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This command is used to construct a standard four-node tetrahedron element objec with one-point Gauss integration.

element FourNodeTetrahedron $eleTag $node1 $node2 $node3 $node4 $matTag <$b1 $b2 $b3>

$eleTag unique element object tag
$node1 $node2

$node3 $node4

four nodes defining element boundaries, input order is shown in the figure.
$matTag tag of nDMaterial
'$b1 $b2 $b3 body forces in global x,y,z directions

Because sometimes bricks will give you headaches! Use this if you don't care much about the stress/strain fields (tets are notoriously bad). Otherwise, you can use the 10-node quadratic tetrahedron (in development).


  1. The valid queries to a FourNodeTetrahedron element when creating an ElementRecorder object are 'forces', 'stresses,' ('strains' version > 2.2.0) 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.
  2. This element can only be defined in -ndm 3 -ndf 3



Carlos Felipa's AFEM Course: Chapter 9 The Linear Tetrahedron.

Code Developed by José A. Abell at Universidad de los Andes, Chile