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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: JJC
Date posted: Fri Nov 17 10:07:10 US/Eastern 2000
Subject: Defining Accelerated Life Tests
Message:
Can anybody help in defining the conditions for accelerated life tests. I have a device that is to go through ALT and I would like some information as to how I determine the accelerated conditions that are to be used. Thanks in advance.


Reply:

Subject: Accelerated Life Testing
Reply Posted by: Bruce Dudley (bdudley@alionscience.com )
Organization: Reliability Analysis Center
Date Posted: Mon Nov 20 9:54:05 US/Eastern 2000
Message:
There are no magic analytical models that accurately estimate the life of complex assemblies. Each life analytical model describes physical change mechanisms associated with specific material characteristics. The first step in constructing accelerated tests is to define the failure mechanisms in terms of the materials used in the product to be tested. The next step is to determine the environmental parameters the product will be exposed when operating and when not operating or stored. Based on the failure mechanisms most likely to limit the life of the product, one can choose a test or tests that will accelerate that failure mechanism. Some of the models that can be considered are: Miner's Rule for accumulated fatigue, Arrhenius Temperature test for accelerated chemical aging effects, Peck's Model for temperature and humididty combined effects, Coffin-Manson non-linear mechanical fatigue damage model and Eyring/Black/Kenney models for temperature and voltage acceleration.


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