ASTM D6415/D6415M-06a(2013)

Standard Test Method for Measuring the Curved Beam Strength of a Fiber-Reinforced Polymer-Matrix Composite

SIGNIFICANCE AND USE
5.1 Out-of-plane stress analyses are not easily performed. Failure criteria are varied and poorly validated. Interlaminar allowables are not readily available. However, stress analysts routinely encounter structural details in which they cannot ignore the out-of-plane loads. This test method is designed to produce out-of-plane structural failure data for structural design and analysis, quality assurance, and research and development. For unidirectional specimens, this test method is designed to produce interlaminar tensile strength data. Factors that influence the curved beam strength and should therefore be reported include the following: material, methods of material preparation, methods of processing and specimen fabrication, specimen preparation, specimen conditioning, environment of testing, speed of testing, time at temperature, void content, and volume percent reinforcement.
SCOPE
1.1 This test method determines the curved beam strength of a continuous fiber-reinforced composite material using a 90° curved beam specimen (Fig. 1 and Fig. 2). The curved beam consists of two straight legs connected by a 90° bend with a 6.4-mm [0.25 in.] inner radius. An out-of-plane (through-the-thickness) tensile stress is produced in the curved region of the specimen when force is applied. This test method is limited to use with composites consisting of layers of fabric or layers of unidirectional fibers.
1.2 This test method may also be used to measure the interlaminar tensile strength if a unidirectional specimen is used where the fibers run continuously along the legs and around the bend.  
1.3 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.  
1.4 The values stated in either SI units or inch-pound units are to be regarded separately as standard. Within the text the inch-pound units are shown in brackets. The values stated in each system are not exact equivalents; therefore, each system must be used independently of the other. Combining values from the two systems may result in nonconformance with the standard.

General Information

• Status: Historical
• Publication Date: 30-Sep-2013
• ICS: 83.120 - Reinforced plastics
• Technical Committee: D30 - Composite Materials
• Drafting Committee: D30.06 - Interlaminar Properties

Standards Content (Sample)

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: D6415/D6415M − 06a (Reapproved 2013)
Standard Test Method for
Measuring the Curved Beam Strength of a Fiber-Reinforced
1
Polymer-Matrix Composite
This standard is issued under the fixed designation D6415/D6415M; 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 D3171Test Methods for Constituent Content of Composite
Materials
1.1 Thistestmethoddeterminesthecurvedbeamstrengthof
D3878Terminology for Composite Materials
a continuous fiber-reinforced composite material using a 90°
D5229/D5229MTestMethodforMoistureAbsorptionProp-
curved beam specimen (Fig. 1 and Fig. 2). The curved beam
erties and Equilibrium Conditioning of Polymer Matrix
consists of two straight legs connected by a 90° bend with a
Composite Materials
6.4-mm [0.25 in.] inner radius. An out-of-plane (through-the-
D5687/D5687MGuide for Preparation of Flat Composite
thickness) tensile stress is produced in the curved region of the
Panels with Processing Guidelines for Specimen Prepara-
specimen when force is applied. This test method is limited to
tion
use with composites consisting of layers of fabric or layers of
E4Practices for Force Verification of Testing Machines
unidirectional fibers.
E6Terminology Relating to Methods of MechanicalTesting
1.2 This test method may also be used to measure the
E122PracticeforCalculatingSampleSizetoEstimate,With
interlaminar tensile strength if a unidirectional specimen is
Specified Precision, the Average for a Characteristic of a
used where the fibers run continuously along the legs and
Lot or Process
around the bend.
E177Practice for Use of the Terms Precision and Bias in
1.3 This standard does not purport to address all of the ASTM Test Methods
safety concerns, if any, associated with its use. It is the
E456Terminology Relating to Quality and Statistics
responsibility of the user of this standard to establish appro- E1309 Guide for Identification of Fiber-Reinforced
priate safety and health practices and determine the applica-
Polymer-Matrix Composite Materials in Databases
bility of regulatory limitations prior to use. E1434Guide for Recording Mechanical Test Data of Fiber-
1.4 The values stated in either SI units or inch-pound units
Reinforced Composite Materials in Databases
are to be regarded separately as standard. Within the text the
E1471Guide for Identification of Fibers, Fillers, and Core
inch-pound units are shown in brackets. The values stated in Materials in Computerized Material Property Databases
each system are not exact equivalents; therefore, each system
3. Terminology
must be used independently of the other. Combining values
from the two systems may result in nonconformance with the
3.1 Definitions—Terminology D3878 defines terms relating
standard.
to high-modulus fibers and their composites. Terminology
D883definestermsrelatingtoplastics.TerminologyE6defines
2. Referenced Documents
terms relating to mechanical testing. Terminology E456 and
2
2.1 ASTM Standards: Practice E177 define terms relating to statistics. In the event of
a conflict between terms, Terminology D3878 shall have
D792Test Methods for Density and Specific Gravity (Rela-
tive Density) of Plastics by Displacement precedence over the other terminologies.
D883Terminology Relating to Plastics
3.2 Definitions of Terms Specific to This Standard:
NOTE 1—If the term represents a physical quantity, its analytical
1 dimensionsarestatedimmediatelyfollowingtheterm(orlettersymbol)in
This test method is under the jurisdiction of ASTM Committee D30 on
fundamental dimension form, using the following ASTM standard sym-
Composite Materials and is the direct responsibility of D30.06 on Interlaminar
bology for fundamental dimensions, shown within square brackets: [M]
Properties.
Current edition approved Oct. 1, 2013. Published October 2013. Originally for mass, [L] for length, [T] for time, [θ] for thermodynamic temperature,
ε1
approved in 1999. Last previous edition approved in 2006 as D6415–06A . DOI: and [nd] for nondimensional quantities. Use of these symbols is restricted
10.1520/D6415_D6415M-06AR13.
to analytical dimensions when used with square brackets, as the symbols
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
may have other definitions when used without the brackets.
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
2 –2
3.2.1 applied moment, M [ML T ], n—the moment applied
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. to the curved test section of the specimen.
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