Nastran-Interface manual


Advanced conditions

This section describes special conditions that can be used in dynamic and static analysis.

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).

Iij: 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:


Output sets

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Allows create sets of points, lines or surfaces. These sets are used to configure output file of NASTRAN. NASTRAN's output file only contains output requests for elements or nodes of these sets. To use this condition, the user has to select which kind of request (see table below) should be associated with the set and after click over geometry elements included in the set.

In case that no output set is defined, the output requests will be printed for all elements and nodes.

This condition is used when only part of the model is of interest and not all results in every element or node have to be printed. The necessary time for running the model can be significantly reduced using this condition.

Table of outputs

Abbreviation

Definition

Entities

Mesh

Displacement

Requests the displacements for a selected set of PHYSICAL points

Points

Nodes

SpcForces

Requests the single-point forces of constraint at a set of points

Points

Nodes

Acceleration

Requests the accelerations for a selected set of PHYSICAL points

Points

Nodes

Velocity

Requests the velocities for a selected set of PHYSICAL points

Points

Nodes

Load

Selects a set of applied loads for output

Points

Nodes

ESE

Requests structural element strain energies

Lines and Surfaces

1-D and 2-D elements.

Forces

Requests the forces in a set of structural elements

Lines and Surfaces

1-D and 2-D elements.

Strain

Requests the strains/curvatures in a set of structural elements (applicable to TRIA1, TRIA2, QUAD1, and QUAD2 only).

Lines and Surfaces

1-D and 2-D elements.

Stress

Requests the stresses in a set of structural elements

Lines and Surfaces

1-D and 2-D elements.