On 12/03/2014 07:40 AM, Marius Liebenberg wrote: > Andy > MTBF is obtained by testing a number of units over a period of time at > accelerated environmental conditions. MTBF CAN be evaluated this way, and it is a more truthful way to do it, but it requires a LOT of units and long testing on hi-rel systems. So, the DoD, long ago, came up with this crazy scheme to do it ALL on paper, with not a single actual test needing to be performed. This was all worked out by the Defense Electronic Supply Center back in the 1970's, and I watched in total shock and amazement when the trade mags described how this all was to be done. DESC no longer exists, and I think this whole debacle had something to do with that.
You look up in a book published by DESC what the reliability of a specific resistor, transistor, capacitor, etc. was, and then add up all of those parts and put them into an equation that gives you a total reliability. NO mechanical parts need APPLY! Motors, fans, bearings, disk drives, etc. are totally reliable! Also, all connectors, switches, and wiring are not prone to failure. The whole system is TOTAL BALONEY, but it is STILL used in many industries, because it makes such WONDERFUL numbers, even though anybody who cares KNOWS it is all FAKE! (DoD knows the whole methodology is bogus, and has gone back to more supportable methods of assessing reliability.) Sorry, rant mode off for now. Jon ------------------------------------------------------------------------------ Download BIRT iHub F-Type - The Free Enterprise-Grade BIRT Server from Actuate! Instantly Supercharge Your Business Reports and Dashboards with Interactivity, Sharing, Native Excel Exports, App Integration & more Get technology previously reserved for billion-dollar corporations, FREE http://pubads.g.doubleclick.net/gampad/clk?id=164703151&iu=/4140/ostg.clktrk _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users