The concept is derived from the human life experience involving infant mortality, chance failures, plus a wear out period of life since data for births and deaths is accumulated by government agencies. Most equipment lacks the birth/death recording by government agencies and most non-human systems can be regenerated to live/die many times before relegation to the scrap heap.
Why: Failure rates are different for both people and equipment at different phases of operation and the medicine to be applied to both humans and equipment need to be considered for effectively treating the roots of the problem.
When: The concept is useful during design, operation, and maintenance of equipment and systems to understand the failure mechanisms
Where: It explains the human experiences to the ordinary person to relate equipment/system failures to those experienced in real life so as to coordinate the design, operation and maintenance of equipment. For other definitions see MIL-HDBK-338, section 9.
These definitions are written by H. Paul Barringer and are also posted on his web site at www.barringer1.com
Comments (1)
As the end of life(EOL) approaches I would like to be able to calculate a value in hours where the failures start to increase at the base of the upward curve of the bathtop, ie, which would be less than the MTBF. The reason is so we may start to replace equipment before it fails.
Some units have been in the field 10 years, some 9 years, some 8 years.....
I have the number of failures that have occurred each year and the number of hours for each failure.
Of course as the number of years that a unit has been in the field decreases the number of failures is less.
Any help would be appreciated and an equation would be great.
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1) Posted 1:51 pm, 17 November 2010 by Dick Silva