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

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.