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.
CAFTA is a Computer-Aided FTA tool from EPRI, and is also known as EPRI Phoenix. Ansys medini analyze provides an interface to CAFTA for the import and export of fault trees. If you migrate fault trees or have customers or stakeholders using CAFTA, you can seamlessly import from and export to .psa and .caf project files.
Prerequisite
Before importing or exporting, make sure you have set up the connection to CAFTA in the medini analyze preferences:
In medini analyze, select Window > Preferences > Integration > EPRI CAFTA.
Browse to the PhoenixAPI.dll in your CAFTA installation, typically under C:\Program Files\EPRI Phoenix\Phoenix Architect\PhoenixAPI.dll. Or click the Auto Detect button to quickly fill the field.
Note: If you cannot find the DLL file, then you most likely do not have a commercial version of CAFTA. The exchange does not work with the free version. Do not confuse this file with the MediniPhoenixAPI.dll included in the medini analyze tool installation.
Click the Apply and Close button to close the preferences dialog with your changes. The CAFTA interface is now ready to be used.
Import
To import fault trees from CAFTA, complete these steps:
In the Model Browser, select an existing FTA model or create a new one.
From the model's context menu, select Import > From CAFTA....
The CAFTA import wizard opens.
In the wizard, specify a project file (.psa) or a folder (.caf) to import, then click Next .
The next page lists all fault trees and files (.caf).
Select the fault trees to import. For each fault tree, you can select a specific event database if multiple exist.
If some files represent only subtrees, this is indicated in the Top Level column with No. Note that these fault trees can also be imported but may not be complete. The safest option is to select only top-level trees.
To make sure that all branches are imported, select Select Dependencies.
From the drop-down below the list of fault trees, you can select a Type Code (TC) to use as the mission time (in hours) for the fault tree calculation
After configuring the content, click Next to run the import.
If there were any problems with the import, they are reported on the next page. Note that the following structural issues in CAFTA fault trees lead to an error:
Loops via transfer gates exist in the CAFTA model
A transfer gate does not point to a unique target event
Gates of following types have just one input:
'A And Not B',
'Not A And B',
'A Or Not B',
'Not A Or B'
Gates with the same name are found in multiple fault trees
Moreover, the following inconsistent probability models lead to a warning and a default probability of 1 is set:
No probability data was found for the basic event
An 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
Click Finish to complete the import.
After a successful import, you can create diagrams as required. Simply drag an event onto a diagram and selectRestore 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 analyze. INHIBIT gates as well as Priority AND gates are mapped to an AND gate (the latter with label "P-AND").
Note: Ansys medini analyze supports the import of failure rates using Type Codes in the columns TYPE and RATE of the BE table. Note that values in the RATE column take precedence over those in the TYPE column.
Export
To export a fault tree from Ansys medini analyze to CAFTA, complete the following steps:
In the Model Browser, select an FTA model and in the context menu,select Export > To CAFTA....
The CAFTA export wizard opens.
In the wizard, first specify the project file, then select the top events to export.
Note that an export of intermediate events is currently not supported.
At the bottom of the wizard page, you can opt to export the fault tree split over multiple files. This option creates a separate file for each intermediate event that is shown as "top level" in the Model Browser.
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.