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    ASTM D6115 - 97(2019)

    Standard Test Method for Mode I Fatigue Delamination Growth Onset of Unidirectional Fiber-Reinforced Polymer Matrix Composites

    Active Standard ASTM D6115 | Developed by Subcommittee: D30.06

    Book of Standards Volume: 15.03

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    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.

    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.

    FIG. 1  DCB Specimen with Piano Hinges

     DCB Specimen with Piano Hinges 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.

    2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.

    ASTM Standards

    D883 Terminology Relating to Plastics

    D2584 Test Method for Ignition Loss of Cured Reinforced Resins

    D2651 Guide for Preparation of Metal Surfaces for Adhesive Bonding

    D2734 Test Methods for Void Content of Reinforced Plastics

    D3171 Test Methods for Constituent Content of Composite Materials

    D3878 Terminology for Composite Materials

    D5229/D5229M Test Method for Moisture Absorption Properties and Equilibrium Conditioning of Polymer Matrix Composite Materials

    D5528 Test Method for Mode I Interlaminar Fracture Toughness of Unidirectional Fiber-Reinforced Polymer Matrix Composites

    E4 Practices for Force Verification of Testing Machines

    E6 Terminology Relating to Methods of Mechanical Testing

    E122 Practice for Calculating Sample Size to Estimate, With Specified Precision, the Average for a Characteristic of a Lot or Process

    E177 Practice for Use of the Terms Precision and Bias in ASTM Test Methods

    E456 Terminology Relating to Quality and Statistics

    E467 Practice for Verification of Constant Amplitude Dynamic Forces in an Axial Fatigue Testing System

    E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method

    E739 Practice for Statistical Analysis of Linear or Linearized Stress-Life (S-N) and Strain-Life (-N) Fatigue Data

    E1049 Practices for Cycle Counting in Fatigue Analysis

    E1150 Definitions of Terms Relating to Fatigue

    ICS Code

    ICS Number Code 83.120 (Reinforced plastics)

    UNSPSC Code

    UNSPSC Code

    Referencing This Standard
    Link Here
    Link to Active (This link will always route to the current Active version of the standard.)

    DOI: 10.1520/D6115-97R19

    Citation Format

    ASTM D6115-97(2019), Standard Test Method for Mode I Fatigue Delamination Growth Onset of Unidirectional Fiber-Reinforced Polymer Matrix Composites, ASTM International, West Conshohocken, PA, 2019, www.astm.org

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