增材制造金属材料多尺度分析的电子-声子两步超快热弹理论

Additive manufacturing technology is moving toward the trend of multi-scale and multi-materials, as a result, thermoelastic mechanism of laser and metal interaction is increasingly important. As the key components in extreme environments such as high temperature and thermal shock, additive manufacturing components contain microscale defects such as pores, inclusions, and cracks, so its multi-scale transient thermo-mechanical coupling analysis is of great significance. In this project, a multiscale ultrafast thermoelastic model will be established with the aids of nonlocal heat conduction, nonlocal elasticity and electron-lattice heat conductive mechanism. The governing equations of the model are complex due to the coupling of physical variables, as a consequence, it is difficult to solve the problems, analytically. And an efficient numerical solution method for this model will be developed, providing reliable means for the analysis of ultra-fast thermal elastic responses of complex structures. The thermoelastic mechanism of the interaction between laser and metal in the additive manufacturing process will be studied, and the thermodynamic behavior of microscale defects of additive manufacturing materials in extreme environments will be investigated. In addition, the effect of defects, interfaces on the overall thermodynamic properties of additive manufacturing metal materials will be discussed. This project will promote the development of multi-scale mechanics and non-equilibrium thermodynamics, and provide theoretical and numerical support for the development of additive manufacturing equipment, optimization of manufacturing processes, and improvement of product performance.

增材制造技术正在向多尺度多材料方向发展，制造过程中激光/金属热力耦合机理的研究日益重要；作为高温、热冲击等极端环境中的关键部件，增材制造结构常含有气孔、夹杂、裂纹等微尺度缺陷，其瞬态热力耦合分析至关重要，对多尺度热弹理论及其数值方法研究提出了迫切要求。本项目拟考虑热传导、弹性理论的非局部效应以及金属材料的电子-声子两步热传导机理，通过热力学原理建立增材制造金属材料的多尺度超快热弹耦合模型。该模型具有多变量、强耦合的特点，导致控制方程复杂、解析求解困难，将发展该理论的高效数值求解方法，为高维复杂结构的超快热弹响应分析提供可靠手段。开展增材制造过程中激光/金属相互作用的热力耦合分析，研究极端环境下增材制造材料内微尺度缺陷的热力学行为，探讨缺陷、界面等对增材制造结构整体热力学性能的影响。本项目将促进多尺度力学和非平衡热力学的发展，为增材制造装备的研发、制造工艺的优化、材料性能的提高提供支撑。

增材制造技术正在向多尺度多材料方向发展，对多尺度热弹耦合理论及其计算方法研究提出了迫切要求。增材制造热弹耦合分析对揭示制造过程中激光/金属相互作用机理、实现增材制造技术高精度、保证增材制造热端部件在极端热力载荷下的安全性具有重要意义。本项目基于拓展热力学原理，并考虑电子-声子耦合热传导模型，建立了增材制造金属材料的多尺度热弹耦合模型，发展了其高效数值求解方法；通过激光热源作用下材料的热弹耦合响应分析，揭示了增材制造过程中激光与金属的相互作用机理；通过热载荷作用下含界面、裂纹结构的热弹耦合行为研究，探讨了界面、缺陷等对增材制造结构整体热弹性能的影响。此外，针对增材制造多尺度材料的微结构特征，在拉伸和剪切本构关系中分别引入尺度效应参数建立了弹性分析模型，并提出了微结构分析的2n+1阶微纳尺度统一梁模型，为增材制造多尺度结构的热弹耦合分析提供了统一理论模型。本项目取得的理论研究成果属于多尺度力学和非平衡热力学的研究范畴，具有重要的科学意义；本项目发展的计算方法，为增材制造高维复杂结构的热弹响应分析提供了可靠手段，具有广阔的工程应用前景。