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Forum: Reliability Testing January 2nd, 2015, 05:09 PM
Replies: 1
Views: 4,719
Posted By avanti
Point Estimate for Reliability

In a Reliasoft authored paper, Reliability Estimation for One-Shot Systems with Zero Component Test Failures by Huairui Guo, equation 14 provides a reliability estimate (E(r) = n/(n+1)) and equation...
Forum: Other Reliability Discussions September 17th, 2014, 10:54 PM
Replies: 2
Views: 6,958
Posted By avanti
Re: Suggestions Dissertation on Reliability Engineering

If not too late how about "reliability of high-cost one-shot mechanical devices based on sample testing".
Forum: Design for Reliablity (DFR) August 2nd, 2014, 05:02 PM
Replies: 2
Views: 7,308
Posted By avanti
Re: Reliability Estimation/ Reliability Growth

Early in the design process I develop a reliability number - based on this number I then decide whether to add redundancy.
Forum: Ask Members for Help July 19th, 2013, 01:52 PM
Replies: 2
Views: 5,218
Posted By avanti
Re: Environmental testing

If you look at MIL-STD-810 it lists the degradation effects due to humidity.

Have you checked the SAE site for specifications applicable to your needs:...
Forum: Ask Members for Help July 3rd, 2013, 04:06 PM
Replies: 1
Views: 6,150
Posted By avanti
Re: Reliability/ Durability

RiAC's "System Design Toolkit" defines these terms.

In my opinion reliability is stated as a number (R = .999 @ 95% confidence level).

And life and duability are defined in hours or cycles.
Forum: Ask Members for Help June 10th, 2013, 09:01 PM
Replies: 6
Views: 9,184
Posted By avanti
Re: Is it design related?

Sory. I don't have any opinion on this metric (as defined by O'Connor). I would expect your customer to define what is acceptable.
Forum: Ask Members for Help June 8th, 2013, 11:38 AM
Replies: 6
Views: 9,184
Posted By avanti
Re: Is it design related?

I am intrigued by your comments.
Could you show an example where a design improvement would not lead to increase in life?
I consider design to include design of production, inspection...
Forum: Ask Members for Help June 7th, 2013, 03:49 PM
Replies: 6
Views: 9,184
Posted By avanti
Re: Is it design related?

Not sure if this what you are looking for:
http://www.reliasoft.com/alta/examples/rc4/index.htm

My experience is that design actions can usually extend life (however often their is an optimum...
Forum: Reliability & Maintenance August 27th, 2012, 04:39 PM
Replies: 2
Views: 12,236
Posted By avanti
Re: Maintainability Target Setting

I searched through all my reliability books and found few of them referred to servicability.

However Kapur and Lambertson define the term in Reliability in Engineering Design (page 225) as...
Forum: Ask Members for Help August 15th, 2012, 11:32 AM
Replies: 3
Views: 4,802
Posted By avanti
Re: textile reliability

Actually the inflatable structures I work with do utilize porous textiles, but I agree that the reliability methods for my products are probably not directly suitable for items like jump suits.
...
Forum: Ask Members for Help August 6th, 2012, 11:11 AM
Replies: 3
Views: 4,802
Posted By avanti
Re: textile reliability

I perform reliability analyses of inflatable textile structures (usually one-use items) subject to high loads. I use structural analysis, sample & joint tests, and overspeed flight test to accumulate...
Forum: Ask Members for Help July 16th, 2012, 09:01 PM
Replies: 4
Views: 6,170
Posted By avanti
Re: Reliability Allocation

I use the equal apportionment, as shown in Kathleens link, as a departure point.
In my product lines I usually have a mixture of parallel and series components with each components being dependent...
Forum: Reliability Testing July 6th, 2012, 03:48 PM
Replies: 3
Views: 7,656
Posted By avanti
Re: Probability of observing failure

