ASTM E3291-21
(Guide)Standard Guide for Reliability Demonstration Testing
Standard Guide for Reliability Demonstration Testing
SIGNIFICANCE AND USE
4.1 Reliability demonstration testing is a methodology for qualifying or validating a product’s performance capability. Demonstration methods are useful for components, devices, assemblies, materials, processes, and systems. Many industries require demonstration testing either for new product development and product introduction, in validating a change to an existing product or as part of an audit. Test plans generally try to answer the questions, “How long will a product last?” or “What is its reliability?”, under stated conditions at some specific time. When time is being used as a life variable, it must be cast in some kind of “time” units. Typical time units are hours (or minutes), cycles of usage, calendar time or some variation of these. In certain cases, “time” can be accelerated in order to reduce a plan’s completion time. In the automotive industry mileage may be used as the time variable. Certain means of accelerating tests involve the use of increased power, voltage, mechanical load, humidity, vibration, or temperature (often in the form of thermal cycling).
4.2 Two fundamental objectives in reliability test planning are: (a) demonstrating that a product meets a specific life requirement, and (b) demonstrating what a product can do – its life capability. In the first case, a requirement is specified; in the second case a series of test results are used to state a result at the present time – its current capability. Both cases share similar inputs and outputs.
4.3 Often a life distribution model is specified such as the Weibull, the exponential, the lognormal or the normal distribution. In addition, for the specific distribution assumed, a parameter is typically assumed (or a range of values for a parameter). For example, in the Weibull case, the shape parameter, β, is assumed; in the lognormal case the scale parameter, σ, is assumed and in the normal case the standard deviation, σ, is assumed. In other cases, a non-parametric analysis can be used. N...
SCOPE
1.1 This standard covers fundamental concepts, applications and mathematical relationships associated with the planning of reliability demonstration tests as applied to components and materials testing.
1.2 The system of units for this guide is not specified. Quantities and examples are presented only as illustrations of a method or a calculation. Any examples used are not binding on any particular product or industry.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
General Information
Standards Content (Sample)
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: E3291 − 21 An American National Standard
Standard Guide for
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Reliability Demonstration Testing
This standard is issued under the fixed designation E3291; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 3. Terminology
1.1 Thisstandardcoversfundamentalconcepts,applications 3.1 Definitions:
and mathematical relationships associated with the planning of
3.1.1 Unless otherwise noted, terms relating to quality and
reliability demonstration tests as applied to components and
statistics are as defined in Terminology E456. Other general
materials testing.
statistical terms and terms related to risk are defined in ISO
3534-1 and ISO Guide 73.
1.2 The system of units for this guide is not specified.
3.1.2 B life, n—for continuous variables, the life at which
Quantities and examples are presented only as illustrations of p
there is a probability, p, (expressed as a percentage) of failure
a method or a calculation.Any examples used are not binding
at or less than this value. E3159
on any particular product or industry.
1.3 This standard does not purport to address all of the 3.1.3 failuremode,n—thewayinwhichadevice,processor
system has failed. E3159
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
3.1.4 hazard rate, n—differential fraction of items failing at
priate safety, health, and environmental practices and deter-
time t among those surviving up to time t, symbolized by h(t).
mine the applicability of regulatory limitations prior to use.
E2555
1.4 This international standard was developed in accor-
3.1.5 mean time between failures (MTBF), n—the average
dance with internationally recognized principles on standard-
time to failure for a repairable item. E3159
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom- 3.1.6 mean time to failure (MTTF), θ, n—in life testing, the
mendations issued by the World Trade Organization Technical average length of life of items in a lot. E2696
Barriers to Trade (TBT) Committee.
3.1.7 reliability, n—the probability that a component,
device, product, process or system will function or fulfill a
2. Referenced Documents
function after a specified duration of time or usage under
2
2.1 ASTM Standards:
specified conditions. E3159
E456Terminology Relating to Quality and Statistics
3.2 Symbols:
E2555Practice for Factors and Procedures forApplying the
3.2.1 The following symbols are used extensively in the
MIL-STD-105 Plans in Life and Reliability Inspection
discussion.
E2696Practice for Life and ReliabilityTesting Based on the
3.2.2 C—confidence coefficient (decimal value between 0
Exponential Distribution
and 1).
E3159Guide for General Reliability
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3.2.3 n—sample size, (positive integer at least 1).
2.2 ISO Standards:
ISO 3534-1Statistics – Vocabulary and symbols, Part 1:
3.2.4 p—failure probability (decimal between 0 and 1, or
Probability and general statistical terms
percentage between 0 and 100).
ISO Guide 73Risk management vocabulary
3.2.5 R—reliability. R=1– por(100– p)%for pexpressed
as a percentage.
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This guide is under the jurisdiction of ASTM Committee E11 on Quality and 3.2.6 r—number of failures allowed (0 ≤ r < n).
Statistics and is the direct responsibility of Subcommittee E11.40 on Reliability.
3.2.7 β—Weibull shape parameter, also referred to as the
Current edition approved May 1, 2021. Published January 2022. DOI: 10.1520/
E3291-21. “Weibull slope.”
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For referenced ASTM standards, visit the ASTM website, www.astm.org, or
3.2.8 θ—fortheexponentialmodel,themean(MTTF)ofthe
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on distribution.
the ASTM website.
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3.2.9 η—for the Weibull model, the characteristic life or
Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
4th Floor, New York, NY 10036, http://www.ansi.org. scale parameter.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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E3291 − 21
3.2.10 λ—for the exponential model, the failure rate; also time, t, and a maximum number of failures, r, allowed by the
equal to 1 / θ. plan. A test concludes and is successful if the n units tested
resultinnotmorethan rfailuresb
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