ASTM D8069-17a

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Designation: D8069 − 17 D8069 − 17a
Standard Test Method for
Determining Flexural Modulus of Full Section Pultruded
Fiber Reinforced Polymer (FRP) Composite Members with
Doubly Symmetric Cross Sections under Bending
This standard is issued under the fixed designation D8069; 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 Scope*
1.1 This test method covers the determination of Flexural Modulus of pultruded open and closed fiber reinforced polymer (FRP)
composites of doubly symmetrical cross sections about (sections having geometric symmetry about both the major and minor axes)
about their geometric centroid subjected to flexure and shear. This test method utilizes a three-point loading system applied to a
simply supported beam.
1.2 The values stated in SI units are to be regarded as the standard. The values provided in parentheses are for information only.
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 safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
NOTE 1—The is no known ISO equivalent to this standard.
1.4 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
2.1 ASTM Standards:
D883 Terminology Relating to Plastics
D790 Test Methods for Flexural Properties of Unreinforced and Reinforced Plastics and Electrical Insulating Materials
D3878 Terminology for Composite Materials
D4000 Classification System for Specifying Plastic Materials
D4762 Guide for Testing Polymer Matrix Composite Materials
D7290 Practice for Evaluating Material Property Characteristic Values for Polymeric Composites for Civil Engineering
Structural Applications
E4 Practices for Force Verification of Testing Machines
E6 Terminology Relating to Methods of Mechanical Testing
E177 Practice for Use of the Terms Precision and Bias in ASTM Test Methods
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
E1309 Guide for Identification of Fiber-Reinforced Polymer-Matrix Composite Materials in Databases (Withdrawn 2015)
E1434 Guide for Recording Mechanical Test Data of Fiber-Reinforced Composite Materials in Databases (Withdrawn 2015)
E2309/E2309M Practices for Verification of Displacement Measuring Systems and Devices Used in Material Testing Machines
3. Terminology
3.1 Definitions—Terminology D3878 defines terms relating to high-modulus fibers and their composites. Terminology D883
defines terms relating to plastics. Terminology E6 defines terms relating to mechanical testing. In the event of a conflict between
terms, Terminology D3878 shall have precedence over the other terminologies.
This test method is under the jurisdiction of ASTM Committee D20 on Plastics and is the direct responsibility of Subcommittee D20.18 on Reinforced Thermosetting
Plastics.
Current edition approved Jan. 1, 2017Dec. 1, 2017. Published January 2017January 2018. Originally approved in 2017. Last previous edition approved in 2017 as
D8069–17. DOI: 10.1520/D8069-17.10.1520/D8069-17A.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
The last approved version of this historical standard is referenced on www.astm.org.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D8069 − 17a
3.2 Definitions of variables used in calculations as shown in Section 11 and 12 are as follows:
P > 20% of estimated ultimate load, N (lbf)
20%
4 4
I = moment of inertia about the neutral axis, mm (in. )
L = test span length, mm (in.)
h = total height of test specimen, mm (in.)
P > 5% of estimated ultimate load, N (lbf)
5%
P = load value used to calculate E, N (lbf)
δ = deflection value used to calculate E, mm (in.)
δ > deflection at 20% of estimated ultimate load, mm (in.)
20%
δ > deflection at 5% of estimated ultimate load, mm (in.)
5%
E = Flexural modulus, MPa (psi)
4. Summary of Test Method
4.1 The full-scale specimen rests on two rounded solid metal cylindrical supports or pivoted end supports and is loaded by
means of a loading ram located midway between the supports. supports, as shown in Fig. 1. The beam span-to-depth ratio (L/h)
should be within the range of 20 ≤ L/h ≤ 32 to determine the flexural modulus.
4.2 The maximum load placed on the specimen shall be approximately equal to 20 percent of the estimated ultimate load
determined in accordance with 11.10.
4.3 Load and deflection are recorded at mid-span during all stages of the test procedure as outlined in Section 11.
4.4 If a span specified by the user, in the contract for a particular application, is under the span-to-depth ratio of 20 (L/h < 20)
or over 32 (L/h > 32), the flexural modulus shall be reported as apparent flexural modulus.
5. Significance and Use
5.1 Determination of flexural modulus by this test method is especially useful for quality control and specification purposes.
5.2 Experimental values for flexural modulus will vary with specimen depth, span length, loading rate, ambient test temperature,
and other atmospheric conditions.
5.3 Before proceeding with this test method, reference should be made to the specification of the material being tested, including
constituent materials of the specimen. Any test specimen preparation, environmental or loading conditioning, dimensions, or
testing parameters covered in the material specification, or both, shall take precedence over those mentioned in this test method.
If there are no material specifications, then these default conditions apply. Table 1 in Classification D4000 lists the ASTM materials
standards that currently exist.
6. Apparatus
6.1 Testing Machine—A properly installed and operated hydraulic or mechanical load actuator, ideally one which can be
operated at constant rates of load or deflection, is used in combination with a properly calibrated load cell. Error in the load
measuring system shall not exceed 61% of the maximum load expected to be measured. The test setup shall also be equipped with
deflection measuring devices. The stiffness of the testing apparatus shall be such that the total elastic deformation of the load frame
FIG. 1 Test Fixture and Setup
D8069 − 17a
does not exceed 1% of the total deflection of the test specimen during testing, or appropriate corrections shall be made. The
accuracy of the testing machine shall be calibrated and verified in accordance with Practices E4.
