Compression and Compression-Shear Strength of Trabecular Metal Structures Produced from Ti6Al4V ELI Alloy with Selected Laser Melting

Öz

Porous structures that can provide properties of material and have started to be needed for production of regenerative biomedical products in orthopedics. The stress-shielding effect, which occurs as a result of remarkable strength difference from solid materials to bone, causes loss of biomedical implants. Porous materials can be designed according to conditions with advantages of additive manufacturing and manufacturing can be made by copying natural geometries. In the study, the geometries obtained by copying the trabecular bones taken from femur and vertebra regions of a sheep by Micro-CT compared to studies on reproducibility and strength of designable unit cell geometries in the literature were produced by selective laser melting from Ti6Al4V ELI alloy. Compression and compression-shear strengths of samples were examined. The elasticity module was obtained from the compression tests and found 3±0.25 GPa on the femur samples and 2±0.15 GPa on the vertebra samples. It was found that the compatibility of finite element analysis with the test results was admirable. As the trabecular metal takes its geometry from bone structure, it is concluded that it is an interface material with high fusion capability for biomedical products by supporting bone inward growth behavior and decreasing stress shielding effect.

Anahtar Kelimeler

• selective laser melting,trabecular bone,additive manufacturing

Seçimli Lazer Ergitme İle Ti6Al4V ELI Alaşımından Üretilen Trabeküler Metal Yapıların Basma Ve Basma-Kayma Dayanımlarının İncelenmesi

Öz

Üretildiği malzemenin dayanım, biyolojik ve yorulma gibi özelliklerini kullanım alanına uygun olarak şartlandırabilen gözenekli yapılara ortopedi alanında özellikle onarıcı biyomedikal ürün üretimi için gereksinim duyulmaya başlanmıştır. Dolu malzemelerin kemik ile dayanım farkının fazla olması sonucu ortaya çıkan gerilme kalkanı etkisi biyomedikal ürün kaybına sebep olmaktadır. Eklemeli imalat yöntemlerinin sağladığı avantaj sayesinde gözenekli malzemeler koşullara uygun olarak tasarlanabilmekte veya doğal yapıya sahip geometrilerin kopyalanması ile üretim yapılabilmektedir. Literatürün genelinde yer alan tasarlanabilir birim hücre geometrilerinin üretilebilirliği ve dayanımı hakkındaki çalışmaların aksine yapılan çalışmada koyuna ait femur ve vertebra bölgelerinden alınan trabeküler kemiklerin Mikro-CT ile kopyalanması sonucu elde edilen geometriler Ti6Al4V ELI alaşımından seçimli lazer ergitme (SLE) metodu ile üretilmiştir. Yapılan üretimlerin basma ve basma-kayma dayanımları incelenmiştir. Destek yapılar kullanılmadan yapılan üretim sonrası karşılaşılabilecek üretim değişimleri göz önünde bulundurularak trabeküler yapının üretiminde 1:1, 1:1,10 ve 1:1,20 ölçekli geometriler kullanılmıştır. Yapılan basma testleri sonucunda elastisite modül femur numunelerinde ortalama 3±0,25 GPa ve vertebra numunelerinde 2±0,15 GPa olarak elde edilmiş olup analizlerin deney sonuçları ile uyumluluğunun yüksek olduğu görülmüştür. Çalışma kapsamında üretilen trabeküler metal yapının biyomedikal ürünlerde kullanılması durumunda sahip olduğu düşük elastisite modül değerleriyle gerilme kalkanı etkisini azaltacağı ve doğal kemik geometrisi avantajı ile kemiğin içe doğru büyüme davranışını destekleyeceği sonucuna varılmıştır.  

