Oasys LS-DYNA Environment 8.1 VOLUME 3 ... - Oasys Software

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Oasys LS-DYNA Environment: User Guide (Version 8.1) How to Restart an Analysis The restarting process is simple. Enter the OASYS command shell, submit the job and opt for restart when the menu appears. You will be asked to select which dump file to restart from; the available dump files are listed with the analysis times at which they were created. Restart Input Files A restart input file is needed only if changes are to be made to the model. There are three cases; ! No restart input file. The analysis will continue unchanged. ! Short restart input file. ! Full deck restart input file (see separate notes below). The short restart input file must be created by hand; keyword style can be used, and it is necessary to create keyword cards only for those items to be changed. Section 28 of the keyword manual lists the available keywords. An example of a short restart input file is given in Appendix B, Example 8. The naming convention for short restart input files is as follows: analysis_ralph_1.key - keyword file for original analysis analysis_ralph_1.key01 - restart input file for first restart analysis_ralph_1.key02 - restart input file for second restart. The naming convention is important because it allows the oasys command shell to find the correct file. The "restart number" is governed by which analysis wrote the restart dump from which the restart takes place: e.g. if we are restarting from analysis_ralph_1.dpf03, and this file was written by the original analysis, then the restart is by definition the first restart (or restart 1). If the first restart writes more restart dump files, including analysis_ralph_1.dpf05, then any restart analysis using analysis_ralph_1.dpf05 as a starting point is by definition the second restart (or restart 2). Effect on Output Files Binary output files (.pft, .ctf, .thf and .xtf) are joined seamlessly at the time of the restart. There is no way of telling which output states were produced by the original analysis and which by the restart analysis. For restarts which began from a point part-way through the original analysis, the restart analysis overwrites the original results from that point. New ASCII output files are started for each restart: root_name.otf01 and root_name.log01 for the first restart, etc. Page 3.4
Oasys LS-DYNA Environment: User Guide (Version 8.1) Full Deck Restart The Full Deck Restart is a very powerful capability allowing many things to be changed. Particularly useful is the ability to redefine contact surfaces, add new contact surfaces, change contact parameters, etc. The facility could also be used to replace or add parts, e.g. the new tools in a multi-stage sheet metal pressing analysis. The full deck restart input file is, as the name suggests, a complete input file. Almost always, the input file is a copy of the original input file but with the required changes edited in, and the keyword *STRESS_INITIALISATION included. Full deck restarts are used to change parameters which cannot be changed with a short restart input file, particularly contact surfaces. The full deck restart process is different from the "no input file" or "short restart input file" cases; it should be thought of as a new analysis but with stresses, strains, displacements and velocities and analysis time carried over from the previous analysis. We recommend the following procedure: 1. Create the full deck restart input file: e.g. copy analysis_ralph_1.key, make the required changes, and call the new file analysis_ralph_2.key01. Note that a different root file name is chosen, but that the naming convention otherwise follows that for short restart input files. 2. Decide which restart dump file to begin from (e.g analysis_ralph_1.dpf03) then copy it as follows: cp analysis_ralph_1.dpf03 analysis_ralph_2.rtf Note that the new file has the new root name and the extension .rtf. 3. Submit analysis_ralph_2 in the normal way, ensuring that the restart option is selected. Provided that the naming conventions are respected, the oasys shell will find the correct files. The results files from full deck restart begin at the time of the restart; results generated by the original analysis are not included. This is why OASYS recommend use of a different root name for the restart analysis. Because of the way the full deck restart operates, certain things cannot be changed. These include: Page 3.5
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Oasys LS-DYNA Environment 8.1 VOLUME 3 ... - Oasys Software

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