Diagrams

If you have ReliaSoft’s BlockSim software installed on your computer, the shared Synthesis Platform makes it possible to use a model (i.e., a shared Synthesis resource) that is based on a Weibull++ or ALTA standard folio to define any of the probabilities in BlockSim’s reliability block diagrams (RBDs) and fault trees. For convenience, a simplified version of BlockSim’s analytical RBD tool is also directly integrated within the Weibull++/ALTA interface.

To create a diagram directly within Weibull++/ALTA, choose Insert > Tools > Diagram or right-click the RBDs folder in the current project explorer and choose Add Diagram on the shortcut menu.

For every standard block that you add to this type of diagram, you will be prompted to select a calculated data sheet from a Weibull++ or ALTA standard folio that the block will represent. You can then use connectors, node blocks and/or junction blocks to build an RBD, calculate the exact system reliability equation for the system, and obtain plots and results based on that equation.

Note: If the analysis in the data sheet changes, the reliability characteristics of the block will be updated automatically, and you can double-click the block to open the associated data folio.

One typical application for this tool is for performing complex failure modes analysis. As explained in the Competing Failure Modes (CFM) Analysis topic, the CFM analysis method that is built-in to the Weibull++ standard folio assumes a series reliability model and uses only one type of distribution to analyze all the modes. If the situation is more complex, an RBD analysis method must be used instead. This applies to any or all of the following circumstances:

The analysis involves more than four failure modes.
The failure modes are described by different life distributions (e.g., Modes A and B follow a Weibull distribution but Mode C follows a lognormal).
The relationship between the failure modes does not follow a series configuration. For example, if more than one failure mode must occur together in order for the component to fail, a parallel configuration must be used for the analysis and this is referred to as "complex failure modes analysis" rather than "competing failure modes analysis."

The topics that follow explain how to build and analyze diagrams in Weibull++/ALTA. For an example of how to use a diagram in failure modes analysis, see Using RBDs for Failure Modes Analysis.