I have read many things about this, but could not find any tutorial on fatigue simulation for example fatigue simulation of round specimen (dog bone) under constant amplitude loading, and need to get stress-life curve.
n the Abaqus you need to choose the "Direct cyclic" method as step definition and there are some parameters related to fatigue which you should give to define the step. as you know in the fatigue analysis you have different loading and you just need to go to amplitude tab and double click to give and amplitude as function or tabular. read the Abaqus analysis user manual for more information. there is an extensive explanation with examples over there.
All what you need is to apply prescribed displacement amplitudes to represent your loading history instead of applying loads. You need to determine the displacement from elastic methods which are easy to calculate like d=PL/EA.