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How to reduce oscillations in a graphic

 

Marso1
(@marso1)
Rookie
Joined: 1 year ago
Posts: 15
Topic starter  

Hi guys!

I have a question for you.

When I see the result of my simulation, the graphic of the strain rate, has a lot of ascillations.

My question is: What do I have to do in order to avoid or reduce the oscillations?

I attached my graphic to clarify better.

Thanks in advance


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Negative Volume
(@negativevolume)
Guru Admin
Joined: 3 years ago
Posts: 537
 

Hi @marso1

There are quite a few things at play with oscillations like this. Explicit vs Implicit, the type of element you are using, the element formulation, hourglass, and even the material itself can all impact this. 

Sometimes there really isn't much to do if you aren't willing to change the fundamentals of your model. In this case, you can just apply a conservative filter and report the data as so. 


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Negative Volume
(@negativevolume)
Guru Admin
Joined: 3 years ago
Posts: 537
 

You can also try running in double precision if your are using LS-Dyna


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Marso1
(@marso1)
Rookie
Joined: 1 year ago
Posts: 15
Topic starter  

Hi @negativevolume

Many thanks for your help.

My simulation  is implicit at first, then it switches to explicit.

I am using quad element with 4 nodes (first order).

 The bar is  made of steel.

I tried to intensify the mesh through the bar using  1 layer = 10mm and then 5 mm, I had a reduction, but it is not enough.

I even tried with a layer of 1 mm but the result is not what I am looking for.

I am using Hypermesh with Ls dyna interface for the Pre-Processing and LS Dyna solutor for the processing, but unfortunately i don't know how to set a double precision.

Could you help me please?

Regards


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Negative Volume
(@negativevolume)
Guru Admin
Joined: 3 years ago
Posts: 537
 

My bad @marso1 for not responding immediately. Double precision is determined through a different ls-dyna solver file which has a "_d_" instead of "_s_". 

https://www.dynasupport.com/howtos/general/double-precision


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Marso1
(@marso1)
Rookie
Joined: 1 year ago
Posts: 15
Topic starter  

Hi@negativevolume 

Do not worry!

Many thanks for your suggestion.

Regards

Marso1


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