Mesh FEM
Creare una Mesh FEM
In FreeCAD ci sono diverse possibilità per creare una Mesh FEM:
- Lo strumento Gui Crea FEM
- Lo strumento Gui di Python
- Direttamente in Python, il che significa creare la Mesh FEM a mano
- Importare una Mesh FEM
Sono supportati gli oggetti creati in Part Design e Parte, così come le copie semplici di tali corpi. Sono disponibili due mesher: Netgen e GMSH. Netgen è incluso in FreeCAD. Fare riferimento a Installare FEM. Per generare una Mesh FEM con GMSH l'utente psicofil ha fornito la Macro GMSHMesh.
("-" significa non supportato dall'interfaccia, quindi non è possibile supportarlo. )
Tipi di elementi FEM
Generale
Maggiori informazioni sui tipi di elementi FEM e la loro struttura dei dati all'interno di FreeCAD si trovano nella pagina Tipi di elementi FEM.
Segment element
Triangle element
Quadratic element
Tetrahedron element
Pyramid element
Hexahedron element
Pentahedron element
Script
Creare una Mesh FEM interamente con python
Creare una mesh con 10 nodi (Tet-10 Elements)
import FreeCAD, Fem
# create a empty mesh
m = Fem.FemMesh()
#create the nodes
m.addNode(0,1,0)
m.addNode(0,0,1)
m.addNode(1,0,0)
m.addNode(0,0,0)
m.addNode(0,0.5,0.5)
m.addNode(0.5,0.03,.5)
m.addNode(0.5,0.5,0.03)
m.addNode(0,0.5,0)
m.addNode(0.03,0,0.5)
m.addNode(0.5,0,0)
# add the volume with the created nodes
m.addVolume([1,2,3,4,5,6,7,8,9,10])
Fem.show(m)
Se si desidera avere elemento predefinito e la numerazione del nodo:
m.addNode(0.0,1.0,0.0,1)
m.addVolume([1,2,3,4,5,6,7,8,9,10],1)
Visual handling
Highlight some nodes on the view:
import FreeCAD, Fem
m = Fem.FemMesh()
m.addNode(0,1,0)
m.addNode(0,0,1)
m.addNode(1,0,0)
m.addNode(0,0,0)
m.addNode(0,0.5,0.5)
m.addNode(0.5,0.03,.5)
m.addNode(0.5,0.5,0.03)
m.addNode(0,0.5,0)
m.addNode(0.03,0,0.5)
m.addNode(0.5,0,0)
m.addVolume([1,2,3,4,5,6,7,8,9,10])
Fem.show(m)
Gui.ActiveDocument.ActiveObject.HighlightedNodes = [1,2,3]
Postprocessing colors and displacement: Highlight some nodes on the view:
# set the volume 1 to red
Gui.ActiveDocument.ActiveObject.ElementColor= {1:(1,0,0)}
# set the node 1 and 2 to a certain Color and interpolate the survace
Gui.ActiveDocument.ActiveObject.NodeColor= {1:(1,0,0),2:(1,0,0)}
# set the node 1 and 2 to a certain displacement
Gui.ActiveDocument.ActiveObject.NodeDisplacement= {1:FreeCAD.Vector(1,0,0),2:FreeCAD.Vector(1,0,0)}
# double the factor of the displacement shown
Gui.ActiveDocument.ActiveObject.animate(2.0)
Script one Element of each supported Element Type
import Fem
#################################################
# Beams
# 2 node line --> seg2 ##########################
seg2 = Fem.FemMesh()
seg2.addNode( 0, 0, 0, 1)
seg2.addNode(10, 0, 0, 2)
seg2.addEdge( 1, 2)
seg2
obj = App.ActiveDocument.addObject("Fem::FemMeshObject","seg2")
obj.FemMesh = seg2
obj.Placement.Base = (0,110,0)
obj.ViewObject.DisplayMode = "Faces, Wireframe & Nodes"
# 3 node line --> seg3 ##########################
# not implemented
#################################################
# Shells
# 3 node triangle --> tria3 #####################
tria3 = Fem.FemMesh()
tria3.addNode( 0, 0, 0, 1)
tria3.addNode( 6, 12, 0, 2)
tria3.addNode(12, 0, 0, 3)
tria3.addFace([ 1, 2, 3])
tria3
obj = App.ActiveDocument.addObject("Fem::FemMeshObject","tria3")
obj.FemMesh = tria3
obj.Placement.Base = (0,80,0)
obj.ViewObject.DisplayMode = "Faces, Wireframe & Nodes"
# 6 node triangle --> tria 6 ####################
tria6 = Fem.FemMesh()
tria6.addNode( 0, 0, 0, 1)
tria6.addNode( 6, 12, 0, 2)
tria6.addNode(12, 0, 0, 3)
tria6.addNode( 3, 6, 0, 4)
tria6.addNode( 9, 6, 0, 5)
tria6.addNode( 6, 0, 0, 6)
tria6.addFace([ 1, 2, 3, 4, 5, 6])
tria6
obj = App.ActiveDocument.addObject("Fem::FemMeshObject","tria6")
obj.FemMesh = tria6
obj.Placement.Base = (30,80,0)
obj.ViewObject.DisplayMode = "Faces, Wireframe & Nodes"
# 4 node quad --> quad4 #########################
quad4 = Fem.FemMesh()
quad4.addNode( 0, 10, 0, 1)
quad4.addNode(10, 10, 0, 2)
quad4.addNode(10, 0, 0, 3)
quad4.addNode( 0, 0, 0, 4)
