Forum: Reliability & Maintainability Questions and Answers

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Posted by: Johnson Wood (wuxiangping@huawei.com )
Organization:Huawei Tech.Ltd.,Co.
Date posted: Mon Oct 23 4:04:59 US/Eastern 2000
Subject: Reliability Training & cooperation
Message:
This is a telecommunication company, we research and develop telecom equipments,systems and networks(e.g.,switching,chansport,ATM,wireless,etc.). We apply reliability engineering technologies in products development, but we have little experiences. We need someone come to give us some trainings, and if possible, can cooperate with us and help us to solve actual problems. Any information will be welcome.

Replies:
Reliability Training
Patrick Hetherington Mon Oct 30 11:36:22 US/Eastern 2000

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Posted by: Glen Hanington (ghanington@littlefeet-inc.com )
Organization:Littlefeet, Inc.
Date posted: Fri Oct 20 19:58:37 US/Eastern 2000
Subject: Temperature Cycling versus Accelerated Life Testing
Message:
I understand that acceleration of life due to the application of a constant stress from a constant elevated temperature can be calculated using the Arrhenius Equation, assuming that the activation energy is known and the delta T is within a range where the equation does apply. But consider this: in order to maintain the system at a constant temperature, the flow of energy into the system must equal the flow out and be constant. Let's say this value is X joules/minute, and it's giving us an acceleration factor of 5 over ambient.
What I want to know is this: Suppose I perform temperature cycling of the system (hot and cold) for a number of cycles and calculate the average flow of energy into the unit as it goes hot, causing its temperature to rise. (This is also equal to the flow of energy out of the unit as it cools down.) If I find this average value to be 10X joules/minute, could this concievably be giving me an acceleration of 5*10=50, since the flow of energy is 10 times greater than that required to yield an AF of 5?

Replies:
Temperature Cycling vs. Accelerated Life Testing
Ken Tonnesen Wed Nov 1 13:16:22 US/Eastern 2000

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Posted by: Sheila Prather (sheila_s_prather@mail.northgrum.com )
Organization:Northrop Grumman Corporation
Date posted: Fri Oct 20 18:23:15 US/Eastern 2000
Subject: Laser Transmitter/Laser Designators Reliability
Message:
Any recent information on laser transmitter/designator (diode) reliability? I have some very old sources, but wondered if any current data available....Thanks

Replies:
Laser Diode Reliability Reference
Mary Priore Mon Oct 30 13:51:48 US/Eastern 2000

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Posted by: Dave White
Date posted: Fri Oct 20 13:20:26 US/Eastern 2000
Subject: Test Connections for ESS
Message:
Does anyone out there have a preferred method for attaching test leads to circuit boards during vibration testing?
The test I have in mind uses pseudo-random, broad band vibration in the 3 to 5 G range. I'm afraid that 'mini grabber' style test leads might give intermittent contact, or worse, provide a higher mass/longer moment arm that might fatigue the boards. Currently I have been temporarily soldering test leads on to the boards. Of course this adds time and I would like to reduce the setup time for the test if possible. I would appreciate any insights that others have. Thank you, Dave White

Replies:
Test Connections for ESS
Ed Sherwin Mon Oct 30 13:48:42 US/Eastern 2000

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Posted by: Ali Ashraf (ali.ashraf@appl.ge.com )
Organization:General Electric
Date posted: Fri Oct 20 9:31:01 US/Eastern 2000
Subject: Arrhenius equation. What is the value for Humidity acceleration Factor
Message:
What is the value for Humidity Acceleration Factor in Arrhenius equation to calculate the Duration of Test time(hours).

Replies:
Humidity Acceleration Factor
Bruce Dudley Mon Oct 30 13:45:32 US/Eastern 2000

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