I am new to Abaqus and experience some difficulties with performing a high cycle fatigue analysis on a stent strut. We would like to apply an internal displacement caused by the pulsation of the blood. We've tried to implement this by creating a uniform boundary condition, with periodic amplitude. However, we don't know how to proceed with Edit Amplitude window.
Dear Maureen,
the magnitude of your boundary condition will be multiplied by the amplitude that you prescribe. In the windows, you have to set, at a specific time step, what is the value of the amplitude. You can create periodic amplitude, or general amplitude.
If, for example, you want to simulate a cyclic loading on a bar in a static step you can apply a displacement at the end of the bar of the maximum amplitude that you want to consider (for example, 0.02 if your bar has length equal to 1 and you want to consider cycles with maximum strain equal to 0.02). Then, you have to create the amplitude. For example, if your time step is equal to 1 (the default), and you want to consider four loading traction-compression cycles, you will have something similar to
Time Amp
0 0
0.25 1
0.5 -1
0.75 1
1 .-1
This table means that, at the time step 0.25, your BC magnitude will be multiplied for 1.
Note that, you have to prescribe in the BC windows, you that your loading follows you Amplitude.
Moreover, in the step module, you have to prescribe a "small" initial increment, something like 0.01. In a different case, ABAQUS will try to solve your problem directly for a time step equal to 1.
I hope this will help you.
Andrea
Dear Maureen
Suggest, you split the load case after stent expansion and recoil state with residual stress and strain state.
Apply in one load case systolic pressure in load case and in another apply distolic pressure... Now with both the load cases you would be in a position to find alternating stress component... Comparing this with endurance limits, you should be in a position to arrive at Fatigue Factor of Safety..
Regards
LR
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