Fabrication and bending performance of ultra-low-density all-composite honeycomb sandwich shell based on stretching process

A sandwich shell with an ultra-low-density honeycomb core was designed and manufactured from a carbon-fibre prepreg via a stretching process. Subsequently, the bending bearing limits of the sandwich shell corresponding to five possible failure modes (shear buckling, shear fracture, intracellular dimpling, face fracture, and core debonding) were obtained through theoretical predictions. Failure mechanism maps were generated to reflect the possibility of each failure mode intuitively. In addition, three-point bending tests were performed on specimens with different shell thicknesses to acquire as many of these typical failure modes as possible. Moreover, the competition mechanism between different failure modes was revealed. The research results provide theoretical guidance for parameter optimisation and applications in advanced engineering fields for ultra-low-density carbon-fibre honeycomb sandwich shells.