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Forum: Reliability & Maintainability Questions and Answers

Topic: Reliability & Maintainability Questions and Answers

Topic Posted by: Reliability & Maintainability Forum ( )
Organization: System Reliability Center
Date Posted: Mon Aug 31 12:47:36 US/Eastern 1998

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Original Message:

Posted by: IC
Date posted: Mon Mar 5 16:07:21 US/Eastern 2007
Subject: Reliability Apportionment
I am looking for information in relation to apportionment and the techniques used for calculating it. I have calculated the apportionment for a System with 6 sub-systems (Using the Equal Apportionment Technique from MIL-HDBK-338). NOW I am trying to calculate the apportionment for the sub systems with the new information that each sub system has now been "weighted" (i.e sub sys 1 will be responsible for 20% fo all system failures and Sub sys 2 47% etc etc). Can anybody tell me how I will calculate the new reliability apportionment based on the "weighted" factors or let me know of any techniques/equations that I can use.

Thanks for the help.

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Subject: Reliability Apportionment
Reply Posted by: IC
Date Posted: Tue Mar 6 6:27:43 US/Eastern 2007
Thanks John, Unfortunately I do not read or speak French. Also thanks for the info, however this techniques does not fit with what I am trying to do as I am only in the requirements definition phase of the project and am only trying to define a sub system reliability requirement based on the system requirement of 0.8. I have 6 subsystems and when using the Equal apportionment technique it gives a reliability of 0.9635, however based on experience I know that each subsystem effects the systems differently, hence the % weighted values (System 1-20%; Sys 2; 47%; Sys 3 8%; Sys 4 8%; sys 5 2%; Sys 6 15%)for system failure. I am just trying to define what the apportioned reliability should be. Is the calculation just a simple proportional calculation or is there some other method of calculating this high level number. Thanks and Regards

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