Mechanical Behaviors of CFRP Composite Sandwich Structures With Hierarchical Skins

This paper presents a hierarchical approach for designing structural skins to achieve additional weight reduction in sandwich structures. The mechanical properties and failure behaviors of carbon fiber-reinforced polymer (CFRP) composite sandwich structures incorporating pyramidal lattice cores and hierarchical skins are systematically investigated under in-plane compression and three-point bending through integrated theoretical analysis, numerical simulations, and experimental testing. Based on the developed theoretical framework, two-dimensional (2D) and three-dimensional (3D) failure mechanism maps are constructed and comparatively analyzed against conventional configurations. Experimental validation is conducted using manufactured CFRP specimens with solid and hierarchical skins tested under both loading conditions. The results demonstrate that the hierarchical design effectively prevents skin wrinkling failure modes, thereby exhibiting superior load-bearing capacity under in-plane compression and bending compared to traditional sandwich configurations, with an approximately sevenfold increase in specific compressive strength and 75% enhancement in specific bending strength.