Anahtar Kelimeler

• Seçimli lazer ergitme,trabeküler kemik,eklemeli imalat

Kaynakça

1. H. Liang et al., “Trabecular-like Ti-6Al-4V scaffolds for orthopedic: fabrication by selective laser melting and in vitro biocompatibility,” J. Mater. Sci. Technol., vol. 35, no. 7, pp. 1284–1297, 2019.
2. M. Schieker and W. Mutschler, “Bridging posttraumatic bony defects. Established and new methods,” Unfallchirurg, vol. 109, no. 9, pp. 715–732, 2006.
3. L. E. Murr, “Open-cellular metal implant design and fabrication for biomechanical compatibility with bone using electron beam melting,” J. Mech. Behav. Biomed. Mater., vol. 76, pp. 164–177, Dec. 2017
4. X. Li et al., “Fully degradable PLA-based composite reinforced with 2D-braided Mg wires for orthopedic implants,” Compos. Sci. Technol., vol. 142, pp. 180–188, Apr. 2017.
5. A. A. Al-Tamimi, C. Peach, P. R. Fernandes, A. Cseke, and P. J. D. S. Bartolo, “Topology Optimization to Reduce the Stress Shielding Effect for Orthopedic Applications,” Procedia CIRP, vol. 65, pp. 202–206, 2017.
6. H. M. Frost, “A 2003 update of bone physiology and Wolff s law for clinicians,” Angle Orthod., vol. 74, no. 1, pp. 3–15, 2004.
7. S. J. Hollister, “Scaffold design and manufacturing: From concept to clinic,” Adv. Mater., vol. 21, no. 32–33, pp. 3330–3342, 2009.
8. M. J. Olszta et al., “Bone structure and formation: A new perspective,” Mater. Sci. Eng. R Reports, vol. 58, no. 3–5, pp. 77–116, 2007.

