The bending of 3D-printed bio-inspired sandwich panels with wavy cylinder cores

• Novel sandwich panels with wavy cylindrical cores that biomimick the structure of the beetle elytra. • First exploration of the four-point bending behaviour of these adhesively bonded biomimetic sandwich panels. • Experimental and finite element simulations evaluate the flexural and shear properties following a parametric analysis. • Comparison and analysis with of the flexural and shear performance against the engineering elastic constants from previous results. • Beetle elytra inspired panels with wavy cylinder cores exhibit better ductility than hexagonal honeycomb sandwich structures. Beetle Elytron Plates (BEPs) represent a new class of biomimetic sandwich cores with excellent mechanical properties inspired by the microstructure of the beetle elytra. The cores have a hexagonal centre-symmetric configuration with through-thickness cylinders in the unit cell. In this work, we describe the behaviour of sandwich panels with novel BEP core configurations possessing wavy cylinders under four-point bending tests. Full-scale simulations are also carried out to validate the experimental data. The results show that all the sandwich panels produced with face skins adhesively bonded have material failure earlier than the adhesive bond failure. BEPs with wavy cylinders have larger peak loads compared to those with straight cylinders, and all BEPs show higher peak loads than those of sandwich panels with classical hexagonal honeycombs. Additionally, all the BEPs exhibit an enhanced ductility compared to honeycomb sandwich panels.