基于SLM工艺的薄壁结构零部件轻量化自支撑优化设计方法研究

Manufacturing support structures by selective laser melting (SLM) will bring a series of disadvantages, for example, manufacturing time increases, materials waste, complicated post-processing and high cost. Therefore, this research focused on the lightweight and self-supporting optimization design method of thin-walled parts based on selective laser melting. Firstly, the forming ability and mechanical properties of thin-walled structures with different structure parameters and positional parameters are analyzed, the mapping relationship between structure parameters, positional parameters and target limit geometric constraints, mechanical properties is established, based on the above a limit geometric constraint database for thin-walled parts is established. In addition, the interaction of laser and metal, the metallurgical dynamics of molten pools and the non-equilibrium solidification behavior of ultra-high temperature moving pools are explored, and the mechanism of stress strain and defect formation during the laser forming process of thin-walled structures are revealed, which will provide a bases for the control of defects forming. Finally, the lightweight and self-supporting optimization design method of thin-walled parts based on SLM is studied, the aerospace eight-claw frame is optimized using above mentioned method and the forming performance is analyzed. The research results will enrich the optimization design method system based on SLM technology, and provide theoretical and technical support for the application of SLM technology for the thin-wall components.

面向零部件轻量化设计需求，针对SLM成形辅助支撑结构导致的加工时间增加、材料浪费、后处理工序复杂、成本高等问题，开展基于SLM极限几何工艺约束的零部件轻量化自支撑优化设计方法研究。分析薄壁结构在不同特征参数及位置参数时的成形能力及力学性能，建立结构特征参数、位置参数与目标极限几何约束、力学性能的映射关系，形成薄壁结构体系极限几何约束数据库。探索薄壁结构激光/金属热交互作用、熔池冶金动力学行为和超高温移动熔池非平衡凝固行为，揭示薄壁结构选区激光熔化成形过程中应力应变和缺陷形成机理，为成形缺陷的控制提供依据。研究基于SLM极限几何约束的零部件轻量化自支撑优化设计方法，以航天八爪框典型结构为对象，开展基于SLM极限几何工艺约束的八爪框轻量化自支撑优化设计及成形性能分析。研究成果将充实基于SLM技术的零件优化设计方法体系，为推进SLM技术在薄壁结构零部件方面的深入应用提供理论及技术支撑。

为解决SLM成形辅助支撑结构过程中产生加工时间增加、材料浪费、后处理工序复杂、成本高等问题，本项目开展了基于SLM极限几何工艺约束的零部件轻量化自支撑优化设计方法研究，成果如下：（1）研究了SLM极限几何工艺约束的描述及表征，揭示了影响薄壁结构SLM成形的关键结构特征参数及位置参数，建立了极限几何工艺约束与性能的映射关系，搭建了薄壁结构体系极限几何约束数据库；（2）研究了薄壁结构SLM成形过程热变形问题，建立了多尺度多物理场耦合数值模拟分析模型，开展了基于响应面分析法的多工艺参数变量多目标系统实验研究，揭示了不同工艺参数对成形过程中移动熔池冶金动力学特性及其传热传质行为的影响规律，形成了薄壁结构—工艺—缺陷的映射关系，揭示了变形、气孔、裂纹、层间熔合不良等缺陷形成机理，为成形缺陷的控制提供依据；（3）研究了薄壁结构的零部件轻量化自支撑优化设计方法的问题，基于零件功能/性能要求、热应力仿真结果及设计空间等多约束条件，开展了零部件轻量化设计方法研究，结合极限几何约束数据库与尺寸优化设计技术，探索了轻量化零件自支撑优化设计及二次轻量化设计方法，在实现零件轻量化设计的同时可以通过SLM技术加工无需支撑结构，以航天八爪框典型结构为对象，开展了基于SLM极限几何工艺约束的八爪框轻量化自支撑优化设计及成形性能分析。本项目提出的基于SLM技术的零件优化设计方法体系，可为推进SLM技术在薄壁结构零部件方面的深入应用提供理论及技术支撑。

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