patch test finite element????

[Leoeng82]

Hi everyone,

I am trying to do a patch test through describe the displacement which called ''The Displacement Test''. The idea to study a small area from whole the geometry and see how is working. I wonder if someone has a simple example in FEMAP about that ??? I attach a file about patch test which I got it from the internet.

 

[rb1957]

a patch test is typically a single element, and compare the results to theoretical.

eg start with a square quad, apply axial load ... should work out well
now a rectangular element ... it'll work out less well
then a trapezoid ... less well again.

then same again with bending moment applied ...
etc

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

 

[ThomasH]

Hi

Like rb1957 says, patch test is a method to test a single element and how good the element formulation is. If I remenber correct, to perform it on a mesh (several elements) is theretically possible but very impractical.

Thomas

 

[Leoeng82]

Thanks Rb1957, Your explanation gives me a good push to my knowledge. Thanks Thomas also for your answer to my question. The problem i was mixing between patch and sub-model in FEMAP. Now, I got a good explanation about patch. Have your worked with sub-model? I have an example which i try to do it and I attach a picture of that. I try to study a small rectangle in global area. I could make a layer of this small rectangle in this picture below but i dont know if that is possible to build solid and shell element from that as picture. The global rectangle consist only laminate of three ply but it will be shell element. The idea of this small rectangle to study the material between shin which gives result from solid element. I dont want to use solid element to whole the geometry because the geometry is bigger than this example which i painted in the picture. Therefore i want to study this small rectangle. Do you have an idea?