Closed rubsy92 closed 4 years ago
The TriangleElement
is going to replace with other elements like CST and DKT. and cst and dkt are going to transfer to DktHelper
and CstHelper
, but not complete yet. So i suggest to work on those codes, my next descriptions are about TriangleElement
and DktHelper
and CstHelper
, not DktElement
and CstElement
etc. DktElement
and CstElement
are going to be deprecated, so please work with TriangleElement
, DktHelper
and CstHelper
.
There are two types of tensor
BriefFiniteElementNet.CauchyStressTensor
.BriefFiniteElementNet.BendingStressTensor
.
image from here:
https://www.scielo.br/scielo.php?script=sci_arttext&pid=S1679-78252014000900010#fig1
Bending behavior (DktHelper) only will change BendingStressTensor
, while membrane behavior (MembraneHelper) only will change CauchyStressTensor
.
As you said, the Cauchy tensor result from triangle element seems to be right, but Bending have incorrect values, i've seen this before and i think you are right. The bending is calculated from standard FEM formula, D.B.U
where D
is matrix compliance matrix (material), B
is matrix calculate from element (derivatives of shape functions) and U
is local displacement vector. If there is problem with bending tensor values, then the corresponding method is DktHelper.GetLocalInternalForceAt()
that should be fixed.
About contributing, can you please make it a pull request?
Hi, I have been watching this repository for some time now and there are some interesting developments going on right now! I am planning on giving it a more up-close look and making some contributions depending on where I can help. For now I want to test and validate the shell elements since the quadrilateral one is being added as we speak. I started off with the TriangleFlatShell-element and the results of the membrane-element seem correct (both translations as stresses). The stresses are however not correct in the bending element, while the displacements are the same as in my validation package. I expect to get some values near 20 MPa, however I only get some kPa… Do you have any idea where the problem may lie?
Also: suppose you have both the bending and the membrane behavior and you would like to get the stress in the element. Based on the “GetInternalForce” method I get a stress from both elements types (GetInternalForce.BendingTensor and GetInternalForce. MembraneTensor). How do I combine these in a single Cauchystresstensor?
I’ve made a small addition to the CauchyStressTensor to get the principal stresses, but I can’t push it to the main branch (probably because I don’t have the correct rights/I cloned it immediately in Visual studio?). How should I clone it to be able to push code back?
PS: Good work so far!