Unit Cell Size Effect on Mechanical Properties of Ti6Al4V Porous Structure

Abstract:

Topology optimized porous lattice structure with different unit cell size (1~6 mm) and porosity (40~80%) were fabricated by Selective Laser Melting, and their compressive deformation behavior and elastic properties were discussed. The results shown that compressive strength and elastic modulus of lattice structure were inversely proportional to unit cell size. Their compressive strength ranged from 126 to 199 MPa and elastic modulus ranged from 3.5 to 55.47 GPa. The stress-strain curves of lattice structures with different unit cell size followed three kinds of stress-strain laws: elastic material, elastic-brittle material and brittle material. The compressive deformation process was simulated by ABAQUS and explained the reason of two 45° fracture band. The numerical results shown a good agreement with experimental results. The stability was evaluated by Gibson-Ashby model, and the stability parameter C decreased with the increase of unit cell size. Meanwhile, the fitting curves based on Gibson-Ashby model were established, and the value of n increased with the increase of unit cell size. A 3D surface mathematical model combining unit cell size, relative density and relative elastic modulus was established, and the design area satisfying mechanical properties of bone implants was proposed.