9. J. Rouwkema, N. C. Rivron, and C. A. van Blitterswijk, “Vascularization in tissue engineering,” Trends Biotechnol., vol. 26, no. 8, pp. 434–441, Aug. 2008.
10. A. Kumar, K. C. Nune, L. E. Murr, and R. D. K. Misra, “Biocompatibility and mechanical behaviour of three-dimensional scaffolds for biomedical devices: Process-structure-property paradigm,” Int. Mater. Rev., vol. 61, no. 1, pp. 20–45, 2016.
11. S. J. Hollister, “Porous scaffold design for tissue engineering,” Nat. Mater., vol. 4, no. 7, pp. 518–524, 2005.
12. D. W. Hutmacher, M. Sittinger, and M. V Risbud, “Scaffold-based tissue engineering: rationale for computer-aided design and solid free-form fabrication systems,” Trends Biotechnol., vol. 22, no. 7, pp. 354–362, Jul. 2004.
13. E. C. Novosel, C. Kleinhans, and P. J. Kluger, “Vascularization is the key challenge in tissue engineering,” Adv. Drug Deliv. Rev., vol. 63, no. 4–5, pp. 300–311, Apr. 2011.
14. W. F. Liu and C. S. Chen, “Engineering biomaterials to control cell function,” Mater. Today, vol. 8, no. 12, pp. 28–35, Dec. 2005.
15. H. A. Zaharin et al., “Effect of unit cell type and pore size on porosity and mechanical behavior of additively manufactured Ti6Al4V scaffolds,” Materials (Basel)., vol. 11, no. 12, 2018.
16. Y. Wang, S. Arabnejad, M. Tanzer, and D. Pasini, “Hip Implant Design With Three-Dimensional Porous Architecture of Optimized Graded Density,” J. Mech. Des., vol. 140, no. 11, p. 111406, 2018.
17. T. B. Kim, S. Yue, Z. Zhang, E. Jones, J. R. Jones, and P. D. Lee, “Additive manufactured porous titanium structures: Through-process quantification of pore and strut networks,” J. Mater. Process. Technol., vol. 214, no. 11, pp. 2706–2715, 2014.
18. T. Eli, “Relationship between unit cell type and porosity and the fatigue behavior of selective laser melted,” J. Mech. Behav. Biomed. Mater., vol. 43, pp. 91–100, 2015.
19. S. M. Ahmadi et al., “Additively Manufactured Open-Cell Porous Biomaterials Made from Six Different Space-Filling Unit Cells: The Mechanical and Morphological Properties,” no. C, pp. 1871–1896, 2015.
20. J. Wieding, A. Wolf, and R. Bader, “Numerical optimization of open-porous bone scaffold structures to match the elastic properties of human cortical bone,” J. Mech. Behav. Biomed. Mater., vol. 37, pp. 56–68, Sep. 2014.
21. J. Parthasarathy, B. Starly, S. Raman, and A. Christensen, “Mechanical evaluation of porous titanium (Ti6Al4V) structures with electron beam melting (EBM),” J. Mech. Behav. Biomed. Mater., vol. 3, no. 3, pp. 249–259, Apr. 2010.
22. R. Wauthle et al., “Additively manufactured porous tantalum implants,” Acta Biomater., vol. 14, pp. 217–225, 2015.
23. J. Kadkhodapour et al., “Failure mechanisms of additively manufactured porous biomaterials: Effects of porosity and type of unit cell,” J. Mech. Behav. Biomed. Mater., vol. 50, pp. 180–191, 2015.
24. R. Wauthle et al., “Effects of build orientation and heat treatment on the microstructure and mechanical properties of selective laser melted Ti6Al4V lattice structures,” Addit. Manuf., vol. 5, pp. 77–84, 2015.
25. S. Arabnejad, R. Burnett Johnston, J. A. Pura, B. Singh, M. Tanzer, and D. Pasini, “High-strength porous biomaterials for bone replacement: A strategy to assess the interplay between cell morphology, mechanical properties, bone ingrowth and manufacturing constraints,” Acta Biomater., vol. 30, pp. 345–356, 2016.
26. M. Fantini, M. Curto, and F. De Crescenzio, “A method to design biomimetic scaffolds for bone tissue engineering based on Voronoi lattices,” Virtual Phys. Prototyp., vol. 11, no. 2, pp. 77–90, 2016.
27. X. P. Tan, Y. J. Tan, C. S. L. Chow, S. B. Tor, and W. Y. Yeong, “Metallic powder-bed based 3D printing of cellular scaffolds for orthopaedic implants: A state-of-the-art review on manufacturing, topological design, mechanical properties and biocompatibility,” Mater. Sci. Eng. C, vol. 76, pp. 1328–1343, 2017.
28. M. Niinomi and C. J. Boehlert, “Titanium Alloys for Biomedical Applications BT - Advances in Metallic Biomaterials: Tissues, Materials and Biological Reactions,” M. Niinomi, T. Narushima, and M. Nakai, Eds. Berlin, Heidelberg: Springer Berlin Heidelberg, 2015, pp. 179–213.
29. M. Dallago, B. Winiarski, F. Zanini, S. Carmignato, and M. Benedetti, “On the effect of geometrical imperfections and defects on the fatigue strength of cellular lattice structures additively manufactured via Selective Laser Melting,” Int. J. Fatigue, vol. 124, no. November 2018, pp. 348–360, 2019.
30. L. Liu, P. Kamm, F. García-Moreno, J. Banhart, and D. Pasini, “Elastic and failure response of imperfect three-dimensional metallic lattices: the role of geometric defects induced by Selective Laser Melting,” J. Mech. Phys. Solids, vol. 107, pp. 160–184, 2017.
31. Z. S. Bagheri, D. Melancon, L. Liu, R. B. Johnston, and D. Pasini, “Compensation strategy to reduce geometry and mechanics mismatches in porous biomaterials built with Selective Laser Melting,” J. Mech. Behav. Biomed. Mater., vol. 70, pp. 17–27, 2017.
32. S. Van Bael, G. Kerckhofs, M. Moesen, G. Pyka, J. Schrooten, and J. P. Kruth, “Micro-CT-based improvement of geometrical and mechanical controllability of selective laser melted Ti6Al4V porous structures,” Mater. Sci. Eng. A, vol. 528, no. 24, pp. 7423–7431, 2011.
33. M. Mazur, M. Leary, M. McMillan, S. Sun, D. Shidid, and M. Brandt, Mechanical properties of Ti6Al4V and AlSi12Mg lattice structures manufactured by Selective Laser Melting (SLM). Elsevier Ltd, 2016.
34. G. Dong, Y. Tang, and Y. F. Zhao, “A survey of modeling of lattice structures fabricated by additive manufacturing,” J. Mech. Des. Trans. ASME, vol. 139, no. 10, pp. 1–13, 2017.
35. H. J. Wilke, A. Kettler, K. H. Wenger, and L. E. Claes, “Anatomy of the sheep spine and its comparison to the human spine,” Anat. Rec., vol. 247, no. 4, pp. 542–555, 1997.
36. H.-J. Wilke, A. Kettler, and L. E. Claes, “Are sheep spines a valid biomechanical model for human spines?,” Spine (Phila. Pa. 1976)., vol. 22, no. 20, pp. 2365–2374, 1997.
37. F. Küçükaltun, A. Balcı, M. F. Aycan, Y. Usta, and T. Demir, “PRODUCTION OF REPLICATED TRABECULAR BONE STRUCTURE BY SELECTIVE LASER MELTING METHOD USING TI6Al4V POWDER AND INVESTIGATION OF GEOMETRIC ACCURACY,” in The Internatinonal Conference on Materials Science, Mechanical and Automotive Engineerings and Technology in CAPPADOCIA/TURKEY (IMSMATEC’19), 2019, pp. 533–538.
38. I. Standard, “ISO 13314: 2011 (E)(2011) Mechanical testing of metals—ductility testing—compression test for porous and cellular metals,” Ref number ISO, vol. 13314, no. 13314, pp. 1–7.
39. A. Standard, “F2077-03.",” Test Methods Intervertebral Body Fusion Devices." ASTM Int. West Conshohocken, PA, 2003.