/INIVEL/AXIS

Block Format Keyword Initialize both translational and rotational velocities on a group of nodes in a given coordinate system.

Format

Field	Contents	SI Unit Example
`inivel_ID`	Initial velocity block identifier. (Integer, maximum 10 digits)
`unit_ID`	Unit Identifier. (Integer, maximum 10 digits)
`inivel_axis_title`	Initial velocity block title. (Character, maximum 100 characters)
`Dir`	Direction X, Y, and Z of the frame defining the rotation axis. (Text)
`frame_ID`	Frame identifier. `frame_ID` is obligatory input. If not given, the initial velocities are applied with respect to the global coordinate system. (Integer)
`grnd_ID`	Node group on which specified initial velocities are applied. (Integer)
`Vx`^t	X component in the local frame of the translational velocity. (Real)	$[\frac{m}{s}]$ $[\frac{m}{s}]$
`Vy`^t	Y component in the local frame of the translational velocity. (Real)	$[\frac{m}{s}]$ $[\frac{m}{s}]$
`Vz`^t	Z component in the local frame of the translational velocity. (Real)	$[\frac{m}{s}]$ $[\frac{m}{s}]$
`V`^r	Rotational velocity about the rotational axis. (Real)	$[\frac{rad}{s}]$ $[\frac{rad}{s}]$

The keyword defines initial rigid body type of motion (translational and rotational) of a group of nodes (for example, initial velocity for rollover simulation of a vehicle).
The initial nodal velocity is calculated as:(1)
$v (M) = V^{t} + V^{r} \frac{U}{‖ U ‖} \land O M$ $v (M) = V^{t} + V^{r} \frac{U}{‖ U ‖} \land O M$

Where,

$U$ $U$

Vector defining the rotation axis.

$O$ $O$

Center of the local coordinate system

$M$ $M$

Nodal point

$V^{r}$ $V^{r}$

Rotation velocity

$V^{t}$ $V^{t}$

Vector of translational velocity
This option cannot be used when /INIVEL/TRA or /INIVEL/ROT is applied on the same node.