Matrix ASTM D5467

ASTM D5467 is a test method used to evaluate the compressive properties of unidirectional polymer matrix composite materials in a sandwich beam configuration. The test involves applying a compressive load to the upper skin of the sandwich beam using a four-point flexural loading system. The skin material is limited to unidirectional continuous fiber composites, while the core material is made of aluminum honeycomb and the opposite skin can either be aluminum sheet or the same material as the test skin. The core and opposite skin induce the appropriate compressive loading in the test skin. To determine strain and modulus, strain gauges are bonded to the face of the test skin.

To prevent local crushing of the sandwich specimen, loads from the supports and noses should be applied through large diameter cylinders, up to 1.5 times the sandwich thickness. Loading pads may also be necessary between the cylinders and the beam.

The sandwich beam components are bonded together to create either individual samples or a larger panel to be machined to size. If strain or modulus measurements are required, a strain gauge is mounted in the center of the test skin according to the manufacturer's recommendations. The test specimen is centered in the four-point bending fixture and tested to failure at a suggested speed of 1.5 mm/min (0.05 in/min) to produce failure in 1 to 10 minutes. A three-part failure identification code is used to document the mode and location of failure for each specimen.

Specimen dimensions are chosen to ensure the proper compressive loading is applied to the upper skin material, but differences in test geometry can significantly affect test results. ASTM D5467 recommends two specimen geometries depending on the orientation of the continuous fiber reinforcement. For 0° orientation, the specimen width and length are both 25mm, the core material thickness is 40mm, and the thickness of the test skin and opposite skin are 0.8mm and 1.6mm, respectively. For 90° orientation, the specimen width and length are both 25mm, the core material thickness is 13mm, and the thickness of the test skin and opposite skin are 1.2mm and 1.6mm, respectively.