Additive Manufacturing (AM) lab at TUDelft

Director: Amir Zadpoor

Research on additive manufacturing started in my lab more than five years ago. Our research interests encompasses not only the AM processes themselves but also the application of AM processes in biomedical areas such as production of complex implants and biomaterials. Optimisation of the AM processes to achieve geometrically complex structures with excellent structural integrity and mechanical properties has been an active area of research. Moreover, we have been working on new types of materials and alloys that could be processed using AM. The portfolio of metallic materials that we have worked with includes titanium alloys (Ti-6Al-4V), pure titanium, stainless steel, CoCr, pure iron, and tantalum. Regarding metallic materials, we have been focusing on the application of selective laser melting. As for polymeric materials and hydrogels, we have used stereolithography (SL) as well as inkjet-based technologies and fused deposition modelling (FDM). There has been a strong collaboration between the AM lab at TU Delft and several commercial companies including Layerwise (now part of 3D systems), ImplantCast, and Realizer.

Equipment
The lab is equipped with several large-scale pieces of equipment that are needed for AM of metallic and polymeric materials, for geometrical characterisation of the resulting parts and products, for mechanical testing of AM pieces, for in situ process monitoring, and for post-processing of AM parts. We have a custom-built selective laser melting machine (SLM 125, Realizer) that is re-designed so that the build chamber could accommodates two infrared temperature measurements cameras that are used for in situ process monitoring. We have also made sure there is enough room for further improvement of the in situ process monitoring system. The equipment needed for pre-processing of metallic powder are the other accessories of the lab and include powder sizers based on laser diffraction, high-safety glove boxes for handling of small powders, and powder sieving equipment. The other general equipment of the lab that are used for pre- and/or post-processing of the AM parts include vacuum furnaces, sinter furnaces, and tube furnaces. There is an equipped chemical laboratory for chemical and electrochemical post-processing of AM parts. The electrochemical surface treatment and coating equipment includes large-scale anodizing setup, two plasma electrolytic oxidation (PEO) benches, plasma spray coating equipment, and electroless coating setup.

Gallery of our AM-related research
The AM lab at TU Delft has been working with several other research centers and companies to process, design, characterise, and test a wide range of AM materials and parts. Many of these parts have been used for biomedical application such as implants and bone substitutes. In the following gallery, you see examples of AM parts from our recent publications.


