Reliability HotWire: eMagazine for the Reliability Professional
Reliability HotWire

Issue 14, April 2002

Tool Tips

*How is the repair time determined when using subdiagram blocks in BlockSim RBDs? 

In BlockSim, a subdiagram is a diagram that is represented as a block in a higher-level diagram. Subdiagram blocks have "folder" shapes in the RBD diagrams, such as the "Circuit Board" block in the following graphic.

Example of RBD with subdiagram

When performing availability simulation on diagrams with subdiagram blocks, BlockSim only retrieves failure information for the subdiagrams and the user specifies the repair distribution for the subdiagrams. This allows for a whole subsystem to be replaced upon failure. For example, a circuit board is made up of many components (e.g. capacitors, resistors, etc.). In most applications, a circuit board failure will result in replacing the whole board rather than replacing the individual component responsible for the failure. These types of subsystems are also known as LRUs (line replaceable units). 

Consequently, the Block Properties window for a subdiagram requires that repair information be entered for the entire subassembly, while the failure information is automatically carried over from the reliability analysis of the subdiagram. The Failure tab of the Block Properties Window for a subdiagram is disabled.

BlockSim Block Properties window

Neglecting to enter the repair information for such a subdiagram will effect the availability simulation results since this block will not be "repaired" after the first simulated failure. For more information on how BlockSim performs availability simulations, see the Reliability HotWire article at

*How do I change the user name and company information in Weibull++ 5.0?

The user name and company information in Weibull++ 5.0 can be changed from the User Setup window, which is accessible from the File menu. When this window is initially opened, the User Name, Company and License Number fields are disabled. In order to activate these fields, click the key icon in the upper right corner of the window.

Webull 5 User Setup window

This will open a security window that requires a password. 

Weibull 5 Security window

The default password is "masterpass." Type this word into the Password field and click the Exit button. This will return you to the User Setup window, but will allow you to change the previously disabled fields. Note that this entire procedure is not necessary in Weibull++ 6. For information on upgrading from Version 5.0 to Version 6, see


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