Related Topics and Links:

Reliability Block Diagrams (RBDs)

Fault Trees

Block Properties

Subdiagrams

Subdiagram blocks represent other diagrams within the project. Using subdiagram blocks allows you to maintain separate diagrams for portions of a system and to incorporate those diagrams as components of another diagram. This also allows you to generate and analyze extremely complex diagrams representing many subsystems, subsubsystems, etc.

Note: Double-clicking a subdiagram block will open the subdiagram that the block is based on. Open the Block Properties window for a subdiagram block by selecting the block and choosing the command on the ribbon or pressing CTRL+E. To get a quick preview of the subdiagram without actually opening it, select the block and either press SPACE or choose [Diagram/Fault Tree/Phase] > Selection > Quick View.

Subdiagram Block vs. Using a Fitted Model

It is appropriate to use a subdiagram block when you want to take into consideration all properties of all individual blocks in the subdiagram. If you are interested only in the outcome of the subdiagram as a whole (i.e., its fitted distribution and/or system reliability equation), you can create a URD that uses the subdiagram's published results as its failure model; you can then represent the subdiagram within the current diagram by creating a standard block using that URD. You might do this:

It is important to remember that in all of these cases, the subdiagram will be treated as an LRU and no results will be available for anything within it.

Selecting the Diagram

To configure a subdiagram block, in addition to the common block properties, you will need to specify the diagram that the subdiagram block represents. You will be prompted for this information when you add the subdiagram block. If you are working with an analytical diagram, only analytical diagrams will be shown in this list; if you are working with a simulation diagram, only simulation diagrams will be available. If the diagram that the subdiagram block will represent has not yet been created, click Create New RBD or Create New Fault Tree .

  

When you are viewing or editing the subdiagram properties in the Block Properties window, you can change the diagram that it represents by choosing an existing diagram from the Based on diagram drop-down list.

Additional Properties

If a duty cycle is specified for the subdiagram block and there are also duty cycles specified for blocks within the diagram that it represents, their effects are compounded. For instance, if the subdiagram block has a duty cycle of 1.5 and one of the blocks in the diagram that it represents has a duty cycle of 0.75, the effective duty cycle for that block within the subdiagram would be 1.5 x 0.75 = 1.125.

 

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