ASTM D7336 Standard Test Method for Static Energy Absorption Properties of Honeycomb Sandwich Core Materials

Scope:

ASTM D7336 is a standard test method for determining the static energy absorption properties of honeycomb sandwich core materials. This method is used in industrial applications such as automotive, building, aerospace, energy, and other industries involving composite materials.

Procedure:

In ASTM D7336, a sandwich honeycomb core material is subjected to a uniaxial compressive force. Platens from the testing machines transmit the loading force to the sandwich honeycomb core material. A compressive force is applied past the initial failure force, such that the honeycomb core material is crushed under continuous displacement of the loading platens. Force versus loading plate displacement data is recorded and used to determine the crush stress and stroke.

The specimen’s length, width, and thickness have to be measured with an accuracy of ± 0.010 inch. The specimens were stored in the conditioned environment until test time if the test environment is different from the conditioning environment. If a honeycomb core material specimen is to be pre-crushed, pre-fail the upper surface of the specimen by pressing the serrated plane into the core material surface. Press the plate into the core material multiple times, in various directions, until the core surface is uniformly pre-crushed. Set the testing speed to completely crush the honeycomb core material within 1 to 3 min. Test the specimen under the same fluid exposure level for conditioning if possible. Mark a rectangle or circle on the lower platen to help center the specimen between the platens. Place the specimen on the lower platen, accommodating the LVDT or compressometer if utilized. The actuator or crosshead is moved so the loading platen contacts the LVDT/compressometer, and a standard initial preload of 45 N is applied. A compressive force is used at the specified rate while the data is recorded. The force vs. head displacement or force vs. LVDT/compressometer deflection data is recorded continuously or at frequent regular intervals.

Sample Size: 

Test specimen: square or circular cross-section.

Thickness: 25mm (1.0 in.).

Largest facing area: 5625 mm² (9.0 in² ). 

Cell size: larger than 9mm (0.375in.).

Pre-crush depth:1.0 ± 0.5 mm.

Data:

The force versus loading plate displacement data are recorded to estimate the crush stroke and crush stress in this test method. The Data stated in SI units or inch-pound units are considered standard. No other units of measurement are included in this standard.

Conclusion: 

ASTM D7336 covers determining static energy absorption properties of honeycomb sandwich core materials.