Enhancing planar compression performance of 3D printed continuous carbon fiber reinforced honeycomb sandwich structures using interleaved core paths

Continuous carbon fiber reinforced composites (CCFRCs) 3D printing technology facilitates the rapid prototyping of lightweight honeycomb sandwich structures. The principal cause of failure in honeycomb sandwich structures is the poor bonding quality between the core units, which adversely affects their compression properties. This paper introduced a novel printing path design strategy termed "core interleaved alignment printing approach", aiming to enhance the planar compressive performance of honeycomb sandwich structures. The proposed approach involved staggering the adjacent printing paths within the core units to mutually reinforce their two adjoining unit edges. This method could increase the effective bonding length between core units by 30 % and significantly improve the bond quality between core units, consequently improving the compressive performance of honeycomb sandwich structures. Experimental validations were conducted to analyze the planar compression behavior of printed honeycomb sandwich structures, comparing the proposed paths design strategy with the commonly used strategy. The damages in 3D printed honeycomb sandwich structures typically included delamination between adjacent layers and debonding among the honeycomb units. The proposed approach can effectively inhibit the rapid damage expansion and significantly improve the compressive performance of honeycomb structures, elevating their compressive strength by 96 % and compressive modulus by 67.5 %. Moreover, this strategy exhibits substantial enhancements in compressive performance, especially as the honeycomb core size decreases, and in the test condtion, the increases in compressive strength and modulus could reached over 167 % and 116 %, respectively.