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Forum: Reliability & Maintainability Questions and Answers

Topic: Reliability & Maintainability Questions and Answers

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

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Original Message:

Posted by: Grib (kgrib@zodiac.com )
Organization:Aérazur
Date posted: Fri Jan 21 5:06:53 US/Eastern 2005
Subject: Activation Energy
Message:
I am looking for the energy activation for the thermostat component (switchs beteewin 0 and 10°C) in order to perform an accelerated test according to Arrhenius model. My interrogation concerns the existing data on this value of energy of activation or is it necessary to determine it by preliminary tests? Thank you in advance for your support.


Reply:

Subject: Activation Energy Thermostat
Reply Posted by: bwd (bdudley@alionscience.com )
Organization: RAC
Date Posted: Thu Feb 3 8:22:47 US/Eastern 2005
Message:
Activation energies are difficult to find and identify as many components have numerous failure mechanisms. In the case of thermostats, mechanical actions are significantly different than electronic types. Mechanical actions would be concerned with metal fatigue due to temperature cycling and vibration stress. Electronic versions would have a number of reactions including high temperature stress, humidity, vibration, electrical stress. The best way to determine any activation energy is to perform a series of tests at different stress levels and plot the results to find the activation energy. This method is shown in detail in the Finn Jensen paper "Activation Energies and the Arrhenius Equation", Quality and Reliability Engineering International, Vol. 1, Page 13-17, 1985. If you do not have the time or samples available to perform experimental testing, then for electronic components you could try a average activation energy. J.D. Seager and C.D. Fieselman wrote a paper for the IEEE Transactions on Reliability, Vol. 37, No. 5, December 1988 called "A Method to Predict an Average Activation Energy for Subassemblies.


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