ASTM D6772-02
(Test Method)Standard Test Method for Dimensional Stability of Sandwich Core Materials
Standard Test Method for Dimensional Stability of Sandwich Core Materials
SCOPE
1.1 This test method covers the determination of the sandwich core dimensional stability in the two plan dimensions.
1.2 The values stated in SI units are to be regarded as the standard. The inch-pound units given may be approximate.
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 and health practices and determine the applicability of regulatory limitations prior to use.
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Designation:D6772–02
Standard Test Method for
Dimensional Stability of Sandwich Core Materials
This standard is issued under the fixed designation D 6772; 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.
1. Scope
1.1 This test method covers the determination of the sand-
wich core dimensional stability in the two plan dimensions.
1.2 The values stated in SI units are to be regarded as the
standard. The inch-pound units given may be approximate.
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 appro-
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use.
2. Referenced Documents
FIG. 1 Dimensional Stability Specimen
2.1 ASTM Standards:
C 271 Test Method for Density of Sandwich Core Materi-
6. Interferences
als
6.1 If oven size is limited, smaller specimens may be used.
C 274 Terminology of Structural Sandwich Constructions
6.2 If the specimen warps, flatten it out while making the
3. Terminology
measurements.
3.1 Definitions—Terminology C 274 defines terms relating
7. Apparatus
to sandwich constructions.
7.1 Oven, capable of maintaining a controlled temperature
3.2 Symbols:
63°C (65°F).
L = initial measured dimension
i
7.2 Scale, capable of measuring accurately to 0.25 mm
L = final measured dimension
f
(0.01 in.).
4. Summary of Test Method
7.3 Micrometer, capable of measuring accurately to 0.025
mm (0.001 in.).
4.1 A small piece of honeycomb is placed in an elevated
temperature environment and after cooling, the dimensional
8. Sampling and Test Specimens
changes in the plan dimensions are measured and compared to
8.1 Test at least five specimens per test condition unless
the initial measurements. A typical honeycomb specimen is
valid results can be gained through the use of fewer specimens,
shown in Fig. 1.
such as in the case of a designed experiment.
5. Significance and Use 8.2 The test specimens, if possible, should be approximately
460 by 915 mm (18 by 36 in.) in plan dimension, and the
5.1 Sandwich panel cores may change plan dimensions
thickness shall be approximately 12.7 mm (0.50 in.). For
when heated. It is prudent to know if this may be a problem
honeycomb cores, the 460-mm (18-in.) dimension is the core’s
with the final part dimensions.
ribbon or L direction. Other dimensions can be used, but must
be reported.
9. Calibration
This test method is under the jurisdiction of ASTM Committee D30 on
Composite Materials and is the direct responsibility of Subcommittee D30.09 on
9.1 The accuracy of all measuring equipment shall have
Sandwich Construction.
certified calibrations that are current at the time of use of the
Current edition approved Mar. 10, 2002. Published May 2002.
Annual Book of ASTM Standards, Vol 15.03. equipment.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D6772
10. Conditioning
10.
...
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SIGNIFICANCE AND USE
5.1 This test method simulates the hydrostatic loading conditions which are often present in actual sandwich structures, such as marine hulls. This test method can be used to compare the two-dimensional flexural stiffness of a sandwich composite made with different combinations of materials or with different fabrication processes. Since it is based on distributed loading rather than concentrated loading, it may also provide more realistic information on the failure mechanisms of sandwich structures loaded in a similar manner. Test data should be useful for design and engineering, material specification, quality assurance, and process development. In addition, data from this test method would be useful in refining predictive mathematical models or computer code for use as structural design tools. Properties that may be obtained from this test method include:
5.1.1 Panel surface deflection at load,
5.1.2 Panel face-sheet strain at load,
5.1.3 Panel bending stiffness,
5.1.4 Panel shear stiffness,
5.1.5 Panel strength, and
5.1.6 Panel failure modes.
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1.1 This test method determines the two-dimensional flexural properties of sandwich composite plates subjected to a distributed load. The test fixture uses a relatively large square panel sample which is simply supported all around and has the distributed load provided by a water-filled bladder. This type of loading differs from the procedure of Test Method C393, where concentrated loads induce one-dimensional, simple bending in beam specimens.
