熔丝增材制造多相流-多场耦合一体化建模仿真方法

The quantitative analysis of a forming process, the prediction of a forming shape and the forming stability are critical issues for the high-precision shape control and process optimization in the fused filament additive manufacturing processes. The applicant will cut into those issues via a high-fidelity simulation and focus on multi-physics effects and material behaviors affecting the forming shape and its stability, proposing a multi-physics unified modeling method based on a multiphase-flow framework, developing a comprehensive model including heat and mass transfer, fluid flow, solidification and interfaces interaction etc., for which an adaptive-resolution gridding and a high-precision interface constructing method and a high-performance computing method will be also developed. The comprehensive model is validated via typical metal- and polymer-based additive manufacturing processes. A high-fidelity simulation and a high-precision prediction for the forming shape of the fused filament additive manufacturing processes will be achieved. The behaviors of the fluid flow, the solidification of the material and the mechanism of the heat transfer will be explored, and a quantitative relationship which determining the forming stability, among the heat and mass input, fluid and solid stress, gravity force, cooling rate, and solidifying rate will be found. This work will contribute a modeling and simulation method to analyzing the process quantitatively, controlling the forming shape precisely and extending the limitation of the forming capacity of the fused filament processes.

熔丝增材制造工艺成形过程量化分析、成形形貌预测以及成形稳定性，是高精度形貌控制与成形工艺优化的关键难题。申请人以成形过程高保真仿真为切入点，紧密围绕影响成形形貌与成形稳定性的多场耦合作用及材料行为，拟提出一种多相流框架下的多场耦合一体化建模仿真方法，构建描述成形过程中的物质传热、流动、凝固以及界面作用等一体化模型，并提出面向高保真仿真的自适应空间分辨率与高精度界面构造方法、一体化模型系统高效高稳定求解算法。同时结合典型金属/非金属熔丝增材制造工艺对模型的准确性进行验证，实现成形过程的高保真仿真以及成形形貌的高精度预测，并探究成形过程中的材料流动、凝固成形机制以及热量流动规律，揭示影响成形稳定性的热输入、物质输入、流体应力、固体应力、重力、散热速率以及凝固速率等关键因素的定量平衡关系，为熔丝增材制造工艺机理量化分析、成形形貌精准控制以及扩展极限成形能力提供理论与建模仿真方法支撑。

熔丝增材制造形性调控面临成形过程量化分析、成形形貌精准预测等关键难题。本项目以成形过程高保真仿真为切入点，开展了熔丝增材制造介观尺度多相流-多场耦合一体化建模框架、自适应空间分辨率及自由界面高精度构建的网格方法、瞬态多相流-多场耦合一体化模型的高稳定高效求解算法、典型熔丝增材制造工艺高保真模拟及弱支撑结构形貌预测、以及多相流-多场耦合一体化模型的扩展应用等研究。建立了包含传热、流动、界面作用、凝固成形等过程的多相流-多场耦合一体化模型，突破了多相流与多物理场耦合建模的难题，实现了熔丝增材制造和激光粉末增材制造成形过程的高保真仿真；提出了与Front-tracking方法相结合的多层级正则自适应加密网格方法、以及扩散项分裂的半隐式方程系统并行求解算法，突破了多相流-多场耦合一体化模型面临的巨大数值计算困难，实现了瞬态多相流-多场耦合一体化模型的高精度高稳定高效求解；揭示了成形过程中材料传热凝固规律、界面作用及形貌形成规律、粘弹性行为影响规律、以及重力作用下弱支撑结构成形稳定性的影响规律。研究成果形成了熔丝增材制造多相流-多场耦合一体化建模仿真的底层核心三维并行代码及其软件工具，为熔丝增材制造工艺机理量化分析、成形形貌精准控制提供了理论与建模仿真方法支撑。

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