I've seen the (n+1) term used before. I recall that it derives from finding failures in multiple lots each of size n. I searched my library but could not locate a source.
Forum: Ask Members for Help June 22nd, 2012, 04:15 PM
Replies: 10
Views: 8,762
Posted By avanti
Re: Cummulative damage model - Life-stress relationship

Until you get a specific answer to your question have you tried making up an Excel spread sheet? Fatigue info for many metals is contained in MIL-HDBK-5 and reliabilty techniques are presented in...
Forum: Accelerated Testing June 18th, 2012, 09:55 AM
Replies: 3
Views: 7,617
Posted By avanti
Re: Vibration testing on Mechanical component

Look at MIL-STD-810 - it specifies vibration testing for a wide range of applications.
Forum: Ask Members for Help June 10th, 2012, 09:53 AM
Replies: 7
Views: 6,313
Posted By avanti
Re: Why lower Confidence Level leads to higher MTBF?

For reliability calculations I use the lower confidence bound. Looking at the two graphs David posted for 100 hours (for example) the reliabilities at the 70% and 95% confidence levels are .96 and...
Forum: Ask Members for Help May 23rd, 2012, 05:19 PM
Replies: 4
Views: 4,616
Posted By avanti
Re: how i can estimate or evaluate the reliability prediction

Mido85,

It appears you are being very ambitious in your masters thesis if you have not previously taken a course in reliability.

However since you mentioned valves and machines I suggest you...
Forum: Accelerated Testing April 13th, 2012, 10:00 PM
Replies: 1
Views: 6,395
Posted By avanti
Re: HALT and Tin Whiskers

I recall reading one report where tin whisker growth was accelerated by submitting test specimens to high pressure (several thousand psig).
Forum: Reliability Analysis March 24th, 2012, 09:18 AM
Replies: 5
Views: 9,479
Posted By avanti
Re: MTBF - Counting failures with the same root cause

Disconnected pneumatic hose: Unless their was a design change to prevent reoccurrence I would count this as a failure.

Blocked orifice: What was the cause of the debris? If it was from within the...
Forum: Ask Members for Help February 20th, 2012, 04:44 PM
Replies: 8
Views: 7,839
Posted By avanti
Re: Gearbox Reliability

I suggest you do a search for gearbox reliability using Google Scholar or in the DTIC and NTIS data bases.

Here are a two of many I found:

http://www.dtic.mil/dtic/tr/fulltext/u2/a226496.pdf...
Forum: Ask Members for Help February 16th, 2012, 03:31 PM
Replies: 8
Views: 7,839
Posted By avanti
Re: Gearbox Reliability

There is a section on gear reliability in the NSWC Carderock Division Handbook of Reliability Prediction Procedures for Mechanical Equipment.
Forum: Other Reliability Discussions January 25th, 2012, 10:16 AM
Replies: 5
Views: 9,334
Posted By avanti
Re: How old is Reliability concept?

Check here for availability including sellers and libraries (also snippets):...
Forum: Other Reliability Discussions January 24th, 2012, 06:34 PM
Replies: 5
Views: 9,334
Posted By avanti
Re: How old is Reliability concept?

The bridge analogy is correct although its reliability is qualitative not quantitave.

In his book Reliability Concepts in Engineering Manufacture the author Dr. R H W Brook discusses how the...
Forum: Ask Members for Help December 20th, 2011, 12:27 PM
Replies: 1
Views: 4,703
Posted By avanti
Re: How to define the reliabilty goal and confidence level

Maybe you can adapt the analysis shown in this document to your product
https://www.ncjrs.gov/pdffiles1/nij/223054.pdf
Maybe an option would be to vary thickness rather than velocity.
A...
Forum: Reliability Testing December 19th, 2011, 02:27 PM
Replies: 7
Views: 16,574
Posted By avanti
Re: Difference between Demonstration testing and qualification testing

I disagree with part of this definition.
Not all acceptance testing is statically derived - cost is often a driver.
Acceptance testing may result in non-conforming items which may be scrapped,...
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