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:

Panel surface deflection at load,

Panel face-sheet strain at load,

Panel bending stiffness,

Panel shear stiffness,

Panel strength, and

Panel failure modes.

1. Scope

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.

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 (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.

ASTM Standards

C274 Terminology of Structural Sandwich Constructions

C365/C365M Test Method for Flatwise Compressive Properties of Sandwich Cores

C393 Test Method for Flexural Properties of Sandwich Constructions

D792 Test Methods for Density and Specific Gravity (Relative Density) of Plastics by Displacement

D2584 Test Method for Ignition Loss of Cured Reinforced Resins

D2734 Test Methods for Void Content of Reinforced Plastics

D3171 Test Methods for Constituent Content of Composite Materials

D3878 Terminology for Composite Materials

E4 Practices for Force Verification of Testing Machines

E6 Terminology Relating to Methods of Mechanical Testing

E251 Test Methods for Performance Characteristics of Metallic Bonded Resistance Strain Gauges

E1237 Guide for Installing Bonded Resistance Strain Gages

Keywords

bending; core; deflection; distributed load; face sheets; flexural properties; hydromat; hydrostatic loading; pressure bladder; sandwich composite; sandwich composite plate; sandwich structure; shear;

ICS Code

ICS Number Code 83.120 (Reinforced plastics)

Citing ASTM Standards

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