ASTM D7249/D7249M-20
(Test Method)Standard Test Method for Facesheet Properties of Sandwich Constructions by Long Beam Flexure
Standard Test Method for Facesheet 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 facesheets’ compressive and tensile strengths. Tests to evaluate core shear strength may also be used to evaluate core-to-facesheet bonds.
5.2 This test method is limited to obtaining the strength and stiffness of the sandwich panel facesheets, and to obtaining load-deflection data for use in calculating sandwich beam flexural and shear stiffness using 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/C273M provided bare core material is available. Test Method C393/C393M may also be used to determine core shear strength. 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 facesheet 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 facesheet strength and shall therefore be reported include the following: facesheet material, core material, adhesive material, methods of material fabrication, facesheet 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, facesheet void content, adhesive void content, and facesheet volume percent reinforcement. Further, facesheet strength may be different between precured/bonded and co-cured facesheets of the s...
SCOPE
1.1 This test method covers determination of facesheet properties of flat sandwich constructions subjected to flexure in such a manner that the applied moments produce curvature of the sandwich facesheet planes and result in compressive and tensile forces in the facesheets. 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 Units—The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system are not necessarily exact equivalents; therefore, to ensure conformance with the standard, each system shall be used independently of the other, and values from the two systems shall not be combined.
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, health, and environmental 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.
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.
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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.
Designation: D7249/D7249M − 20
Standard Test Method for
Facesheet 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. Scope 2. Referenced Documents
2
2.1 ASTM Standards:
1.1 This test method covers determination of facesheet
C273/C273MTestMethodforShearPropertiesofSandwich
propertiesofflatsandwichconstructionssubjectedtoflexurein
Core Materials
such a manner that the applied moments produce curvature of
C393/C393MTest Method for Core Shear Properties of
the sandwich facesheet planes and result in compressive and
Sandwich Constructions by Beam Flexure
tensileforcesinthefacesheets.Permissiblecorematerialforms
D3410/D3410MTest Method for Compressive Properties of
include those with continuous bonding surfaces (such as balsa
Polymer Matrix Composite Materials with Unsupported
wood and foams) as well as those with discontinuous bonding
Gage Section by Shear Loading
surfaces (such as honeycomb).
D3878Terminology for Composite Materials
D5229/D5229MTestMethodforMoistureAbsorptionProp-
1.2 Units—The values stated in either SI units or inch-
erties and Equilibrium Conditioning of Polymer Matrix
pound units are to be regarded separately as standard. The
Composite Materials
values stated in each system are not necessarily exact equiva-
D5467/D5467MTest Method for Compressive Properties of
lents; therefore, to ensure conformance with the standard, each
Unidirectional Polymer Matrix Composite Materials Us-
system shall be used independently of the other, and values
ing a Sandwich Beam
from the two systems shall not be combined.
D7250/D7250MPractice for Determining Sandwich Beam
1.2.1 Within the text, the inch-pound units are shown in
Flexural and Shear Stiffness
brackets.
E4Practices for Force Verification of Testing Machines
E6Terminology Relating to Methods of Mechanical Testing
1.3 This standard does not purport to address all of the
E122PracticeforCalculatingSampleSizetoEstimate,With
safety concerns, if any, associated with its use. It is the
Specified Precision, the Average for a Characteristic of a
responsibility of the user of this standard to establish appro-
Lot or Process
priate safety, health, and environmental practices and deter-
E177Practice for Use of the Terms Precision and Bias in
mine the applicability of regulatory limitations prior to use.
ASTM Test Methods
NOTE 1—Alternate procedures for determining the compressive E251Test Methods for Performance Characteristics of Me-
strength of unidirectional polymer matrix composites materials in a tallic Bonded Resistance Strain Gages
sandwich beam configuration may be found in Test Method D5467/
E456Terminology Relating to Quality and Statistics
D5467M.
E1237Guide for Installing Bonded Resistance Strain Gages
1.4 This international standard was developed in accor-
3. Terminology
dance with internationally recognized principles on standard-
ization established in the Decision on Principles for the
3.1 Definitions—Terminology D3878 defines terms relating
Development of International Standards, Guides and Recom-
to high-modulus fibers and their composites. Terminology E6
mendations issued by the World Trade Organization Technical
definestermsrelatingtomechanicaltesting.TerminologyE456
Barriers to Trade (TBT) Committee. and Practice E177 define terms relating to statistics. In the
event of a conflict between terms, Terminology D3878 shall
have precedence over the other terminologies.
1
This test method is under the jurisdiction of ASTM Committee D30 on
Composite Materials and is the direct responsibility of Subcommittee D30.09 on
2
Sandwich Construction. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Feb. 1, 2020. Published February 2020. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 2006. Last previous edition approved in 2018 as D7249/D7249M–18. Standards volume information, refer to the standard’s Document Summary page on
DOI: 10.1520/D7249_D7249M-20. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1
---------------------- Page: 1 ----------------------
D7249/D7249M − 20
3.2 Symbols: 5.3 Core shear strength and shear modulus are best deter-
mined in accordance withTest Method C273/C273M provided
b
...
This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D7249/D7249M − 18 D7249/D7249M − 20
Standard Test Method for
Facesheet 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. Scope
1.1 This test method covers determination of facesheet properties of flat sandwich constructions subjected to flexure in such a
manner that the applied moments produce curvature of the sandwich facesheet planes and result in compressive and tensile forces
in the facesheets. 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 Units—The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated
in each system are not necessarily exact equivalents; therefore, to ensure conformance with the standard, each system shall be used
independently of the other, and values from the two systems shall not be combined.
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, health, and environmental 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.
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
2.1 ASTM Standards:
C273/C273M Test Method for Shear Properties of Sandwich Core Materials
C393/C393M Test Method for Core Shear Properties of Sandwich Constructions by Beam Flexure
D3410/D3410M Test Method for Compressive Properties of Polymer Matrix Composite Materials with Unsupported Gage
Section by Shear Loading
D3878 Terminology for Composite Materials
D5229/D5229M Test Method for Moisture Absorption Properties and Equilibrium Conditioning of Polymer Matrix Composite
Materials
D5467/D5467M Test Method for Compressive Properties of Unidirectional Polymer Matrix Composite Materials Using a
Sandwich Beam
D7250/D7250M Practice for Determining Sandwich Beam Flexural and Shear Stiffness
E4 Practices for Force Verification of Testing Machines
E6 Terminology Relating to Methods of Mechanical Testing
E122 Practice for Calculating Sample Size to Estimate, With Specified Precision, the Average for a Characteristic of a Lot or
Process
E177 Practice for Use of the Terms Precision and Bias in ASTM Test Methods
E251 Test Methods for Performance Characteristics of Metallic Bonded Resistance Strain Gages
1
This test method is under the jurisdiction of ASTM Committee D30 on Composite Materials and is the direct responsibility of Subcommittee D30.09 on Sandwich
Construction.
Current edition approved April 1, 2018Feb. 1, 2020. Published April 2018February 2020. Originally approved in 2006. Last previous edition approved in 20162018 as
ɛ1
D7249/D7249M – 16D7249/D7249M – 18. . DOI: 10.1520/D7249_D7249M-18.10.1520/D7249_D7249M-20.
2
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.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1
---------------------- Page: 1 ----------------------
D7249/D7249M − 20
E456 Terminology Relating to Quality and Statistics
E1237 Guide for Installing Bonded Resistance Strain Gages
3. Terminology
3.1 Definitions—Terminology D3878 defines terms relating to high-modulus fibers and their composites. Terminology E6
defines terms relating to mechanical testing. Terminology E456 and Practice E177 define terms relating to s
...
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