6.2 Reaction Supports and Loading Nose—The beam specimen shall be placed over two rounded metal cylindrical supports or
over pivoted bearing surfaces which can accommodate free rotation at the ends of the beam specimen. If the metal cylindrical
supports or pivoted bearing surfaces cause any local crushing to the test specimen under loading, the beam specimen shall be
supported by metal bearing plates to prevent damage to the beam at the point of contact between the beam specimen and reaction
support. The plates shall be of sufficient length, thickness, and width to provide a firm bearing surface and ensure a uniform bearing
stress across the flange width of the beam specimen. The bearing plates shall be supported by devices that provide unrestricted
longitudinal deformation and rotation of the beam specimen at the reactions due to loading.
6.3 Loading Nose—The transverse loading at the center of the test specimen span shall be applied through a metal block with
4 in. width (along the length of the beam specimen) by ⁄2 in. thick, with rounded edges or with a radius of curvature approximately
equal to two times the beam specimen depth, extending across the entire specimen flange width. If the user chooses to test the
specimen by placing an elastomeric pad in between the metal block and the top flange surface of the beam specimen to avoid any
local crushing of the sample, a ⁄2 in. thick Shore A durometer hardness 40 to 60 shall be used and the deflection shall be measured
at the bottom flange surface of the test specimen using a dial gauge or LVDT.
6.4 Measuring Devices for Sectional Dimensions—All measuring devices used to measure cross-sectional dimensions shall be
accurate to within 60.0254 mm (60.001 in.). Devices used to measure span length shall be accurate to within 6 1.5875 mm (6 ⁄16
in.).
6.5 Deflection Measuring Device—A properly calibrated device to measure the deflection of the beam at mid-span shall be used.
The device shall record the deflection during the test for certain magnitude of applied load (in accordance with 11.10). In the
absence of an automated system, a properly calibrated deflection dial gauge may be used with at least one reading for every five
seconds throughout the duration of the test. The deflection dial gauge shall be accurate to 60.0254 mm (60.001 in).
7. Sampling and Test Specimens
7.1 Sampling—Test at least five specimens per test condition unless valid results within 1 % can be gained through the use of
at least three specimens, as in the case of a designed experiment.
7.2 Specimens—The test beam specimens shall be molded shapes manufactured using a pultrusion process. Specimens shall be
full-scale samples, tested at the desired span length. The span-to-depth ratio of specimens shall never be less than 20 or greater
than 32 unless the sample needs to be tested in accordance with 13.4 for apparent modulus. Sufficient overhang (a length of 5 %
- 10 % of the test span) shall be provided over each end support to prevent sample from slipping from the supports.
7.3 Specimen Preparation—Take precautions when cutting beam specimens to the desired span length to avoid notches, rough
or uneven surfaces, or delaminations due to inappropriate test specimen preparation methods. The use of diamond coated
machining tools are recommended in the preparation of test specimens.
7.4 Labeling—Label the test specimens (date, batch number, line number) so that they will be distinct from each other and
traceable back to the specimen of origin of manufacturing, and will neither influence the test nor be affected by it.
8. Hazards
8.1 Precautions shall be taken to prevent the sample from kicking out of place under increasing transverse load resulting in
lateral torsional movement, to avoid any accidents while testing under 3-point bending.
9. Calibration
9.1 The accuracy of all testing and measuring equipment shall have certified calibrations that are current at the time of use of
the equipment.
10. Conditioning
10.1 If the test requestor does not explicitly specify a pre-test conditioning environment, conditioning is not required and the
test specimens may be tested at normal room temperature (20-25°C or 68-77°F).
10.2 If no explicit conditioning process is performed the specimen conditioning process shall be reported as “unconditioned.”
11. Test Setup and Procedure
11.1 If needed, condition test specimens as required. Store the test specimens in the conditioned environment until test time if
the test environment is different than the conditioning environment.
11.2 Before testing, measure and record the cross-sectional shape and dimensions as necessary. Record the dimensions to three
significant figures.
11.3 Measure and record the length of the support and loading spans.
D8069 − 17a
11.4 Rate of Testing—Set the loading nose displacement to be continuous and at a rate as calculated by Eq 1:
R 5 ~Z 3 L !⁄~6 3 h! (1)
where:
R = loading nose displacement rate, mm/min (in./min),
Z = rate of straining of the outer fiber, mm/mm/min (in./in./min), which shall be rangning from 0.001 to 0.0008,
L = test span length, mm (in.), and
h = depth of test specimen, mm (in.).
11.5 The actual loading nose displacement rate range shall be within 610 % of that calculated by Eq 1.
11.6 Fixture Installation—Arrange the loading fixture for a three-point bend test, and place specimen in the testing apparatus
accordingly.
11.7 Specimen Insertion and Alignment—Place the specimen into the test fixture. Align the fixture and specimen so that the
longitudinal axis of the specimen is perpendicular (within 1°) to the longitudinal axis of the loading nose, and the loading nose
is para
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