MPM Restart
Before even launching the simulation it is important to activate the restart capability so that Kratos is saving the restart files in the desired intervals. To do this, inside GiD when using the Kratos problemtype, open the Results-tab where the Restart-Output-option is found. Here the restart output can be enabled (it is enabled by default) and the output frequency can be defined. The output frequency can be set based on the number of time steps or the time between outputs.
After generating the calculation files the following entries can be found in the ProjectParameters.json containing the information about the restart process.
At this point, the simulation can be launched normally and Kratos will write the restart files into a folder called MPM_Material__restart_files. The restart files will be named MPM_Material_{time step/time}.rest. These files can then be used to restart the simulation if necessary.
Once a simulation has been launched and the restart files have been written, the simulation can be restarted from any of the existing restart files. To do this open the "ProjectParameters.json" and modify the model_import_settings. The only value that needs to be modified is the restart_load_file_label entry. This entry should contain the label of the restart file to be used, i.e. the time step or the time that is given in the MPM_Material_{time step/time}.rest name to be used. It is important to write this number as a string!
When launching the simulation again, the simulation will start from the restart file, instead of starting from the beginning. It is important to note, that the previous result outputs (including the restart files) after the point of the restart will be overwritten! So if any specific outputs after the restart time should be saved, they need to be moved to a different folder or renamed.