ASTM D6115-97(2004)
(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
Susceptibility to delamination is one of the major weaknesses of many advanced laminated composite structures. Knowledge of a laminated composite material’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.
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 . 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.
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 D 5528).
1.3 The values stated in SI units are to be regarded as standard. 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 and health practices and determine the applicability of regulatory limitations prior to use.
General Information
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Standards Content (Sample)
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Designation:D6115–97 (Reapproved 2004)
Standard Test Method for
Mode I Fatigue Delamination Growth Onset of Unidirectional
1
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
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.
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
FIG. 1 DCB Specimen with Piano Hinges
experience gained in round robin testing.This test method may
proveusefulforothertypesandclassesofcompositematerials,
D2651 Guide for Preparation of Metal Surfaces for Adhe-
however,certaininterferenceshavebeennoted(seeSection6.5
sive Bonding
of Test Method D5528).
D2734 Test Methods for Void Content of Reinforced Plas-
1.3 The values stated in SI units are to be regarded as
tics
standard. The values provided in parentheses are for informa-
D3171 Test Methods for Constituent Content of Composite
tion only.
Materials
1.4 This standard does not purport to address all of the
D3878 Terminology for Composite Materials
safety concerns, if any, associated with its use. It is the
D5229/D5229M Test Method for Moisture Absorption
responsibility of the user of this standard to establish appro-
Properties and Equilibrium Conditioning of Polymer Ma-
priate safety and health practices and determine the applica-
trix Composite Materials
bility of regulatory limitations prior to use.
D5528 Test Method for Mode I Interlaminar Fracture
Toughness of Unidirectional Fiber-Reinforced Polymer
2. Referenced Documents
Matrix Composites
2
2.1 ASTM Standards:
E4 Practices for Force Verification of Testing Machines
D883 Terminology Relating to Plastics
E6 TerminologyRelatingtoMethodsofMechanicalTesting
D2584 Test Method for Ignition Loss of Cured Reinforced
E122 Practice for Calculating Sample Size to Estimate,
Resins
With Specified Precision, the Average for a Characteristic
of a Lot or Process
E177 Practice for Use of the Terms Precision and Bias in
1
This specification is under the jurisdiction of ASTM Committee D30 on
ASTM Test Methods
Composite Materials and is the direct responsibility of Subcommittee D30.06 on
E456 Terminology Relating to Quality and Statistics
Interlaminar Properties.
E467 Practice for Verification of Constant Amplitude Dy-
Current edition approved March 1, 2004. Published March 2004. Originally
namic Forces in an Axial Fatigue Testing System
approved in 1997. Last previous edition approved in 1997 as D6115 – 97. DOI:
10.1520/D6115-97R04.
E691 Practice for Conducting an Interlaboratory Study to
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Determine the Precision of a Test Method
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
E739 Practice for Statistical Analysis of Linear or Linear-
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. ized Stress-Life ( S-N) and Strain-Life (e-N) Fatigue Data
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
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D6115–97 (2004)
E1049 Practices for Cycle Counting in Fatigue Analysis 3.3.13 G–N—relationship between the cyclic strain energy
3
E1150 Definitions of Terms Relating to Fatigue release rate and the number of cycles to onset of delamination
growth.
3. Terminology 3.3.14 h—thickness of DCB specimen.
3.3.15 N—number of elapsed fatigue cycles.
3.1 Terminology D3878 defines terms relating to high-
3.3.16 N —application dependent value of N at which
a
modulus fibers and their composites. Terminology D883 de-
delamination growth onset will occur.
fines terms relating to plastics. Terminology E6 defines terms
1 %
3.3.17 N —numberoffatiguecyclesforthevalueof P
a max
relating to mechanical testing. Terminology E456 and Practice
at N = 1 to decrease by 1 %.
E177 define terms relating to statistics. Definition E1150
ViS
3.3.18 N —number of fatigue cycles at which the onset
a
defines
...
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