Mean time between failures
McGraw-Hill Science & Technology Dictionary:
Top
mean time between failures
(′mēn ′tīm bi′twēn ′fāl·yərz)
(computer science) A measure of the reliability of a computer system, equal to average operating time of equipment between failures, as calculated on a statistical basis from the known failure rates of various components of the system. Abbreviated MTBF.
Top
(Mean Time Between Failure) The average time a component works without failure. It is the hours of observation divided by the number of failures.
Download Computer Desktop Encyclopedia to your PC, iPhone or Android.
abbr.mean time between failures; a measure of how reliable a system or system component is, determined by intensive testing or experience, or predicted by analyzing known factors. It may be expressed as a quantity of time or of successful usages or cycles between failures.
See the Introduction, Abbreviations and Pronunciation for further details.
Abbreviations:
Top
MTBF
is short for:
| Meaning | Category |
| Mean Time Between Failures | Academic & Science->Electronics Computing->Hardware Computing->Security Governmental->Military Computing->Drivers Governmental->NASA Governmental->FDA Miscellaneous->Aircraft Academic & Science->Physics |
| Mean Time Between The Failures | Miscellaneous->Unfiled |
| Mean To Between Failures | Miscellaneous->Unfiled |
| More Time Before Finals | Academic & Science->Universities |
Click here to submit an acronym.
McGraw-Hill Dictionary of Aviation:
Top
mean time between failures
A statistical measure of the average length of time between the successive failures of equipment or a system. For the specified time interval, the total operating time of the population of material divided by the total number of failures within the same population.
Wikipedia on Answers.com:
Top
Mean time between failures
 |
This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. (December 2010) |
Mean time between failures (MTBF) is the predicted elapsed time between inherent failures of a system during operation.[1] MTBF can be calculated as the arithmetic mean (average) time between failures of a system. The MTBF is typically part of a model that assumes the failed system is immediately repaired (MTTR), as a part of a renewal process. This is in contrast to the mean time to failure (MTTF), which measures average time to failures with the modeling assumption that the failed system is not repaired (infinite repair rate).
The definition of MTBF depends on the definition of what is considered a system failure. For complex, repairable systems, failures are considered to be those out of design conditions which place the system out of service and into a state for repair. Failures which occur that can be left or maintained in an unrepaired condition, and do not place the system out of service, are not considered failures under this definition.[2] In addition, units that are taken down for routine scheduled maintenance or inventory control, are not considered within the definition of failure.
|
Contents
|
Overview
For each observation, downtime is the instantaneous time it went down, which is after (i.e. greater than) the moment it went up, uptime. The difference (downtime minus uptime) is the amount of time it was operating between these two events.
MTBF value prediction is an important element in the development of products. Reliability engineers / design engineers, often utilize Reliability Software to calculate products' MTBF according to various methods/standards (MIL-HDBK-217F, Telcordia SR332, Siemens Norm, FIDES,UTE 80-810 (RDF2000), etc.). However, these "prediction" methods are not intended to reflect fielded MTBF as is commonly believed. The intent of these tools is to focus design efforts on the weak links in the design.
Formal definition of MTBF
By referring to the figure above, the MTBF is the sum of the operational periods divided by the number of observed failures. If the "Down time" (with space) refers to the start of "downtime" (without space) and "up time" (with space) refers to the start of "uptime" (without space), the formula will be:
The MTBF is often denoted by the Greek letter θ, or
The MTBF can be defined in terms of the expected value of the density function ƒ(t)
where ƒ is the density function of time until failure – satisfying the standard requirement of density functions –
Variations of MTBF
There are many variations of MTBF, such as mean time between system aborts (MTBSA) or mean time between critical failures (MTBCF) or mean time between unit replacement (MTBUR). Such nomenclature is used when it is desirable to differentiate among types of failures, such as critical and non-critical failures. For example, in an automobile, the failure of the FM radio does not prevent the primary operation of the vehicle. Mean time to failure (MTTF) is sometimes used instead of MTBF in cases where a system is replaced after a failure, since MTBF denotes time between failures in a system which is repaired. MTTFd is an extension of MTTF, where MTTFd is only concerned about failures which would result in a dangerous condition.
MTTF and MTTFd calculation
,
,
where B10 is the number of operations that a devices will operate prior to 10% of a sample of those devices would fail. B10d is the same calculation, but where 10% of the sample would fail to danger. nop is the number of operations/cycles.[3]
Notes
- ^ Jones, James V., Integrated Logistics Support Handbook, page 4.2
- ^ Colombo, A.G., and Sáiz de Bustamante, Amalio: Systems reliability assessment – Proceedings of the Ispra Course held at the Escuela Tecnica Superior de Ingenieros Navales, Madrid, Spain, September 19–23, 1988 in collaboration with Universidad Politecnica de Madrid, 1988
- ^ [http:\\www.tuv.com/web/media_get.php?mediaid=29575&fileid...2 "B10d Assessment - Reliability Parameter for Electro-Mechanical Components"]. TUVRheinland. http:\\www.tuv.com/web/media_get.php?mediaid=29575&fileid...2. Retrieved 16 April 2012.
See also
References
- Jones, James V., Integrated Logistics Support Handbook, McGraw–Hill Professional, 3rd edition (June 8, 2006), ISBN 0-07-147168-5
External links
This entry is from Wikipedia, the leading user-contributed encyclopedia. It may not have been reviewed by professional editors (see full disclaimer)
Post a question - any question - to the WikiAnswers community:
Copyrights:
McGraw-Hill Science & Technology Dictionary
McGraw-Hill Dictionary of Scientific and Technical Terms. Copyright © 2003, 1994, 1989, 1984, 1978, 1976, 1974 by McGraw-Hill Companies, Inc. All rights reserved.
Read more
Computer Desktop Encyclopedia
THIS DEFINITION IS FOR PERSONAL USE ONLY.
All other reproduction is strictly prohibited without permission from the publisher.
© 1981-2012 The Computer Language Company Inc. All rights reserved. Read more
All other reproduction is strictly prohibited without permission from the publisher.
© 1981-2012 The Computer Language Company Inc. All rights reserved. Read more
Oxford Dictionary of the US Military
The Oxford Essential Dictionary of the U.S. Military. Copyright © 2001, 2002 by Oxford University Press, Inc. All rights reserved.
Read more
Abbreviations
STANDS4.com - The source for acronyms and abbreviations. Copyright © 2004-2012 STANDS4 LLC. All rights reserved.
Read more
McGraw-Hill Dictionary of Aviation
An Illustrated Dictionary of Aviation.. Copyright © 2005 by McGraw-Hill Companies, Inc. All rights reserved.
Read more
