The Study Of Static Compressive Mechanical Behavior Of Porous Tantalum Bone Implants Fabricated By Laser Melting Based Additive Manufacturing

Porous tantalum(Ta)has been widely used clinically for bone tissue repair and reconstruction,due to its excellent corrosion resistance,biocompatibility,osteointegration,and osteoconductivity properties.Additive manufacturing is a new advanced fabrication technology,which can be used to manufacture bone implants with controllable porous structures,complex three-dimensional shapes,and anatomy-matching shapes.As a new type of bone repairing material,porous Ta has a extensive application prospect and has attracted increasing attention in academia and industry.Before pre-clinical animal researches and clinical studies,it is essential to investigate the mechanical behavior and failure mechanism of porous Ta fabricated by additive manufacturing to evaluate its safety and effectiveness for implantation.In this study,porous Ta scaffolds with three different pore configurations of cube,rhombic dodecahedron and biomimetic trabecular were fabricated by laser melting based additive manufacturing technology.The strut diameter was 250 μm and porosities were65%,75%,and 85%.The structure of porous Ta samples was characterized by scanning electron microscope(SEM),compression mechanical experiment,and finite element analysis to evaluate their compression mechanical properties,study their compression mechanical behavior,and understand their failure mechanism.The main conclusions are summarized as follows.(1)The compressive mechanical properties of porous Ta fabricated by laser based additive manufacturing decreased significantly with the increase of porosity.The65%-85% porosity porous Ta with cube,rhombic dodecahedron and trabecular pore configurations,has a compressive yield strength of 10-40 MPa and an elastic modulus of 0.6-3 GPa,which lies in the range of compressive mechanical properties of human cancellous bone and trabecular bone,promising for otheopedic applications.(2)The failure mechanism of porous Ta material with cubic,rhombic dodecahedron and biomimetic bone trabecular configurations by laser melting based additive manufacturing is micro plastic deformation and micro fracture of struts,and its mechanical reliability is better than that of porous Ti6Al4 V alloy.The mechanical behaviors of porous Ta with three different pore configurations are significantly different.The sample with cube configuration has the largest strain corresponding to the yield point and the strongest resistance to deformation.The sample with trabecular configuration was the second,and the sample with rhombic dodecahedron configuration was the lowest.(3)The compressive stress distribution of porous Ta fabricated by laser melting based additive manufacturing is significantly different.The maximum stress of cube configuration specimen is mainly distributed in the longitudinal struts,and the maximum stress of trabecular configuration specimen and rhombic dodecahedral configuration specimen is mainly distributed at the junction of struts,that is,where the micro plastic deformation fractures on the struts.In conclusion,laser-based AM porous Ta scaffold is a promising new orthopaedic implantable material with controllable porous structure,appropriate mechanical properties matching those of human cancellous bone,superior ductility and mechanical reliability.