Experimental 3D printed re-entrant auxetic and honeycomb spinal cages based on Ti-6Al-4 V: Computer-Aided design concept and mechanical characterization. (15th April 2023)

• Record Type: Journal Article
• Authors: Lvov, V.A.; Senatov, F.S.; Shinkaryov, A.S.; Chernyshikhin, S.V.; Gromov, A.A.; Sheremetyev, V.A.
• Is Part Of: Composite structures. Volume 310(2023)
• Publication Date: 2023-04-15
• Subjects: Auxetic metamaterial -- Honeycomb structure -- 3D printing -- Ti-6Al-4V -- Mechanical testing -- Spinal interbody cage; Composite construction -- Periodicals; Composites -- Périodiques; 624.18
• DOI: 10.1016/j.compstruct.2023.116766
• Languages: English
• ISSNs: 0263-8223

Abstract

Graphical abstract: Highlights: Spinal interbody cages adapted for an auxetic, and honeycomb using standard CAD software operations and manufactured with SLM. Auxetic-based cages exhibit higher strength properties than honeycomb-based cages. The stiffness of the auxetic cages is comparable to stiffness of human cortical bone. The honeycomb cages exhibit lower value of Young's modulus closer to that for vertebrae. Abstract: This paper presents a method for modeling a biomedical device by adaptation a commercially available interbody cage for an auxetic metamaterial and honeycomb structure using standard operations in Computer-Aided design software. The mechanical properties of experimental prototypes of Ti-6Al-4 V cages made by selective laser melting using computer modeling (finite element analysis), static and low-cycle fatigue compression tests (up to 3500 cycles) are characterized. 3D printed cells with structures with an angle of inclination between cell edges of less than 90˚ (auxetic metamaterial) are shown to exhibit higher static compressive strength and fatigue resistance than cells based on structures with an angle of inclination greater than 90˚ (honeycomb structure). The changes in the inclination angle differently affect to the porosity and consequently to mechanical behavior of auxetic metamaterial and honeycomb structure. The Young modulus of the auxetic-based interbody cage is 6.68 ± 0.28 GPa and comparable to the elastic modulus of human cortical bone. The honeycomb-based cage exhibits lower values of Young modulus (1.19 ± 0.03 GPa) close to that of trabecular bone and vertebrae. Importantly, the auxetic-based cage is not destroyed after 3500 cycles under 14 kN load with residual deformations ≤ 1 % (0.21 ± 0.10 mm displacements).