Standard Test Methods for Tensile, Compressive, and Flexural Creep and Creep-Rupture of Plastics

SIGNIFICANCE AND USE
Data from creep and creep-rupture tests are necessary to predict the creep modulus and strength of materials under long-term loads and to predict dimensional changes that may occur as a result of such loads.  
Data from these test methods can be used: (1) to compare materials, (2) in the design of fabricated parts, (3) to characterize plastics for long-term performance under constant load, and ( 4) under certain conditions, for specification purposes.
Before proceeding with this test method, reference should be made to the specification of the material being tested. Any specimen preparation, conditioning, dimensions, and/or testing parameters covered in the material specification shall take precedence over those mentioned in this test method, except in cases where to do so would conflict with the purpose for conducting testing. If there are no material specifications, then the default conditions apply.
SCOPE
1.1 These test methods cover the determination of tensile and compressive creep and creep-rupture of plastics under specified environmental conditions (see 3.1.3).
1.2 While these test methods outline the use of three-point loading for measurement of creep in flexure, four-point loading (which is used less frequently) can also be used with the equipment and principles as outlined in Test Methods D790.
1.3 For measurements of creep-rupture, tension is the preferred stress mode because for some ductile plastics rupture does not occur in flexure or compression.  
1.4 Test data obtained by these test methods are relevant and appropriate for use in engineering design.  
1.5 The values stated in SI units are to be regarded as the standard. The values in parentheses are for information only.  
1.6  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 and health practices and determine the applicability of regulatory limitations prior to use.  A specific warning statement is given in 6.8.2.
Note 1—This standard and ISO 899 are similar in content, but are not equivalent.

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Publication Date
09-Aug-2001
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ASTM D2990-01 - Standard Test Methods for Tensile, Compressive, and Flexural Creep and Creep-Rupture of Plastics
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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation:D2990–01
Standard Test Methods for
Tensile, Compressive, and Flexural Creep and Creep-
1
Rupture of Plastics
This standard is issued under the fixed designation D2990; 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 (e) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the Department of Defense.
1. Scope* D638 Test Method for Tensile Properties of Plastics
D695 Test Method for Compressive Properties of Rigid
1.1 These test methods cover the determination of tensile
Plastics
and compressive creep and creep-rupture of plastics under
D790 TestMethodsforFlexuralPropertiesofUnreinforced
specified environmental conditions (see 3.1.3).
andReinforcedPlasticsandElectricalInsulatingMaterials
1.2 While these test methods outline the use of three-point
D1822 Test Method for Tensile-Impact Energy to Break
loadingformeasurementofcreepinflexure,four-pointloading
Plastics and Electrical Insulating Materials
(which is used less frequently) can also be used with the
D2236 Test Method for Dynamic Mechanical Properties of
equipment and principles as outlined in Test Methods D790.
3
Plastics by Means of a Torsional Pendulum
1.3 For measurements of creep-rupture, tension is the pre-
D4000 Classification System for Specifying Plastic Mate-
ferred stress mode because for some ductile plastics rupture
rials
does not occur in flexure or compression.
D4968 Guide for Annual Review of Test Methods and
1.4 Testdataobtainedbythesetestmethodsarerelevantand
Specifications for Plastics
appropriate for use in engineering design.
1.5 The values stated in SI units are to be regarded as the
3. Terminology
standard. The values in parentheses are for information only.
3.1 Definitions of Terms Specific to This Standard:
1.6 This standard does not purport to address all of the
3.1.1 creep modulus—the ratio of initial applied stress to
safety concerns, if any, associated with its use. It is the
creep strain.
responsibility of the user of this standard to establish appro-
3.1.2 creep strain—the total strain, at any given time,
priate safety and health practices and determine the applica-
produced by the applied stress during a creep test.
bility of regulatory limitations prior to use. Aspecific warning
3.1.2.1 Discussion—The term creep, as used in this test
statement is given in 6.8.2.
method,reflectscurrentplasticsengineeringusage.Inscientific
NOTE 1—This standard and ISO899 are similar in content, but are not
practice, creep is often defined to be the nonelastic portion of
equivalent.
strain. However, this definition is not applicable to existing
engineering formulas. Plastics have a wide spectrum of retar-
2. Referenced Documents
dation times, and elastic portions of strain cannot be separated
2
2.1 ASTM Standards:
in practice from nonelastic. Therefore, wherever “strain” is
D543 Practices for Evaluating the Resistance of Plastics to
mentioned in these test methods, it refers to the sum of elastic
Chemical Reagents
strain plus the additional strain with time.
D618 Practice for Conditioning Plastics for Testing
3.1.3 deformation—a change in shape, size or position of a
D621 Test Methods for Deformation of Plastics Under
test specimen as a result of compression, deflection, or exten-
3
Load
sion:
3.1.4 compression—in a compressive creep test, the de-
1
creaseinlengthproducedinthegagelengthofatestspecimen.
These test methods are under the jurisdiction of ASTM Committee D20 on
Plastics and are the direct responsibility of Subcommittee D20.10 on Mechanical
3.1.5 deflection—in a flexural creep test, the change in
Properties.
mid-span position of a test specimen.
Current edition approved August 10, 2001. Published October 2001. Originally
3.1.6 extension—in a tensile creep test, the increase in
published as D2990–71. Last previous edition D2990–95. These test methods
length produced in the gage length of a test specimen.
and Practice D2991 replace Practices D674, which has been discontinued.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
3.1.7 slenderness ratio—the ratio of the length of a column
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
of uniform cross section to its least radius of gyration; for
Standards volume information, refer to the standard’s Document Summary page on
specimens of uniform rectangular cross section, the radius of
the ASTM website.
3
Withdrawn. gyration is 0.289 times the smaller cross-sectional dimension;
*A Summary of Changes section appears at the end of this standard.
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