基于正交切削理论的熔石英高温本构参数的逆向识别

Reverse identification of high-temperature constitutive parameters of fused silica based on orthogonal cutting theory

激光辅助加工(laser-assisted machining, LAM)是一种新型的热机械加工技术,它为熔石英玻璃等硬脆材料的高效、低成本的优质加工提供了一种新的途径.但LAM工艺通常涉及大应变、大应变率和高温,这些变量在实验中是难以观测的.有限元切削模拟是预测切削过程切削机理的一种有效手段,而准确的材料本构模型是进行精确仿真的关键.为了获得更准确的模拟结果,本文提出了一种基于正交切削理论的材料本构关系的构建方法,以弥补熔石英本构模型的缺失.根据Oxley切削理论,建立了主剪切区应力、应变、应变率和温度等参数的场分布数学模型.搭建了正交切削实验平台,并根据实验结果计算出等效流动应力,然后通过遗传算法(genetic algorithm, GA)确定了熔石英的高温本构方程并应用于模拟中,最后通过实验验证了切削仿真模型.结果表明,仿真能较好地反映实际切削实验中的切削力和切屑形貌,这说明了本构参数的准确性和GA识别方法的可靠性.

Laser-assisted machining(LAM) is a new type of thermomechanical processing technology that provides high-efficiency, low-cost,and high-quality processing of fused silica and other hard, brittle materials. However, the LAM process usually involves large strains,large strain rates, and high temperatures, which are difficult to observe in experiments. Finite element cutting simulations are effective for predicting the cutting mechanism of the cutting process, but an accurate material constitutive equation must be used for an accurate simulation. To obtain more accurate simulation results, this paper proposes a method for constructing the constitutive relationship of materials based on orthogonal cutting theory to compensate for the lack of a constitutive model for fused silica.According to the Oxley cutting theory, a mathematical model of the field distribution of parameters, such as stress, strain, strain rate,and temperature, in the main shear zone was established. An orthogonal cutting test platform was established, and the equivalent flow stress was calculated according to the test results. Then, a high-temperature constitutive equation for fused silica was determined by the genetic algorithm(GA) and applied to the simulation. Finally, the cutting simulation model was verified by experiments. The results showed that the simulation can better reflect the cutting force and chip morphology during an actual cutting test, which confirms the accuracy of the constitutive parameters and the reliability of the GA identification method.