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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: chandu (chandra_hari@rediffmail.com )
Organization:Nagarjuna univeristy
Date posted: Tue Mar 4 6:33:32 US/Eastern 2003
Subject: PREDICITON OF PARAMETER
Message:
I have some laboratory data (accelerated test)for Grade 1 item and Grade 2 item, i have estimated parameters of weibull distribution. For the Grade 1 item i have field data and i have estimated the parameters of weibull distribution. Here i have a problem in correlating the field data with laboratory data for grade 1 item. How can i correlate this Grade 1 data? By using this same same logic How can one predict the field data parameters for Grade 2 ? Please help me in this case....


Reply:

Subject: Test Extrapolation
Reply Posted by: bwd (bdudley@alionscience.com )
Organization: RAC
Date Posted: Tue Mar 4 16:15:06 US/Eastern 2003
Message:
The problem that you try to describe is difficult to understand. It seems that you have performed stress testing and are trying to correlate this with actual operating data. The correlation is showing that the stress data is not in agreement. This indicated to me that you have overstressed the accelerated test parameters resulting in failures that are not observed at normal conditions. Therefore, if grade one and two are similar items similar test conditions will result in overstressing this sample. Since we do not know anything about the grades and items being tested it is impossible to project field parameters based on the failure testing.


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