Mechanical behavior of all-composite pyramidal truss cores sandwich panels

•An improved-pyramidal truss core is presented to manufacture sandwich panel.•Four mechanical properties are carried out to explore the failure mechanisms.•The node failure is still a key issue for the improvement of mechanical property.•Comparisons suggest the improved structure has a superior comprehensive property•An improved layer form of cores is proposed to overcome the node problem.

A new improved carbon fiber-reinforced pyramidal lattice truss cores sandwich panel is manufactured based on the post-forming process under the hot-press molding method. A series of experimental and analytical studies on the structural mechanical behavior are conducted under the out-of-plane compression, in-plane shear, in-plane compression and three-point bending, providing a visualized insight into the failure mechanisms of all-composite sandwich panels. The predicted collapse limits are in reasonable agreements with the measurements under out-of-plane loading, while significant discrepancies are observed under in-plane loading. Comparisons suggest that the improved structure has a superior comprehensive performance. Besides, an expected improved layer form of the pyramidal truss cores is proposed to overcome the intractable node problem. All these results indicate that much space and opportunities still remain for the improvement and development of structural mechanical performance, even the achievement of multifunctional integration.