Hi,

I'd like to understand how fatigue study works for simple cases like the one described below.

Let's say that I have a model with complex shape subjected to combined loading (some kind of machine part). I perform static analysis and then proceed to fatigue study selecting "Constant amplitude events with defined cycles". I define the S-N curve data for my material and add new event specifying the number of cycles, loading type (let's assume zero-based) and associate static study. How will the software calculate the number of cycles to failure with these settings ? Will it simply compare the stress intensity (difference between max and min principal stress) at each point (known from static study) with S-N curve or perform some additional operations too ?  From what I've seen in analysis options, mean stress correction is turned off by default so this factor won't be included in such analysis (even for zero-based cycle). Rainflow counting also won't apply since the amplitude is constant. Is there anything else the software calculates in a case like that ? What about the cumulative damage ? I guess that it's not used as well for constant amplitude cycles. By the way, why do we have to specify the number of cycles in even settings ? Is it needed only for damage calculations ?

Thanks in advance for your help