TiNi Alloy Lattice Structures with Negative Poisson Ratio: Computer Simulation

Abstract

Today, one of the problems of modern implants is their high rigidity, which can lead to bone resorption at the interface between the implant and the bone and to the gradual detachment of the implant. In addition, implant detachment can occur due to the positive Poisson's ratio of the implant along its entire length. This phenomenon is described in detail in [1]. As a possible solution to these problems, it is proposed to use lattice structures with negative Poisson's ratio from TiNi alloy. This alloy has a fairly low modulus of elasticity - about 48 GPa. The use of a porous (lattice) structure of an implant made of TiNi alloy will reduce the modulus of elasticity and bring it closer to the modulus of human cortical bone – 12-17 GPa [2], and possibly the modulus of elasticity of cancellous bone – 0.1-5 GPа [3]. In this work, a computer numerical simulation of strut based lattice structures with several variants of unit cell topology with a negative Poisson's ratio is carried out. For the obtained structures, the following characteristics were calculated - elastic modulus (Young's modulus), modulus of elasticity in shear, Poisson's ratio. The modeling process is implemented using the ANSYS 2019 R2 SpaceClaim finite element analysis package. The data obtained confirmed the promising possibility of modeling and fabricating lattice structures with a low elastic modulus and negative Poisson's ratio from a TiNi alloy. Also, on the basis of this data, conclusions about the influence of the topology and porosity of unit cells on the resulting characteristics of the lattice structure were made.