Publications on AM processes and products
  1. Hedayati, R, Sadighi, M, Mohammad-Aghdam, M, Zadpoor, AA, 2015, "Mechanics of additively manufactured porous biomaterials based on the rhombicuboctahedron unit cell”, Journal of the Mechanical Behavior of Biomedical Materials, in press.
  2. Hedayati, R, Sadighi, M, Mohammad-Aghdam, M, Hosseini Toudeshki, H, Zadpoor, AA, 2016, “Computational prediction of the fatigue behavior of additively manufactured porous metallic biomaterials”, International Journal of Fatigue, vol 84, pp 67-79.
  3. Hedayati, R, Sadighi, M, Mohammad-Aghdam, M, Zadpoor, AA, 2016, “Mechanical properties of regular porous biomaterials made from truncated cube repeating unit cells: analytical solutions and computational models”, Materials Science and Engineering C, vol 60, pp 163-183.
  4. Hedayati, R, Sadighi, M, Mohammad-Aghdam, M, Zadpoor, AA, 2016, “Effect of mass multiple counting on the elastic properties of open-cell regular porous biomaterials”, Materials & Design, vol 89, pp 9-20.
  5. Hedayati, R, Sadighi, M, Mohammad-Aghdam, M, Zadpoor, AA, 2016, “Mechanical behavior of additively manufactured porous biomaterials made from truncated cuboctahedron unit cells”, International Journal of Mechanical Sciences, vol 106, pp 19-38.
  6. Amin Yavari, S, Ahmadi, SM, Wauthle, R, Pouran, B, Schrooten, J, Weinans, H, Zadpoor, AA, 2015, “Relationship between unit cell type and porosity and the fatigue behavior of selective laser melted meta-biomaterials”, Journal of the Mechanical Behavior of Biomedical Materials, vol 43, pp 91-100.
  7. Wauthle, R, Van der Stok, J, Amin Yavari, S, Van Humbeeck, J, Kruth, JP, Zadpoor, AA, Weinans, H, Mulier, M, Schrooten, J, 2015, “Additively manufactured porous tantalum implants”, Acta Biomaterialia, vol 14, pp 217-225.
  8. Van der Stok, J, Koolen, MKE, de Maat, MPM, Amin Yavari, S, Alblas, J, Patka, P, Verhaar, JAN, van Lieshout, EMM, Zadpoor, AA, Weinans, H, Jahr, H, 2015, “Full regeneration of segmental bone defects using porous titanium implants loaded with BMP-2 containing fibrin gels”, European Cells & Materials, vol 29, pp 141-154.
  9. Van der Stok, J, Lozano, D, Chin Chai, Y, Amin Yavari, S, Bastidas Coral, AP, Verhaar, JAN, Gómes-Barrera, E, Schrooten, J, Jahr, H, Zadpoor, AA, Esbrit, P, Weinans, H, 2015, “Osteostatin-coated porous titanium implants can improve early bone regeneration in cortical bone defects in rats”, Tissue Engineering Part A, vol 21, pp 1495-1506.
  10. Kadkhodapour, J, Montazerian, H, Darabi, AC, Ahmadi, SM, Zadpoor, AA, Schmauder, S, 2015, “Failure mechanisms of additively manufactured porous biomaterials: effects of porosity and type of unit cell”, Journal of the Mechanical Behavior of Biomedical Materials, vol 50, pp 180-191.
  11. Amin Yavari, S, Chai, YC, Wauthle, R, Schrooten, J, Weinans, H, Zadpoor, AA, 2015, “Effects of anodizing parameters and heat treatment on nanotopographical features, bioactivity, and cell culture response of additively manufactured porous titanium”, Materials Science and Engineering C, vol 51, pp 132-138.
  12. Wauthle, R, Ahmadi, SM, Amin Yavari, S, Mulier, M, Zadpoor, AA, Weinans H, Van Humbeeck, J, Kruth, J-P, Schrooten, J, 2015, "Revival of pure titanium for dynamically loaded porous implants using additive manufacturing", Materials Science and Engineering C, vol 54, pp 94-100.
  13. Ahmadi, SM, Amin Yavari, S, Wauthle, R, Pouran, B, Schrooten, J, Weinans, H, Zadpoor, AA, 2015, “Additively manufactured open-cell porous biomaterials made from six different space-filling unit cells: the mechanical and morphological properties”, Materials, vol 8, pp 1871-1896.
  14. Bsat, S, Amin Yavari, S, Munsch, M, Valstar, ER, Zadpoor, AA, 2015, “Effect of alkali-acid-heat chemical surface treatment on electron beam melted porous titanium and its apatite forming ability”, Materials, vol 8, pp 1612-1625.
  15. Amin Yavari, S, van der Stok, J, Chai, YC, Wauthle, R, Tahmasebi Birgani, Z, Habibovic, P, Mulier, M, Schrooten, J, Weinans, H, Zadpoor, AA, 2014, "Bone regeneration performance of surface treated porous titanium”, Biomaterials, vol 35, pp 6172–6181.
  16. Ahmadi, SM, Campoli, G, Amin Yavari, S, Sajadi, B, Wauthle, R, Schrooten, J, Weinans, H, Zadpoor, AA, 2014, "Mechanical behavior of regular open-cell porous biomaterials made of diamond lattice unit cells", Journal of the Mechanical Behavior of Biomedical Materials, vol 34, pp 106-115.
  17. Amin Yavari, S, Ahmadi, SM, van der Stok, J, Wauthle, R, Riemslag, AC, Janssen, M, Schrooten, J, Weinans, H, Zadpoor, AA, 2014, "Effects of bio-functionalizing surface treatments on the mechanical behavior of porous titanium implants", Journal of the Mechanical Behavior of Biomedical Materials, vol 36, pp 109–119.
  18. Amin Yavari, S, Ahmadi, SM, van der Stok, J, Wauthle, R, Schrooten, J, Weinans, H, Zadpoor, AA, 2014, "Mechanical analysis of a rodent segmental bone defect model: the effects of surgical variability and implant stiffness on load transfer", Journal of Biomechanics, vol 47, pp 2700-2708.
  19. Amin Yavari, S, Wauthle, R, Bottger, A, Schrooten, J, Weinans, H, Zadpoor, AA, 2014, "Crystal structure and nanotopographical features on the surface of heat-treated and anodized porous titanium biomaterials produced using selective laser melting", Applied Surface Science, vol 290, pp 287–294.
  20. Van der Stok, J, Wang. H, Amin Yavari, S, Siebelt, M, Sandker, M, Waarsing, JH, Jahr, H, Zadpoor, AA, Leeuwenburgh, SCG, Weinans, H, 2013, “Enhanced bone regeneration of cortical segmental bone defects using porous titanium scaffolds incorporated with colloidal gelatin gels for time and dose controlled delivery of dual growth factors”, Tissue Engineering Part Avol 19, pp 2605-2614.
  21. Amin Yavari, S, Wauthle, R, Riemslag, AC, Janssen, M, Schrooten, J, Weinans, H, Zadpoor, AA, 2013, "Fatigue behavior of porous titanium biomaterials manufactured using selective laser melting", Materials Science and Engineering Cvol. 33(8), p.p. 4849–4858
  22. Van der Stok, J, van der Jagt, OP, Amin Yavari, S, De Haas, MFP, Waarsing, JH, Jahr, H, van Lieshout, EMM, Patka, P, Verhaar, JAN, Zadpoor, AA, Weinans, H, 2013, “Selective laser melting produced porous titanium scaffolds regenerate bone in critical size cortical bone defects”, Journal of Orthopedic Research, vol. 31, pp. 792–799.
  23. Campoli, G, Borleffs, MS, Amin Yavari, S, Wauthle, R, Weinans, H, Zadpoor, AA, 2013, "Mechanical properties of open-cell metallic biomaterials manufactured using additive manufacturing", Materials & Designvol. 49, pp. 957–965.
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