Compressive properties of cuttlebone-like lattice (CLL) materials with functionally graded density

Complex and small-scale architectures, e.g., topology-optimised materials and functionally graded lattice materials (FGLMs), can be well fabricated with the assistance of additive manufacturing (AM). This work investigates the compressive properties of a functionally graded cuttlebone-like lattice (CLL) material. Experimental compression tests are performed on both uniform and graded lattice materials, which are made of Inconel 718 via selective laser melting (SLM) technology. In addition, the body-centred-cubic (BCC) lattice materials are also fabricated to be compared with the CLL materials in terms of deformation behaviour, mechanical property and energy-absorbing capability. Tensile tests of additively manufactured Inconel 718 exhibit higher hardening modulus than additively manufactured Al–Si10–Mg, 316L stainless steel and Ti–6Al–4V. Compressive results show that the collapse of FGLMs always initiates in the low-density layer and spreads to the high-density layer, whereas uniform density samples deform collectively in each repeated layer. Although the uniform CLL material exhibits abrupt buckling failures throughout the whole material, CLL materials generally have better mechanical properties and energy absorption capability than the corresponding BCC materials. Overall, the graded CLL material with layer-by-layer deformation outperforms the other three types of lattice materials in this study. Both the specific energy absorption and plateau stress of the graded CLL material are higher than those of the graded BCC material by approximately 1.2 times.