8-node brick element load vector

[peto24ap]

Hi friends,

I am trying to calculate 8-node brick element load vecotr. Top face consist from points 1-2-3-4, bottom face from points 5-6-7-8.
When I am calculating self weight (body forces) I am using 8-node brick shape functions (8 shape functions).

When I have a surface load perpendicular to face 1-2-3-4, do I use 4-node plane sheet shape functions ? (4 shape functions) Result of surface load on face 1-2-3-4 are only nodal fprces in nodes 1,2,3, and 4?
How about traction on the 1-2 edge of brick element, do I use only 2-node link element shape functions (2 shape functions)?

Or do I always have to use 8 shape functions for brick element for any type of forces (body, surface, or edge traction)?

How can I solve the problem on the attached picture ?

Thank you for your suggestions!

 

[rb1957]

is this a professional (or a student) post ?

another day in paradise, or is paradise one day closer ?

 

[peto24ap]

Professional structural engineer, but new to FEA (self-learning)..

 

[stressebookllc]

I am not sure why you are bothering with shape functions etc. If I were you, I'd focus on modeling the structure first using an appropriate element type.

If you are using a reputable FEA program they have all been through a lot of bench marking of all their element types against NAFEMS standards.

If you have a column or a beam or a plate or a potato type structure use the appropriate element type and get going with the loads and constraints. Then try to verify the results..

Shape functions etc. are all grad school or PhD topics. Unless you want to go into research I'd say focus on the application.

Again just my personal opinion..

http://www.stressebook.com

Stressing Stresslessly!

 

[peto24ap]

Thank you for your opinion,
I also often do it like this - I analyse my problem in ceftified FEA soft, and then tune my theory. But this time I cant move from a place, no matter the results So I am looking for somebody experienced to discuss my problem.

But still - thank you.