Failure Rate Types for Assemblies and Parts

Windchill Risk and Reliability Desktop Help > Windchill Prediction > Prediction Assembly Data > Calculation Data Pane > Calculation Data for Specifying Whether Assembly Results are Calculated or Specified > Failure Rate Types for Assemblies and Parts

In the Calculation Data pane for an assembly, and also in the General Data pane for a part, Failure rate type indicates whether the failure rate or MTBF (mean time between failures) is allocated, calculated, or specified. The default for both assemblies and parts is to calculate the failure rate.

• The units for failure rate are specified by Failure Rate Multiplier under General in the System file properties. The default is 1000000 because several commonly used models base their calculations on failures per million hours. For more information, see General System File Properties.

• The units for MTBF are always hours.

The following table describes the choices available for Failure rate type.

Failure Rate Type	Description
Allocated	When selected, the failure rate or MTBF is allocated based on the method specified by Allocation method, which appears under Prediction in the System file properties. The default is Base, Non-normalized. For more information, see Prediction System File Properties. • For an assembly, the form for the selected method is shown in the Allocation pane so that you can specify how to allocate the failure rate or MTBF. For more information, see Allocation Pane (Assembly). • For a part, the Allocation pane is shown only when Base, Non-normalized or Base, Normalized is the selected method so that you can supply the numeric weight factor that identifies the portion of its parent assembly’s allocated failure rate or MTBF to attribute to this part. For more information, see Allocation Pane (Part).
Calculated	When selected (default), the failure rate is calculated using the selected model. Consequently, subsequent fields on the form for supplying either a specified failure rate or MTBF value are unavailable.
Specified, Failure Rate	When selected, Failure rate, specified becomes available so that you can enter the failure rate. No calculations are performed when the failure rate is specified. Additionally, all calculated or specified failure rates for the parts in this assembly are ignored.
Specified, MTBF	When selected, MTBF specified becomes available so that you can enter the MTBF. No calculations are performed when the MTBF is specified. Additionally, all calculated or specified MTBF values for the parts in this assembly are ignored.