光学玻璃的多尺度力学响应机理及表面质量主动控制磨削工艺基础研究

In order to solve the present problems on grinding process of optical glass, which are the multiple random factors, uncontrollable grinding quality, large crack damage depth and low grinding efficiency, it is presented a new surface quality controllable grinding method based on the "materials genes" characteristics of optical glass in this research. Firstly, the multi-scale mechanical response mechanisms of optical glass will be revealed focused on the amorphous space network structure characteristics. The origin and quiddity of optical glass's deformation and fracture will be illustrated. The hydrostatic pressure sensitive constitutive model with strain gradient effect will be established. The effect mechanisms of densification deformation on material removal behaviors will be researched. Secondly, a simulation will be carried on to calculated the stress field during the single grit scratching optical glass based on the new constitutive model. A critical energy model for crack propagation during single grit scratching optical glass will be developed. A new method to decrease the micro cracks damage depth will be proposed on the view of strain energy consumption. Finally, the vertical mapping relationships among microstructural evolution, continuum mechanical response, material removal behaviors and grinding surface generation of optical glass will be illustrated. The grinding quality controllable model of optical glass will be established. The brittle precision grinding cracks damage depth of optical glass will be decreased while the efficiency of the following ductile ultra-precision grinding will be increased. The achievements of the research have theoretical significance and practical application value for increasing the grinding quality and efficiency of optical glass.

为解决光学玻璃磨削过程中随机因素多，磨削质量控制被动，裂纹损伤深度大，磨削效率低的问题，本项目提出基于光学玻璃的非晶态“材料基因”特点，进行表面质量主动控制磨削的新方法。首先，针对光学玻璃的无定形态空间网状结构特点，揭示其多尺度力学响应机理。阐释光学玻璃非晶体变形及断裂的起源和本质；建立含应变梯度效应的静水压力敏感性本构模型，研究致密化变形对光学玻璃材料去除的影响机理。进而，基于新的本构模型对单颗磨粒划擦光学玻璃的应力场进行仿真，建立单颗磨粒划擦过程的裂纹失稳临界能量模型，从应变能耗散角度提出控制磨削微裂纹损伤深度的新方法。最后，揭示磨削过程中材料微观结构演变-连续介质力学响应-材料去除行为-磨削表面创成之间的映射关系，建立光学玻璃磨削质量的主动控制模型，对其进行低裂纹损伤脆性域精磨削和高效可控塑性域超精密磨削。本项目的研究成果对提高光学玻璃磨削加工的质量和效率具有重要的理论和应用价值。

为解决光学玻璃磨削过程中随机因素多，磨削质量控制被动，裂纹损伤深度大，磨削效率低的问题，本项目提出基于光学玻璃的非晶态微观结构特点，进行表面质量主动控制磨削的方法。主要研究内容包括：通过分子动力学仿真和纳米压痕实验，研究了光学玻璃的多尺度力学响应机理；从能量角度研究了单颗磨粒划擦光学玻璃的材料去除机理；建立了砂轮动态磨损过程的高效可控磨削模型。取得的主要研究成果包括：通过分子动力学仿真探究了光学玻璃非晶态变形和断裂的本质与起源，阐释了光学玻璃的微观结构参数（包括原子堆积密度、平均键能和网状结构三维化程度）与宏观力学性能（包括弹性模量、泊松比、硬度、致密化变形阻和剪切流动性能）之间的映射关系；建立了单颗磨粒划擦光学玻璃的裂纹失稳临界能量模型，通过优化磨削参数调控磨粒划擦应变能耗散机制，可以实现光学玻璃的塑性域磨削或者损伤可控脆性域磨削，使磨削力、表面粗糙度和亚表面损伤深度基本稳定在一个范围内；对砂轮动态磨损过程的三维地貌进行统计学参数提取，包括砂轮表面三维高度数据的平均值、方差、偏态、峰度和自相关长度等，分析了统计学参数随砂轮磨损的变化规律，利用数字滤波矩阵对动态磨损砂轮地貌进行了随机重构，基于此建立了砂轮磨损过程中磨削力、磨削温度场和磨削表面创成机理的数学模型，并通过磨削实验对模型进行验证，实现了光学玻璃的高效可控磨削。本项目按照项目任务书提出的研究计划开展研究，顺利完成项目计划书提出的研究目标。研究成果对提高光学玻璃磨削加工的质量和效率具有重要的理论和应用价值。