Pilot study of lattice endoprosthesis buckling by compression in-situ using X-ray tomography

Take into account additive manufacturing while design lattice implant can improve load-bearing properties and decrease construction weight. The usage of lattice structure and biomaterials makes it possible to solve the main problem of arthroplasty - preservation of the implant after surgery in the patient's body. Unfortunately, nowadays biomaterials do not have the necessary strength capacity. In spite of this, a lot of researches are directed towards to develop new design methods or improve the existing ones. There are number of articles focused on in-situ testing and quality control of lattice structures. The study is devoted to investigate the buckling of lattice structures under uniaxial compression with synchronous X-ray computed tomography scanning. In the article an experimental study of lattice structures of two kinds has been carried out. Edges of hexagonal bipyramid were a basic cell of the samples. The distribution of basic cells in the first type of construction was uniform, and was non-uniform in the second type. The studied samples were manufactured by laser stereolithography method. The lattice structures were loaded step-by-step with a longitudinal compressive load. The loading of the specimens was carried out in cooperation with their scanning by X-ray computed tomography. As a result, the displacement fields of structures at each step of loading were obtained. The general and local buckling of lattice structures was revealed. The general buckling occurred at the second loading step for each type of structure. Local buckling was observed at the third loading step. The influence of the architecture of the lattice structures on the buckling process was revealed. The effect of interruption of the buckling process was observed in the specimen with non-uniform distribution of basic cells. And because of that the structure continued to work in compression. In other words, the lattice architecture "dampened " the bending components of the displacement vector.