Speaker
Description
Diatoms, which occur in thousands of forms in our oceans, have a filigree, highly porous yet strong and resistant structure. It has been shown that better impact values can be achieved in the parametric lightweight optimization of crash-relevant components based on diatom structures than with conventional lightweight structures, despite being lighter. These properties make them suitable for endoprosthetics, where biocompatibility and the stability of anchoring in the bone are crucial. In-growing structures are preferred over cemented ones to avoid stress shielding.
The open porosity of biocompatible materials promotes bone ingrowth, increasing the stability of endoprostheses. Sustainable stability is also supported by optimal stress distribution to avoid stress shielding. This is achieved using data from the Charité hospital in Berlin for realistic stresses in the design. Implementation is done via additive manufacturing in the powder bed fusion of metal with a laser beam (PBF-LB/M) with Ti-6Al-4V powder.
This contribution aims to develop a method for AI-supported structuring of pressure swelling and crack growth samples to successfully structure endoprostheses in future projects. An extensive database of open-pore, gyroidal, and lattice structures forms the basis for the development of an AI tool that optimizes these structures with regard to their suitability for endoprostheses. Parametric models and genetic algorithms are used to evaluate the design principles. The AI tool initially serves as a decision-making instrument for the best design concepts and should later deliver reliable results on its own.
As part of the project, eight lattice structures were selected, and corresponding samples were additively manufactured from Ti-6Al-4V. The respective printed samples were tested under static compressive and bending stress to investigate the deformation behavior. The deformation fields were recorded using digital image correlation, from which the macroscopic behavior of the respective lattice structure under compression or bending was derived. Furthermore, crack propagation tests were carried out using printed CT samples to make a relative assessment of the fatigue behavior of the structures in relation to each other.
The structural optimization method is now being refined and evaluated based on the experimental results. The aim is to calculate a stress-optimized pressure threshold specimen that can withstand the required oscillating and impact loads in a femur without excessively unloading the surrounding bone. Finally, this optimized structure is to be verified by experimental investigations.
