Related Topics and Links:

Creating Diagrams from Synthesis Data

Building RBDs from Lambda Predict

Building Effect Fault Trees from Synthesis

Building RBDs and Fault Trees from Xfmea/RCM++/RBI

You can create RBDs that represent items from analyses performed in the current project in XFMEA/RCM++/RBI in order to perform system maintainability and availability analysis for these items. To do this, choose Home > Insert > Build RBDs and FTs from Synthesis.

The Build RBDs and FTs from Synthesis window consists of two steps. When the window opens, you will see the Options step. Specify that you want to use RCM++/XFMEA/RBI as the data source in the Synthesis Element to Build From area.

In the Diagram Type area:

The reliability information for each branch of the FMRA hierarchy is taken from the highest-level item for which reliability is specifically defined, rather than inherited. For example, imagine that you are importing from the following hierarchy and creating fault trees from the information:

If a URD is assigned to the Automobile item, then only the following diagram will be created:

If a URD is assigned to the Body Closures item and the Automobile item is set to inherit its reliability characteristics from that, then the following diagram will be created:

If a URD is assigned to the Front Door L.H. item and the Automobile and Body Closures items are set to inherit their reliability characteristics, then the following diagrams will be created:

Finally, if all items are set to inherit their reliability characteristics and URDs are assigned only to the causes in the FMEA for the Front Door L.H. item, then the following diagrams will be created:

If you are creating RBDs or a hybrid of RBDs and fault trees, the Subdiagram Grouping area will be available. The options in this area allow you to control which levels of analysis will be represented by subdiagrams. For example, consider the final case above, where all system hierarchy items are set to inherit their reliability characteristics and URDs are assigned only to the causes in the FMEA for the Front Door L.H. item.

By combining these options, you can control the levels that are represented in the RBD(s) created. Bear in mind that, as with fault trees, the reliability information for each branch of the FMRA hierarchy is taken from the highest-level item for which reliability is specifically defined, rather than inherited. This is true not only for system hierarchy items, but also for FMEA records. For example, if reliability is defined for a function, that function will be shown as a block in the resulting RBD and no subdiagram will be created for it (i.e., any failures and causes assigned to the functions will not be imported, as they are not relevant to the reliability).

The Create subdiagrams for functions and Create subdiagrams for failures check boxes control only how information is organized, not what information is imported. All items with reliability information defined will be imported, regardless of your selections for these check boxes. For example, consider a component with an FMEA that includes three functions, each of which has a failure and a cause defined. Its FMRA is shown next.

As you can see, the reliability is defined at the function level for Function 1, at the failure level for Failure 2 and at the cause level for Cause 3. If you imported this configuration with both the Create subdiagrams for functions and Create subdiagrams for failures check boxes selected, you would get the diagrams shown next.

On the other hand, if you imported the same configuration with neither of the two check boxes selected, you would get the following diagram:

When creating either fault trees or RBDs, you can use the Overridden Items area to import items that would normally not be imported.

Click the Next button to view the Hierarchical Representation step, which displays a hierarchical view that corresponds to the diagram(s) that will be created. You can select or clear items in this tree to specify whether they will be included in the diagram(s). If the tree does not correspond to the diagram(s) you have in mind, you can click the Back button to return to the Options step and try again. Otherwise, click OK to create the diagram(s).

 

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