**release_nodal_dof#

Description#

This command allows a time-based progressive release of a fixed condition. The crack length is given by the loading table of the condition. Using a function or table of values one can specify complex crack growth rates. For example crack growth measurements can be input as a table, and the crack propagated as actually seen. Then loading parameters such as \(\Delta K\) or maximum crack tip opening can be correlated to the growth.

Syntax#

**release_nodal_dof \(~\,~\,\) nset  dof  base-val  table

Note

The crack length is measured as the distance sum of distances between nodes with the initial tip being at the first node of the given node set (i.e. its the arc length \(s\) of the line drawn by the node set). Curved crack paths are therefore possible. The node set should be ordered beforehand.

Example#

***bc
 **release_nodal_dof
   crack U2 0.9 time
 **impose_nodal_dof
  x1 U1 0.
  y1 U2  0.1 time
../../_images/release_nodes.gif