Investigation of additive manufactured Ti6Al4V solid-lattice structure fabricated via electron beam melting for bio-implants

Abstract

With the rapid advancements in technology, there has been an increased usage of Additive Manufacturing (AM) for the medical industry due to its ability and flexibility in customisation. Bio-implants of intricate geometries with complex architectures can now be fabricated with ease. Current design of a solid hip implant is limited in abilities due to the different needs of people. Generally, children and elderly require an implant which is lower in strength and stiffness as compared to young adults or athletes who have higher strength and stiffness demand as a result of their daily activities and difference in bone densities. There have been increased researches on the mechanical properties of EBM-fabricated Ti6Al4V (Ti64) lattice structures, but little studies had been done on combination structures such as lattice-solid-lattice (LSL). This study investigated the strength of solid-lattice interface in LSL and how it can better mimic the properties of a femoral stem. Lattice geometries fabricated were G6, G7 and G8, each with varying unit cell sizes of 1.2 mm, 1.5 mm and 2.0 mm. Both full solid and full lattice structures were investigated first via compressive testing to obtain a base value for comparison with the values obtained from LSL structures. Deformation behaviour, maximum compressive stress, and elastic modulus were evaluated to obtain the optimal lattice design. Due to inherent manufacturing limitations of the EBM system, assessment on the influence of defects on the properties was also included.