Print Email Facebook Twitter Fatigue crack propagation in additively manufactured porous biomaterials Title Fatigue crack propagation in additively manufactured porous biomaterials Author Hedayati, R. (TU Delft Biomaterials & Tissue Biomechanics) Amin Yavari, S. (TU Delft Biomaterials & Tissue Biomechanics; University Medical Center Utrecht) Zadpoor, A.A. (TU Delft Biomaterials & Tissue Biomechanics) Date 2017 Abstract Additively manufactured porous titanium implants, in addition to preserving the excellent biocompatible properties of titanium, have very small stiffness values comparable to those of natural bones. Although usually loaded in compression, biomedical implants can also be under tensional, shear, and bending loads which leads to crack initiation and propagation in their critical points. In this study, the static and fatigue crack propagation in additively manufactured porous biomaterials with porosities between 66% and 84% is investigated using compact-tension (CT) samples. The samples were made using selective laser melting from Ti-6Al-4V and were loaded in tension (in static study) and tension-tension (in fatigue study) loadings. The results showed that displacement accumulation diagram obtained for different CT samples under cyclic loading had several similarities with the corresponding diagrams obtained for cylindrical samples under compression-compression cyclic loadings (in particular, it showed a two-stage behavior). For a load level equaling 50% of the yield load, both the CT specimens studied here and the cylindrical samples we had tested under compression-compression cyclic loading elsewhere exhibited similar fatigue lives of around 104 cycles. The test results also showed that for the same load level of 0.5 Fy, the lower density porous structures demonstrate relatively longer lives than the higher-density ones. This is because the high bending stresses in high-density porous structures gives rise to local Mode-I crack opening in the rough external surface of the struts which leads to quicker formation and propagation of the cracks. Under both the static and cyclic loading, all the samples showed crack pathways which were not parallel to but made 45° angles with respect to the notch direction. This is due to the fact that in the rhombic dodecahedron unit cell, the weakest struts are located in 45° direction with respect to the notch direction. Subject Additive manufacturingBiomedical scaffoldsCrack propagationFatigue behaviorPorous biomaterials To reference this document use: http://resolver.tudelft.nl/uuid:c229afae-1e73-46f5-8936-818d24730a52 DOI https://doi.org/10.1016/j.msec.2017.03.091 Embargo date 2019-03-16 ISSN 0928-4931 Source Materials Science and Engineering C: Materials for Biological Applications (online), 76, 457-463 Bibliographical note Accepted Author Manuscript Part of collection Institutional Repository Document type journal article Rights © 2017 R. Hedayati, S. Amin Yavari, A.A. Zadpoor Files PDF Experimental_CT_samples_ver24.pdf 3.6 MB Close viewer /islandora/object/uuid:c229afae-1e73-46f5-8936-818d24730a52/datastream/OBJ/view