FEM Modeling > Patran Element Library > Tria Element Topology
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Tria Element Topology
Patran contains six different triangular element topologies: Tria3, Tria4, Tria6, Tria7, Tria9, Tria13.
General Shape
For Tri elements, area coordinates [L1/L2/L3] are commonly used. See Area coordinate system for
more information.
Tri elements can be obtained by degenerating a Quad element.
1. Quad corner node 2 collapses onto 1.
2. Tri corner nodes 1/2/3 match 1/3/4 for the Quad.
General Data
Shape = Triangular
Element dimensionality= 2
Number of corner nodes = 3
Number of edges = 3
Number of faces = 1
Number of face edges = 3
Table 15‑7
Face ID
Sense
Edge 1
Edge 2
Edge 3
1
1
1
2
3
Specific Data ‑ Tria3
Element name = Tria3
Number of nodes = 3
Order = linear
Degenerate element name = <none>
 
Table 15‑8
Edge Number
Node 1
Node 2
1
1
2
2
2
3
3
3
1
Table 15‑9
Node Number
Xi/Eta or L2/L3
1
0.0, 0.0
2
1.0, 0.0,0.0
3
0.0, 1.0
To obtain a Tri3 by degenerating a Quad4, the following are corresponding nodes
Tri3
Quad4
1
1
2
3
3
4
For more information, see Tri3.
Specific Data ‑ Tria4
Element name = Tria4
Number of nodes = 4
Order = linear
Degenerate element name = <none>
Table 15‑10
Edge Number
Node 1
Node 2
1
1
2
2
2
3
3
3
1
Table 15‑11
Node Number
Xi/Eta or L2/L3
1
0.0, 0.0
2
1.0, 0.0
3
0.0, 1.0
4
1/3, 1/3
To obtain a Tri4 by degenerating a Quad5, the following are corresponding nodes:
 
Tri4
Quad5
1
1
2
3
3
4
4
5
For more information, see Tri4.
Specific Data ‑ Tria6
Element name = Tria6
Number of nodes = 6
Order = Quadratic
Degenerate element name = <none>
Table 15‑12
Edge Number
Node 1
Node 2
Node 3
1
1
4
2
2
2
5
3
3
3
6
1
Table 15‑13
Node Number
Xi/Eta or L2/L3
1
0.0, 0.0
2
1.0, 0.0
3
0.0, 1.0
4
0.5, 0.0
5
0.5, 0.5
6
0.0, 0.5
To obtain a Tri6 by degenerating a Quad8, the following are corresponding nodes:
Tri6
Quad8
1
1
2
3
3
4
4
6
5
7
6
8
For more information, see Tri6.
Specific Data ‑ Tria7
Element name = Tria7
Number of nodes = 7
Order = Quadratic
Degenerate element name = <none>
Table 15‑14
Edge Number
Node 1
Node 2
Node 3
1
1
4
2
2
2
5
3
3
3
6
1
 
Table 15‑15
Node Number
Xi/Eta or L2/L3
1
0.0, 0.0
2
1.0, 0.0
3
0.0, 1.0
4
0.5, 0.0
5
0.5, 0.5
6
0.0, 0.5
7
1/3, 1/3
To obtain a Tri7 by degenerating a Quad9, the following are corresponding nodes:
Tri7
Quad9
1
1
2
3
3
4
4
6
5
7
6
8
7
9
For more information, see Tri7.
Specific Data ‑ Tria9
Element name = Tria9
Number of nodes = 9
Order = Cubic
Degenerate element name = <none>
 
Table 15‑16
Edge Number
Node 1
Node 2
Node 3
Node 4
1
1
4
5
2
2
2
6
7
3
3
3
8
9
1
 
Table 15‑17
Node Number
Xi/Eta or L2/L3
1
0.0, 0.0
2
1.0, 0.0
3
0.0, 1.0
4
1/3, 0.0
5
2/3, 0.0
6
1/3, 2/3
7
1/3, 2/3
8
0.0, 2/3
9
0.0, 1/3
To obtain a Tri9 by degenerating a Quad12, the following are corresponding nodes:
 
Tri9
Quad12
1
1
2
3
3
4
4
7
5
8
6
9
7
10
8
11
9
12
For more information, see Tri9.
Specific Data ‑ Tria13
Element name = Tria13
Number of nodes = 13
Order = Cubic
Degenerate element name = <none>
 
Table 15‑18
Edge Number
Node 1
Node 2
Node 3
Node 4
1
1
4
5
2
2
2
6
7
3
3
3
8
9
1
 
Table 15‑19
Node Number
Xi/Eta or L2/L3
1
0.0, 0.0
2
1.0, 0.0
3
0.0, 1.0
4
1/3, 0.0
5
2/3, 0.0
6
2/3, 1/3
7
1/3, 2/3
8
0.0, 2/3
9
0.0, 1/3
10
2/9, 1/9
11
4/9, 2/9
12
2/9, 4/9
13
1/9, 2/9
To obtain a Tri13 by degenerating a Quad16, the following are corresponding nodes:
 
Tri13
Quad16
1
1
2
3
3
4
4
7
5
8
6
9
7
10
8
11
9
12
10
14
11
15
12
16
13
13
For more information, see Tri13.