# quad4.addQuad( 1, 2, 3, 4) # without brackets
# addQuad adds a Face of four nodes --> see FmMeshPyImp.cpp --> redundant with addFace !
quad4.addFace([ 1, 2, 3, 4])
quad4
obj = App.ActiveDocument.addObject("Fem::FemMeshObject","quad4")
obj.FemMesh = quad4
obj.Placement.Base = (60,80,0)
obj.ViewObject.DisplayMode = "Faces, Wireframe & Nodes"
# 8 node quad --> quad8 #########################
quad8 = Fem.FemMesh()
quad8.addNode( 0, 10, 0, 1)
quad8.addNode(10, 10, 0, 2)
quad8.addNode(10, 0, 0, 3)
quad8.addNode( 0, 0, 0, 4)
quad8.addNode( 5, 10, 0, 5)
quad8.addNode(10, 5, 0, 6)
quad8.addNode( 5, 0, 0, 7)
quad8.addNode( 0, 5, 0, 8)
quad8.addFace([ 1, 2, 3, 4, 5, 6, 7, 8])
quad8
obj = App.ActiveDocument.addObject("Fem::FemMeshObject","quad8")
obj.FemMesh = quad8
obj.Placement.Base = (90,80,0)
obj.ViewObject.DisplayMode = "Faces, Wireframe & Nodes"
#################################################
# Volumes
# 4 node tetrahedron --> tetra4 #################
tetra4 = Fem.FemMesh()
tetra4.addNode( 6, 12, 18, 1)
tetra4.addNode( 0, 0, 18, 2)
tetra4.addNode(12, 0, 18, 3)
tetra4.addNode( 6, 6, 0, 4)
tetra4.addVolume([ 1, 2, 3, 4])
tetra4
obj = App.ActiveDocument.addObject("Fem::FemMeshObject","tetra4")
obj.FemMesh = tetra4
obj.Placement.Base = (0,50,0)
obj.ViewObject.DisplayMode = "Faces, Wireframe & Nodes"
# 10 node tetrahedron --> tetra10 ###############
tetra10 = Fem.FemMesh()
tetra10.addNode( 6, 12, 18, 1)
tetra10.addNode( 0, 0, 18, 2)
tetra10.addNode(12, 0, 18, 3)
tetra10.addNode( 6, 6, 0, 4)
tetra10.addNode( 3, 6, 18, 5)
tetra10.addNode( 6, 0, 18, 6)
tetra10.addNode( 9, 6, 18, 7)
tetra10.addNode( 6, 9, 9, 8)
tetra10.addNode( 3, 3, 9, 9)
tetra10.addNode( 9, 3, 9,10)
tetra10.addVolume([1, 2, 3, 4, 5, 6, 7, 8, 9, 10])
tetra10
obj = App.ActiveDocument.addObject("Fem::FemMeshObject","tetra10")
obj.FemMesh = tetra10
obj.Placement.Base = (30,50,0)
obj.ViewObject.DisplayMode = "Faces, Wireframe & Nodes"
# 8 node Hexahedron --> hexa8 ###################
hexa8 = Fem.FemMesh()
hexa8.addNode( 0, 10, 10, 1)
hexa8.addNode( 0, 0, 10, 2)
hexa8.addNode(10, 0, 10, 3)
hexa8.addNode(10, 10, 10, 4)
hexa8.addNode( 0, 10, 0, 5)
hexa8.addNode( 0, 0, 0, 6)
hexa8.addNode(10, 0, 0, 7)
hexa8.addNode(10, 10, 0, 8)
hexa8.addVolume([1, 2, 3, 4, 5, 6, 7, 8])
hexa8
obj = App.ActiveDocument.addObject("Fem::FemMeshObject","hexa8")
obj.FemMesh = hexa8
obj.Placement.Base = (60,50,0)
obj.ViewObject.DisplayMode = "Faces, Wireframe & Nodes"
# 20 node Hexahedron --> hexa20 #################
hexa20 = Fem.FemMesh()
hexa20.addNode( 0, 10, 10, 1)
hexa20.addNode( 0, 0, 10, 2)
hexa20.addNode(10, 0, 10, 3)
hexa20.addNode(10, 10, 10, 4)
hexa20.addNode( 0, 10, 0, 5)
hexa20.addNode( 0, 0, 0, 6)
hexa20.addNode(10, 0, 0, 7)
hexa20.addNode(10, 10, 0, 8)
hexa20.addNode( 0, 5, 10, 9)
hexa20.addNode( 5, 0, 10, 10)
hexa20.addNode(10, 5, 10, 11)
