How Failures and Repairs are Represented in Time

When a repair or failure is generated in GoldSim by a Function or Action element, the failure or repair may not fall exactly on a “scheduled” timestep (i.e., a timestep that was defined in the Time tab of the Simulation Settings dialog). That is, the failure or repair event may actually occur between scheduled timesteps.

These trigger an “unscheduled update” of the model. Unscheduled updates are timesteps that are dynamically inserted by GoldSim during the simulation in order to more accurately simulate the system. That is, they are not specified directly prior to running the model. GoldSim inserts them automatically (and, generally, without you needing to be aware of it).

For example, if you had specified a one day timestep, and failure occurs at 33.65 days (i.e., between the scheduled one-day updates), GoldSim would insert an unscheduled update at 33.65 days.

A key and important difference between scheduled updates and unscheduled updates is that scheduled updates are included in time history plots and tables (unless you choose to exclude them). Unscheduled updates, however, do not appear in time history plots and tables. That is, although these timesteps may affect the results (e.g., by making them more accurate at the scheduled timesteps), unscheduled updates of the model are not saved and plotted. Only the scheduled updates are actually saved and plotted.

Note: In some cases, it may be of interest to see the values of selected outputs that were computed at unscheduled updates. To facilitate this, Time History Result elements provide an option to do so.