The objective of the DFG Research Unit 5250 (FOR 5250) is the development and validation of an integrated solution for the manufacturing, characterization and simulation-based design of additively manufactured (AM) medical implants, considering local physiological conditions of the individual bone situation. Therefore, a holistic qualification approach, as well as an interdisciplinary consideration of materials science and engineering, medical engineering and numeric simulation, is required. Based on this, novel mechanism-based in vitro and in vivo testing methods, including multi-scale simulation and modeling methods (in silico), are implemented in order to describe the mechanical, biological and corrosive processes and their interactions.
This paper deals with the mechanical-biological behavior of permanent implants with tailored functionality made of PBF-LB/M manufactured Ti6Al4V alloy. To considering local bone structures and to minimize stress-shielding, implant-bone interface stiffness is adjusted by using cellular, triply periodic minimal surface (TPMS) structures. Hereby, the influence of cellular structuring on microstructure, defects formation, topography and the corresponding property profile is characterized. Finally, a simultaneous instrumentation consisting of digital image correlation (DIC), quantitative acoustic emission (AE) analysis and infrared thermography (IRT) was applied for PBF-LB/M manufactured TPMS structures of Ti-6Al-4V alloy. The damage localization was detected by DIC and IRT, while the cascade-like damage evolution from strut to strut could be monitored by all measurement techniques especially AE analysis.
By developing a resource-efficient experiment- and simulation-based characterization methodology, the quality by means of long-term survival rate can be increased and qualification period accelerated for future implants.

Acknowledgements

The authors gratefully acknowledge the funding by the German Research Foundation (DFG) for the subproject coordination SP-Z within the Research Unit FOR 5250 “Permanent and bioresorbable implants with tailored functionality” (No. 449916462).