Fabrication and mechanical behavior of an all-composite interlocked triangular honeycomb sandwich structure: Experimental investigation and numerical analysis

The interlocked composite honeycomb structures have high specific strength and specific stiffness, convenient processing, and low cost with great application potential in aerospace, marine, construction, and civil fields. In this study, an effective method is proposed for manufacturing an all-composite interlocked triangular honeycomb (CITH), and the quasi-static mechanical properties of the honeycomb and the corresponding sandwich structure (CITHSS) are examined. Through experimental tests, the basic mechanical properties of CITH and CITHSS are analyzed. Further, the effective strength and stiffness coefficient of the slotted carbon sheets constituting CITH are measured through tensile experiments. The in-plane stiffness model of CITH is derived based on the continuous equivalent method. The failure strength models of CITHSS are also established. At the same time, the failure modes under three-point bending and edge compression loads are predicted. The experimental results reveal that compared with the interlocked Kagome and square honeycomb, the specific strength of CITH is increased by 27.8% and 24.4%, respectively. Further, the specific stiffness is increased by 148.4% and 8.3%, respectively. Compared with aluminum honeycomb sandwich, the compressive and bending specific strengths of CITHSS are increased by more than 46.5% and 15.2%, respectively. The debonding failure and edge effect are found to be the main weakness of CITHSS. Overall, CTIH and CITHSS exhibit excellent mechanical properties and create feasible options for processing complex multifunctional composite honeycombs by interlocking technology.