Competing Failure Modes
In the Weibull Parameters pane for a parametric life data set, selecting Competing Failure Modes as the model is possible for any of five distributions: Weibull, lognormal, normal, exponential, or Rayleigh. When you select this model, a few additional parameters are shown for providing values required by the competing failure modes model. The following table describes these additional parameters. Additionally, in the Weibull Data Points pane, you must enter a group name for each data point. Group Name is always the first table column in the Data Points pane for this model. For more information, see Weibull Data Points Pane for a Parametric Life Data Set.
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Parameter
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Description
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Number of CFM modes
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Specifies the number of failure modes to use to perform the analysis. The selection that you make here determines the failure modes entries present in the Competing Failure Modes Setup window, which appears when you click the CFM Setup button, which is described below. Choices are 1 Failure Mode through 5 Failure Modes.
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Result CFM mode
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Before the data set is calculated, this parameter is unavailable and empty. After the data set is calculations, it displays the number of unique failure modes specified in the Competing Failure Modes Setup window.
For example, if you selected 3 Failure Modes for Number of CFM modes but did not associate a group name with Failure Mode 2 in the Competing Failure Modes Setup window, after the data set is calculated, choices for this parameter are only Failure Mode 1 and Failure Mode 3. When you change the failure mode selected for this parameter, calculation results are updated in the lower portion of the pane to display those for the newly chosen mode.
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When clicked, the Competing Failure Modes Setup window opens. In this window, you associate each unique group name entered in the data set’s Weibull Data Points pane with any available failure mode or no failure mode. For more information, see Competing Failure Modes Setup Window.
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The following table indicates the model that is used with distributions that support competing failure modes. When you run calculations, the View Calculation Results window displays results for each failure mode.
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Distribution
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Model
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Weibull
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2 Parameters
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Lognormal
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2 Parameters
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Normal
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2 Parameters
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Exponential
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1 Parameter
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Rayleigh
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1 Parameter
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A probability plot for the results from the competing failure modes model displays the total system probability line as well as probability lines for each failure mode. Confidence bounds are plotted only for the total system probability. Other plots available for this model include the following: Reliability vs Time, Unreliability vs Time, Failure Rate vs Time, and PDF. For more information, see Plot Types. When generating multiple plots, they can vary only by type, not by distribution. For more information, see Options for Multiple Weibull Plots.