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Problem/Question(December 7, 2005):

Hello

I’m just collecting information about the scientific reliability scene especially for mechatronic (embedded) systems. As I do not have an appropriate overview about the American/Anglo-Saxon activities I use this way to get some Expert information additionally to the www.

Can you give me some names of scientific institutions (Universities, …) that are concerned with that subject?

Thank you in advance

Patrick Jäger
-------------------------------------------

Dipl.-Ing. Patrick Jäger
JHP Jäger, Hitziger & Partner
Pfaffenwaldring 9
70569 Stuttgart
Tel.: 0711-685-6953
Fax: 0711-685-6319
jaeger@ima.uni-stuttgart.de

Solution/Answer: Can you help?

Problem/Question(Oct 16, 2005):

Hi

Does anybody have an idea on Confidence levels of Wiebull analysis for bearing reliability testings ?

Regards

Rohan Dubey

Application Engineer-Automatic Transmissons
Timken Engineering and Research India Pvt. Ltd.
Electronic City Phase- II,
Hosur Road Bangalore

dubeyr@timken.com

Solution/Answer: Can you help?

Problem/Question(Oct 10, 2005):c

Hello,

We are using ceramic chip capacitor 15KPF/100V X7R 10 % in our CDI pulser circuit application as by pass capacitors.Maximum signal voltage is 50 V peak. In our production line we are facing capacitor short. This is also observed before electical testing of the product. At incoming inspection stage some of the capacitors were checked and found O.K. We have checked our process of manufacturing but could not identify the root cause.
Please help us in finding possible reasons of the failue.

P.C.Kandpal
pc.kandpal@lml.co.in

Solution/Answer: Can you help?

Problem/Question(Aug 26, 2005):

Hello,

I'm new in the reliability subject and I have to calculate the MTBF for one product that we manufacturate, (electronic product). This product has a front bezel (LCD), power supply, fan and of course a lot of electronic components, (capacitors, resistors, IC's, etc).

What I need to know is if it's ok if I put togheter the bezel and the fan MTBF's with the electronic board MTBF?

Somebody told me that these two parts can not be in the same calculation as the board because they have diferent distribution, (normal distribution), as the electronics components, (exponential distribution).

Somebody who can explain me this? Or recommend a website to read about this?

I'll appreciate your help.

Regards,

Juan Mexia
juan.mexia@gmail.com

Reply, October 27, 2005

The answer depends on the tools that you are using. If you are using a closed form calculation, for example in a spreadsheet, then the failure distributions need to be the same. If you are using a monte-carlo tool, then you should be able to mix and match any failure distributions. Since you use the term MTBF for all of the components, it appears that you are dealing with only exponential failure distributions. You should be able to sum up all of the failure rates on a spreadsheet consistent with the series/parallel configuration of the system. You should be able to find the appropriate formulae in any reliability text book.

Ted Hardwicke
GE Energy

Solution/Answer: Can you help?

Problem/Question(Jul 17, 2005):

Gentlemen:

I am seeking assistance in undertaking a Reliability and Availability Characrteristic study of duty/standby ventilation fans for a 'critical process' application.

We have the capacity to undertake the engineering analysis but need guidance on the process and/or standards that may apply.

For example, I am aware Blanchard and Fabricky have published a handbook some years ago that is helpful. Are you in a position to advise other publications that may assist?

Are there US and/or ISO and/or IEC standards that are recognised as definitive?

I look forward to your response.

Alan A. Irwin
a.irwin@ndy.com
Senior Associate
Group Manager, Infrastructure and Industrial

NORMAN DISNEY & YOUNG
Level 10, 1 Chandos St
St Leonards NSW 2065
AUSTRALIA
http://www.ndy.com

Solution/Answer: Can you help?

Problem/Question(Jul 17, 2005):

Hi !

The MTBF requirements for our products are to be 4yrs. Our products are installed in a combined environment of temperature and vibration.The normal vibration is 0.74 grms and the operating temperture levels are -40 to 70 deg according to specification.The normal average temperature where these units are to be installed is 25 deg. I want to run an ALT to confirm the MTBF of 4yrs by running the units at 70 deg for a period of 91 days which will equate to 4yrs using the arrhenuis equation. But my biggest problem is because it's a combined environment I have to excute vibration with temperature, since our average vibration is 0.74 grms I must use a higher value. Surely I cannot run this continously for 91 days. Can you help?. I don't have a problem wuth temperature just what vibration to expose and for how long.

Your assistance in this matter will be highly appreceiated.

Deven

Deven Subramoney
deven.subramoney@prolificx.com

Solution/Answer: Can you help?

Problem/Question(Jul 17, 2005):

Looking for help:

I have an application that requires a 28mm x 40mm cooling fan with a CFM of 21, but I need a fan with high reliability with a low cost. The fan where currently using has an MTBF of 40,000 hours. Does anyone know of other fans with higher MTBF or longer life? Please send your replies to rhiggins@coldwatt.com

Thank you,

EurPhys Dr. Richard Higgins, CSci, CPhys, PE

Solution/Answer: Can you help?

Problem/Question(Mar 30, 2005):

Dear Sir/Madam,
We recently adjusted the danger and the alarm setpoint of our 3300/20 card from 16 danger and 12 alarm setpoints to 23 danger and 19 alarm. After setting switches to their original positions (bypass and setpoint selector switches). We reinstalled the face plate in place. The OK green LED's are blinking at 5 Hz which indicates "errors in code", How can we determine the error and what exactly can we do to resolve this error? ?

Thank you,

Vincent Lee
vincentlee@siemens.com

Solution/Answer: Can you help?

Problem/Question(Mar 13, 2005):

Dear Sir/Madam,
At the plant where I work we are now developing a RCM programme, one of the issue arising is a Spare Pump Philosophy, we want the spare pump to be Reliable even more so than the Main pump.The question is however, which is best, to run the main pump for a period of three months and then the spare for one month, or continue as it is now, the spare being run for a period of eight hours every week?.

There are two different views on this matter, one is, the longer run period is better because it puts the spare under a more reliable test and reducing the wear associated with frequent start ups(bathtub curve). The other view is you want the spare pump to be in as "new " a state as possible therefore shorter run times are required.

Could you shed some views on this matter?

Thank you,

Vishnu Mahabir
Vishnu.Mahabir@petrotrin.com

Solution/Answer: Can you help?