ASTM C365-03

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Designation:C365–03
Standard Test Method for
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Flatwise Compressive Properties of Sandwich Cores
This standard is issued under the fixed designation C 365; 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 (e) 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 3.2 This test method provides a standard method of obtain-
ing the flatwise compressive strength and modulus for sand-
1.1 This test method covers the determination of the com-
wich panel design and research and development.
pressive strength and modulus of sandwich cores. These
properties are usually determined for design purposes in a
4. Apparatus
direction normal to the plane of facings as the core would be
4.1 Testing Machine, capable of maintaining a controlled
placed in a structural sandwich construction. The test proce-
loading rate and indicating the load with an accuracy of 61%
dures pertain to compression in this direction in particular, but
of the indicated value. The accuracy of the test machine shall
also can be applied with possible minor variations to determin-
be verified in accordance with Practices E 4.
ing compressive properties in other directions.
4.2 Spherical Bearing Block, preferably of the suspended,
1.2 The values stated in SI units are to be regarded as the
self-aligning type.
standard. The inch-pound units given may be approximate.
4.3 Deflectometer or Compressometer, capable of measur-
1.3 This standard does not purport to address all of the
ing the displacement with a precision of at least 61 %. Bonded
safety concerns, if any, associated with its use. It is the
resistance strain gages are not usually considered satisfactory
responsibility of the user of this standard to establish appro-
because of their stiffness. The reinforcing effect of bonding
priate safety and health practices and determine the applica-
these gages to some cores leads to large errors in measurement
bility of regulatory limitations prior to use.
of strains. Also, using the test machines cross-head travel
2. Referenced Documents reading is not satisfactory as large modulus errors can result.A
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transducer and rod setup as shown in Fig. 1 and Fig. 2 have
2.1 ASTM Standards:
been found to work satisfactorily. Here a small hole is drilled
E 4 Practices for Force Verification of Testing Machines
in the center of the specimen and in the bottom loading platen,
3. Significance and Use and a transducer rod is inserted that contacts the upper loading
platen.
3.1 The flatwise compressive strength and modulus are
4.4 Micrometer, Gage, or Caliper, capable of measuring
fundamental mechanical properties of sandwich cores that are
accurately to 0.025 mm (0.001 in.).
used in designing sandwich panels. Deformation data can be
obtained, and from a complete load-deformation curve it is
5. Test Specimens
possible to compute the compressive stress at any load (such as
5.1 Test specimens shall be of core or of sandwich construc-
compressive stress at proportional limit load or compressive
tion and shall be of square or circular cross section having
strength at maximum load) and to compute the effective
2 2
areas not exceeding 10 000 mm (16 in. ), but not less than the
modulus of the core.
following minimum areas for various types of cores:
5.1.1 For continuous cores, such as balsa wood and foams,
2 2
the minimum cross-sectional area shall be 625 mm (1 in. ).
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This specification is under the jurisdiction of ASTM Committee D30 on
5.1.2 For open-celled cores, such as honeycomb, having
Composite Materials and is the direct responsibility of Subcommittee D30.09 on
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cells less than 6 mm ( ⁄4 in.) the minimum cross-sectional area
Sandwich Construction.
2 2
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shall be 2500 mm (4 in. ) and for cells 6 mm ( ⁄4 in.) or
Current edition approved Dec. 1, 2003. Published December 2003. Originally
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approved in 1955. Last previous edition approved in 2000 as C 365 – 00.
greatertheminimumcross-sectionalareashallbe5800mm (9
2
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For referenced ASTM standards, visit the ASTM website, www.astm.org, or
in. ).
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
5.2 The height of the specimen shall be as agreed upon by
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. the purchaser and the seller.
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C365–03
FIG. 2 Close-up of Specimen
FIG. 1 Transducer and Rod Setup
dimension to the nearest 0.025 mm (0.001 in.). Weigh t
...