Restarting an LS-DYNA AnalysisRestarting an LS-DYNA Analysis

IntroductionIntroduction

Simple RestartSimple Restart

Small RestartSmall Restart

Full RestartFull Restart

RestartsRestarts

All 3 classes of restarts require a binary dump file All 3 classes of restarts require a binary dump file which contains a complete record of the model which contains a complete record of the model (stress, strain, deformation, etc) at a particular (stress, strain, deformation, etc) at a particular point in time. point in time.

• Binary dump files are written during an analysis at intervals Binary dump files are written during an analysis at intervals according to *DATABASE_BINARY_D3DUMP and/or according to *DATABASE_BINARY_D3DUMP and/or *DATABASE_BINARY_RUNRSF.*DATABASE_BINARY_RUNRSF.

• In addition, a binary d3dump file is automatically written at the In addition, a binary d3dump file is automatically written at the normal termination of a run unless “d=nodump” on the normal termination of a run unless “d=nodump” on the execution line.execution line.

• In v. 971, the number of runrsf files retained is controlled by In v. 971, the number of runrsf files retained is controlled by the parameter NR in *database_binary_runrsf. the parameter NR in *database_binary_runrsf. • Default is NR=1Default is NR=1• If NR is greater than 1, the runrsf files are written in If NR is greater than 1, the runrsf files are written in

cyclical fashion.cyclical fashion.

RestartsRestarts

When doing a restart:

• Use the same executable

• Use same numbers of CPU’s

Simple RestartSimple Restart

Restart made from any dump file written prior to Restart made from any dump file written prior to termination time.termination time.

No changes are made (not even termination time) and No changes are made (not even termination time) and thus no input file is needed.thus no input file is needed.

Sample execution line:Sample execution line:

ls971 r=d3dump01ls971 r=d3dump01

Small RestartSmall Restart Only certain changes are permitted. The keywords in the *RESTART section Only certain changes are permitted. The keywords in the *RESTART section

of the User’s Manual (excepting *STRESS_INITIALIZATION) pertain to small of the User’s Manual (excepting *STRESS_INITIALIZATION) pertain to small restarts. Some of the changes allowed in a small restart…restarts. Some of the changes allowed in a small restart…• change termination time change termination time • change output intervalschange output intervals• change timestep controlschange timestep controls• modify load curvesmodify load curves• add nodal boundary conditionsadd nodal boundary conditions• delete contacts, parts, elementsdelete contacts, parts, elements• Rigid/Deformable switching of partsRigid/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 RestartFull Restart

Changes of a general nature can be made including addition of parts, Changes of a general nature can be made including addition of parts, loads, and contacts.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. full description of the model is given.• Input for retained parts, materials, contacts, loads, etc. is copied directly Input for retained parts, materials, contacts, loads, etc. is copied directly

from the original input deckfrom the original input deck• That input which is copied from the original input deck can be modified as That input which is copied from the original input deck can be modified as

desireddesired• Input for new parts, materials, contacts, loads, etc. is addedInput 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 RestartFull Restart

One cannot change the mesh topology of preexisting parts One cannot change the mesh topology of preexisting parts when doing a full restartwhen doing a full restart• Except for solid elements (use Q=remap on the execution line)Except for solid elements (use Q=remap on the execution line)

*DELETE commands should *DELETE commands should notnot be used in a full restart. be used in a full restart.• To eliminate elements, don’t include their definition in the full restart deckTo eliminate elements, don’t include their definition in the full restart deck

Do not use *INITIAL_VELOCITY for nodes carried over from Do not use *INITIAL_VELOCITY for nodes carried over from previous run. Use *CHANGE_VELOCITY_<option> to modify previous run. Use *CHANGE_VELOCITY_<option> to modify velocities of such nodes.velocities of such nodes.

Preexisting contacts that are to be initialized should include the Preexisting contacts that are to be initialized should include the _ID option so that the contact ID numbers in the original input _ID option so that the contact ID numbers in the original input deck match those in the full restart input deck.deck match those in the full restart input deck.

Full RestartFull Restart

BEWARE! Output from full restart will overwrite existing output in BEWARE! Output from full restart will overwrite existing output in version 970version 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 3bExercise 3a and 3b