激光增材制造Ti6Al4V点阵结构的抗压吸能特性

人体骨骼受到碰撞后的断裂过程伴随着能量吸收，多孔骨植入体的设计需考虑结构的抗压吸能特性。在空间尺寸（20 mm×20 mm×30 mm）内，通过拓扑优化设计和激光增材制造技术制备不同胞元尺寸和相对密度的Ti6Al4V点阵结构，采用熔池监控、单向压缩实验和有限元仿真方法，探究了点阵结构的表面质量、断裂形变规律和吸能特性。结果表明，点阵结构的结构参数受熔池温度场和粉末支持力的影响；点阵结构的抗压行为遵循弹脆性变化规律，断裂带与制造方向呈45°；点阵结构的断裂机制为韧性断裂，裂纹沿内部微孔洞分布方向扩展；能量吸收能力随着相对密度增大呈递增趋势，随着胞元尺寸增大呈递减趋势；能量吸收效率随着相对密度增大呈递减趋势，随着胞元尺寸增大呈递增趋势。

Compressive Behavior and Energy Absorption of Ti6Al4V Lattice Structure Fabricated by Laser Additive Manufacturing

The fracture process of human bone under impacting is accompanied by the absorption of energy. The design of porous implant should consider compressive behavious and energy absorption characteristics of the whole structure. A series of lattice structures with different unit cell size and relative density is established by topology optimization designing and laser additive manufacturing fabricating, and the suface quality, fracture and deformation regularity and energy absorption performance of lattice structure are investigated by melt pool monitoring, unidirectional compression test and finite element simulation. The results show that the structure parameters of lattice structure are affected by the temperature field of molten pool and the supporting force of powder layer. The compressive behavious of lattice structures follows the law of elasticity and brittleness foam, the crush band forms at an angle of 45o with the fabricating direction. The fracture mechanism of lattice structure is ductile fracture, and the crack propagation direction is distributed along the internal micro-pores. The energy absorption capacity is directly proportional to the relative density and inversely proportional to unit cell size. The energy absorption efficiency is inversely proportional to the relative density and proportional to the cell size.