A novel hybrid design method of lattice structure based on failure mode

Adjusting the mechanical properties of lattice structures is important for many modern application fields. In this paper, a new design method for hybrid multi-layer lattice structures was developed to improve the mechanical properties and energy absorption, by altering and suppressing the formation of the shear band. In these hybrids, all unit cells were divided into two parts: (i) diagonal unit cells and (ii) matrix unit cells. Four categories of unit cells were selected to construct the hybrid multi-layer structures. The compressive moduli, ultimate strengths, and energy absorption properties of the laser powder bed fusion (L-PBF) fabricated structures were assessed by experiments and finite element analysis (FEA). The results revealed the great impact of diagonal unit cells on the mechanical properties of the structures. Stronger diagonal unit cells than matrix unit cells led to hybrid structures with enhanced mechanical properties. Compared with a uniform body-centered cubic (BCC) lattice structure, the relative density of the lattice structure consisting of the weakest BCC matrix unit cells and strongest BFVC diagonal unit cells (coupling of BCC, FCC, and VC) exhibited an increase of 20%. The compressive modulus and ultimate strength of this structure rose by more than 200% and 90%, respectively. Two types of structures with specific properties were generated by hybrid design. The first displayed higher modulus, superior strength, and elevated specific energy absorption (SEA) but lower crash load efficiency (CLE). The second illustrated simultaneously higher SEA and elevated CLE. The present results provide a new insight for improving the load-bearing and energy absorption capacities of lattice structures.