Effects of internal configurations and its processing quality on compressive performance for 3D printed continuous fiber reinforced composites honeycomb sandwich

•The CFRCs honeycomb sandwich structures are fabricated integrally by 3D printing technique.•The damage types at each stage of the flatwise compression process of 3D printed CFRCs honeycomb sandwich structures are successfully characterized.•A 3D printing method for CFRCs honeycomb sandwich structures with multilayer sandwich and core/panel variable printing thickness is proposed.•The compressive strength and energy absorption capacity of multilayer CFRCs honeycomb sandwich structures have obvious advantages. Continuous fiber reinforced composites (CFRCs) 3D printing technology has the advantage of integrated fabricating for honeycomb sandwich structures, the load-bearing capacity of the fabricated honeycomb sandwich structures still needs to be investigated and improved. This study aims to reveal compression failure modes of 3D printed CFRCs honeycomb sandwich structures with various internal configurations by conducting flatwise compression tests. The deviations of single-layer CFRCs honeycomb cores with different core sizes and core heights and their impacts on the compression failure process were analyzed. A 3D printing method with multilayer cores and core/panel variable printing thickness was proposed, and the effects of multilayer core structure and different core printing parameters on the compressive properties of honeycomb sandwich structures were investigated. The results showed that interlayer cracking caused by core buckling deformation was the leading cause of failure of 3D printed CFRCs honeycomb sandwich structures when subjected to compression. The core buckling deformation could be suppressed by printing multilayer cores and using low core printing thickness, and the compression strength and specific energy absorption of the sandwich structures reached 38.1 MPa and 25.4 kJ/kg, respectively. This study provides guidance for the customization of the 3D printing process of CFRCs honeycomb sandwich structures. [Display omitted]