**centrifugal

Description

The centrifugal boundary condition is used to apply body forces \(\rho \omega^2 r\) to a defined set of elements (elset) due to rotational acceleration, with \(\rho\) the volumetric mass, \(\omega\) the rotational rate and \(r\) the distance to the rotational axis.

Syntax

**centrifugal [updated] [square] \(~\,~\,\) elset_name (v) dir value  table …  [ tableN ]

elset_name

Character name for the set of elements which are subjected to the centrifugal loading.

updated

Uses the current configuration rather than the initial configuration for determining the distance \(r\) to the rotational axis as well as the direction of the centrifugal force.

square

Applies a force proportional to the rotational rate \(\omega\) instead of \(\omega^2\).

v

Vector giving a point position through which the rotational axis passes. Axisymmetric problems require that the origin is input as (0.0 0.0).

dir

Direction of the rotational axis (d1, d2, or d3). Axisymmetric 2D problems are required to use the d2 axis direction. Planar 2D geometries require that the axis is d3.

value

Base value (real) which scales a table value to determine the applied rotational rate \(\omega\).

table

Character name for a valid loading table or tables which, after multiplication with value, will describe the time evolution of the rotational rate.

To apply a centrifugal force, it is required to give the volumetric mass \(\rho\) for the material in the material file. This is specified with the ***coefficient command.

Units required depend of course on the consistency of units within the problem. For example, if the dimensional unit is millimeter, the forces are given in Newton, and the rotational rate \(\omega\) is in radians per second, the volumetric mass must be in tons (metric)/mm\(^{3}\).

Example

**centrifugal
   str (0.0 0.0) d2 1.e7 tab1