Compressive Mechanics and Hyperelasticity of Ni-Ti Lattice Structures Fabricated by Selective Laser Melting

Abstract

Additively manufactured Ni-Ti lattice structures have controllable bio/mechanical properties, as well as excellent large deformation and damping properties similar to those of natural bone. They have broad application prospects in the field of bone implantation. Triply Periodic Minimal Surface (TPMS) structures are believed to be the most potential and ideal bionic bone structures. In this work, Ni-Ti Gyroid-type TPMS lattice structures were fabricated by selective laser melting (SLM) and their manufacturing fidelity and compression properties were evaluated. By changing the maximum strain value, the hyperelastic recovery performance under cyclic stress was investigated. The results showed that the Ni-Ti Gyroid lattice structures fabricated by SLM had excellent manufacturability (relative density can reach 98.93%) and mechanical properties (elastic modulus is about 130.8 MPa, ultimate strength is about 2.7 MPa). The hyperelastic cycle testing showed that the elastic modulus, yield strength and ultimate strength of the lattice structures tended to stablilize gradually with increasing numbers of cycles. The residual strain increased with the number of cycles, and as the maximum strain increased from 4% to 8%, the residual strain also increased from 1% to 4%.

A Systematic Approach to Optimize Parameters in Manufacturing Complex Lattice Structures of NiTi Using Electron Beam Powder Bed Fusion Process

“…This is a common method to calculate the stress on porous structures. [20,[28][29][30] The cyclic compression test was done incrementally from 2% to 10% compressive strain along the build direction (xz) depending on the condition of the samples. After the highest cyclic compression cycles, the sample was compressed until rupture.…”

Design and additive manufacturing of bionic hybrid structure inspired by cuttlebone to achieve superior mechanical properties and shape memory function

“…Currently, Nickel-Titanium (NiTi) shape memory alloy has garnered attention as a raw material for designing intelligent components due to its unique properties, including superelasticity (SE) and shape memory effect (SME) [24]. Nevertheless, existing NiTi porous structures, such as triply periodic minimal surface structures [25] and cellular lattice structures [26,27], are prone to severe stress concentration accompanied by irreversible plastic deformation under loading, or catastrophic failure if their strength is exceeded. These limitations hinder the full utilization of the NiTi alloy's potential.…”