ASTM C393/C393M-06
(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 D 7250.
Note 1—Core shear strength and shear modulus are best determined in accordance with Test Method C 273 provided bare core material is available.
Facing strength is best determined in accordance with Test Method D 7249.
Practice D 7250 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. Wider load pads ...
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. 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.
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
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
Designation: C393/C393M – 06
Standard Test 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 Department of Defense.
1. Scope D7249/D7249M Test Method for Facing Properties of
Sandwich Constructions by Long Beam Flexure
1.1 This test method covers determination of the core shear
D7250/D7250M Practice for Determining Sandwich Beam
propertiesofflatsandwichconstructionssubjectedtoflexurein
Flexural and Shear Stiffness
such a manner that the applied moments produce curvature of
E4 Practices for Force Verification of Testing Machines
the sandwich facing planes. Permissible core material forms
E6 TerminologyRelatingtoMethodsofMechanicalTesting
include those with continuous bonding surfaces (such as balsa
E122 Practice for Calculating Sample Size to Estimate,
wood and foams) as well as those with discontinuous bonding
With Specified Precision, the Average for a Characteristic
surfaces (such as honeycomb).
of a Lot or Process
1.2 The values stated in either SI units or inch-pound units
E177 Practice for Use of the Terms Precision and Bias in
are to be regarded separately as standard. Within the text the
ASTM Test Methods
inch-pound units are shown in brackets. The values stated in
E456 Terminology Relating to Quality and Statistics
each system are not exact equivalents; therefore, each system
E1309 Guide for Identification of Fiber-Reinforced
must be used independently of the other. Combining values
Polymer-Matrix Composite Materials in Databases
from the two systems may result in nonconformance with the
E1434 Guide for Recording Mechanical Test Data of Fiber-
standard.
Reinforced Composite Materials in Databases
1.3 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
3. Terminology
responsibility of the user of this standard to establish appro-
3.1 Definitions—Terminology D3878 defines terms relating
priate safety and health practices and determine the applica-
to high-modulus fibers and their composites. Terminology
bility of regulatory limitations prior to use.
C274 defines terms relating to structural sandwich construc-
2. Referenced Documents tions. Terminology D883 defines terms relating to plastics.
2
Terminology E6 defines terms relating to mechanical testing.
2.1 ASTM Standards:
Terminology E456 and Practice E177 define terms relating to
C273 Test Method for Shear Properties of Sandwich Core
statistics.Intheeventofaconflictbetweenterms,Terminology
Materials
D3878 shall have precedence over the other terminologies.
C274 Terminology of Structural Sandwich Constructions
3.2 Symbols:
D883 Terminology Relating to Plastics
b = specimen width
D3878 Terminology for Composite Materials
c = core thickness
D5229/D5229M Test Method for Moisture Absorption
CV = coefficient of variation statistic of a sample population
Properties and Equilibrium Conditioning of Polymer Ma-
for a given property (in percent)
trix Composite Materials
d = sandwich total thickness
F,nom
D = effective sandwich flexural stiffness
1
This test method is under the jurisdiction of ASTM Committee D30 on E = effective facing chord modulus
f
Composite Materials and is the direct responsibility of Subcommittee D30.09 on
´ = measuring strain in facing
Sandwich Construction.
u
F = facing ultimate strength (tensile or compressive)
Current edition approved Sept. 1, 2006. Published October 2006. Originally
F = core compression allowable strength
approved in 1957. Last previous edition approved in 2000 as C393 – 00. DOI:
c
10.1520/C0393_C0393M-06.
F = core shear allowable strength
s
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or ult
F = core shear ultimate strength
s
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
yield
F = core shear yield strength
Standards volume information, refer to the standard’s Document Summary page on s
the ASTM website. k = core shear strength factor to ensure core failure
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
1
---------------------- Page: 1 ----------------------
C393/C393M – 06
L = length of loading span tion, core geometry (cell size), core density, adhesive thick-
S = length of support span ness, specimen geometry, specimen preparation, specimen
l = length of loading pad conditioning, environment of testing, specimen alignment,
pad
n = number
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.