Enhanced compressive properties of a CFRP honeycomb with quasi-elliptical cell topology: From fabrication to mechanical response

A carbon fiber reinforced polymer (CFRP) quasi-elliptical honeycomb structure was developed in this paper. Geometric parameters under manufacturing constraints were optimized using an analytical prediction model, and the defects induced by secondary bonding in the fabrication of the honeycomb cells were effectively eliminated through an integrated molding process. The experimental results demonstrated that the symmetric laminate configurations achieved a 33 % improvement in specific energy absorption (SEA) compared to the antisymmetric structures, revealing the effectiveness of lamination sequence as a defect control strategy. The buckling-dominated failure mode evolved into the hybrid failures, and ultimately to the crushing-dominated collapses with the increase of the relative density of the CFRP quasi-elliptical honeycomb under the out-of-plane compression. The analytical predictions and finite element (FE) simulations showed reasonable agreement with the experiments in terms of the ultimate load. The SEA exhibited an improvement when transitioning from 2-layer to 4-layer structures, whereas the enhancement became marginal between the 4-layer and 8-layer configurations. Simultaneously, the adoption of symmetric lamination contributed to the SEA, providing a novel manufacturing strategy for high-performance CFRP honeycomb structures. The proposed performance enhancement approach holds promising application potential in aerospace, marine, and civil engineering.