Modeling Fail-On with Non-Fatal Failure Modes

The model demonstrates how non-fatal failure modes can be used in your reliability models. By default, a failure mode is added to the element's logic tree so that the component stops operating when the failure occurs. However in certain cases (such as when components fail on) the component continues to perform its function normally even when a failure occurs.

To model a failed on situation, one must first delete the failure mode from the internal logic tree. When setting up the "Off" trigger, the "Then check if Required Condition is true" field can be used to simulate a "failed on" situation by referencing the ~Failed available property for that mode. In this example, the non-fatal mode for the Component is mode 1, so Not ~Failed [1] is entered in that field, preventing the component from shutting off if that mode occurs when it is triggered by the Off_Trigger element. Similar logic can be used to model Failed Off, and failed Actions.

You can also use the ~Failed local property in Child elements as well as Input Fields within the reliability element. In this model, the Component is initially Off, but is triggered On on once every ten days. It then runs for five days and then is shut down (as long as the failure mode has not occurred).

The Results element shows the status of the Failure Mode and the Component's Status. After the Failure Mode fails, the Component remains operating for the duration of the simulation.

To Open the Model File:

1. Start GoldSim
2. Click on the File and select Open Example...
3. Browse to Reliability Examples
4. Select the file called FailsOn.gsm