PSI - Issue 18

S. Raghavendra et al. / Procedia Structural Integrity 18 (2019) 93–100 Author name / Structural Integrity Procedia 00 (2019) 000–000

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behavior of the as-built and as-designed samples, finite element analysis was carried out on the as-designed and regular as-built structures. Following conclusions are drawn from the discussion in the previous section.  Comparing the samples produced from SLM with the as-designed structures, an increased strut thickness is obtained. This increase in the thickness affects the mechanical properties and their behavior with respect to the topology.  From the stress-strain behavior it is seen that, with increase in the porosity of the structures, effect of topology is clearly seen. The structures with the lowest porosity values showed least variation in the mechanical properties with increase in the randomness of the structure.  In general, regular structures have higher strength and stiffness under all porosity ranges since the orientation of the struts are along the loading directions which is not the case for irregular and random configurations.  In compression loading, the regular structures are susceptible to buckling phenomenon and the irregular and random structures are subjected to bending. Thus, regular structures are more suitable for structural applications, while irregular and random structures are suitable for applications with bending/compression loading since they exhibit a large and constant plateau region.  The simulation results of the as-built regular structures indicate that, matching the porosity of the FE model and the printed samples can yield comparable results in the elastic region.  In order to replicate the exact behavior of the structures, inclusion of defects such as strut waviness, missing struts and varying thickness play a major role. Since an early yielding is observed in the experiments when compared to the simulation curve. Acknowledgements This work is part of the FAMAC Research Project, co-sponsored by Eurocoating S.p.A. and Provincia Autonoma di Trento (Regional Public Authority). References Amin Yavari, S., Ahmadi, S. M., Wauthle, R., Pouran, B., Schrooten, J., Weinans, H., & Zadpoor, A. A. (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, 43, 91–100. https://doi.org/10.1016/j.jmbbm.2014.12.015 Bobbert, F. S. L., Lietaert, K., Eftekhari, A. A., Pouran, B., Ahmadi, S. M., Weinans, H., & Zadpoor, A. A. (2017). Additively manufactured metallic porous biomaterials based on minimal surfaces: A unique combination of topological, mechanical, and mass transport properties. Acta Biomaterialia, 53, 572–584. https://doi.org/10.1016/j.actbio.2017.02.024 Cuadrado, A., Yánez, A., Martel, O., Deviaene, S., & Monopoli, D. (2017). Influence of load orientation and of types of loads on the mechanical properties of porous Ti6Al4V biomaterials. Materials and Design, 135, 309–318. https://doi.org/10.1016/j.matdes.2017.09.045 Dallago, M., Winiarski, B., Zanini, F., Carmignato, S., & Benedetti, M. (2019). On the effect of geometrical imperfections and defects on the fatigue strength of cellular lattice structures additively manufactured via Selective Laser Melting. International Journal of Fatigue, 124(November 2018), 348–360. https://doi.org/10.1016/j.ijfatigue.2019.03.019 Hanzl, P., Zetek, M., Bakša, T., & Kroupa, T. (2015). The influence of processing parameters on the mechanical properties of SLM parts. Procedia Engineering, 100(January), 1405–1413. https://doi.org/10.1016/j.proeng.2015.01.510 Helou, M., Vongbunyong, S., & Kara, S. (2016). Finite Element Analysis and Validation of Cellular Structures. Procedia CIRP, 50, 94–99. https://doi.org/10.1016/j.procir.2016.05.018 ISO Standard, ISO 13314, 2011. Mechanical testing of metals – Ductility testing – Compression test for porous and cellular metals. International Organization of Standards, Switzerland. www.iso.org Kadkhodapour, J., Montazerian, H., Darabi, A. C., Anaraki, A. P., Ahmadi, S. M., Zadpoor, A. A., & 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, 50, 180–191. https://doi.org/10.1016/j.jmbbm.2015.06.012 Qiu, C., Yue, S., Adkins, N. J. E., Ward, M., Hassanin, H., Lee, P. D., …Attallah, M. M. (2015). Influence of processing conditions on strut structure and compressive properties of cellular lattice structures fabricated by selective laser melting. Materials Science and Engineering A, 628, 188– 197. https://doi.org/10.1016/j.msea.2015.01.031 Raghavendra, S., Molinari, A., Fontanari, V., Luchin, V., Zappini, G., Benedetti, M., … Klarin, J. (2018). Tensile and compression properties of variously arranged porous Ti-6Al-4V additively manufactured structures via SLM. Procedia Structural Integrity, 13, 149–154. https://doi.org/10.1016/j.prostr.2018.12.025