hexa20.addNode( 5, 10, 10, 12)
hexa20.addNode( 0, 5, 0, 13)
hexa20.addNode( 5, 0, 0, 14)
hexa20.addNode(10, 5, 0, 15)
hexa20.addNode( 5, 10, 0, 16)
hexa20.addNode( 0, 10, 5, 17)
hexa20.addNode( 0, 0, 5, 18)
hexa20.addNode(10, 0, 5, 19)
hexa20.addNode(10, 10, 5, 20)
hexa20.addVolume([1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20])
hexa20
obj = App.ActiveDocument.addObject("Fem::FemMeshObject","hexa20")
obj.FemMesh = hexa20
obj.Placement.Base = (90,50,0)
obj.ViewObject.DisplayMode = "Faces, Wireframe & Nodes"
# 6 node pentahedron --> penta6 #################
penta6 = Fem.FemMesh()
penta6.addNode(10,10,10, 1)
penta6.addNode( 0, 0,10, 2)
penta6.addNode(20, 0,10, 3)
penta6.addNode(10,10, 0, 4)
penta6.addNode( 0, 0, 0, 5)
penta6.addNode(20, 0, 0, 6)
penta6.addVolume([1, 2, 3, 4, 5, 6])
penta6
obj = App.ActiveDocument.addObject("Fem::FemMeshObject","penta6")
obj.FemMesh = penta6
obj.Placement.Base = (0,0,0)
obj.ViewObject.DisplayMode = "Faces, Wireframe & Nodes"
# 15 node pentahedron --> penta15 ###############
penta15 = Fem.FemMesh()
penta15.addNode(10,10,10, 1)
penta15.addNode( 0, 0,10, 2)
penta15.addNode(20, 0,10, 3)
penta15.addNode(10,10, 0, 4)
penta15.addNode( 0, 0, 0, 5)
penta15.addNode(20, 0, 0, 6)
penta15.addNode( 5, 5,10, 7)
penta15.addNode(10, 0,10, 8)
penta15.addNode(15, 5,10, 9)
penta15.addNode( 5, 5, 0,10)
penta15.addNode(10, 0, 0,11)
penta15.addNode(15, 5, 0,12)
penta15.addNode(10,10, 5,13)
penta15.addNode( 0, 0, 5,14)
penta15.addNode(20, 0, 5,15)
penta15.addVolume([1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15])
penta15
obj = App.ActiveDocument.addObject("Fem::FemMeshObject","penta15")
obj.FemMesh = penta15
obj.Placement.Base = (40,0,0)
obj.ViewObject.DisplayMode = "Faces, Wireframe & Nodes"
# 5 node pyramid --> pyra5 ######################
pyra5 = Fem.FemMesh()
pyra5.addNode( 0,20, 0, 1)
pyra5.addNode(20,20, 0, 2)
pyra5.addNode(20, 0, 0, 3)
pyra5.addNode( 0, 0, 0, 4)
pyra5.addNode(10,10,10, 5)
pyra5.addVolume([1, 2, 3, 4, 5])
pyra5
obj = App.ActiveDocument.addObject("Fem::FemMeshObject","pyra5")
obj.FemMesh = pyra5
obj.Placement.Base = (80,0,0)
obj.ViewObject.DisplayMode = "Faces, Wireframe & Nodes"
# 13 node pyramid --> pyra13 ####################
pyra13 = Fem.FemMesh()
pyra13.addNode( 0,20, 0, 1)
pyra13.addNode(20,20, 0, 2)
pyra13.addNode(20, 0, 0, 3)
pyra13.addNode( 0, 0, 0, 4)
pyra13.addNode(10,10,10, 5)
pyra13.addNode(10,20, 0, 6)
pyra13.addNode(20,10, 0, 7)
pyra13.addNode(10, 0, 0, 8)
pyra13.addNode( 0,10, 0, 9)
pyra13.addNode( 5,15, 5,10)
pyra13.addNode(15,15, 5,11)
pyra13.addNode(15, 5, 5,12)
pyra13.addNode( 5, 5, 5,13)
pyra13.addVolume([1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13])
pyra13
obj = App.ActiveDocument.addObject("Fem::FemMeshObject","pyra13")
obj.FemMesh = pyra13
obj.Placement.Base = (120,0,0)
obj.ViewObject.DisplayMode = "Faces, Wireframe & Nodes"