ASTM C365/C365M-16

Standard Test Method for Flatwise Compressive Properties of Sandwich Cores

SIGNIFICANCE AND USE
5.1 Flatwise compressive strength and modulus are fundamental mechanical properties of sandwich cores that are used in designing sandwich panels. Deformation data can be obtained, and from a complete force versus deformation curve, it is possible to compute the compressive stress at any applied force (such as compressive stress at proportional limit force or compressive strength at the maximum force) and to compute the effective modulus of the core.  
5.2 This test method provides a standard method of obtaining the flatwise compressive strength and modulus for sandwich core structural design properties, material specifications, research and development applications, and quality assurance.  
5.3 In order to prevent local crushing of some honeycomb cores, it is often desirable to stabilize the facing plane surfaces with a suitable material, such as a thin layer of resin or thin facings. Flatwise compressive strength data may be generated using either stabilized specimens (reported as stabilized compression strength) or non-stabilized specimens (reported as bare compression strength). It is customary aerospace industry practice to determine compression modulus only when using stabilized specimens.  
5.4 Factors that influence the flatwise compressive strength and shall therefore be reported include the following: core material, methods of material fabrication, core geometry (cell size), core density, specimen geometry, specimen preparation, specimen conditioning, environment of testing, specimen alignment, loading procedure, and speed of testing.
SCOPE
1.1 This test method covers the determination of compressive strength and modulus of sandwich cores. These properties are usually determined for design purposes in a direction normal to the plane of facings as the core would be placed in a structural sandwich construction. The test procedures pertain to compression in this direction in particular, but also can be applied with possible minor variations to determining compressive properties in other directions. 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 This test method does not cover the determination of compressive core crush properties. Reference Test Method D7336/D7336M for determination of static energy absorption properties of honeycomb sandwich core materials.  
1.3 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.  
1.3.1 Within the text the inch-pound units are shown in brackets.  
1.4 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

• Status: Historical
• Publication Date: 14-May-2016
• ICS: 83.120 - Reinforced plastics
• Technical Committee: D30 - Composite Materials
• Drafting Committee: D30.09 - Sandwich Construction

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: C365/C365M − 16
Standard Test Method for
1
Flatwise Compressive Properties of Sandwich Cores
This standard is issued under the fixed designation C365/C365M; 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.
1. Scope C271/C271M Test Method for Density of Sandwich Core
Materials
1.1 This test method covers the determination of compres-
D883 Terminology Relating to Plastics
sive strength and modulus of sandwich cores. These properties
D3878 Terminology for Composite Materials
are usually determined for design purposes in a direction
D5229/D5229M Test Method for MoistureAbsorption Prop-
normal to the plane of facings as the core would be placed in
erties and Equilibrium Conditioning of Polymer Matrix
a structural sandwich construction. The test procedures pertain
Composite Materials
to compression in this direction in particular, but also can be
D7336/D7336M Test Method for Static Energy Absorption
appliedwithpossibleminorvariationstodeterminingcompres-
Properties of Honeycomb Sandwich Core Materials
sive properties in other directions. Permissible core material
E4 Practices for Force Verification of Testing Machines
forms include those with continuous bonding surfaces (such as
E6 Terminology Relating to Methods of Mechanical Testing
balsa wood and foams) as well as those with discontinuous
E122 Practice for Calculating Sample Size to Estimate,With
bonding surfaces (such as honeycomb).
Specified Precision, the Average for a Characteristic of a
1.2 This test method does not cover the determination of
Lot or Process
compressive core crush properties. Reference Test Method
E177 Practice for Use of the Terms Precision and Bias in
D7336/D7336M for determination of static energy absorption
ASTM Test Methods
properties of honeycomb sandwich core materials.
E456 Terminology Relating to Quality and Statistics
1.3 The values stated in either SI units or inch-pound units
3. Terminology
are to be regarded separately as standard. The values stated in
3.1 Definitions—Terminology D3878 defines terms relating
each system may not be exact equivalents; therefore, each
to high-modulus fibers and their composites, as well as terms
system shall be used independently of the other. Combining
relating to sandwich constructions. Terminology D883 defines
values from the two systems may result in non-conformance
terms relating to plastics. Terminology E6 defines terms
with the standard.
relating to mechanical testing. Terminology E456 and Practice
1.3.1 Within the text the inch-pound units are shown in
E177 define terms relating to statistics. In the event of a
brackets.
conflict between terms, Terminology D3878 shall have prece-
1.4 This standard does not purport to address all of the
dence over the other terminologies.
safety concerns, if any, associated with its use. It is the
3.2 Symbols:
responsibility of the user of this standard to establish appro-
3.2.1 A—cross-sectional area of a test specimen
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use.
3.2.2 CV—coefficient of variation statistic of a sample
population for a given property (in percent)
2. Referenced Documents
fc
3.2.3 E —flatwise compressive modulus
z
2
2.1 ASTM Standards:
fcu
3.2.4 F —ultimate flatwise compressive strength
z
fc 0.02
3.2.5 F —flatwise compressive strength at 2 % LVDT/
z
1
This test method is under the jurisdiction of ASTM Committee D30 on
compressometer deflection
Composite Materials and is the direct responsibility of Subcommittee D30.09 on
Sandwich Construction. 3.2.6 P —maximumforcecarriedbytestspecimenbefore
max
Current edition approved May 15, 2016. Published June 2016. Originally
failure
approved in 1955. Last previous edition approved in 2011 as C365/C365M – 11A.
3.2.7 P —force carried by test specimen at 2 % LVDT/
DOI: 10.1520/C0365_C0365M-16.
0.02
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
compressometer deflection
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
3.2.8 S —standard deviation statistic of a sample popula-
Standards volume information, refer to the standard’s Document Summary page on n–1
the ASTM website. tion for a given property
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

