====== PLANI ======

===== Description =====

Plane membrane. \\
The element is defined by 4 nodes.\\
{{  :elements:plani.png?300|}} \\
Element type: 5 \\
Implemented by: I. Bertarini (1986)

==== Files ====
Prepro: PLANIA.F \\
Lagamine: PLANIB.F

===== Input file =====

^Title (A5)^^
|TITLE|"PLANI" in columns 1 to 5|
^ Control data (2I5, 2G10.0) ^^
|NELEM| Number of elements |
|MDIRW| Gravity direction: \\ 0 → No gravity \\ ± 1 → Gravity in the X direction \\ ± 2 → Gravity in the Y direction \\ ± 3 → Gravity in the Z direction|
|SPEWG|Volumic weight|
|SPEMA|Volumic mass|
^Definition of the elements (I5, G10.0, I5/4I5) ^^
|LMATE| Material |
|PRESO|Uniform stress|
|MDIRL|Direction of the stress \\ 0 → No stress \\ ± 1 → Stress in the X direction \\ ± 2 → Stress in the Y direction \\ ± 3 → Stress in the Z direction|
|NODES(4)| List of nodes|

===== Results =====
The mechanical Cauchy stresses are ordered as: $\sigma_x, \sigma_y, \tau_{xy}, \sigma_z$. These stresses are expressed in the local axis system: \\ X ⁄⁄ ξ (isoparametric axis) \\ Y ⊥ X in the plane of PLANI \\ Z ⊥ (X,Y)