ASTM D7791-22

Standard Test Method for Uniaxial Fatigue Properties of Plastics

SIGNIFICANCE AND USE
5.1 These fatigue tests are used to determine the effect of processing, surface condition, stress, and so forth, on the fatigue resistance of plastic material subjected to uniaxial stress for relatively large numbers of cycles. The results can also be used as a guide for the selection of plastic materials for service under conditions of repeated flexural stress.  
5.2 Properties can vary with specimen depth and test frequency. Test frequency can be 1-25 Hz but it is recommended that a frequency of 5 Hz or less be used.  
5.3 Material response in fatigue is not identical for all plastics. If a plastic does not exhibit an elastic region, where strain is reversible, plastic deformation will occur during fatigue testing, causing the amplitude of the programmed load or deformation to change during testing. In this situation, caution shall be taken when using the results for design as they are generally not indicative of the true fatigue properties of the material.  
5.4 The results of these fatigue tests are suitable for application in design only when the specimen test conditions realistically simulate service conditions or some methodology of accounting for service conditions is available and clearly defined.  
5.5 This procedure accommodates various specimen preparation techniques. Comparison of results obtained from specimens prepared in different manners shall not be considered comparable unless equivalency has been demonstrated.
SCOPE
1.1 This test method covers the determination of dynamic fatigue properties of plastics in uniaxial loading. This method is applicable to rigid and semi-rigid plastics. Uniaxial loading systems with tension and compression capabilities are used to determine these properties. Stress and strain levels are below the proportional limits of the material where the strains and stresses are relatively elastic.  
1.2 This test method can be used with two procedures:  
1.2.1 Procedure A, fatigue testing in tension.  
1.2.2 Procedure B, fatigue testing in compression, only for rigid plastics.  
1.3 Comparative tests can be run in accordance with either procedure, provided that the procedure is found satisfactory for the material being tested.  
1.4 The values stated in SI units are to be regarded as the standard. The values provided in parentheses are for information only.  
1.5 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.
Note 1: There is no known ISO equivalent to this standard.  
1.6 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

• Status: Published
• Publication Date: 30-Jun-2022
• ICS: 83.080.01 - Plastics in general
• Technical Committee: D20 - Plastics
• Drafting Committee: D20.10 - Mechanical Properties

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: D7791 − 22
Standard Test Method for
1
Uniaxial Fatigue Properties of Plastics
This standard is issued under the fixed designation D7791; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope* D638 Test Method for Tensile Properties of Plastics
D695 Test Method for Compressive Properties of Rigid
1.1 This test method covers the determination of dynamic
Plastics
fatigue properties of plastics in uniaxial loading. This method
D792 Test Methods for Density and Specific Gravity (Rela-
is applicable to rigid and semi-rigid plastics. Uniaxial loading
tive Density) of Plastics by Displacement
systems with tension and compression capabilities are used to
D883 Terminology Relating to Plastics
determine these properties. Stress and strain levels are below
D1505 Test Method for Density of Plastics by the Density-
the proportional limits of the material where the strains and
Gradient Technique
stresses are relatively elastic.
D2839 Practice for Use of a Melt Index Strand for Deter-
1.2 This test method can be used with two procedures:
mining Density of Polyethylene
1.2.1 Procedure A, fatigue testing in tension.
D3479/D3479M Test Method for Tension-Tension Fatigue
1.2.2 Procedure B, fatigue testing in compression, only for
of Polymer Matrix Composite Materials
rigid plastics.
D4883 Test Method for Density of Polyethylene by the
Ultrasound Technique
1.3 Comparative tests can be run in accordance with either
procedure,providedthattheprocedureisfoundsatisfactoryfor D5947 Test Methods for Physical Dimensions of Solid
the material being tested. Plastics Specimens
E4 Practices for Force Calibration and Verification of Test-
1.4 The values stated in SI units are to be regarded as the
ing Machines
standard. The values provided in parentheses are for informa-
E83 Practice for Verification and Classification of Exten-
tion only.
someter Systems
1.5 This standard does not purport to address all of the
E177 Practice for Use of the Terms Precision and Bias in
safety concerns, if any, associated with its use. It is the
ASTM Test Methods
responsibility of the user of this standard to establish appro-
E466 Practice for Conducting Force Controlled Constant
priate safety, health, and environmental practices and deter-
Amplitude Axial Fatigue Tests of Metallic Materials
mine the applicability of regulatory limitations prior to use.
E691 Practice for Conducting an Interlaboratory Study to
Determine the Precision of a Test Method
NOTE 1—There is no known ISO equivalent to this standard.
E1942 Guide for Evaluating DataAcquisition Systems Used
1.6 This international standard was developed in accor-
in Cyclic Fatigue and Fracture Mechanics Testing
dance with internationally recognized principles on standard-
ization established in the Decision on Principles for the
3. Terminology
Development of International Standards, Guides and Recom-
mendations issued by the World Trade Organization Technical
3.1 Definitions—Definitions of terms applying to this test
Barriers to Trade (TBT) Committee.
method appear in Terminology D883.
2. Referenced Documents
3.2 Definitions:
2
2.1 ASTM Standards: 3.2.1 compressive proportional limit—maximum elastic
D618 Practice for Conditioning Plastics for Testing stress or strain exhibited by a material in compression as
observed in Test Method D695.
1
This test method is under the jurisdiction ofASTM Committee D20 on Plastics
3.2.2 mean strain, n—algebraic average of the maximum
and is the direct responsibility of Subcommittee D20.10 on Mechanical Properties.
and minimum strains in one cycle.
Current edition approved July 1, 2022. Published July 2022. Originally approved
in 2012. Last previous edition approved in 2017 as D7791 - 17. DOI:10.1520/
3.2.3 mean stress, n—algebraic average of the maximum
D7791-22.
2
and minimum stresses in one cycle.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
3.2.4 R ratio, n—ratio of the minimum stress or strain to the
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. maximum stress or strain that the specimen is loaded.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

