Scope:

Compressive Strength Test of Sandwich Cores by ASTM C365 determines compressive strength and modulus of sandwich cores. Compressive strength is determined in the direction where the core would be placed in structural construction. This test can be applied to stabilized and unstabilized core materials with continuous (foams) or discontinuous (honeycomb) bonding surfaces. The results obtained are used for sandwich core material specifications, structural design and development applications, and quality assurance purposes.

Test Procedure:

ASTM C365 test method is a uniaxial compressive force normal to the facings of the sandwich core is applied during this test. Compressive Strength Test is performed with a Universal Test Machine comprising compression platens. At the start of the test, conditioned square or circular samples of sandwich core, in compliance with ASTM C365, are placed at the center of the lower platen. Next, the machine applies a compressive load to the specimen at a specified rate to achieve failure within three to six minutes. The standard speed is 0.50 mm/min [or 0.020 inches/min]. Conditioned samples provide the best results in this test.

Specimen size:

Generally, five specimens, at a particular thickness, are tested as per the ASTM C365 method. For continuous bonding surfaces, the minimum facing area of the specimen needs to be 625 mm² (1 inch²). For discontinuous cellular bonding surfaces, there should be a minimum of 60 cells per test specimen.

Data:

Following calculations are done using the results obtained from the Flatwise Compressive Properties test by ASTM C365

1. Ultimate Strength
2. 2% Deflection Stress
3. Failure type/mode
4. Compressive Modulus

Conclusion:

ASTM C365 is used to determine the compressive properties of structural sandwich construction in a direction parallel to the sandwich facing plane.