Simulating fatigue test with a remote displacement

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  • Last Post 07 May 2020
SamuelMechanicalEng posted this 06 May 2020

Hi, I'm going to simulate a fatigue test, which consists of applying a 10 degree movement at point C at a frequency of 1 Hz.

The model has a remote mass of 10 kg at point A, which is constant and causes inertia effects on the system.

So I'm using a transient structural study. What should I put in the remote displacement?

   -The first cycle?

            

   -Or just maximum rotation to one side (5 degrees)?

And what should I use in the fatigue tool loading type?

 

Notes: The effort is less than the yield stress, therefore many cycles are performed in the fatigue test.

This is a continuous test and it is important that the inertia effects are maintained from the end of one cycle to the beginning of another.
Thank you 

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peteroznewman posted this 06 May 2020

You have drawn a triangular displacement profile. That is not correct because at the peak, the slope changes instantaneously from a positive to a negative velocity. A step change in velocity. That creates an infinite acceleration.  That is just wrong.  You really want a sinusoidal angular profile.

What are you checking the fatigue on, the two green shafts?

SamuelMechanicalEng posted this 07 May 2020

hi, thanks for the reply.

What I want is to put a rotation at point c, applied to the shaft.

One test run cycle is turn to the left, then turn everything to the right and turn to the left again.

The first image is the angle range of the system during the test cycle.

The purpose is check the two green shafts and the blue block.

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