Compressive Behavior of Novel Additively Manufactured Ti-6Al-4V Lattice Structures: Experimental and Numerical Studies

Abstract

This paper presents novel configurations for additively manufactured lattice structures, including helical and elliptic designs, in addition to the pyramid base model. Functionally graded versions of the pyramid and elliptic lattice structures are developed by considering desirable relative densities in each layer. The lattice structures were manufactured using Ti-6Al-4V powder in a three-dimensional selective laser melting printer. The averaged porosities are 0.86, 0.91, 0.916, 0.93 and 0.74 for pyramid, functionally graded pyramid, elliptic, functionally graded elliptic and helical, respectively. The mechanical behavior of the lattice structures was characterized through compression tests using a universal testing machine and computationally analyzed using finite element code. The results indicate that the elliptic and functionally graded elliptic lattices have elastic moduli of 0.76 and 0.67 GPa, while the yield strengths are 41.32 and 32.24 MPa, respectively, in comparison to cancellous bone. Moreover, pyramid, functionally graded pyramid, and helical lattices show relatively lower elastic moduli of 0.57, 0.65 and 0.41 GPa and higher yield strengths of 54.1, 52.15 and 61.02 MPa, respectively. This could be an indication that they are fit for cortical bones. All samples have low elastic moduli coupled with high yield strengths. This could reduce or eliminate stress shielding, making them suitable for some load-bearing bio-inspired applications. A comparative study utilizing experimental and numerical models was conducted to evaluate the performance of the proposed designs.

Keywords

• additive manufacturing
• selective laser melting
• porous biomaterials
• lattice structures
• functionally graded