---------------------- Page: 1 ----------------------
D7791 − 22
3.
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D7791 − 17 D7791 − 22
Standard Test Method for
1
Uniaxial Fatigue Properties of Plastics
This standard is issued under the fixed designation D7791; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope*
1.1 This test method covers the determination of dynamic fatigue properties of plastics in uniaxial loading. This method is
applicable to rigid and semi-rigid plastics. Uniaxial loading systems with tension and compression capabilities are used to
determine these properties. Stress and strain levels are below the proportional limits of the material where the strains and stresses
are relatively elastic.
1.2 This test method can be used with two procedures:
1.2.1 Procedure A, fatigue testing in tension.
1.2.2 Procedure B, fatigue testing in compression, only for rigid plastics.
1.3 Comparative tests can be run in accordance with either procedure, provided that the procedure is found satisfactory for the
material being tested.
1.4 The values stated in SI units are to be regarded as the standard. The values provided in parentheses are for information only.
1.5 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 safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
NOTE 1—There is no known ISO equivalent to this standard.
1.6 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.
2. Referenced Documents
2
2.1 ASTM Standards:
D618 Practice for Conditioning Plastics for Testing
D638 Test Method for Tensile Properties of Plastics
D695 Test Method for Compressive Properties of Rigid Plastics
D792 Test Methods for Density and Specific Gravity (Relative Density) of Plastics by Displacement
1
This test method is under the jurisdiction of ASTM Committee D20 on Plastics and is the direct responsibility of Subcommittee D20.10 on Mechanical Properties.
Current edition approved May 1, 2017July 1, 2022. Published May 2017July 2022. Originally approved in 2012. Last previous edition approved in 20122017 as
D7791 - 12.D7791 - 17. DOI:10.1520DOI:10.1520/D7791-22.⁄D7791-17.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

---------------------- Page: 1 ----------------------
D7791 − 22
D883 Terminology Relating to Plastics
D1505 Test Method for Density of Plastics by the Density-Gradient Technique
D2839 Practice for Use of a Melt Index Strand for Determining Density of Polyethylene
D3479/D3479M Test Method for Tension-Tension Fatigue of Polymer Matrix Composite Materials
D4883 Test Method for Density of Polyethylene by the Ultrasound Technique
D5947 Test Methods for Physical Dimensions of Solid Plastics Specimens
E4 Practices for Force Calibration and Verification of Testing Machines
E83 Practice for Verification and Classification of Extensometer Systems
E177 Practice for Use of the Terms Precision and Bias in ASTM Test Methods
E466 Practice for Conducting Force Controlled Constant Amplitude Axial Fatigue Tests of Metallic Materials
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
E1942 Guide for Evaluating Data Acquisition Systems Used in Cyclic Fatigue and Fracture Mechanics Testing
3. Terminology
3.1 Definitions—Definitions of terms applying to this test method appear in Terminology D883.
3.2 Definitions:
3.2.1 compressive proportional limit—maximum elastic stress or strain exhibited by a material in compression as observed in Test
Method D695.
3.2.2 mean strain—strain, n—algebraic average of the maximum and minimum strains in one cycle.
3.2.3 mean
...