ASTM D6115-97(2019)
(Test Method)Standard Test Method for Mode I Fatigue Delamination Growth Onset of Unidirectional Fiber-Reinforced Polymer Matrix Composites
Standard Test Method for Mode I Fatigue Delamination Growth Onset of Unidirectional Fiber-Reinforced Polymer Matrix Composites
SIGNIFICANCE AND USE
5.1 Susceptibility to delamination is one of the major weaknesses of many advanced laminated composite structures. Knowledge of a laminated composite material's resistance to interlaminar fracture under fatigue loads is useful for product development and material selection. Furthermore, a measurement of the relationship of the mode I cyclic strain energy release rate and the number of cycles to delamination growth onset, G–N, that is independent of specimen geometry or method of load introduction, is useful for establishing design allowables used in damage tolerance analyses of composite structures made from these materials.
5.2 This test method can serve the following purposes:
5.2.1 To establish quantitatively the effects of fiber surface treatment, local variations in fiber volume fraction, and processing and environmental variables on G–N of a particular composite material.
5.2.2 To compare quantitatively the relative values of G–N for composite materials with different constituents.
5.2.3 To develop criteria for avoiding the onset of delamination growth under fatigue loading for composite damage tolerance and durability analyses.
SCOPE
1.1 This test method determines the number of cycles (N) for the onset of delamination growth based on the opening mode I cyclic strain energy release rate (G), using the Double Cantilever Beam (DCB) specimen shown in Fig. 1. This test method applies to constant amplitude, tension-tension fatigue loading of continuous fiber-reinforced composite materials. When this test method is applied to multiple specimens at various G-levels, the results may be shown as a G–N curve, as illustrated in Fig. 2.
FIG. 1 DCB Specimen with Piano Hinges
FIG. 2 G–N Curve
1.2 This test method is limited to use with composites consisting of unidirectional carbon fiber tape laminates with single-phase polymer matrices. This limited scope reflects the experience gained in round robin testing. This test method may prove useful for other types and classes of composite materials, however, certain interferences have been noted (see Section 6.5 of Test Method D5528).
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3.1 Exception—The values provided in parentheses are for information only.
1.4 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.
1.5 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
Relations
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: D6115 − 97 (Reapproved 2019)
Standard Test Method for
Mode I Fatigue Delamination Growth Onset of Unidirectional
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Fiber-Reinforced Polymer Matrix Composites
This standard is issued under the fixed designation D6115; 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 2. Referenced Documents
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1.1 This test method determines the number of cycles (N) 2.1 ASTM Standards:
for the onset of delamination growth based on the opening
D883 Terminology Relating to Plastics
mode I cyclic strain energy release rate (G), using the Double
D2584 Test Method for Ignition Loss of Cured Reinforced
Cantilever Beam (DCB) specimen shown in Fig. 1. This test
Resins
method applies to constant amplitude, tension-tension fatigue
D2651 GuideforPreparationofMetalSurfacesforAdhesive
loading of continuous fiber-reinforced composite materials.
Bonding
When this test method is applied to multiple specimens at
D2734 TestMethodsforVoidContentofReinforcedPlastics
various G-levels, the results may be shown as a G–N curve, as
D3171 Test Methods for Constituent Content of Composite
illustrated in Fig. 2.
Materials
D3878 Terminology for Composite Materials
1.2 This test method is limited to use with composites
D5229/D5229M TestMethodforMoistureAbsorptionProp-
consisting of unidirectional carbon fiber tape laminates with
erties and Equilibrium Conditioning of Polymer Matrix
single-phase polymer matrices. This limited scope reflects the
Composite Materials
experience gained in round robin testing.This test method may
D5528 TestMethodforModeIInterlaminarFractureTough-
proveusefulforothertypesandclassesofcompositematerials,
ness of Unidirectional Fiber-Reinforced Polymer Matrix
however,certaininterferenceshavebeennoted(seeSection6.5
Composites
of Test Method D5528).
E4 Practices for Force Verification of Testing Machines
1.3 The values stated in SI units are to be regarded as
E6 Terminology Relating to Methods of Mechanical Testing
standard. No other units of measurement are included in this
E122 Practice for Calculating Sample Size to Estimate,With
standard.
Specified Precision, the Average for a Characteristic of a
1.3.1 Exception—Thevaluesprovidedinparenthesesarefor
Lot or Process
information only.
E177 Practice for Use of the Terms Precision and Bias in
ASTM Test Methods
1.4 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the E456 Terminology Relating to Quality and Statistics
responsibility of the user of this standard to establish appro- E467 Practice for Verification of Constant Amplitude Dy-
priate safety, health, and environmental practices and deter-
namic Forces in an Axial Fatigue Testing System
mine the applicability of regulatory limitations prior to use.
E691 Practice for Conducting an Interlaboratory Study to
Determine the Precision of a Test Method
1.5 This international standard was developed in accor-
E739 PracticeforStatisticalAnalysisofLinearorLinearized
dance with internationally recognized principles on standard-
Stress-Life (S-N) and Strain-Life (ε-N) Fatigue Data
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom- E1049 Practices for Cycle Counting in Fatigue Analysis
mendations issued by the World Trade Organization Technical E1150 Definitions of Terms Relating to Fatigue (Withdrawn
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Barriers to Trade (TBT) Committee. 1996)
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This test method is under the jurisdiction of ASTM Committee D30 on For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Composite Materials and is the direct responsibility of Subcommittee D30.06 on contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Interlaminar Properties. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved March 15, 2019. Published March 2019. Originally the ASTM website.
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approved in 1997. Last previous edition approved in 2011 as D6115 – 97(2011). The last approved version of this historical standard is referenced on
DOI: 10.1520/D6115-97R19. www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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D6115 − 97 (2019)
3.3.5 CV—coefficient of variation, %.
3.3.6 da—infinitesimal increase in delamination length.
3.3.7 dU—infinitesimal increase in strain energy.
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