1.2 This test method is applicable to composite structures of the sandwich type which involve a relatively thick layer of core material bonded on both faces with an adhesive to thin-face sheets composed of a denser, higher-modulus material, typically, a polymer matrix reinforced with high-modulus fibers.
1.3 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.
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SIGNIFICANCE AND USE
5.1 Often the most critical stress to which a sandwich panel core is subjected is shear. The effect of repeated shear stresses on the core material can be very important, particularly in terms of durability under various environmental conditions.
5.2 This test method provides a standard method of obtaining the sandwich core shear fatigue response. Uses include screening candidate core materials for a specific application, developing a design-specific core shear cyclic stress limit, and core material research and development.
Note 3: This test method may be used as a guide to conduct spectrum loading. This information can be useful in the understanding of fatigue behavior of core under spectrum loading conditions, but is not covered in this standard.
5.3 Factors that influence core fatigue response and shall therefore be reported include the following: core material, core geometry (density, cell size, orientation, etc.), specimen geometry and associated measurement accuracy, specimen preparation, specimen conditioning, environment of testing, specimen alignment, loading procedure, loading frequency, force (stress) ratio and speed of testing (for residual strength tests).
Note 4: If a sandwich panel is tested using the guidance of this standard, the following may also influence the fatigue response and should be reported: facing material, adhesive material, methods of material fabrication, adhesive thickness 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 materials.
SCOPE
1.1 This test method determines the effect of repeated shear forces on core material used in sandwich panels. 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 is limited to test specimens subjected to constant amplitude uniaxial loading, where the machine is controlled so that the test specimen is subjected to repetitive constant amplitude force (stress) cycles. Either shear stress or applied force may be used as a constant amplitude fatigue variable.
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 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. Within the text, the inch-pound units are shown in brackets.
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SIGNIFICANCE AND USE
5.1 The determination of the creep rate provides information on the behavior of sandwich constructions under constant applied force. Creep is defined as deflection under constant force over a period of time beyond the initial deformation as a result of the application of the force. Deflection data obtained from this test method can be plotted against time, and a creep rate determined. By using standard specimen constructions and constant loading, the test method may also be used to evaluate creep behavior of sandwich panel core-to-facing adhesives.
5.2 This test method provides a standard method of obtaining flexure creep of sandwich constructions for quality control, acceptance specification testing, and research and development.
5.3 Factors that influence the sandwich construction creep response and shall therefore be reported include the following: facing material, core material, adhesive material, methods of material fabrication, facing stacking sequence and overall thickness, core geometry (cell size), core density, core thickness, adhesive thickness, specimen geometry, specimen preparation, specimen conditioning, environment of testing, specimen alignment, loading procedure, speed of testing, facing void content, adhesive void content, and facing volume percent reinforcement. Further, facing and core-to-facing strength and creep response may be different between precured/bonded and co-cured facesheets of the same material.
SCOPE
1.1 This test method covers the determination of the creep characteristics and creep rate of flat sandwich constructions loaded in flexure, at any desired temperature. 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 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 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.
1.4 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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SIGNIFICANCE AND USE
5.1 The honeycomb tensile-node bond strength is a fundamental property than can be used in determining whether honeycomb cores can be handled during cutting, machining and forming without the nodes breaking. The tensile-node bond strength is the tensile stress that causes failure of the honeycomb by rupture of the bond between the nodes. It is usually a peeling-type failure.
5.2 This test method provides a standard method of obtaining tensile-node bond strength data for quality control, acceptance specification testing, and research and development.
SCOPE
1.1 This test method covers the determination of the tensile-node bond strength of honeycomb core materials.
1.2 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 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.
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SIGNIFICANCE AND USE
5.1 The edgewise compressive strength of short sandwich construction specimens provides a basis for judging the load-carrying capacity of the construction in terms of developed facing stress.
5.2 This test method provides a standard method of obtaining sandwich edgewise compressive strengths for panel design properties, material specifications, research and development applications, and quality assurance.
5.3 The reporting section requires items that tend to influence edgewise compressive strength to be reported; these include materials, fabrication method, facesheet lay-up orientation (if composite), core orientation, results of any nondestructive inspections, specimen preparation, test equipment details, specimen dimensions and associated measurement accuracy, environmental conditions, speed of testing, failure mode, and failure location.
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1.1 This test method covers the compressive properties of structural sandwich construction in a direction parallel to the sandwich facing plane. 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).
