Nastran reference manual : Concentrated Mass Element


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Defines a concentrated mass at a node of the structural model.
There are two different ways the condition information can be introduced:
-CONM1: Properties of the concentrated mass have to be introduced using a symmetric mass matrix. This format gives total control to the user to perform the properties of the element.
-CONM2: For a less general means of defining concentrated mass at nodes. See the following statements descriptions:
- Mass Value : Real
-Offset distances : (X1, X2, X3) Offset distances for the mass in the global coordinate system (Real).
Ii j : Mass moments of inertia measured at the mass center of gravity in global coordinate system.
Remarks
The form of the inertia matrix about its center of gravity (c.g.) is taken as: