Reliability HotWire

Issue 96, February 2009

Tool Tips

* What tools does ReliaSoft offer to help engineers design reliability tests?

ReliaSoft offers several tools to help engineers design effective reliability tests:

  • Weibull++ and ALTA include the Design of Reliability Testing (DRT) utility. This utility allows you to determine the required number of units and/or test time required to demonstrate a certain reliability result. It is a useful tool when you need to evaluate the number of units, the test time required under a certain testing scenario or the reliability and confidence that can be demonstrated if such a scenario were actually implemented. The Reliability HotWire article entitled Design of Reliability Tests (Issue 24) shows how to use the utility. While the article was written for Weibull++ 6, the material is still valid in Weibull++ 7 and ALTA.
  • Weibull++ and ALTA also include the SimuMatic utility. This utility allows you to perform a large number of reliability analyses on data sets that have been created using Monte Carlo simulation. This can help you to a) better understand life data analysis concepts, b) experiment with the influences of sample sizes and censoring schemes on analysis methods, c) construct simulation-based confidence bounds, d) better understand the concepts behind confidence bounds and e) design reliability tests.
  • ALTA includes the Accelerated Life Test Plans utility, which assists you in designing an accelerated life test that will yield the closest possible estimate of product life at the percentile and the use stress level you specify. You can design plans for one or two stresses. The Reliability Edge article entitled "Accelerated Life Test Plans" (Volume 8, Issue 1) demonstrates the use of this utility.
  • DOE++ is designed to facilitate traditional Design of Experiments (DOE) techniques for studying the factors that may affect a product or process in order to identify significant factors and optimize designs.

ReliaSoft also offers two courses that provide information about reliability tests.

In addition, the following publications include information that you can use:

  • The Test Design topic in ReliaSoft's Life Data Analysis Reference provides an overview of test design theory.
  • The Cumulative Binomial for Test Design and Analysis Reliability Edge article presents a summary of the techniques available to use the cumulative binomial distribution to assist in the design of effective reliability demonstration tests and also to determine the reliability that has been demonstrated in a test with few or no failures.
  • The Using OC Curves in Design of Reliability Tests Reliability HotWire article describes how to use operating characteristic curves when designing reliability tests.
  • Several of ReliaSoft's team members have published papers and/or given presentations that talk about reliability tests. For a list, refer to

* What discounts are available for ReliaSoft's training seminars?

When you are registering for training seminars with ReliaSoft, bear in mind that there are several money-saving opportunities that you may be able to take advantage of. Please visit for the latest info.

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