Forum: Reliability & Maintainability Questions and Answers
Posted by: Andrew Comons
Date posted: Fri Mar 29 13:59:26 US/Eastern 2002
Subject: Exponential Conditional Reliability...A Paradox?
I recently came across a derivation of the "Exponential Conditional Reliability" equation which states that regardless of previous accumulated age, the reliability of a system is only dependent on the duration of the present mission, i.e., no "memory" of what occurred prior to the present mission.
I fully understand the arithmetic of the derivation, but not the principle. According to the theory, I could momentarily shut a system down in the middle of a mission, turn it back on and expect the same probability of success as at the start of the initial mission. This does not seem practical or realistic, but the math says oterwise. Can anyone explain this paradox?? Thanks in advance
Posted by:Al Johnson (firstname.lastname@example.org )
Organization:HS Missile, Space & Undersea
Date posted: Fri Mar 22 10:43:02 US/Eastern 2002
Subject: Aging mechanism on electronic components
Could anyone direct me to published papers on the failure mechanisms for aging electronic components? The concern is for failure predictability of electronic components in a defensive missile system stored in a canister environment for ten plus years.
Posted by: Charles Workman
Date posted: Thu Mar 21 8:47:38 US/Eastern 2002
Subject: failure mode/mech of tantalum capacitors
We are experiencing failures of tantalum capacitors, they exhibit a resistive (~17K ohm) slope on a curve tracer after approx. 1-2 hours of bias. This failure mode will recover in a few hours and they operate normally, this phenomenon is repeatable. Also, they have recieved a bias burn in prior to use which is unable to screen this problem. Any ideas as to what is causing this?
Posted by: Terry MCCrossan (Terry.McCrossan@nokia.com )
Date posted: Wed Mar 20 10:43:20 US/Eastern 2002
Subject: Value of Reliability Engineering Tasks
Could anyone help me with some information on published papers on the value of reliability engineering tasks within product development or a good source of data on this subject. The type of information is what tasks should be used and what value has it been shown to give to the project. I think RAC conducted a study by I can't find the paper. Best Regards Terry
Posted by: Ricardo DiScioscia (email@example.com )
Date posted: Fri Mar 15 14:46:38 US/Eastern 2002
Subject: RADC-TR-89-281 update?
Does anyone know where I find a copy of this document or an updated version of this document. What I am looking for is a physics of failure methodology and a way to relate it to a MTBF. Thanks