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mdowns8357
Posts: 10
Registered: ‎04-02-2013

Using Symmetry Planes for Analysis?

214 Views, 1 Replies
08-05-2013 08:39 AM

Hi all,

 

I'd like to speed up my simulations, and I'm wondering if I can use symmetry since my model is symmetric about two axes. Attached is a birds eye view sketch of what I'm trying to model. It is just two spaced out joists connected  to a header with the use of a steel connector. All parts are cold formed steel. My question is, I'm aware that Simulation Mechanical allows you to apply symmetry to an axis if you select a face of an individual part, but does it allow you to apply symmetry to a model about a plane? For example, if I took the CAD model of my setup and cut away the two symmetrical sides so that i"m left with a fourth of the original model, can I apply symmetry to the entire assembly about these two mirror planes? It seems like I should be able to but I havent figured it out yet....

 

Thanks,

M

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*Expert Elite*
AstroJohnPE
Posts: 575
Registered: ‎08-30-2012

Re: Using Symmetry Planes for Analysis?

08-06-2013 01:35 PM in reply to: mdowns8357

You can use symmetry in a static stress analysis and heat transfer analysis, and some fluid analyses. You should not use symmetry in a dynamic analysis (transient stress, modal analysis, impact analysis) unless you are absolutely positive that the symmetry will not filter out some of the frequencies. In other words, vibration modes of a model are usually not all symmetric. The first mode may be symmetric, but the second mode may not be symmetric.

 

In regards to your second question, is there a difference between applying symmetry boundary conditions to N planar surfaces on M different part compared to applying it to a plane? The only difference I see is how many items need to be selected -- which should not stop you from making a symmetry model (in my opinion).

 

John Holtz, PE
Mechanical Engineer
Pittsburgh, PA

Simulation Mechanical user since Dec 1997
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