Design of porous structure based on the Voronoi diagram and stress line for better stress shielding relief and permeability

Abstract

In the process of artificial metal bone implantation, the mismatch of elastic modulus and bad permeability behavior lead to obvious stress shielding and poor bone tissue ingrowth. For these problems, this paper proposed a new design method of the variable porosity porous structure based on the stress line and Voronoi diagram. In the design process, the principal stress line was determined by mechanical finite element analysis, which controlled the seeds distribution of the 3D Voronoi diagram, making local porosity conforms to the stress distribution. In addition, the designed samples were fabricated through laser powder bed fusion (L-PBF) technology with TC4 powders. The mechanical characteristics were evaluated by static mechanical simulation with ABAQUS and compression tests, and the permeability characteristics were analyzed by fluid simulation with COMSOL and in vitro and vivo test. The research results showed that the designed structure obtained the relatively low elastic modulus and higher mechanical strength, the designed structure has closer permeability characteristics to the reconstructed natural bone, and was conducive to cell proliferation. So the porous structure based on the stress line and Voronoi diagram might have good application potential in the bionic design of bone implants.

Keywords

• Porous structure
• Stress line
• Porosity
• Mechanical properties
• Permeability characteristics
• Voronoi