ShellMITC4

This command is used to construct a ShellMITC4 element, which uses a bilinear isoparametric formulation in combination with a modified shear interpolation to improve thin-plate bending performance. The element is named for the Mixed-Interpolated Tensorial Components formulation (see references below).

element ShellMITC4 $eleTag $iNode $jNode $kNode $lNode $secTag

`eleTag`	unique element object tag
`iNode jNode kNode lNode`	four nodes defining element boundaries, input in counter-clockwise order around the element.
`secTag`	tag associated with previously-defined SectionForceDeformation object. Currently must be either a PlateFiberSection, or ElasticMembranePlateSection

Notes:

The valid queries to a Quad element when creating an ElementRecorder object are ‘forces’, ‘stresses,’ and
```
 material $matNum matArg1 matArg2 ...
```
Where $matNum refers to the material object at the integration point corresponding to the node numbers in the isoparametric domain.
This is a 3D element with 6 dofs and CAN NOT be used in 2D domain.

Examples

set t 100.0 
model basic -ndm 3 -ndf 6 
nDMaterial ElasticIsotropic 1 200000 0.3 
nDMaterial PlateFiber 4 1 
set secArgs "7"
section PlateFiber $secArgs 4 $t 
set EleType ShellMITC4 
block2D $n1 $n2 1 1 $EleType $secArgs {
  1  0.0   0.0   0.0 
  2  0.0    10   0.0 
  3 1000    10   0.0 
  4 1000   0.0   0.0 
}

References

Dvorkin, E.N. and Bathe, K. (1984), “A continuum mechanics based four‐node shell element for general non‐linear analysis”, Engineering Computations, Vol. 1 No. 1, pp. 77-88. https://doi.org/10.1108/eb023562

Original implementation by: Ed “C++” Love

Reimplementation by: Leopoldo Tesser, Diego A. Talledo, Véronique Le Corvec