Feasibility of Objectives Allocation Method Calculations

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The feasibility of objectives allocation method was developed primarily to allocate the reliability of non-repairable mechanical-electrical systems. In this method, weight factors are computed as a function of the four numeric ratings described in the following table. Based on engineering know-how and experience, design engineers assign each rating a value based on a scale from 1 to 10. Rating values may also be assigned based on a group of engineers using a voting method such as the Delphi technique.

Rating	Equation Term	Range Description	Description
Intricacy	r1k	1-Simple to 10-Very Complex	Considers the probable number of parts or components making up the subsystem as well as the assembled intricacy of these parts or components. A subsystem with little or no intricacy is rated at 1, and a highly intricate subsystem is rated at 10.
State-of-the-Art	r2k	1-Mature to 10-New	Considers how technologically advanced the design of the subsystem is. The present technological progress in all engineering fields is weighed. The most highly developed design or method is rated at 1, and the least developed design or method is rated at 10.
Time	r3k	1-Low Duty Cycle to 10-Continuous Operation	Considers how long the subsystem operates during the entire mission time. A subsystem that operates only a very small amount of the mission time is rated at 1, and a subsystem that operates for the entire mission time is rated at 10.
Environment	r4k	1-Benign to 10-Severe	Considers the environmental conditions in which the subsystem operates. A subsystem that is to operate in a very mild environment is rated at 1, and a subsystem that is to operate in a very harsh or severe environment is rated at 10.

The four ratings for the subsystem are multiplied together to give an overall value between 1 and 10000. The weight factor for a subsystem is then computed by determining the total of all ratings and then normalizing this value. The equation for this normalized rating is:

Normalized Rating = Rating / Total of All Ratings

Example

Total FR Goal = 500.

Subsystem	Intricacy	State-of-the-Art	Time	Environment	Total Rating	Normalized Rating	Failure Rate
A	2	3	2	8	96	0.448598	224.299
B	10	1	5	2	100	0.467290	233.645
C	1	3	3	2	18	0.084112	42.056
					214	---	500

For the top-most assembly (system), you enter a failure rate goal of 500 in its Allocation pane. For more information, see Feasibility of Objectives Method. For subsystems A through C, you enter rating values for the four different ratings in their Allocation panes. The total ratings, normalized ratings, and allocated failure rates that are calculated when allocation calculations run are shown in the table above.