EFFECT OF GEOMETRIC MODIFICATIONS ON THE COMPRESSIVE STRENGTH AND MECHANICAL PERFORMANCE OF GYROID-BASED BONE SCAFFOLDS

Porous structures are of great interest in biomedical and engineering applications due to their light weight, high mechanical strength, and biological compatibility. In this study, based on the widespread use of gyroid structures in bone scaffolds and their potential to adapt to the heterogeneous mechanical properties of bone tissue, the effect of geometric arrangements on mechanical strength was investigated. Using the tri-periodic minimal surface trigonometric function, the reference model G(0) with 80% porosity was taken as a basis, and three different geometries were created by reducing the unit cell of the gyroid on the y-axis by 25% (G(-25)), keeping it constant (G(0)), and enlarging it by 25% (G(+25)). Using the biomaterial PLA, these non-isotropic structures were fabricated through Fused Deposition Modeling (FDM) and 3D printed in the longitudinal and lateral axes, then subjected to compression tests. The compression test results showed that the printing direction and loading direction play a decisive role in mechanical strength. Especially when the printing and loading directions were the same, an increase in strength was observed, with the G(-25) model exhibiting 37.8% higher strength than G(0) in the PLt-CLt (Printed Lateral – Compression Lateral) configuration. Conversely, increasing the pore size resulted in a 14.7% reduction in strength for G(-25) compared to G(0). Furthermore, when the printing and loading directions were aligned, the lateral axis exhibited 38.4% higher strength than the longitudinal axis in the G(-25) model. It was found that the arrangement of the pores parallel to the load direction minimized strength loss, and the increase in porosity did not significantly affect mechanical strength. In addition, the structure of the compression layers before and after the test was examined in detail by SEM analysis. The findings show that the geometrical arrangements of the gyroid structures have a significant effect on mechanical strength and that these structures can be optimized and used in biomedical applications.