ASTM D8388/D8388M-22
(Practice)Standard Practice for Flexural Residual Strength Testing of Damaged Sandwich Constructions
Standard Practice for Flexural Residual Strength Testing of Damaged Sandwich Constructions
SIGNIFICANCE AND USE
5.1 This practice provides supplemental instructions that allow the use of Test Method D7249/D7249M to determine residual compressive or tensile strength properties of damaged sandwich constructions. Susceptibility to damage from concentrated out-of-plane forces is one of the major design concerns of many structures made using sandwich constructions. Knowledge of the residual strength properties of a sandwich panel is useful for product development, establishing design allowables, and material selection.
5.2 The residual compressive or tensile strength data obtained using this test practice is most commonly used in material selection, research and development activities, and establishing design allowables.
5.3 The properties obtained using this test practice can provide guidance in regard to the anticipated compressive or tensile residual strength capability of sandwich constructions of similar facesheet and core material, adhesive, facesheet and core thickness, facesheet stacking sequence, and so forth. However, it must be understood that the residual strength of sandwich constructions is highly dependent upon several factors including geometry, thickness, stiffness, support conditions, and so forth. Significant differences in the relationships between the damage state and the residual compressive or tensile strength can result due to differences in these parameters.
5.4 The compression strength from this test may not be equivalent to the compression strength of sandwich structures subjected to pure edgewise (in-plane) compression.
5.5 The reporting section requires items that tend to influence residual strength to be reported; these include the following: facesheet and core materials, core density, cell size and wall thickness if applicable, film adhesive, methods of material fabrication, accuracy of lay-up orientation, facesheet stacking sequence and thickness, core thickness, overall specimen thickness, specimen geometry, specimen preparation, specim...
SCOPE
1.1 This practice provides instructions for modifying the long beam flexure test method to determine the tensile or compressive residual strength properties of sandwich constructions that have been subjected to quasi-static indentation or drop-weight impact per Practice D7766/D7766M. The tensile or compressive strength result is determined by which facesheet contains the damage, either the loaded-span or support-span facesheet, based on how the specimen is positioned in the fixture.
1.2 This practice supplements Test Method D7249/D7249M with provisions for testing damaged sandwich specimens. Several important test specimen parameters (for example, facesheet thickness, core thickness and core density) are not mandated by this practice; however, repeatable results require that these parameters be specified and reported.
1.3 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.
1.3.1 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.5 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.
General Information
Relations
Standards Content (Sample)
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: D8388/D8388M − 22
Standard Practice for
Flexural Residual Strength Testing of Damaged Sandwich
1
Constructions
This standard is issued under the fixed designation D8388/D8388M; 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 practice provides instructions for modifying the
long beam flexure test method to determine the tensile or D883 Terminology Relating to Plastics
D3410/D3410M Test Method for Compressive Properties of
compressive residual strength properties of sandwich construc-
tions that have been subjected to quasi-static indentation or Polymer Matrix Composite Materials with Unsupported
Gage Section by Shear Loading
drop-weight impact per Practice D7766/D7766M. The tensile
or compressive strength result is determined by which D3878 Terminology for Composite Materials
D5687/D5687M Guide for Preparation of Flat Composite
facesheet contains the damage, either the loaded-span or
support-span facesheet, based on how the specimen is posi- Panels with Processing Guidelines for Specimen Prepara-
tioned in the fixture. tion
D7249/D7249M Test Method for Facesheet Properties of
1.2 This practice supplementsTest Method D7249/D7249M
Sandwich Constructions by Long Beam Flexure
with provisions for testing damaged sandwich specimens.
D7766/D7766M Practice for Damage Resistance Testing of
Several important test specimen parameters (for example,
Sandwich Constructions
facesheet thickness, core thickness and core density) are not
E6 Terminology Relating to Methods of Mechanical Testing
mandated by this practice; however, repeatable results require
E122 Practice for Calculating Sample Size to Estimate,With
that these parameters be specified and reported.
Specified Precision, the Average for a Characteristic of a
1.3 Units—The values stated in either SI units or inch-
Lot or Process
pound units are to be regarded separately as standard. The
E177 Practice for Use of the Terms Precision and Bias in
values stated in each system are not necessarily exact equiva-
ASTM Test Methods
lents; therefore, to ensure conformance with the standard, each
E456 Terminology Relating to Quality and Statistics
system shall be used independently of the other, and values
from the two systems shall not be combined. 3. Terminology
1.3.1 Within the text, the inch-pound units are shown in
3.1 Definitions—Terminology D3878 defines terms relating
brackets.
to high-modulus fibers and their composites, as well as terms
1.4 This standard does not purport to address all of the
relating to sandwich constructions. Terminology D883 defines
safety concerns, if any, associated with its use. It is the
terms relating to plastics. Terminology E6 defines terms
responsibility of the user of this standard to establish appro-
relating to mechanical testing. Terminology E456 and Practice
priate safety, health, and environmental practices and deter-
E177 define terms relating to statistics. In the event of a
mine the applicability of regulatory limitations prior to use.
conflict between terms, Terminology D3878 shall have prece-
1.5 This international standard was developed in accor-
dence over the other terminologies.
dance with internationally recognized principles on standard-
NOTE 1—If the term represents a physical quantity, its analytical
ization established in the Decision on Principles for the
dimensionsarestatedimmediatelyfollowingtheterm(orlettersymbol)in
Development of International Standards, Guides and Recom-
fundamental dimension form, using the following ASTM standard sym-
mendations issued by the World Trade Organization Technical bology for fundamental dimensions, shown within square brackets: [M]
for mass, [L] for length, [T] for time, [θ] for thermodynamic temperature,
Barriers to Trade (TBT) Committee.
and[nd]fornon-dimensionalquantities.Useofthesesymbolsisrestricted
to analytical dimensions when used with square brackets, as the symbols
1
This practice is under the jurisdiction ofASTM Committee D30 on Composite
2
Materials and is the direct responsibility of Subcommittee D30.09 on Sandwich For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Construction. contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Current edition approved May 1, 2022. Published June 2022. DOI: 10.1520/ Standards volume information, refer to the standard’s Document Summary page on
D8388_D8388M-22. the
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