ICROTATE
ICROTATE, NODE,
OMEGA, X1,
Y1, Z1,
X2, Y2,
Z2, Vx,
Vy, Vz,
ACCEL
Specifies initial velocity at nodes as a sum of rotation about an axis and
translation.
-
NODE Node at which the initial velocity is to be specified. If ALL, apply to all selected nodes (NSEL). A component name may be input for
NODE.-
OMEGA Scalar rotational velocity about the rotational axis.
-
X1,Y1,Z1 Coordinates (in the global Cartesian coordinate system) of the beginning point of the rotational axis vector.
-
X2,Y2,Z2 Coordinates (in the global Cartesian coordinate system) of the end point of the rotational axis vector.
-
Vx Initial translational velocity in direction x of the nodal coordinate system.
-
Vy Initial translational velocity in direction y of the nodal coordinate system.
-
Vz Initial translational velocity in direction z of the nodal coordinate system.
-
ACCEL Key to initialize acceleration due to centrifugal effects:
(blank)
—
Do not initialize acceleration (default).
CENT
—
Initialize acceleration due to centrifugal effects along with the initial velocity.
Notes
The ICROTATE command specifies initial velocity for all translational degrees of freedom of the specified nodes. The velocity value is a combination of velocity due to rotation about an axis and translation. The velocity at the node is calculated as:
where
v
N
=
velocity of node N in the nodal coordinate
system |
vtrans = translational velocity
input as [Vx, Vy, Vz] |
ω = scalar angular velocity input as OMEGA
|
x1 and x2 denote the coordinates of points prescribing the beginning [X1, Y1, Z1] and end [X2, Y2, Z2] of the rotation axis |
x
N
denotes
the coordinates of node N
|
All coordinates are input in the global Cartesian coordinate system, and the velocity due to rotation is then converted to the nodal coordinate system and added to the prescribed translation.
If ACCEL = CENT is specified,
acceleration due to centrifugal effects is initialized as well. The acceleration at node
aN is initialized as:
The ICROTATE command is valid only for static analysis and full method transient analysis (TIMINT,ON with TRNOPT,FULL). The initial value is specified at the beginning of the first load step; that is, at time = 0.0.
The command calculates the nodal velocities and saves them in the database as if the IC command had been used to calculate these velocities. Thus, when the Jobname.cdb or Jobname.db file is written, the velocities prescribed by the ICROTATE command appear as IC commands. All assumptions, recommendations, and restrictions for the IC command are also true for the ICROTATE command.
This command is also valid in PREP7.