mass1,mass2
Purpose
Concentrated mass elements.
Description
mass1 places a diagonal concentrated mass and inertia at one node.
In a model description matrix, element property rows for mass1 elements follow the format
[NodeID mxx myy mzz ixx iyy izz EltID]
where the concentrated nodal mass associated to the DOFs .01 to .06 of the indicated node is given by
diag([mxx myy mzz ixx iyy izz])
Note feutil GetDof eliminates DOFs where the inertia is zero. You should thus use a small but non zero mass to force the use of all six DOFs.
For mass2 elements, the element property rows follow the format
[n1 M I11 I21 I22 I31 I32 I33 EltID CID X1 X2 X3 MatId ProId]
which, for no offset, corresponds to matrices given by
|
[ |
| M |
|
|
symmetric |
|
|
| |
M |
| |
|
M |
| |
|
|
I11 |
| |
|
|
-I21 |
I22 |
| |
|
|
-I31 |
-I32 |
I33 |
|
]=[ |
ó
õ dV |
|
|
symmetric |
|
|
| |
M |
| |
|
M |
| |
|
|
ó
õ (x2+y2)dV |
| |
|
|
-I21 |
I22 |
| |
|
|
-I31 |
-I32 |
I33 |
|
]
|
Note that local coordinates CID are not currently supported by mass2 elements.
See also
femesh, feplot
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