Data part, apply gravity time-steps

control_timestep 10 1.e-1 1.0
control_print 10 -time_current -post_node_rhside_ratio

control_print_gid 20 -yes

control_reset_dof 30 -disx -disy -eppxx -eppxy -eppxz -eppyy -eppyz -eppzz

Time-steps are actually started with control_timestep 10. There is one important topic about all control_* records that we need to discuss first. These control_* records also have an index, here the indices are 10, 20 and 30. Specifically for control_* records these indices are important: these records will be performed in order of increasing index. Here that means that the records control_timestep 10 and control_print 10 are performed first, after that the record control_print_gid 20 is performed, and after that the record control_reset_dof 30 is performed.

The control_timestep 10 record tells Tochnog to take time-steps of size $0.1$ until a total time increment of $1.0$ is obtained. The control_print 10 record specifies that some data records need to be printed, specifically the current time -time_current and the accuracy ratio -post_node_rhside_ratio. The accuracy ratio contains the maximum out-of-balance force on a free node (that is a node without prescribed displacement) divided by the maximum external force on a node with prescribed displacement. Normally all printing during a calculation goes to the computer monitor (but the advanced user can redirect printed output to a file).

Now look back at how we defined the gravity in time. It was increased from 0.0 at time 0.0 to its final value of 10 at time 0.5. Thus, the time increment of 1.0 is enough for getting gravity imposed (from time 0.0 to time 0.5), and also allows the equilibrium with full gravity to be established accurately with additional time-steps (from time 0.5 to time 1.0).

The control_print_gid 20 record takes care that the results at the end of gravity are printed in the tochnog_flavia.msh and tochnog_flavia.res files. These can be post-processed with Gid.

Finally, to prepare the safety factor calculation itself, some results are set to 0.0 in order to be able to distinguish clearly after the safety factor calculation between safety factor results (instability results) and gravity results. To be specific, the displacement components -disx, -disy are set to 0.0 and the components of the plastic strains -eppxx -eppxy -eppxz -eppyy -eppyz -eppzz are set to 0.0.