Transcript ftp.lstc.com

Restarting an LS-DYNA Analysis

Introduction

Simple Restart

Small Restart

Full Restart
Restarts

All 3 classes of restarts require a binary dump file
which contains a complete record of the model
(stress, strain, deformation, etc) at a particular
point in time.
•
•
•
Binary dump files are written during an analysis at intervals
according to *DATABASE_BINARY_D3DUMP and/or
*DATABASE_BINARY_RUNRSF.
In addition, a binary d3dump file is automatically written at the
normal termination of a run unless “d=nodump” on the
execution line.
In v. 971, the number of runrsf files retained is controlled by the
parameter NR in *database_binary_runrsf.
•
Default is NR=1
•
If NR is greater than 1, the runrsf files are written in
cyclical fashion.
Restarts
 When doing a restart:
• Use the same executable
• Use same numbers of CPU’s
Simple Restart

Restart made from any dump file written prior to
termination time.

No changes are made (not even termination time) and
thus no input file is needed.

Sample execution line:
ls971 r=d3dump01
Small Restart

Only certain changes are permitted. The keywords in the *RESTART section
of the User’s Manual (excepting *STRESS_INITIALIZATION) pertain to small
restarts. Some of the changes allowed in a small restart…
• change termination time
• change output intervals
• change timestep controls
• modify load curves
• add nodal boundary conditions
• delete contacts, parts, elements
• Rigid/Deformable switching of parts

Need a binary dump file and a small restart input deck, the latter of which
might be as simple as …
*KEYWORD
*CONTROL_TERMINATION
15e-03
*END
Sample execution line:
ls971 i=restart_in.k r=d3dump01
where restart_in.k is the small restart input deck.
Full Restart

Changes of a general nature can be made including addition of parts,
loads, and contacts.

A full restart requires a binary dump file and a full restart input deck.
In the full restart input deck a full description of the model is given.
• Input for retained parts, materials, contacts, loads, etc. is copied directly
from the original input deck
• That input which is copied from the original input deck can be modified as
desired
• Input for new parts, materials, contacts, loads, etc. is added

The command *STRESS_INITIALIZATION must be specified in the
full restart input deck for parts to be initialized.
• Initializes stress, strain, displacement, etc. for all parts which are carried
over or, optionally, for only a subset of those parts
Full Restart

One cannot change the mesh topology of preexisting parts
when doing a full restart
• Except for solid elements (use Q=remap on the execution line)

*DELETE commands should not be used in a full restart.
• To eliminate elements, don’t include their definition in the full restart
deck

Do not use *INITIAL_VELOCITY for nodes carried over from
previous run. Use *CHANGE_VELOCITY_<option> to modify
velocities of such nodes.

Preexisting contacts that are to be initialized should include the
_ID option so that the contact ID numbers in the original input
deck match those in the full restart input deck.
Full Restart

BEWARE! Output from full restart will overwrite existing output in
version 970
• Submit full restart from a new directory
• Output from original run and output from full restart cannot be
combined and must be postprocessed separately

Version 971 will append output from full restart to exisiting output.

The binary dump file necessary to submit a full restart when running
MPP-DYNA is named d3fullXX (not d3dumpXX)
• Use n=d3fullXX on execution line, not r=d3dumpXX
Exercise 3a and 3b