Finite element loads calculation

[nastranuser123]

Hello,

I shall be grateful if someone can chelp me with this and I'm really desperate for the solution!

As of now, I have written a finite element program for the analysis of plates.

In the pre-processor, I have applied the loads at the nodes of the finite element (or) at the edges of the finite element.

All this works perfectly fine.

However, now, instead of applting loads at the nodes of the finite element or the edges of the finite eleement, I would like to apply the loads on the edges of the polygon (OR) on the face of the polygon and then find tarnsfer the loads onto the element edges and/or nodes.

Can anyone help if there is some procedure to do this. Any help will be gratefully appreciated

 

[GregLocock]

I wonder if a free body diagram would help?

Cheers

Greg Locock


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[bkal]

I would just use a standard aproximation used to develop all the system matrices. In case of loads, this means integrating a product of the shape function (displacement interpolation function) matrix with the applied load vector over the element volume / surface.

I am not sure that the free body diagram would work OK for 8-noded elements (if that is what you are using) as equivalent nodal forces could be counter-intuitive. It could work fine for 4-noded elements, I think.

I think that you should try to align your elements with the applied loads, otherwise I am not sure how can you account fro approximation errors.

(I have not done FE programming for ages, so please take above with a pinch of salt).

 

[nastranuser123]

Hi bkal,

Thanks. Yes, I understand that by integrating a product of the shape function (displacement interpolation function) matrix with the applied load vector over the element volume / surface we can get the nodal loads.

I just wanted to know, when the user defines a face load (on the face of the geometry/polygon), how will I get a list of elements that cover the geomery face?

IS that soemthing to eb conveyed by the mesh generator?

Thanks again.

 

[nastranuser123]

Please can anyone help if possible?

 

[bkal]

I would say this is more of an issue regarding your pre-processor / mesh generator rahter than the FE program.