ASTM C393/C393M-11e1
(Test Method)Standard Test Method for Core Shear Properties of Sandwich Constructions by Beam Flexure
Standard Test Method for Core Shear Properties of Sandwich Constructions by Beam Flexure
SIGNIFICANCE AND USE
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.
This test method is limited to obtaining the core shear strength or core-to-facing shear strength and the stiffness of the sandwich beam, and to obtaining load-deflection data for use in calculating sandwich beam flexural and shear stiffness using Practice D7250/D7250M.
Note 1—Core shear strength and shear modulus are best determined in accordance with Test Method C273 provided bare core material is available.
Facing strength is best determined in accordance with Test Method D7249/D7249M.
Practice D7250/D7250M covers the determination of sandwich flexural and shear stiffness and core shear modulus using calculations involving measured deflections of sandwich flexure specimens.
This test method can be used to produce core shear strength and core-to-facing shear 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.
Factors that influence the shear strength and shall therefore be reported include the following: facing material, core material, adhesive material, methods of material fabrication, core geometry (cell size), core density, adhesive thickness, specimen geometry, specimen preparation, specimen conditioning, environment of testing, specimen alignment, loading procedure, speed of testing, and adhesive void content. Further, core-to-facing strength may be different between precured/bonded and co-cured facings in sandwich panels with the same core and facing material.
Note 2—Concentrated loads on beams with thin facings and low density cores can produce results that are difficult to interpret, especially close to the failure point....
SCOPE
1.1 This test method covers determination of the core shear properties of flat sandwich constructions subjected to flexure in such a manner that the applied moments produce curvature of the sandwich facing planes. 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.
General Information
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Standards Content (Sample)
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Designation: C393/C393M − 11
StandardTest Method for
Core Shear Properties of Sandwich Constructions by Beam
1
Flexure
This standard is issued under the fixed designation C393/C393M; 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.
This standard has been approved for use by agencies of the U.S. Department of Defense.
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ε NOTE—Sections 7 and 11 were editorially corrected in February 2012.
1. Scope D5229/D5229M Test Method for MoistureAbsorption Prop-
erties and Equilibrium Conditioning of Polymer Matrix
1.1 This test method covers determination of the core shear
Composite Materials
propertiesofflatsandwichconstructionssubjectedtoflexurein
D7249/D7249M Test Method for Facing Properties of Sand-
such a manner that the applied moments produce curvature of
wich Constructions by Long Beam Flexure
the sandwich facing planes. Permissible core material forms
D7250/D7250M Practice for Determining Sandwich Beam
include those with continuous bonding surfaces (such as balsa
Flexural and Shear Stiffness
wood and foams) as well as those with discontinuous bonding
E4 Practices for Force Verification of Testing Machines
surfaces (such as honeycomb).
E6 Terminology Relating to Methods of Mechanical Testing
1.2 The values stated in either SI units or inch-pound units
E122 Practice for Calculating Sample Size to Estimate,With
are to be regarded separately as standard. The values stated in
Specified Precision, the Average for a Characteristic of a
each system may not be exact equivalents; therefore, each
Lot or Process
system shall be used independently of the other. Combining
E177 Practice for Use of the Terms Precision and Bias in
values from the two systems may result in non-conformance
ASTM Test Methods
with the standard.
E456 Terminology Relating to Quality and Statistics
1.2.1 Within the text the inch-pound units are shown in
E1309 Guide for Identification of Fiber-Reinforced
brackets.
Polymer-Matrix Composite Materials in Databases
1.3 This standard does not purport to address all of the E1434 Guide for Recording Mechanical Test Data of Fiber-
safety concerns, if any, associated with its use. It is the Reinforced Composite Materials in Databases
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
3. Terminology
bility of regulatory limitations prior to use.
3.1 Definitions—Terminology D3878 defines terms relating
to high-modulus fibers and their composites. Terminology
2. Referenced Documents
C274 defines terms relating to structural sandwich construc-
2
2.1 ASTM Standards:
tions. Terminology D883 defines terms relating to plastics.
C273 Test Method for Shear Properties of Sandwich Core
Terminology E6 defines terms relating to mechanical testing.
Materials
Terminology E456 and Practice E177 define terms relating to
C274 Terminology of Structural Sandwich Constructions
statistics.Intheeventofaconflictbetweenterms,Terminology
D883 Terminology Relating to Plastics
D3878 shall have precedence over the other terminologies.
D3878 Terminology for Composite Materials
3.2 Symbols:
b = specimen width
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This test method is under the jurisdiction of ASTM Committee D30 on c = core thickness
Composite Materials and is the direct responsibility of Subcommittee D30.09 on
CV = coefficient of variation statistic of a sample population
Sandwich Construction.
for a given property (in percent)
Current edition approved Oct. 1, 2011. Published November 2011. Originally
d = sandwich total thickness
approved in 1957. Last previous edition approved in 2006 as C393 – 06. DOI:
F,nom
10.1520/C0393_C0393M-11.
D = effective sandwich flexural stiffness
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
E = effective facing chord modulus
f
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
ε = measuring strain in facing
Standards volume information, refer to the standard’s Document Summary page on
u
the ASTM website. F = facing ultimate strength (tensile or compressive)
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C393/C393M − 11
F = core compression allowable strength design allowables, material specifications, and research and
c
F = core shear allowable strength development applications; it may also be used as a quality
s
ult
F = core shear ultimate strength control test for bonded sandwich panels.
s
yield
F = core shear yield strength
s
5.6 Factors that influence the shear strength and shall
k = core shea
...
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