Reliability Growth

Reliability Growth


“Reliability growth is the improvement in a product’s reliability that results from the elimination or mitigation of the root causes of an item’s identified failure modes.” Stated another way: “Reliability growth is the improvement in a reliability parameter over a period of time due to changes in the product design or in operation, maintenance and manufacturing practices caused by the successful identification and correction of deficiencies in an item’s design or manufacture.”

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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:

July 2013

Table of Contents

1. What is Reliability Growth       2
  1.1. Cost-Benefit Tradeoff     3
2. Reliability Growth Terminology       5
3. The Process       8
  3.1. Applicable Methods     8
    3.1.1. Reliability Growth During Design   9
    3.1.2. Reliability Growth During Testing   12
  3.2. Required Inputs     13
  3.3. Process Flow     13
  3.4. Applications and Tailoring     15
4. The Details       15
  4.1. Design     16
    4.1.1. Failure Modes and Effects Analysis/Failure Modes, Effects and Criticality Analysis
    4.1.2. Fault Tree Analysis (FTA)   17
    4.1.3. Reliability Physics (Physics of Failure (PoF))   17
    4.1.4. Design of Experiments (DOE)   18
    4.1.5. Accelerated Stress Testing (AST)/Highly Accelerated Stress Testing (HAST)   19
  4.2. Test     20
    4.2.1. Test-Fix-Test   21
    4.2.2. Test-Find-Test   22
    4.2.3. Test-Fix-Test with Delayed Fixes (including Test-Fix-Find-Test)   23
    4.2.4. Combined Influence of Factors on Reliability Growth Curve Shapes   24
    4.2.5. Reliability Growth Models (Duane and Crow/AMSAA)   25
5. Examples       27
  5.1. FMEA/FMECA Example     27
  5.2. Duane Planning Model Examples     28
    5.2.1. Example 1: How to Determine the Idealized Growth Curve   28
    5.2.2. Example 2: How to Determine the MTBF for a Test Phase   29
    5.2.3. Example 3: How to Determine How Much Test Time is Needed   31
  5.3. Crow/AMSAA Model Example     32
6. For More Information       34

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