Compression, bending, energy absorption properties, and failure modes of composite Kagome honeycomb sandwich structure reinforced by PMI foams

Abstract

Owing to its high strength and modulus, convenient processing, and low cost, the composite interlocked Kagome honeycomb sandwich structure exhibits immense potential in several fields including naval and aeronautical applications. However, the main defect of this structure is the easy debonding between the face and core, and the weak edges greatly reduce the stiffness and strength. The innovation of this study is to fill the high-strength and high-modulus polymethacrylimide (PMI) foams into the composite interlocked Kagome honeycomb structure to form a new type of sandwich structure. It is compared with the isolated PMI foam and composite interlocked Kagome honeycomb sandwich structure through three-point bending (TPB) and edge compression (EC) tests. The compression, bending, energy absorption characteristics, and failure modes of the new structure are analyzed by experiments along with the finite element method (FEM). A numerical model is established for the equivalent in-plane stiffness of the combined sandwich structure. The results shows that the filled PMI foam greatly improves the overall strength, stiffness, and energy absorption with a small increase in the weight. Further, the limitation of the weak edges of the interlocked Kagome honeycomb structure is effectively surmounted. The proposed structure also shows significantly enhanced anti-debonding ability.