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Harmonic body load using non-linear static analysis

Experimenter
Experimenter

Hi everybody ,

 

I am trying to apply a rotational acceleration (body load) varying in time (using a sinusoidal function). 

image.png

I am performing a nonlinear static analysis where I've defined 100 increments to cover the distribution of the above function. What I get in terms of stress is only a linear distribution through all the 100 steps performed, reaching only the first positive maximum value of the function.

Question: 1) what can I do to get the sinusoidal variation of the stress?

2) is it possible to get this result on a nonlinear-static solution (SOL106)?

3) if yes, what analysis parameters should I pay attention to?

 

Thank you!

 

2 REPLIES

Re: Harmonic body load using non-linear static analysis

Experimenter
Experimenter

I tried but I get the same results as you.. I believe the work around for SOL 106 is (and you are not going to like it).  Break up your sinusiodal time load function into individual loads at each time step and create a subcase for each one. Each Subcase will be a load step, in which the load will be incremented in the non-linear section of the analysis manage setup (Read through the Non-Linear Material ROD example in the FEMAP help)  Sol 106 is going to divide the individual loads up in increments. So when you give it a function it seem to take the min and max load from the function and subdivided it in linear form.  It you want non-linear transient then a difference solution sequence would be required.  Remember you will need to include a unload case as the last step (something with a very small load).  I believe if you set it up right in SOL 106, each subcase will be restart for the previous subcase.  

Re: Harmonic body load using non-linear static analysis

Experimenter
Experimenter
Hi Phillipseb ,

Thanks a lot for you help!
Indeed I think that the best way to actually represent the harmonic load is
though a transient analysis.

Your solution seems to be a great compromise!

Thanks again!