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FaultTree+™ in Isograph's Reliability Workbench™ is a powerful systems reliability analysis tool containing integrated Fault Tree, Event Tree and Markov analysis features. It can also be used in conjunction with Prediction, FMECA and RBD modules within Reliability Workbench™. Fault tree, Event tree and Markov diagrams can be created very quickly. Automatic drawing facilities are used to create professional diagrams.


FaultTree+ in Isograph's Reliability Workbench™ includes three modules:

  • Fault Tree Analysis. Allowing you to construct and analyse fault tree diagrams.
  • Event Tree Analysis. Event trees allow you to analyse the possible outcomes of an event occurring.
  • Markov Analysis. Enabling the construction of Markov models for components with large interdependencies.

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Features of FaultTree+™:

  • Intuitive interface enables fast creation of fault tree, event tree and Markov diagrams
  • Enterprise facilities for large-scale collaboration and version control
  • Robust minimal cut set algorithm with NOT logic
  • Choice of quantitative solution methods - rare, Esary-Proschan or exact
  • Integrated fault and event tree analysis for Probabilistic Risk Assessment (PRA)
  • Markov models can be integrated into component failure analysis 
  • Dynamic (sequential) and disjoint failure models
  • Common cause failure, importance, phased-mission, uncertainty and sensitivity analysis
  • IEC 61508 failure models
  • Integrated parts libraries with data for electronic and mechanical parts
  • Customisable reports with output to Word® and PDF 
  • Import and Export facilities to delimited text formats, Office®, SQL Server® and Oracle®

What is Fault Tree Analysis?

Fault tree diagrams represent the logical relationship between sub-system and component failures and how they combine to cause system failures. The TOP event of a fault tree represents a system event of interest and is connected by logical gates to component failures known as basic events.

After creating the diagram, failure and repair data is assigned to the system components. The analysis is then performed, to calculate reliability and availability parameters for the system and identify critical components.


What is Event Tree Analysis?

Event tree diagrams provide a logical representation of the possible outcomes following a hazardous event. Event tree analysis provides an inductive approach to reliability and risk assessment and are constructed using forward logic.

FaultTree+™ in Reliability Workbench™ includes integrated event tree analysis. The event tree model may be linked to the fault tree model by using fault tree gate results as the source of event tree probabilities.


What is Markov Analysis?

Markov analysis provides a method of analysing the reliability and availability of sub-systems representing components with strong interdependencies. Markov analysis is often used to model dependencies such as:

  • Components in Warm/Cold Standby
  • Common maintenance personnel
  • Common spares with a limited on-site stock

FaultTree+™ in Reliability Workbench™ allows the user to construct Markov models for use as the source of basic event data. The Markov models may also be analysed independently of the fault tree analysis.

It can efficiently solve fault trees of the order of 20,000 gates and 20,000 basic events, using world class analytical methods.


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