基于多尺度缺陷表征的超精密加工亚表层损伤机理研究

Ultra-precision machining technology is widely used in the fields of military, aerospace and computer with its extremely high processing precision. While the sub-surface damage caused by processing affects the enhancement of ultra-precision machining accuracy and surface performance seriously, and restricts the biggest performance of weapon equipments and high precision instruments. This project is aimed at studying the multi-scale damage mechanism of sub-surface layer and the suppression strategy of sub-surface damage, which is directed against the lack of advanced defect recognition technology and characterizing the cross-scale transfer of defects inaccurately in the study of sub-surface damage in ultra-precision machining. On the basis of the identification of complex defects in sub-surface layer, the cross-scale transfer mechanism of dislocation defects is discussed, and the multi-scale defect characterization is realized. The distribution of residual stress in sub-surface layer, the influence of process parameters on the thickness of damage layer, and the influence of subsurface damage on the surface mechanics performance are analyzed comprehensively. The multi-scale mathematical model of appraising sub-surface quality is constructed, and the multi-scale damage mechanism of ultra-precision machining sub-surface was revealed. The parameter control method of ultra-precision machining technology is studied, and the technological strategy of suppressing sub-surface damage formation is optimized. The research achievements of the project provide the theoretical basis for optimizing the ultra-precision machining technology, enhancing the precision of ultra-precision machining, and improving the surface performance of the ultra-precision machining. Thus the results have great significance for enhancing the performance of the national defense weapon equipments and the high precision instruments.

超精密加工技术以其极高的加工精度被广泛应用于军事、航天、计算机领域，而加工引起的亚表层损伤严重影响超精密加工精度及零件表面性能的提升，制约武器装备和高精密仪器仪表性能的最大发挥。针对超精密加工亚表层损伤的研究中存在缺乏先进的缺陷识别技术、无法准确表征缺陷的跨尺度传递等问题，本项目以研究亚表层多尺度损伤机理和探索亚表层损伤的抑制策略为目标，在对亚表层复杂缺陷识别的基础上，探讨位错缺陷的跨尺度传递机制，实现多尺度缺陷表征；综合分析亚表层残余应力的分布、工艺参数对损伤层厚度的影响、亚表层损伤对材料表面力学性能影响，构建评价亚表层质量的多尺度数学模型，揭示超精密加工亚表层多尺度损伤机理；研究超精密加工工艺的参数化控制方法，优化抑制亚表层损伤形成的工艺策略。项目研究成果为优化超精密加工工艺、提高超精密加工精度、改善超精密加工表面性能提供理论依据，进而对提升国防武器装备及高精密仪器的性能具有重要意义。

随着超精密加工技术的发展，其应用从军事、航天领域扩展到计算机、半导体、光学精密仪器等民用领域。而加工中引起的亚表层损伤严重影响零件的表面质量及力学性能，制约着武器装备及高精度仪器仪表的使用性能及寿命。因此研究超精密加工中材料亚表层损伤机理、探索抑制亚表层损伤形成的工艺优化策略具有重要意义。.目前针对超精密加工亚表层损伤机理的研究主要采用分子动力学方法，而该方法存在仿真规模小、模拟时间尺度小、与实验尺度不匹配、获得的损伤层厚度不准确等局限性，限制了MD方法在超精密加工中的进一步应用。多尺度方法可以提升模拟尺度，但无法将原子尺度产生的缺陷传递到连续介质区域，不能有效表征亚表层损伤过程。离散位错动力学能够将位错缺陷进行分解及受力分析，并通过引入镜像力实现位错缺陷在跨尺度界面的传递。.本项目以晶体铜为研究对象，首先基于构建的晶体铜超精密加工多尺度模型，采用球谐函数法及共近邻分析实现对亚表层复杂缺陷的识别，并深入研究各类缺陷的形成机理。然后采用离散位错动力学实现对位错缺陷跨尺度传递的表征，深入研究亚表层缺陷的跨尺度传递机制。最后基于残余应力、损伤层厚度及表面力学性能分析，提出亚表层质量评价的数学模型，揭示超精密加工亚表层多尺度损伤机理；并在此基础上深入研究工艺参数对亚表层损伤的影响规律，提出基于加工工艺参数化控制的亚表层损伤抑制策略。研究中拟采用超精密加工实验对模拟结果进行针对性验证。经过本项目研究，目前已实现了对超精密加工亚表层损伤的多尺度识别表征，通过对亚表层缺陷的分析研究，探讨了超精密加工亚表层多尺度损伤机理。经过超精密加工仿真和实验分析，本研究提出了亚表层质量评价的数学模型，并经过分析研究提出了抑制亚表层损伤的工艺优化策略。另外，借助本项目研究成果，目前共发表学术论文4篇，其中二区SCI论文2篇，EI论文2篇，共参加相关学术会议2次，共培养研究生2名，总体完成了项目规定的相关指标。