基于多尺度不确定性分析的增材制造点阵结构可靠性优化研究

As a new multifunctional material, the lattice multilevel structure by additive manufacturing is one of the future trends in advanced equipment research field. The development of high reliability and multi-functional equipment depend on the optimization design based on multi-scale reliability, that is to say, it requires stable mechanical properties. At present, people only rely on empirical methods to control uncertainty. Advanced design of numerical simulation based on a large number of basic manufacturing data and model libraries has just begun. How to optimize the reliability of manufacturable multilevel structures has become a hot academic problem. In this project, the lattice structure by additive manufacturing is taken as the research object. The variation transportation mechanism of macro-mechanical properties is developed based on the micro-uncertainties of material properties and geometric defects in actual manufactured products. The multi-scale mechanical properties and variation prediction methods from micro-RVEs to macro-structure are studied. The macro-micro concurrent optimization design method which meets the reliability requirements is studied to find a method to improve the efficiency of solving such probabilistic reliability optimization problems with a large number of design and random variables. The multi-scale uncertainty analysis and reliability optimization model are modified based on experimental research. This project provides theoretical and experimental basis for the practical application of lattice multi-level structure in augmented material manufacturing.

增材制造点阵多级结构作为一种新兴的多功能材料，已成为先进装备研究领域的前沿。开发高可靠性、多功能部件离不开基于多尺度可靠性的优化设计，即要求其具有稳定力学性能。目前，人们仅依靠经验方法来控制不确定性，面向基于大量制造基础数据和模型库的数值模拟先进设计才刚刚起步。如何优化多级结构可靠性已成为学术界新问题。本项目以增材制造点阵结构作为研究对象，基于实际增材制造点阵结构中的材料物性和几何缺陷形成统计数据库，研究微观不确定性带来的宏观力学性能误差传递机制，提出由微观单胞杆元、单胞至宏观结构的多尺度力学性能和误差预测方法。研究满足可靠性约束条件的宏微观协同优化设计方法。针对内含大量设计变量和随机变量的可靠性优化问题，研究提高求解效率的方法。并基于实验验证，发展仿真模型的修正方法。该研究成果可为增材制造点阵多级结构的实用化提供理论和实验依据。

增材制造点阵多级结构作为一种新兴的多功能材料，已成为先进装备研究领域的前沿。开发高可靠性、多功能部件离不开基于多尺度可靠性的优化设计，即要求其具有稳定力学性能。目前，人们仅依靠经验方法来控制不确定性，面向基于大量制造基础数据和模型库的数值模拟先进设计才刚刚起步。如何优化多级结构可靠性已成为学术界新问题。项目完成了几种负泊松比新型结构的设计、制备及力学性能实验，研究了基于桁架杆和曲面等多种拓扑构型的多尺度点阵结构，建立了多尺度结构设计参数和负泊松比性能、准静态压缩应力应变关系、冲击吸能等性能的构效关系，多级结构参数对抗冲击和吸能设计性能的影响规律。其次建立了以上复杂构型增材制造技术，并对制备后的样品利用μCT扫描进行缺陷评价，建立了基于x射线层析成像的材料重建模型，并将设计参数从固定变量改为随机变量，对仿真模型的可靠性分析，修正了数值仿真模型。最后进行了优化设计，采用多维梯度设计使点阵结构中低应变率下能量吸收效率提升了60%。实现了项目中提出的预定研究目标。