Transient initial conditions (Nastran)

Use the Transient Initial Conditions command to define separate magnitudes for displacement and velocity at each degree of freedom, to be applied at the start of a structural transient analysis. You can use this constraint with the following solution sequences:

• Simcenter Nastran solutions 109, 112, 129, 601, and 701.

• MSC Nastran solutions 109, 112, and 129.

The options in the Transient Initial Conditions dialog box correspond to the fields on the TIC bulk data entry. For more information about initial conditions, see the Simcenter Nastran Basic Nonlinear Analysis User's Guide.

Methods

You can apply an initial condition using one of these methods:

• Magnitude and direction — Lets you define a displacement and velocity magnitude in a single direction.

• Normal — Lets you define a displacement and velocity magnitude and a +/– direction normal to the selected geometry or element faces.

• Components — Lets you define the initial displacement and velocity magnitudes for each of the six degrees of freedom (DOF).

With the Magnitude and direction method, if the vector you select does not match the work coordinate system Z direction, the software creates a local displacement coordinate system with the Z axis aligned with the selected vector.

With the Normal method, if the normal direction does not match the work coordinate system Z direction, the software creates a displacement coordinate system with the Z axis aligned with the normal direction.

You can apply this type of constraint	To this geometry or FEM entity
Magnitude and direction****Component	curvepointmesh pointpolygon facepolygon edgenode
Normal	curvepointmesh pointpolygon facepolygon edgeelement

Graphical symbol

In the graphics window, the symbol that represents a transient initial condition denotes the displacement and velocity conditions for each axis.

Displacement and velocity conditions at all six DOFs

At the tip of the symbol:

• A circle indicates an initial displacement along that axis.

• A cone indicates an initial velocity along that axis.

In the middle of the symbol:

• Two circles indicate an initial displacement about that axis.

• Two cones indicate an initial velocity about that axis.

Also, the length of each axis in the symbol is scaled relative to the maximum value along or about that axis.

Where do I find it?

Application	Pre/Post
Prerequisite	A Simulation file as the work part and displayed partSimcenter Nastran or MSC Nastran as the specified solver and a supported solution active
Command Finder	Transient Initial Conditions
Simulation Navigator	Right-click Constraint Container→New Constraint→Transient Initial Conditions

Quick links

Command reference

Pre/Post video examples

Bulk Entry Descriptions

Simcenter 3D tutorials

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Transient initial conditions (Nastran), Simcenter 3D 2021.1 Series

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