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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 khider (kgrib@zodiac.com )
Organization:Aérazur - Zodiac group
Date posted: Mon Nov 8 7:10:55 US/Eastern 2004
Subject: Accelerated testing
Message:
We have performed an accelerated test using Arrhenius acceleration factor in order to obtain a service life of fuel tank (acceleration factor between life t at temperature T and life t’ at reference temperature T’). For the test we have filled a tank with air instead of fuel. I am looking for a factor between air and fuel to apply in order to be more representative of tank utilization. I will really appreciate if someone have a method to obtain this factor or how we can do to be more realistic?


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Reply:

Subject: Fuel Tank Accelerated Testing
Reply Posted by: Ken
Date Posted: Thu Nov 11 16:29:00 US/Eastern 2004
Message:
In addition to RACs reply, consider the following: Air is compressible and will not apply the same stresses as non-compressible fluids; therefore, I doubt any reliable conversion exists. Testing of a tank that is designed to carry liquid fuel by filling it with air is not a comprehensive test. The weight of the fuel is needed to stress the seams and any integral hanger brackets/attach points. Also, some of the testing should be performed using a full tank and something other than full to account for sloshing forces on the tank, baffles, internal plumbing, and hanger sway stresses. Operational profile needs to be applied to determine the amount to fill or pick a worse case. A full tank becomes something less than full as soon as it is placed in use. Fill lines and discharge lines need to be attached at both ends, filled with fluids as they would be in operation, and pressurized, as they would be in operation, to stress fittings to the tank.


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