Reliability Demonstration Testing

Reliability Demonstration Testing


There are many forms of reliability testing that may be applied at the component, assembly, product, equipment and/or system level. Some are intended to find design problems so that they can be fixed (accelerated tests; test, analyze and fix (TAAF) or reliability growth testing (RGT)). Others are intended to find manufacturing defects and repair them prior to shipping the item (environmental stress screening (ESS) or highly accelerated stress screening (HASS)). Reliability demonstration/qualification tests are a subset of a larger group, collectively known as compliance tests. In general, the purpose of compliance tests is to demonstrate, often statistically, that a specific item performance parameter is in compliance with a requirement. Reliability compliance tests like RDT/RQT focus on reliability parameters such as MTBF, meantime- to-failure (MTTF), failure rate (failure intensity), or probability of failure.

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Product Description

The series name has a double meaning:
(1) the spelling of the name r-e-l-e-a-s-e indicates that the series is intended to “release“ the non-expert down the path to reliable products and
(2) the complementary terms “REL” with “ease”, implying the series goal of “reliability made easy.”

Of course, reliability success is seldom easy, requiring expertise and tailoring with tradeoffs addressing life-cycle costs and other issues, but we hope that the series will help those not familiar with reliability practices understand the basics.

While it is unlikely that the reader will become an instant expert in reliability by reading the RELease guides, it is likely that he/she will gain a better appreciation of the basic tools that lead to designing and building reliability into products and systems. The number of pages in each guide is intentionally limited to address only the basics, with comprehensive authoritative references listed for those wanting to know more. The initial set of guides will be continuously expanded in the future. Please let us know how the series can be improved to meet your needs in introducing reliability to the non-expert, or suggest other topics you would like to see developed.

Additional information

File Type:



Richard Wisniewski





Publication Date:

December 2013

Table of Contents

1. What is Reliability Demonstration/Qualification Testing       2
  1.1. Cost-Benefit Tradeoff     3
2. RDT/RQT Terminology       4
3. The Process       5
  3.1. Applicable Methods     5
  3.2. Required Inputs     7
  3.3. Process Flow     8
  3.4. Applications and Tailoring     9
4. The Details       10
  4.1. Planning     10
  4.2. RDT/RQT Test Procedure Development     12
  4.3. RDT/RQT Type Selection     12
    4.3.1. Failure-free Execution Interval Test   13
    4.3.2. Fixed-Length Test   13
    4.3.3. Probability-Ratio Sequential Test (PRST)   14
5. Examples       15
  5.1. Failure-Free Execution Interval Test Example     15
  5.2. Fixed Length Test Example     16
  5.3. Probability-Ratio Sequential Test Example     18
6. For More Information       21