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In this issue: |
Issue 7, September 2001 |
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Reliability HotWire is a service of
ReliaSoft Corporation
To subscribe or update your e-mail preferences, go to
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Hot Topics |
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Using
Accelerated Life Testing Analysis to Characterize "Shelf Life"
In this case
study, we take a look at how ReliaSoft's ALTA software can be utilized to
characterize the "shelf life" of certain chemicals. Most life data or
accelerated testing analyses have time as the dependent variable and other
inputs as stress factors. However, in this case, time will be considered
to be the stress factor, while the dependent variable is a particular
characteristic of the chemical, such as concentration. Through this type
of analysis, one can determine the probability that the chemical's
characteristic will be outside an acceptable range of values based on test
readings taken at various time intervals.
To read more, see
http://www.reliasoft.com/alta/examples/a7ex6/index.htm
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Reliability Basics |
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The purpose of this section is to offer background and advice to the novice
reliability engineer.
The Reliability Function
The most frequently used function in life data analysis and
reliability engineering is the reliability function. This function gives
the probability of an item operating for a certain amount of time without
failure. As such, the reliability function is a function of time, in that
every reliability value has an associated time value. In other words, one
must specify a time value with the desired reliability value, i.e.
95% reliability at 100 hours. This degree of flexibility makes the
reliability function a much better reliability specification than the
MTTF, which represents only one point along the entire reliability
function.
In this article, we will take a
look at the reliability function, how it is derived, and an elementary
statistical background.
To read more, see
http://weibull.com/hotwire/issue7/relbasics7.htm
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Tool Tips |
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The Tool Tips
section addresses helpful hints and frequently asked questions about
ReliaSoft software products.
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How do I remove the
Program ID from the plots in Weibull++ and ALTA?
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Is there a quick
way to specify stress profiles in ALTA 6 PRO?
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Can I have circular
references in my RBD in BlockSim?
To read more, see
http://weibull.com/hotwire/issue7/tooltips7.htm
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Hot News |
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 Sold
Out Reliability Seminar -
We want to express our appreciation to everyone who attended the
sold out "Master the Subject, Master the Tools" reliability
training seminar in San Diego, California last week. Thanks for your
participation!
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BlockSim
MT for the Machine Tool Industry
- ReliaSoft has been working closely with Ford Motor Company and
their machine tool suppliers to develop a customized version of
BlockSim. BlockSim MT, which was released earlier this month, was
designed to provide an easily understandable standardized R&M
report, including an Operational Availability Tree for machine tool
equipment.
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Next
Seminar in Tucson, October 15 - 19 -
The next ReliaSoft "Master the Subject, Master the Tools"
reliability training seminar will be held October 15 - 19, 2001 in
Tucson, Arizona at the Sheraton Hotel and Suites. Topics for this
five-day seminar include life data analysis, accelerated life
testing data analysis, and system reliability, maintainability and
availability. For more information on course content and how to
register, see
http://Seminars.ReliaSoft.com.
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QALT
Boot Camp -
ReliaSoft will begin offering an intensive three-day course on
advanced topics, concepts and applications of quantitative accelerated
life testing (QALT) with its "QALT Boot Camp." This is a three-day
seminar that covers advanced topics in accelerated life test data
analysis such as time-varying stresses and multiple stress testing.
The next QALT Boot Camp will be held in Tucson, Arizona on November 14
- 16, 2001 (New dates!). For more information on
course content and how to register, see
http://seminars.reliasoft.com/gencourses/rs521.htm. |
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From the Edge |
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Every quarter,
ReliaSoft publishes Reliability Edge, a printed journal that
includes articles and information related to the field of reliability
engineering. Articles of interest in the current edition:
- Using Degradation Data for Life Data Analysis - One of the
obstacles to performing a complete life data test is the amount of
time it may incur. Given reduced development cycle time and increased
product reliability, it may be unrealistic to run test units to
failure in a timely fashion.
The analysis of
degradation data is one way to overcome this obstacle. Degradation
analysis involves the measurement of the degradation of a product,
where the degradation can be directly related to the expected failure
of the product. This information is then used to estimate the eventual
failure time for the product. See http://www.ReliaSoft.com/newsletter/2q2001/degradation.htm.
- Classic Case Studies in Reliability Analysis: The Weibull
Distribution - It has been exactly 50 years since Professor
Walloddi Weibull published his groundbreaking paper, "A Statistical
Distribution Function of Wide Applicability," in the Journal of
Applied Mechanics. The 1951 paper contained seven case studies.
This article revisits the first of these examples using modern
computer tools.
See
http://www.ReliaSoft.com/newsletter/2q2001/classic_weibull.htm.
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Contribute to Hotwire
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Contributions Welcome
As always, your feedback and contributions are appreciated.
ReliaSoft is able to provide the most user-friendly reliability software
packages and support because we listen to our customers. This applies to
our newsletters and publications as well. We welcome any suggestions or
contributions you may have for Reliability HotWire. If you have a
topic or article that you think would be useful to the readers of
Reliability HotWire, feel free to contact us. We can be reached by
e-mail at HotWire@ReliaSoft.com,
or by standard mail at 1450 S. Eastside Loop, Tucson, AZ 85710-6703,
USA.
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Copyright © 2001
ReliaSoft Corporation, ALL RIGHTS RESERVED
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