高孔隙度可再生骨支架仿真与实验研究

Simulation and Experiment of High Porosity Renewable Bone Scaffold

目的 确定单元体与股骨的最佳孔隙度骨支架结构。方法 通过扫描电镜分析选区激光熔化(Selective lasermelting,SLM)成形试样的微观结构;通过静力学模拟与实验分析不同孔隙度下标准结构与Voronoi多孔结构的压缩变形规律;通过生物力学仿真实验分析步态周期下标准结构与Voronoi多孔结构的应力分布情况。结果 在选区激光熔化成形的316L不锈钢微观组织中,均匀分布着细小的近六边形、伸长六边形的胞状结构和条柱状亚结构,受压时有利于分散应力,提高整体结构的稳定性;在压缩变形时,标准结构应力集中于垂直棱柱,易导致棱柱断裂引起试样倾斜;Voronoi结构连接杆的不均匀分布有利于分散应力,使Voronoi结构的最大等效应力(250.34 MPa)远低于标准结构(738.07 MPa),保证了整体受力均匀与结构稳定;在步态周期下,2种骨支架结构的应力随孔隙度的增加而增加,75%孔隙度的Voronoi结构具有更优异的承压能力与缓解应力屏蔽的作用。结论 通过模拟与试验分析,确定了单元体与股骨的最佳孔隙度及Voronoi结构优异的力学性能,验证了在步态周期下高孔隙度Voronoi骨支架结构的可靠性,为股骨置换手术提供了理论依据。

The work aims to determine the optimal porosity bone scaffold structure between the unit body and the femur.The microstructure of the sample formed by selective laser melting(SLM) was analyzed by scanning electron microscope. The compression deformation law of standard structure and Voronoi porous structure under different porosity was analyzed by static simulation and experiment. The stress distribution of the standard structure and the Voronoi porous structure under the gait cycle was analyzed by biomechanical simulation experiment. The microstructure of 316L stainless steel formed by selective laser melting was evenly distributed with fine cell structures of near hexagon, elongated hexagon and strip columnar substructure,which was conducive to the stress dispersion and improved the stability of the whole structure. During the compression deformation, the stress of the standard structure was concentrated in the vertical prism, which easily led to the fracture of the prism and caused the sample tilt. The non-uniform distribution of Voronoi structure was conducive to the stress dispersion, so that the maximum equivalent stress of Voronoi structure(250.34 MPa) was much lower than that of the standard structure(738.07 MPa),ensuring the uniform stress and stability of the whole structure. Under the gait cycle, the stress of the two bone scaffold structures increased with the increase of porosity, and the Voronoi structure with 75% porosity had better bearing capacity and relieved the effect of stress shielding. Through simulation and experimental analysis, the optimal porosity of the unit body and the femur and the excellent mechanical properties of the Voronoi structure are determined and the reliability of the high porosity Voronoi bone scaffold structure under the gait cycle is verified, which provides a theoretical basis for femoral replacement surgery.