While many Abaqus veterans should have dealt with Abaqus restarts at some point in their career, for those who are new to it, it is worth to mention that restart does not necessarily mean “start again from scratch.” In-fact the intent of restart is somewhat opposite. Restart is particularly useful when model is large in size and analysis prematurely fails in middle because of convergence issues. Instead of executing the simulation from scratch every time after fixing the model for convergence, it makes sense to rerun the model from last converged step. Nothing really changes in the model from physics perspective. Recomputing everything from scratch to fix a numerical instability is a waste of time and compute resources. Restart helps in saving compute resources in such case. The analysis however may fail or forced to stop in middle due to other reasons as well and Restart is equally beneficial in such cases too:

• License server breakdowns
• License file expirations
• Analysis converging too slowly due to cutbacks
• Analysis forced to terminate due to incorrect results
• Multi step simulation in which first few steps are the same

Now that we understand the importance of Restarts, let’s see how restart is done in Abaqus CAE. The process includes requesting a restart file that has .res extension in the main simulation and then calling that restart file in the Restart simulation. There are primarily two ways to do this:

• Requesting and calling Restart file from same CAE model. That means first simulation and Restart simulation are launched from same CAE model.
• Requesting Restart file in main CAE model and calling Restart file from another CAE model.

Restart file can be requested as follows. This may result in a single restart file or multiple restart files.

Next the CAE model file is copied. If there are steps modifications, then additional steps are defined. Next the appropriate Restart file is being called and Restart analysis is submitted as follows:

Lastly, the user must remember there should not be any changes in the restart model with respect to geometry or meshing compared to the original model. Moreover, any other modification in Restart model such as addition of steps or loads should be done after the step in which Restart file is being called. For further information, please contact us.