ASTM D7249/D7249M-12e1
(Test Method)Standard Test Method for Facing Properties of Sandwich Constructions by Long Beam Flexure
Standard Test Method for Facing Properties of Sandwich Constructions by Long Beam Flexure
SIGNIFICANCE AND USE
5.1 Flexure tests on flat sandwich construction may be conducted to determine the sandwich flexural stiffness, the core shear strength, and shear modulus, or the facings’ compressive and tensile strengths. Tests to evaluate core shear strength may also be used to evaluate core-to-facing bonds.
5.2 This test method is limited to obtaining the strength and stiffness of the sandwich panel facings, and to obtaining load-deflection data for use in calculating sandwich beam flexural and shear stiffness using Standard Practice D7250/D7250M. Due to the curvature of the flexural test specimen when loaded, facesheet compression strength from this test may not be equivalent to the facesheet compression strength of sandwich structures subjected to pure edgewise (in-plane) compression.
5.3 Core shear strength and shear modulus are best determined in accordance with Test Method C273 provided bare core material is available. Test Method C393 may also be used to determine core shear strength. Standard Practice D7250/D7250M may be used to calculate the flexural and shear stiffness of sandwich beams.
5.4 This test method can be used to produce facing strength data for structural design allowables, material specifications, and research and development applications; it may also be used as a quality control test for bonded sandwich panels.
5.5 Factors that influence the facing strength and shall therefore be reported include the following: facing material, core material, adhesive material, methods of material fabrication, facing stacking sequence and overall thickness, core geometry (cell size), core density, adhesive thickness, specimen geometry, specimen preparation, specimen conditioning, environment of testing, specimen alignment, loading procedure, speed of testing, facing void content, adhesive void content, and facing volume percent reinforcement. Further, facing strength may be different between precured/bonded and co-cured facesheets of the same material.Note 2—Con...
SCOPE
1.1 This test method covers determination of facing properties of flat sandwich constructions subjected to flexure in such a manner that the applied moments produce curvature of the sandwich facing planes and result in compressive and tensile forces in the facings. Permissible core material forms include those with continuous bonding surfaces (such as balsa wood and foams) as well as those with discontinuous bonding surfaces (such as honeycomb).
1.2 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.
1.2.1 Within the text, the inch-pound units are shown in brackets.
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.Note 1—Alternate procedures for determining the compressive strength of unidirectional polymer matrix composites materials in a sandwich beam configuration may be found in Test Method D5467/D5467M.
General Information
Relations
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
´1
Designation: D7249/D7249M − 12
StandardTest Method for
Facing Properties of Sandwich Constructions by Long
1
Beam Flexure
This standard is issued under the fixed designation D7249/D7249M; 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
ε NOTE—Figure 6 was corrected editorially in March 2014.
1. Scope C393Test Method for Flexural Properties of Sandwich
Constructions
1.1 This test method covers determination of facing prop-
D3878Terminology for Composite Materials
erties of flat sandwich constructions subjected to flexure in
D5229/D5229MTestMethodforMoistureAbsorptionProp-
such a manner that the applied moments produce curvature of
erties and Equilibrium Conditioning of Polymer Matrix
the sandwich facing planes and result in compressive and
Composite Materials
tensile forces in the facings. Permissible core material forms
D5467/D5467MTest Method for Compressive Properties of
include those with continuous bonding surfaces (such as balsa
Unidirectional Polymer Matrix Composite Materials Us-
wood and foams) as well as those with discontinuous bonding
ing a Sandwich Beam
surfaces (such as honeycomb).
D7250/D7250MPractice for Determining Sandwich Beam
1.2 The values stated in either SI units or inch-pound units
Flexural and Shear Stiffness
are to be regarded separately as standard. The values stated in
E6Terminology Relating to Methods of Mechanical Testing
each system may not be exact equivalents; therefore, each
E122PracticeforCalculatingSampleSizetoEstimate,With
system shall be used independently of the other. Combining
Specified Precision, the Average for a Characteristic of a
values from the two systems may result in non-conformance
Lot or Process
with the standard.
E177Practice for Use of the Terms Precision and Bias in
1.2.1 Within the text, the inch-pound units are shown in
ASTM Test Methods
brackets.
E251Test Methods for Performance Characteristics of Me-
1.3 This standard does not purport to address all of the
tallic Bonded Resistance Strain Gages
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-
Reinforced Composite Materials in Databases
NOTE 1—Alternate procedures for determining the compressive
strength of unidirectional polymer matrix composites materials in a
sandwich beam configuration may be found in Test Method D5467/
3. Terminology
D5467M.
3.1 Definitions—Terminology D3878 defines terms relating
2. Referenced Documents
to high-modulus fibers and their composites. Terminology
2
C274 defines terms relating to structural sandwich construc-
2.1 ASTM Standards:
tions. Terminology C393 defines terms relating to plastics.
C274Terminology of Structural Sandwich Constructions
Terminology E6 defines terms relating to mechanical testing.
Terminology E456 and Practice E177 define terms relating to
statistics.Intheeventofaconflictbetweenterms,Terminology
1
This test method is under the jurisdiction of ASTM Committee D30 on
D3878 shall have precedence over the other terminologies.
Composite Materials and is the direct responsibility of Subcommittee D30.09 on
Sandwich Construction.
3.2 Symbols:
Current edition approved Aug. 1, 2012. Published December 2012. Originally
approved in 2006. Last previous edition approved in 2006 as D7249/
b = specimen width
D7249M–06.DOI: 10.1520/D7249_D7249M-12.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or c = core thickness
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
CV = coefficient of variation statistic of a sample popu-
Standards volume information, refer to the standard’s Document Summary page on
lation for a given property (in percent)
the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1
---------------------- Page: 1 ----------------------
´1
D7249/D7249M − 12
d = sandwich total thickness
1
---------------------- Page: 2 ----------------------
´1
D7249/D7249M − 12
F,nom
5.4 This test method can be used to produce facing strength
D = effective sandwich flexural stiffness
f
data for structural design allowables, material specifications,
E = effective facing chord modulus
andresearchanddevelopmentapplications;itmayalsobeused
ε = measuring strain
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.