1. Discretization

1.1. Degrees of freedom

The degrees of freedom of discretization are, at each node of the support mesh, the two components of translational displacement and rotation.

+——————–+——————————————–+–+—++++ |**Finished element**|**Degrees of freedom (at each vertex node)** | +--------------------+--------------------------------------------+--+---++++ |2D_ DIS_T |DX |DY| |||| +——————–+——————————————–+–+—++++ |2D_ DIS_TR |DX |DY|DRZ|||| +——————–+——————————————–+–+—++++

1.2. Support mesh for stiffness matrices

The support cells for discrete elements, in displacement formulation, are segments with two nodes SEG2 or point cells POI1 combined with one node:

Modeling	Mesh	Finished Element	Remarks
2D_ DIS_T	POI1	MECA_2D_DIS_T_N
	SEG2	MECA_2D_DIS_T_L
2D_ DIS_TR	POI1	MECA_2D_DIS_TR_N
	SEG2	MECA_2D_DIS_TR_L

For POI1 cells, the internal forces are calculated from the differences in the degrees of freedom of the cell with the fixed coordinate system (as if this discrete node were attached to a fixed coordinate system).

For mesh SEG2, the efforts are calculated from the differences in the degrees of freedom carried by each of the 2 knots.