Forum: Reliability & Maintainability Questions and Answers
Posted by: Terry McCrossan Date posted: Mon Jul 5 17:24:19 US/Eastern 1999 Subject: Component Derating Message: Does anyone have any new quantifiable data on the use of component parameter derating (thermal, power etc). I am used to the usual "margin of ignorance" type arguments, package glass transition temperatures and the junction/channel type Arrhenius relationships (generally with assumed activation energies). However, is there any more recent quantifiable data available to convince a sceptical design engineer and to what extent is derating used?
Posted by: Russell Davies (russell.davies@elekta.com ) Organization:Elekta Date posted: Wed Jun 16 5:38:36 US/Eastern 1999 Subject: X-Rays and Electronics Message: I am a safety/reliability engineer for a medical electronics company that manufactures radiotherapy equipment. I was wondering is there any specific information regarding the reliability of electronic systems operating in the region of high energy kV and MV level X-rays. All information that I seem to uncover on radiation seems to focus on solar radiation levels.
Posted by: Julien NICO (ARZ_ST_ELB@compuserve.com ) Organization:Aérazur Date posted: Tue Jun 15 9:52:43 US/Eastern 1999 Subject: Reliability system analysis Message: I am working for a compagny which begin to design aeronautic system (we were before supplier of single component for helicopters and aircraft). New project need to have more complex studies and answer lot of points defined by the manufacturer. In order to answer these points, we have to establish several documents and to answer qualitatives and quantitatives requirements such as design features (safety factors, part derating criteria, redundancies...) or a high level of integrity or the equipment shall be design and manufactured to prevent injury to the personnel during the installation, operation, maintenance, and repair or interchanging of the complete equipment or equipment part thereof. I know that for reliability and safety analyses, I have to create FMEA and Fault Trees (I know how to do) but I don't know how to perform this type of analyses (answer qualitative and quantitaitves requirements). I don't know if for each statement, I have to answer with just a sentence with reference to a standard or thing like that or to perform an analysis. I really need help because all documents that I found for the moment have not been really helpfull for me (such as SAE ARP 4761, MIL STD 785B) I will really appreciate if someone can give me some (lot of) help. Many thanks
Posted by: Jose Valderrabano (c80986@casa.es ) Organization:Construcciones Aeronauticas S.A. Date posted: Fri Jun 11 8:26:33 US/Eastern 1999 Subject: Component obsolescence Message: The equipment suppliers are changing the military components of their equipments to commercial components. These commercial components will not have the same MTBF. Is there any handbook for reliability prediction of these kind of components?
Posted by: Tami Szerencse (taszerencse@crownintl.com ) Organization:Crown International Date posted: Wed Jun 9 11:22:13 US/Eastern 1999 Subject: environmental stress tests Message: Help! I am an engineering intern at an audio electronics manufacturer, Crown International. My job for this summer is to write up a new set of Product Validation Specifications for our amplifiers which are in widely used at concerts, sporting events, and the like. I would appreciate any information that anyone could give me, including web sites and reference articles, that would point me in the right direction as to what kind of tests we need to perform (thermal shock, vibration, mechanical shock/drop, etc.), what the standards for these tests might be, and how to go about performing these tests. I have little experience in this area but am anxious to learn. Thank you in advance for any help.
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