?
Amir Janghorban
Hi Max Andrew Hui,
In order to find the fatigue strength you should start the test with a stress near the ultimate stress and count the cycles till the fraction, and step by step reduce the stress and repeat the test. by drawing the data (stress - number of cycles) you will find the strength when the cure is getting almost horizontal.
- High cycle fatigue strength (about 104 to 108 cycles) can be described by stress-based parameters. A load-controlled servo-hydraulic test rig is commonly used in these tests, with frequencies of around 20–50 Hz. Other sorts of machines—like resonant magnetic machines—can also be used, to achieve frequencies up to 250 Hz.
- Low-cycle fatigue (loading that typically causes failure in less than 104 cycles) is associated with localized plastic behavior in metals; thus, a strain-based parameter should be used for fatigue life prediction in metals. Testing is conducted with constant strain amplitudes typically at 0.01–5 Hz.
best regards,
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