Get info from a FemMesh object

[johnwang]

Hi,

Try to use this code to get info of a FemMesh obj. Nodes is good. Edges only have edge num, but no edge node number. Where is it stored? or it is not stored?

Code: Select all

import Fem
femmesh = Fem.FemMesh()

femmesh.addNode(0, 0, 0, 1)
femmesh.addNode(1, 0, 0, 2)
femmesh.addNode(0.5, 1, 0, 3)

femmesh.addEdge([1,2], 1)
femmesh.addEdge([2,3], 2)
femmesh.addEdge([3,1], 3)

Fem.show(femmesh)

print (femmesh.Nodes)
print (femmesh.Edges)

Result

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{1: Vector (0.0, 0.0, 0.0), 2: Vector (1.0, 0.0, 0.0), 3: Vector (0.5, 1.0, 0.0)}
(1, 2, 3)

Regards,

John

[wmayer]

Code: Select all

femmesh.getElementNodes(1) # (1, 2)
femmesh.getElementNodes(2) # (2, 3)
femmesh.getElementNodes(3) # (3, 1)

[johnwang]

femmesh.getElementNodes(1) # (1, 2)

Interesting. Edge and Face all called element in FemMesh.

Thank you very much.

[bernd]

femmesh.getElementNodes(1) # (1, 2)

Interesting. Edge and Face all called element in FemMesh.

and Volumes too.

[johnwang]

and Volumes too.

Is there Element Type? I use the node length of a FemMesh element to decide how to add a Face. If 2d & 3d mixed, maybe there is problem.

Code: Select all

import Fem

femmeshOrg = Fem.FemMesh()
femmeshOrg.addNode(0, 0, 0, 1)
femmeshOrg.addNode(1, 0, 0, 2)
femmeshOrg.addNode(0.5, 1, 0, 3)
femmeshOrg.addFace([1,2,3])
#Fem.show(femmeshOrg)

nodes=femmeshOrg.Nodes
faces=femmeshOrg.Faces

femmeshNew = Fem.FemMesh()
for id in range(len(nodes)):
	femmeshNew.addNode(nodes[id+1].x,nodes[id+1].y,nodes[id+1].z,id+1)

for id in range(len(faces)):
	nd=femmeshOrg.getElementNodes(id+1)
	#femmesh.addFace([nd])
	nlen=len(nd)
	if nlen==3:
		femmeshNew.addFace([nd[0],nd[1],nd[2]])
	elif nlen==4:
		femmeshNew.addFace([nd[0],nd[1],nd[2],nd[3]])

Fem.show(femmeshNew)

vol.jpg (21.96 KiB) Viewed 1173 times

[bernd]

ATM no there is no problem. All edge elemnts have different node lengths, all face elements have different node lengths and all volume elements have different node lengths.

But mainly you are right. If there where some elements with same node length we would be in trouble.


https://github.com/berndhahnebach/FreeC ... p.cpp#L277
https://github.com/berndhahnebach/FreeC ... p.cpp#L367
https://github.com/berndhahnebach/FreeC ... p.cpp#L500

FEM_Mesh

[wmayer]

Is there Element Type? I use the node length of a FemMesh element to decide how to add a Face. If 2d & 3d mixed, maybe there is problem.

To figure out of what type an element is use the method getElementType(Id). It returns a string like, "Node", "Edge", "Face", "Volume", "0DElement" or "Ball".

Unless it's intended your code has some flaws because you won't copy over all nodes. The Nodes attribute already returns a dict with Id+Vector and can be easily copied with:

Code: Select all

for i in femmesh.Nodes.items():
    femmeshNew.addNode(*i[1], i[0])

Then when adding the faces there is no need to explicitly check for the number of nodes. Just use the * operator and you are done:

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for id in faces:
    nd = femmesh.getElementNodes(id)
    femmeshNew.addFace([*nd])

Full example:

Code: Select all

import Fem
femmesh = Fem.FemMesh()

femmesh.addNode(0, 0, 0, 1)
femmesh.addNode(2, 0, 0, 2)
femmesh.addNode(2, 2, 0, 3)
femmesh.addNode(0, 2, 0, 4)
femmesh.addNode(1, 1, 1, 5)

femmesh.addEdge([1,2], 1)
femmesh.addEdge([2,3], 2)
femmesh.addEdge([3,4], 3)
femmesh.addEdge([4,1], 4)

femmesh.addEdge([1,5], 5)
femmesh.addEdge([2,5], 6)
femmesh.addEdge([3,5], 7)
femmesh.addEdge([4,5], 8)

femmesh.addFace([1,4,3,2], 9)
femmesh.addFace([1,2,5], 10)
femmesh.addFace([2,3,5], 11)
femmesh.addFace([3,4,5], 12)
femmesh.addFace([4,1,5], 13)

Fem.show(femmesh)

nodes = femmesh.Nodes
faces = femmesh.Faces

femmeshNew = Fem.FemMesh()
for i in femmesh.Nodes.items():
    femmeshNew.addNode(*i[1], i[0])

for id in faces:
    nd = femmesh.getElementNodes(id)
    femmeshNew.addFace([*nd])

Fem.show(femmeshNew)

[johnwang]

Then when adding the faces there is no need to explicitly check for the number of nodes. Just use the * operator and you are done:

Code: Select all

for id in faces:
    nd = femmesh.getElementNodes(id)
    femmeshNew.addFace([*nd])

I thought of this, but haven't figured it out. So I comment this line out.

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#femmesh.addFace([nd])

Yeah, I need that * operator.

Thank you very much again.