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SIGNIFICANCE AND USE
5.1 This test method is designed to produce tensile property data for material specifications, research and development, quality assurance, and structural design and analysis. Factors that influence the tensile response and should be reported include the following: material, methods of material preparation and lay-up, specimen stacking sequence, specimen preparation, specimen conditioning, environment of testing, specimen alignment and gripping, speed of testing, time at temperature, and volume percent reinforcement. Properties, in the test direction, which may be obtained from this test method include the following:
5.1.1 Ultimate tensile strength,
5.1.2 Ultimate tensile strain,
5.1.3 Tensile modulus of elasticity, and
5.1.4 Poissons ratio.
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1.1 This test method covers the determination of the tensile properties of metal matrix composites reinforced by continuous and discontinuous high-modulus fibers. Nontraditional metal matrix composites as stated in 1.1.6 also are covered in this test method. This test method applies to specimens loaded in a uniaxial manner tested in laboratory air at either room temperature or elevated temperatures. The types of metal matrix composites covered are:
1.1.1 Unidirectional laminates (all fibers aligned in a single direction) containing either continuous or discontinuous reinforcing fibers. Both longitudinal and transverse properties may be obtained.
1.1.2 0°/90° balanced crossply laminates containing either continuous or discontinuous reinforcing fibers.
1.1.3 Angleply laminates containing continuous reinforcing fibers, with layups that do not include 0° reinforcing fibers (that is, (±45)ns, (±30)ns, and so forth).
1.1.4 Multidirectional laminates containing continuous reinforcing fibers, with layups including 0° reinforcing fibers (that is, (0/±45/90)ns quasi-isotropic laminates, (0/±30)ns laminates, and so forth).
1.1.5 Laminates containing unoriented and random discontinuous fibers.
1.1.6 Directionally solidified eutectic composites.
1.2 The technical content of this standard has been stable since 1996 without significant objection from its stakeholders. As there is limited technical support for the maintenance of this standard, changes since that date have been limited to items required to retain consistency with other ASTM D30 Committee standards. The standard therefore should not be considered to include any significant changes in approach and practice since 1996. Future maintenance of the standard will only be in response to specific requests and performed only as technical support allows.
1.3 The values stated in SI units are to be regarded as the standard. The values given in parentheses are provided for information purposes only.
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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.
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SIGNIFICANCE AND USE
5.1 Characterizing tack for different prepreg materials, test parameters, surface combinations, and environmental conditions provides insight for optimizing process parameters (particularly deposition rate and deposition temperature) for industrial automated material placement processes.
5.2 Results obtained through employing the continuous application-and-peel method, as described in studies (1-3),3 reflect the effects of adhesion forming between prepreg layers or between prepreg and metal substrate, and loss of cohesion within the resin in the prepreg, upon tack. This test method allows the adhesive properties of B-staged resin to be explored in a manner relevant for dynamic material deposition processes, where timescales for bonding of prepreg to the substrate or previously placed prepreg layers are short prior to curing. In contrast, Test Methods D3167 and D1781 determine the peel resistance of adhesive bonds for adhesion measurement and process control of laminated or bonded adherends.
5.3 The test method is suitable to quantify tack of prepregs for acceptance and process control and can be extended to determine resin shelf life or to adjust process parameters to resin out-time. Direct comparison of different resins/prepregs or processes can only be made when specimen preparation and test conditions are identical.
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1.1 This test method covers measurement of adhesion (tack) between partially cured (B-staged) composite prepreg and a surface in a peel test, under specified conditions. The test may be conducted to measure tack between a flexible layer of prepreg and another prepreg layer bonded to a rigid substrate (Method I) or a rigid metal substrate (Method II). This test method is primarily geared towards material characterization for automated material layup but can be modified for use with other processes. It is well known that material tack is a function of multiple processing and environmental variables. Permissible composite prepreg materials include carbon, glass, and aramid fibers within a B-staged thermoset resin.
1.2 Measured tack is specified in terms of a peel force at a given specimen width.
1.3 Units—The values stated in SI units are to be regarded as standard. The values given in parentheses after SI units are provided for information only and are not considered 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.
1.4 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.
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SIGNIFICANCE AND USE
5.1 This test method is designed to determine the glass transition temperature of continuous fiber reinforced polymer composites using the DMA method. The DMA Tg value is frequently used to indicate the upper use temperature of composite materials, as well as for quality control of composite materials.
