Toughness-improving design of lattice sandwich structures

•The toughened model of lattice sandwich structures was established based on the characteristics of the lattice structure.•The design method of lattice sandwich structures for improving toughness was proposed based on the failure modes of lattice sandwich structures.•The failure mode and fracture characteristics of the lattice sandwich structure were analysed under a low-velocity impact load.•It was found that the sandwich structure has a dimensional effect. With this effect, the core and the skin could synergistically improve toughness.