孔结构对电子束粉末床熔融多孔钽支架变形行为及力学性能的影响

Influence of pore structures on deformation behavior and mechanical properties of porous tantalum scaffolds fabricated by electron beam powder bed fusion

采用电子束粉末床熔融技术制备菱形十二面体、G7及简单立方3种孔结构的多孔钽支架。通过压缩试验、拉伸试验、三点弯曲试验及有限元模拟,研究孔结构对多孔钽支架变形行为和力学性能的影响。在压缩试验中,G7和简单立方结构的多孔钽支架以杆筋的屈服变形为主,而菱形十二面体支架以弯曲变形为主,导致菱形十二面体多孔钽支架的压缩强度较低。另一方面,菱形十二面体多孔钽支架具有较好的拉伸性能和弯曲性能。在拉伸变形和弯曲变形中,菱形十二面体多孔钽支架的最大应力分布均匀,均匀的结构变形使得杆筋断裂延缓;而G7和简单立方结构多孔钽支架由于应力集中在横杆上,变形初期即出现杆筋断裂。因此,应根据不同的力学性能需求,合理选择电子束选区熔化多孔钽支架的孔结构。

Porous tantalum scaffolds with the dodecahedron,G7,and cubic structures were fabricated by electron beam powder bed fusion(EB-PBF).The influence of pore structures on the deformation behavior and mechanical properties of porous tantalum scaffolds was investigated by compressive testing,tensile testing,three-point bending testing,and finite element analysis(FEA).In the compressive test,the deformation of G7 and cubic scaffolds was dominated by buckling.The dodecahedron scaffold was deformed mainly by bending,leading to its lower compressive strength.On the other hand,the dodecahedron scaffold had superior tensile and bending properties.The uniform maximum stress distributions of the dodecahedron scaffold in the tensile and bending tests contributed to the homogeneous structural deformation,which delayed the fracture of struts;whereas,the maximum stresses of G7 and cubic scaffolds were concentrated in the transverse struts,resulting in the fracture of transverse struts in the early deformation stage.Therefore,pore structures should be properly selected for EB-PBF manufactured porous tantalum scaffolds based on the requirements for mechanical properties.