**impose_nodal_dof_rate

Description

This boundary condition imposes degrees of freedom located at nodes on a rate basis. The loading table will be scaled by the base value at any time to give the loading rate.

Syntax

The syntax required to impose nodal DOF rates is:

**impose_nodal_dof_rate \(~\,~\,\) nset_name  dof_name  value  table_name

nset_name

This is the name of a valid node set (nset) which gives all the nodes where the DOF is to be imposed.

dof_name

The character name of the DOF to be imposed. This must be one of the defined DOF types given by the problem, and as indexed in the appendix. DOF names are also listed in the problem.ut reference file.

value

This real value acts as a multiplier on the current applied load table value. If the value is zero, no table will be required.

table_name

A character name for the loading table which describes the DOF value in time. A corresponding table must therefore be given elsewhere (see the procedure ***table).

Example

This example is for an axisymmetric specimen with applied hydrostatic pressure of 52 MPa, followed by strain rate controlled compression cycling along one axis, while the hydrostatic pressure is maintained. Note the use of zero in *dtime to apply step loading of the strain rate. Expiring (exp) is also applied to the DOF rate condition because the DOF is not active at all times.

***bc
  **pressure
    press     -1. ptab
    top   exp -1. ptab2
  **impose_nodal_dof
    y=0      U2  0.0
    x=0      U1  0.0
  **impose_nodal_dof_rate
    y=1  exp U2  1.0 seg
***table
  **name ptab
    *time  0.0  100. 5000.
    *value 0.0  52.0 52.0
  **name ptab2
    *time  0.0  100.
    *value 0.0  52.0
  **name seg
    *dtime  100.0
            0.0  3.1579e+01
            0.0  7.8947e+01
            0.0  5.5263e+01
    *value  0.0
           -3.8e-05 -3.8e-05
            3.8e-05  3.8e-05
           -3.8e-05 -3.8e-05