Optimization process
Session start options

In ProTOp the term optimization session is used to denote the environment that holds all data and manages all processes related to a particular optimization task. Once a session is created, it contains a complete definition of the optimization task and this definition can not be changed. An exception here are the setting and tuning parameters that can be changed interactively at any time.

ProTOp offers several options how to start a session. These options are:

• create and start a new session,
• create and start a new session from another session, and
• open and restart an existing session.

Create and start a new session

This is the conventional start option. A fresh new session is created and run from the initial design, as defined by the configurators.

Create and start a new session from another session

This is the so called start-from option. A fresh new session is created and run from the design that was generated by another session. This procedure is quite useful when the FEA or optimization model has to be changed after some partially optimized design was obtained. A few of the most common situations that would require this step are as follows.

• Mesh refinement. Initial optimization steps can usually be run very efficiently on a rather coarse mesh. However, after some material is removed, it is often necessary to refine the mesh.
• Load cases adjustment. During a running optimization session it might become clear that the load case set needs adjustments, for example, additional combined load cases might be necessary.
• Technological constraints adjustment. As optimization progresses it might become apparent that either dropping constraints or enforcing additional constraints would be useful, for example, to turn an almost-symmetrical part into a symmetrical one.

All of the above situations necessitate to end the current session, change the model accordingly, and start a new session from the previously obtained design. The start-from option is intended to be used for this procedure.

NOTE. The start-from option can be used irrespective of the consistency between the current model and the referenced previous model. Neither the mesh nor the optimization data need to be consistent.

Open and restart an existing session

This is the so called restart option. An existing session is opened, loaded into memory, and started. This option continues to run an existing session as if there would be no interruption. Note, however, that this option requires to load the data of the restarting session into the current model. This means that changes, made to the current model after the restarting session was created, will be lost. Therefore, this option should only be used, if the underlying model was not changed after the restarting session was created.

WARNING. The restart option should not be used, if the underlying model was changed after the restarting session was created. Otherwise, data loss will occur.