**init_d_dof

Description

This procedure sets the initial increment DOF values for iteration \(i+1\) as a function of the previous solution \(i\):

(117)\[\Delta {\rm DOF}_{i+1} = {\rm ratio} \times \frac{\Delta t_{i+1}}{\Delta t_i} \times \Delta {\rm DOF}_i\]

The objective of this method is to accelerate convergence during relatively stable loading paths. The assumption is that the next solution will not vary greatly from the previous one. This method is therefore dangerous to convergence if the loading changes rapidly, such as a newly unloaded section of the structure.

Syntax

**init_d_dof [ ratio ][ sequence ]

ratio

is a real value acting as a scaling factor, as shown above. The default value is 1.0.

sequence

indicates that the initialization is only applied within each sequence, based on the first solution of that sequence. In absence of this option the initialization is carried out for the entire calculation, even across sequence boundaries.

Example

**init_d_dof 0.9 sequence