钛粉末激光快速成形三维建模与成形机理

3D modeling and forming mechanism of Ti metallic powder via laser rapid prototyping

金属快速成形技术具有能够快捷地制造形状精度很高的复杂金属制件的优点,尤其在生物仿生复杂多孔结构制造方面具有较大的发展空间。为了解决金属快速成形加工过程中的成形质量不一致、组织形态差异大的问题,采用三维造型、温度场模拟与组织生长技术进行分析与求解。使用有限元法实现成形过程温度场的仿真,分析相关工艺参数对温度的影响作用。在求解温度场的基础上,通过耦合有限元法和元胞自动机可以再现快速成形过程的晶体组织形成过程。基于晶体的形核和生长机理建立纯金属晶体组织形成的元胞自动机模型,该模型需要能够实现晶粒的择优生长。结果表明:基于温度场分析的宏观有限元模型结合微观元胞自动机模型进行耦合计算能够实现快速成形晶体组织的优化与控制,其仿真结果和相关文献一致度达到95%以上。

Complex structure metal work pieces, especially bionic porous structures in tissue engineering, can be manufactured with high shape precisions and efficieneies using laser direct depositing technology. Three-dimensional modeling, finite unit analyses of thermo field, and tissue growing technology were applied to metal selected laser sintering （SLS） to solve the problem of forming quality difference and nucleation discrepancy. The thermo field was simulated and analyzed using finite element method, with correlative affection of technical parameters then discussed. According to the thermo field analyses, metal nucleation growing process was provided by using the cellular automaton model based on the coupling finite element method and the growing mechanism, where thenucleation could be optimized by adjusting the correlated technical parameters. Based on the analytical results, the optimization and control of nucleation were realized by combining the macro model of thermo field analyses and the micro model of cellular automation. The simulation results are almost the same as those of the correlated experiments at a consistency level of 95%.