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| In this
issue: |
Issue
17, July 2002 |
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Reliability HotWire is a service of ReliaSoft
Corporation
To subscribe or update your e-mail preferences, go to http://www.weibull.com/hotwire/index.htm
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| Hot Topics |
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Let the Data Speak
About Activation Energy
There
are many factors to consider when conducting an analysis of accelerated
test data. One factor that is often overlooked or misrepresented is the
activation energy. When considering accelerated life tests, the activation
energy represents the magnitude of effect that the applied stress will
have on the product under test. A large activation energy indicates that
the applied stress will have a large effect on the life of the product.
Understanding activation energy is one thing, but obtaining an accurate
value is another. Currently, the published values of activation energy
relate to a particular material, technology, or failure mode, but how this
value relates to a product, which may be composed of many different
materials, is unknown.
One possible method to
alleviate the problem of selecting the most representative activation
energy is to estimate the value based on collected data. Utilizing maximum
likelihood theory, the parameters of the Arrhenius model are solved while
using the Weibull distribution as the underlying life distribution. Once
the parameters have been estimated, the activation energy and acceleration
factor can be easily calculated.
To
read more, see http://www.weibull.com/hotwire/issue17/hottopics17.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.
Differences Between Type I (Time) and Type II (Reliability)
Confidence Bounds
When displaying confidence bounds on a plot there are many decisions
to be made, such as whether to use one-sided or two-sided confidence
bounds, what confidence level should be used and which confidence
interval method is to be implemented. But when creating a probability plot
you must also decide whether to display confidence bounds on time (Type I)
or on reliability (Type II). A probability plot contains both an axis for
time (x-axis) and an axis for reliability (y-axis), although the y-axis is
usually displayed in terms of probability of failure. Both types of
confidence bounds can be shown on a probability plot, so which one should
you use? This article will explain the differences between the two types
of confidence bounds and offer suggestions to help you decide which type
to use.
To read more, see http://www.weibull.com/hotwire/issue17/relbasics17.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 view a plot of Life vs. Stress, AF vs. Stress or Std vs.
Stress for multiple stresses at the same time in ALTA 6?
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In ALTA 6 PRO, what
do the Time Varying Stress Calculation options on the Calculations tab of
the User Setup mean?
To read more, see http://www.weibull.com/hotwire/issue17/tooltips17.htm
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Latest
Software Updates |
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Service Pack 3b (CRV 6.0.9)
is now available for ALTA
6. To download the latest service pack and to get information
regarding the modifications that were made, go to http://www.reliasoft.com/altaupdates.htm.
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| Hot
News |
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Reliability
Training Seminars - Next seminar in August in San Diego! The next ReliaSoft "Master the Subject, Master the Tools" seminar will be held in San Diego,
California from August 19 - 23, 2002 at the Holiday Inn by the Bay. For more information on course content and how to register, see http://www.ReliaSoft.com/seminars/master.htm.
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11th Annual Applied Reliability Engineering and Product Assurance Institute for Engineers and Managers
- Along with Boeing, Dade Behring, General Electric and Whirlpool, ReliaSoft will once again be co-sponsoring the Annual Applied Reliability Engineering and Product Assurance Institute for Engineers and
Managers. The institute will be held July 22-25, 2002 in San Diego, California. If you will be participating in the institute, be sure to attend the overview of ReliaSoft's reliability engineering software tools, given by ReliaSoft's President and CEO Pantelis Vassiliou on Thursday,
July 25th.
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Delphi joins the ranks of customers with ReliaSoft Corporate Wide Licensing - Delphi Automotive Systems is the most recent
company to obtain Corporate Wide Licensing of ReliaSoft's Weibull++ software. Welcome aboard Delphi!
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Ford Motor Company R&M Standardization Initiative - The Weibull++ MT software, which was specifically designed to address the needs of the
Ford Failure Reporting, Evaluation & Display program (aka "FRED"), has been released for a year now. ReliaSoft would like to thank Ford Motor Company and all Ford suppliers participating in this initiative for their support of the Weibull++ MT and BlockSim software.
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Summer Time Special - For the months of July and August only, ReliaSoft is offering
a US$575 discount for customers purchasing ALTA 6 PRO and Weibull++ 6 at the same time. This limited time offer can be used in addition
to the standard discounts for bundled purchases of software and training. For more information on bundled pricing options,
see http://www.ReliaSoft.com/bundles.htm.
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Reliability
Training at GM Knowledge Center - We
are pleased to announce that once again ReliaSoft will be providing
training classes for GM employees at the General Motors Knowledge
Center in Warren, Michigan. The courses offered will cover three
diverse disciplines of reliability engineering and include life data
analysis, accelerated life testing analysis and system reliability,
maintainability and availability analysis. For more information,
visit the GMU Knowledge Center Web site at http://www.gmulearning.com
or contact ReliaSoft at +1.520.886.0410. Class size is limited. GM
suppliers should check with GM for class availability. The remaining
2002 class schedule is as follows:
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August 5 - 7, 2002 - Life Data Analysis
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August 8, 2002 - Accelerated Life Testing
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October 14 - 16, 2002 - Life Data Analysis
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October 17, 2002 - System Reliability
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| From
The Edge |
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In addition to the
monthly Reliability HotWire, 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:
- Analyzing
Data from Equipment Downtime Logs
- For
product manufacturers who rely on repairable manufacturing
equipment, downtime logs can be a valuable source of life data for
reliability, maintainability and availability analyses. In order to
prepare the data for reliability analysis, the analyst must convert
the information in the equipment downtime logs into times-to-failure
and times-to-repair. This can be a time-consuming and error-prone
process when performed manually. This article describes the process
for converting equipment downtime logs to usable reliability data
and introduces Weibull++
MT, a special version of ReliaSoft's Weibull++ life data
analysis software package that provides utilities to automate the
process. See http://www.ReliaSoft.com/newsletter/1q2002/downtime.htm.
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Contribute
to HotWire
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Contributions
Welcomed
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.
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Copyright 2002 ReliaSoft
Corporation, ALL RIGHTS RESERVED
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