1. Discretization

1.1. Degrees of freedom

For the three three-dimensional plate models, the degrees of freedom of discretization are, at each node of the support mesh, the six displacement components (three translations and three rotations) at the apex nodes of the support mesh. These nodes are supposed to describe a facet tangent to the middle layer of the shell.

Finite element

Degrees of freedom (at each vertex node)

DKT/DKQ/DKTG	DX	DX	DY	DY	DZ	DRX	DRY	DRZ
DST/DSQ	DX	DY	DY	DZ	DRX	DRY	DRZ
Q4G (Q4 \(\gamma\))/Q4GG	DX	DX	DY	DZ	DRX	DRY	DRZ

1.2. Support mesh for stiffness matrices

The support cells for finite elements, in displacement formulation, can be triangles or quadrangles. In the latter case, the cells are assumed to be plane (4 co‑planar vertex nodes):

Modeling

Mesh

Finished Element

Remarks

DKT	TRIA3 QUAD4	MEDKTR3 MEDKQU4
DKTG	TRIA3 QUAD4	MEDKTG3 MEDKQG4
DST	TRIA3 QUAD4	MEDSTR3 MEDSQU4
Q4G (Q4 \(\gamma\))	QUAD4 TRIA3	MEQ4QU4 MET3TR3
Q4GG	TRIA3 QUAD4	MET3GG3 MEQ4GG4

1.3. Cargo support mesh

All the loads applicable to the facets of the plate elements are treated by direct discretization on the support mesh of the element in displacement formulation.

No load support mesh is therefore necessary for the faces of the plate elements.

For loads applicable to the edges of the plate elements, a SEG2 type support mesh can be used:

Modeling

Mesh

Finished Element

Remarks

DKT	SEG2	MEBODKT
DST	SEG2	MEBODST
DKTG	SEG2	MEBODKT
Q4G (Q4 \(\gamma\))	SEG2	MEBOQ4G
Q4GG	SEG2	MEBOQ4G