About the System Architecture Tree

A functional, logical, or physical system architecture is the backbone of an analysis. Open at least one function, logical component, or product reference to start a safety analysis. The root architecture reference is displayed, along with its children instances. The fault tree elements point to different references in this architecture.

For more information, see Opening a System Architecture.

A fallible reference is a list of failure modes. It points to a functional, logical, or physical reference and contains failures modes. A fallible reference has its own revision, lifecycle, and ownership.

For more information, see About Fault Trees.

A failure mode is the core object of a safety model and represents a basic failure. Its rate is defined by a reliability formula. In the architecture tree, a failure mode is contained in a fallible reference (pointing to a function, logical component, or part). In the fault tree, an event points to a failure mode (the event models the failure that is propagated to the function, logical component, or part through the failure mode). A dependent system failure (DSF) is a type of failure mode. The failure mode revision, lifecycle, and ownership are inherited from the fallible reference that contains it.

For more information, see Creating a Failure Mode.

A reliability formula is a mathematical formula that describes a law of probability. This formula describes the probability of failure of a component over time. A reliability formula is stored in a reliability source and can be associated to a failure mode.

The reliability formula is used to compute the probability of the top event or of the intermediate events.

For more information, see Managing Formulas and Reliability Sources.