结构尺寸对Ti6Al4V多孔结构力学性能的影响

采用激光选区熔化技术制造了不同单元结构尺寸（1~6 mm）、孔隙率（40~80%）的拓扑优化多孔阵列结构，研究了单元结构尺寸对其压缩形变规律和弹性性能的影响。结果表明，多孔阵列结构的抗压强度、弹性模量均与单元结构尺寸成反比，抗压强度在126~199 MPa，弹性模量在3.5~55.47 GPa；压缩应力-应变曲线与单元结构尺寸有关，分别遵循弹性、弹脆性和脆性多孔材料三种应力应变规律；通过数值模拟多孔阵列结构的压缩形变过程，解释了两种45°断裂带的成因，力学性能与实验结果基本吻合；利用Gibson-Ashby模型评价多孔结构的稳定性，稳定性参数C与单元结构尺寸成反比；给出Gibson-Ashby拟合方程，特征参数n随单元结构尺寸增加而增大；建立了单元结构尺寸、相对密度和相对弹性模量的三维曲面数学模型，提出骨植入体的设计区域。

Unit Cell Size Effect on Mechanical Properties of Ti6Al4V Porous Structure

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.