Fault Tree, Event Tree & Markov

FaultTree+ Fault Tree Analysis

The FaultTree+ module in Reliability Workbench is the latest version of the world leading FaultTree+ software package. Isograph has built its reputation on the efficiency, accuracy, stability and ruggedness of its FaultTree+ product.

The FaultTree+ module provides an easy to use interface for constructing fault tree diagrams. Gates, events and failure models can be added with just a few clicks.

Fault tree diagrams represent hierarchies of sub-system and component failures and how they could cause system failures. The TOP event of a fault tree represents a system event of interest and is connected by a series of gates to component failures.

Failure and repair data is assigned to the system components. The Fault Tree module will perform a detailed analysis to calculate reliability and availability parameters for the system and identify critical components.

IEC 61508 Failure Models

The Fault Tree module now includes IEC 61508 failure models. If you are using the new IEC 61508 failure models, Reliability Workbench will automatically determine HFT (hardware fault tolerance) requirements where appropriate.

IEC 61508 also includes Dormant Modeling features. The averaging algorithms for multiple dormant failures in a cut set are now performed for up to 4 dormant failures in a cut set.

Event Tree Module

The Event Tree module is able to handle large problems and to fully handle success logic. An event tree model may be created independently of the fault tree model or may use fault tree analysis gate results as the source of event tree probabilities.

The event tree module handles both primary and secondary event trees, multiple branches and multiple consequence categories. Isograph customers have created and analysed event trees with over 30,000 branches.

Markov Analysis Module

The Markov module allows users to easily build state transition diagrams and performs numerical integration to solve complex problems. State transition diagrams represent the discrete states of the system and the possible transitions between those states.

The Markov module models multiple phases representing continuous or discrete transitions. The module also analyses non-homogeneous processes by allowing time dependent transition rates to be defined. The phases allow the system lifetime to be split into periods representing (for example) preventative maintenance or standby.

The models created in the Markov analysis module may be linked to basic events in the fault tree and event tree analysis modules.