---------------------- Page: 1 ----------------------
C365/C365M − 16
3.2.9 t—thickness of a test specimen 6.2 System Alignment—Non-uniform loading over the sur-
face of the test sp
...

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: C365/C365M − 11a C365/C365M − 16
Standard Test Method for
1
Flatwise Compressive Properties of Sandwich Cores
This standard is issued under the fixed designation C365/C365M; 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.
1. Scope
1.1 This test method covers the determination of compressive strength and modulus of sandwich cores. These properties are
usually determined for design purposes in a direction normal to the plane of facings as the core would be placed in a structural
sandwich construction. The test procedures pertain to compression in this direction in particular, but also can be applied with
possible minor variations to determining compressive properties in other directions. 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 This test method does not cover the determination of compressive core crush properties. Reference Test Method
D7336/D7336M for determination of static energy absorption properties of honeycomb sandwich core materials.
1.3 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.
1.3.1 Within the text the inch-pound units are shown in brackets.
1.4 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.
2. Referenced Documents
2
2.1 ASTM Standards:
C271/C271M Test Method for Density of Sandwich Core Materials
3
C274 Terminology of Structural Sandwich Constructions (Withdrawn 2016)
D883 Terminology Relating to Plastics
D3878 Terminology for Composite Materials
D5229/D5229M Test Method for Moisture Absorption Properties and Equilibrium Conditioning of Polymer Matrix Composite
Materials
D7336/D7336M Test Method for Static Energy Absorption Properties of Honeycomb Sandwich Core Materials
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
E456 Terminology Relating to Quality and Statistics
3
E1309 Guide for Identification of Fiber-Reinforced Polymer-Matrix Composite Materials in Databases (Withdrawn 2015)
3
E1434 Guide for Recording Mechanical Test Data of Fiber-Reinforced Composite Materials in Databases (Withdrawn 2015)
E1471 Guide for Identification of Fibers, Fillers, and Core Materials in Computerized Material Property Databases (Withdrawn
3
2015)
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 Nov. 1, 2011May 15, 2016. Published December 2011June 2016. Originally approved in 1955. Last previous edition approved in 2011 as
C365/C365M – 11.C365/C365M – 11A. DOI: 10.1520/C0365_C0365M-11A.10.1520/C0365_C0365M-16.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. 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 ----------------------
C365/C365M − 16
3. Terminology
3.1 Definitions—Terminology D3878 defines terms relating to high-modulus fibers and their composites.
Terminologycomposites, as C274 defineswell as terms relating to structural sandwich constructions. Terminology D883 defines
terms relating to plastics. Terminology E6 defines terms relating to mechanical testing. Terminology E456 and Pr
...