Abstract: Three-dimensional hollow sandwich composites（3D composites）is a group of new sandwich-structure materials, which have been increasingly used in various industries covering aerospace, automobile,oil tank, ship, building and energy for their excellent properties, such as low weight, high strength, high modulus, impact resistance, sound insulation and thermal insulation. Two group of the 3D composites were investigated in terms of flat-compression properties by using Instron 3385H universal testing machine as a function of the z-direction pile height（2, 4, 6 and 8 mm）and pile distance（4, 6 and 8 mm）, and the influence of structural parameters such as pile height and pile density on the 3D composites was mainly studied, and the compression feature and damage mechanism of the 3D composites were analyzed too. The results show that the typical failure mode of the 3D composites is brittle damage when they suffered flat-compression loads, which is mainly reflected in resin fracture, fiber breakage and interface de-bonding. The flat-compression property of the 3D composites decreased with the increase of pile height and pile distance.

The results will lay a foundation for further study on the 3D composites’ designing optimization and property analysis.

Key words: three-dimensional hollow sandwich composite; flat-compression property; pile height; pile distance; failure mode; compressive characterization