Ansys medini analyze supports the exchange of fault trees with third-party tools based on import and export of fault trees. These tool integrations are meant to seamlessly exchange fault trees with suppliers, customers or colleagues that use a different FTA software tool. They are not designed for collaboration, that is, to edit the same fault tree in two different tools.
Fault trees can be imported to and exported from Isograph's FaultTree+/Reliability Workbench™ (RWB). The exchange is based on the XML exchange format of FaultTree+ (not to be confused with an RWBX file).
To prepare to import fault trees from FaultTree+, make sure you have correctly exported a fault tree database to XML using the FaultTree+ tools export wizard. You do not need to include the full database, but at least the tables FailureModels, Gates, PrimaryEvents, and GateInputs and all fields of those tables.
Note that the import to medini analyze includes the FaultTree+ diagrams in the same paginated diagram hierarchy.
To import a FaultTree+ XML file, do the following:
In the Model Browser, create a new FTA model or select an existing one.
From the context menu of the model, select > .
Select the XML file you want and confirm with .
The export to FaultTree+ is as simple as the import:
Select an FTA model in the Model Browser. Note that the export does not work on a top-event, only on a complete model.
In the context menu, select > .
Specify the target file and confirm with .
After export you can open FaultTree+ and go to the "Import → XML" wizard to load the fault tree.
The tool provides an interface to CAFTA ("Computer Aided FTA") provided by EPRI for the import and export of fault trees. If you migrate fault trees or have customers and/or stakeholders using CAFTA, you can seamlessly import from and export to .psa/.caf project files.
Before using the the import or export make sure you have setup the connection to CAFA in the preferences:
Open the preferences via the menu "Window | Preferences..." and go to the settings "Integration | EPRI CAFTA".
Select the PhoenixAPI.dll that is available in your CAFTA installation, typically under C:\Program Files\EPRI Phoenix\Phoenix Architect\PhoenixAPI.dll. You can use "Auto Detect" to quickly fill the field.
Important note: If you cannot find the DLL than you most likely do not have a commercial version of CAFTA (also named Phoenix Architect). The exchange will not work with the free version. Note further that this file is not the MediniPhoenixAPI.dll which comes with our tool installation.
Apply and Close the preferences dialog. The CAFTA interface is now ready to be used.
To import fault trees from CAFTA you have to follow these steps:
Create a new empty FTA model or select an existing FTA model in the Model Browser
Open the context menu and select "Import | From CAFTA..." which bring up the CAFTA import wizard
The wizards let's you specify the project file (.psa) to import. After selecting a file press Next
The next page lists all fault trees and files (.caf) and you can select the fault trees to import. For each fault tree the event database can be selected (if multiple exists).
If some files represent sub-trees only, the Top Level column will indicate this by "No". Note that these fault trees can be imported also, but obviously might not be complete. The safest option is to select only top level trees. You can use the "Select Dependencies" to make sure that all branches are imported.
After configuring the content, proceed with Next to run the import. Any problem will be reported on the last page. The following structural issues in CAFTA fault tree will lead to an error:
Loops via transfer gates exist in the CAFTA model
A transfer gate has no unique target event it points to
Gates of following types have just one input: 'A And Not B', 'Not A And B', 'A Or Not B', 'Not A Or B'
If gates with the same name are found in multiple fault trees
Moreover, the following inconsistent probability models will lead to a warning and a default probability of 1 will be set:
No probability data was found for the basic event
Unsupported probability calculation method is used for the basic event
The value of the probability, factor parameter or failure rate parameter of basic event is not a valid value
The value of the probability is out of range [0..1]
The units of factor parameter or failure rate parameter of basic event are not specified or not supported
After successful import you can create diagrams as required. Simply drag an event onto a diagram and select "Restore subtree" from the context menu.
The import creates events and gates by using the Name field as ID and Desc field as text. All gate types are imported, combined gates such as "Not-OR" are split into two gates in medini. An INHIBIT gate as well as a Priority AND will mapped to an AND gate (the latter with label "P-AND").
To export a fault tree from Ansys medini analyze to CAFTA you have to do the following:
Select an FTA model in the Model Browser and open the context menu with a right click
Choose "Export | To CAFTA..." from the context menu. This will bring up the CAFTA export wizard
The first wizard page you can specify the name of the project and select the top events to export. Note that an export of intermediate events is currently not supported.
At the bottom of the wizard page there is an additional option to split the fault tree over multiple files. This option will create for each intermediate event that is shown in the Model Browser as "top level" a separate file.
For both import and export of fault trees the following mapping is applied for the CAFTA probability models:
0 Fixed probability: fixed probability
1 Exposure * rate: Risk time model with failure rate and specific interval exposure
2 Periodic test: Monitored events with test interval tau
3 Mission time, no repair: Exponential model with failure rate
4 Repairable: Exponential with failure rate and repairable cycle and repair time mu
5 Periodic test: Monitored events with monitor interval tau
6 Repair and mission time: Exponential with failure rate and repairable cycle and repair time mu
9 Initiator (rate): failure rate value is interpreted as fixed probability
+ TRUE (import only): fixed probability P=1.0
- FALSE (import only): fixed probability P=0.0
= EQUATION (import only): A warning will be reported during import and probability is set to P=1.0
Ansys medini analyze provides an export into the OpenPSA Model Exchange Format (cp. https://github.com/open-psa/mef). The export is currently experimental and need to be activated in the tools preferences. If you want to export to OpenPSA XML format do the following:
Activate the feature via Window | Preferences and go to Integration | FTA. The option is named Support OpenPSA export at top level events. Make sure this option is checked.
Go to a fault tree in the Model Browser (or FTA diagram) and open the context menu on a top level event. If the event if not of kind TOP_LEVEL the export action will not be available.
Select Export | As OpenPSA XML... from the context menu
A file dialog comes up that let's you select the target file. Confirm with OK.