Using YETI
Input files reference
A basic input dataset in yeti is composed of a *.inp file and a *.NB (both files have the same base name).
*.inp file is greatly inspired from Abaqus input files and *.NB contains specific data for NURBS/B-Spline representation.
Connectivity convention
Nodes order in connectivity table defines parametric directions of an element.
Defining an element
Nodes list starts at higher value of all parametric directions, then decrease along 1st parametric direction, then 2nd parametric direction and finally 3rd parametric direction. For example, with a 2nd degree solid element with following coordinates in parametric space (see figure Fig. 1):
Node # |
coord #1 |
coord #2 |
coord #3 |
|---|---|---|---|
1 |
0.0 |
0.0 |
0.0 |
2 |
0.5 |
0.0 |
0.0 |
3 |
1.0 |
0.0 |
0.0 |
4 |
0.0 |
0.5 |
0.0 |
5 |
0.5 |
0.5 |
0.0 |
6 |
1.0 |
0.5 |
0.0 |
7 |
0.0 |
1.0 |
0.0 |
8 |
0.5 |
1.0 |
0.0 |
9 |
1.0 |
1.0 |
0.0 |
10 |
0.0 |
0.0 |
0.5 |
11 |
0.5 |
0.0 |
0.5 |
12 |
1.0 |
0.0 |
0.5 |
13 |
0.0 |
0.5 |
0.5 |
14 |
0.5 |
0.5 |
0.5 |
15 |
1.0 |
0.5 |
0.5 |
16 |
0.0 |
1.0 |
0.5 |
17 |
0.5 |
1.0 |
0.5 |
18 |
1.0 |
1.0 |
0.5 |
19 |
0.0 |
0.0 |
1.0 |
20 |
0.5 |
0.0 |
1.0 |
21 |
1.0 |
0.0 |
1.0 |
22 |
0.0 |
0.5 |
1.0 |
23 |
0.5 |
0.5 |
1.0 |
24 |
1.0 |
0.5 |
1.0 |
25 |
0.0 |
1.0 |
1.0 |
26 |
0.5 |
1.0 |
1.0 |
27 |
1.0 |
1.0 |
1.0 |
Node list defining connectivity should read : 27, 26, 25, 24, 23, 22, 21, 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1
Fig. 1 Nodes numbering for a degree 2 solid element.
Defining faces
- From connectivity table and parametric direction, faces indices are defined as follows :
Face 1 : minimal value of 1st parametric direction
Face 2 : maximal value of 1st parametric direction
Face 3 : minimal value of 2nd parametric direction
Face 4 : maximal value of 2nd parametric direction
Face 5 : minimal value of 3rd parametric direction
Face 6 : maximal value of 3rd parametric direction
Loads
Constant pressure
In the *.inp file, constant pressure is identified with keys Uxy, where x is the index of the face (see Defining faces) and y specify the load direction:
0for normal load
1,2or3for load in respectively direction 1, 2 or 3
For example, a normal load of 60 per unit of surface on face 4 of elements contained in the set I1.EltToLoad is defined with :
*Dload
I1.EltToLoad, U40, 60.
Distributed pressure
For distributed pressure, a pressure value should be defined for each control point of the mesh.
In the *.inp file, distributed pressure is identified with key Ux4, where x is the index of the face (see Defining faces).
For example, a distributed pressure defined with a nodal distribution presField on face 6 of the elements contained in the set I1.EltToLoad is defined with :
*Dload
I1.EltToLoad, U64, presField
Define a nodal distribution
TO BE DONE
Elements library
Element U1
U1 is a solid element
Element U3
U3 is a Kirchhoff-Love shell element
Element U0
U0 is a mapping element
Element U30
U30 is an immersed Kirchhoff-Love shell element
Property #2 is the ID of the corresponding mapping patch
Property #3 is the shell thickness
Element U00
U00 is an interface element for couling 2 domains
Property #2 is the ID of the domain
Property #3 is the ID of the Lagrange multiplier
Property #4 indicate if the corresponding domain is master
Element U4
- U4 is a Lagrange multiplier
Property #2 indicates if it concerns displacement DOF (0) or totation DOF (1)