SCOPE
1.1 This test method covers the procedure for the determination of the dry or wet (moisture conditioned) glass transition temperature (Tg) of polymer matrix composites containing high-modulus, 20 GPa (> 3 × 106 psi), fibers using a dynamic mechanical analyzer (DMA) under flexural oscillation mode, which is a specific subset of the Dynamic Mechanical Analysis (DMA) method.
1.2 The glass transition temperature is dependent upon the physical property measured, the type of measuring apparatus and the experimental parameters used. The glass transition temperature determined by this test method (referred to as “DMA Tg”) may not be the same as that reported by other measurement techniques on the same test specimen.
1.3 This test method is primarily intended for polymer matrix composites reinforced by continuous, oriented, high-modulus fibers. Other materials, such as neat resin, may require non-standard deviations from this test method to achieve meaningful results.
1.4 The values stated in SI units are standard. The values given in parentheses are non-standard mathematical conversions to common units that are provided for information only.
1.5 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.
1.6 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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SIGNIFICANCE AND USE
5.1 The prepreg volatiles content, matrix content, reinforcement content, and filler content of composite prepreg materials are used to control material manufacture and subsequent fabrication processes, and are key parameters in the specification and production of such materials, as well as in the fabrication of products made with such materials.
5.2 The extraction products resulting from this test method (the extract, the residue, or both) can be analyzed to assess chemical composition and degree of purity.
SCOPE
1.1 This test method covers a Soxhlet extraction procedure to determine the matrix content, reinforcement content, and filler content of composite material prepreg. Volatiles content, if appropriate, and required, is determined by means of Test Method D3530.
1.1.1 The reinforcement and filler must be substantially insoluble in the selected extraction reagent and any filler must be capable of being separated from the reinforcement by filtering the extraction residue.
1.1.2 Reinforcement and filler content test results are total reinforcement content and total filler content; hybrid material systems with more than one type of either reinforcement or filler cannot be distinguished.
1.2 This test method focuses on thermosetting matrix material systems for which the matrix may be extracted by an organic solvent. However, other, unspecified, reagents may be used with this test method to extract other matrix material types for the same purposes.
1.3 Alternate techniques for determining matrix and reinforcement content include Test Methods D3171 (matrix digestion), D2584 (matrix burn-off/ignition), and D3529 (matrix dissolution and ignition loss). Test Method D2584 is preferred for reinforcement materials, such as glass, quartz, or silica, that are unaffected by high-temperature environments.
1.4 The technical content of this standard has been stable since 1997 without significant objection from its stakeholders. As there is limited technical support for the maintenance of this standard, changes since that date have been limited to items required to retain consistency with other ASTM D30 Committee standards. The standard therefore should not be considered to include any significant changes in approach and practice since 1997. Future maintenance of the standard will only be in response to specific requests and performed only as technical support allows.
1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.6 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. Specific precautionary statements are given in Section 9 and 7.2.3 and 8.2.1.
1.7 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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SIGNIFICANCE AND USE
5.1 Refer to Guide D8509.
SCOPE
1.1 This test method determines the fastener pull-through resistance of multidirectional polymer matrix composites reinforced by high-modulus fibers. Fastener pull-through resistance is characterized by the force-versus-displacement response exhibited when a mechanical fastener is pulled through a composite plate, with the force applied perpendicular to the plane of the plate. The composite material forms are limited to continuous-fiber or discontinuous-fiber (tape or fabric, or both) reinforced composites for which the laminate is symmetric and balanced with respect to the test direction. The range of acceptable test laminates and thicknesses is defined in 8.2.
1.2 Two test procedures and configurations are provided. The first, Procedure A, is suitable for screening and fastener development purposes. The second, Procedure B, is configuration-dependent and is suitable for establishing design values. Both procedures can be used to perform comparative evaluations of candidate fasteners/fastener system designs.
1.3 The specimens described herein may not be representative of actual joints which may contain one or more free edges adjacent to the fastener, or may contain multiple fasteners that can change the actual boundary conditions.
1.4 This test method is consistent with the recommendations of CMH-17, which describes the desirable attributes of a fastener pull-through test method.
1.5 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.
1.5.1 Within the text, the inch-pound units are shown in brackets.
1.6 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.
1.7 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.
- Standard10 pagesEnglish languagesale 15% off
- Standard10 pagesEnglish languagesale 15% off
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