Research on Breakage Characteristics in Side Milling of Titanium Alloy with C emented Carbide End Mill

Aiming at the breakage of tool and low precision of the machined surface in the high-speed milling process of titanium alloy, damage mechanics is used to reveal the formation mechanism of tool fatigue breakage during the milling and determine the critical condition of tool breakage. Cutting edge chipping caused by random impact fracture during the evolution of tool damage is the main failure form of tool fatigue breakage. Based on continuous damage mechanics, fatigue crack growth theory and sliding crack energy balance equation, the crack growth law of tool material is studied under different cutting impact, and the initial damage value and critical damage value of tool material fracture based on the interval method are obtained. And the impact fracture limit conditions of the end mill edge are established including cutting parameters, material hardness, tool damage, tool wear, and cutting impact, which provide a theoretical basis for determining the cutting parameters. A titanium alloy milling experiment is carried out to define the impact damage morphology of the tool in different states after the tool is damaged. The obtained tool safety area range is verified, and the research results provide parameter optimization for the high-speed and high-efficiency milling titanium alloy process.

Impact Fracture and Fragmentation of Glass via the 3D Combined Finite-Discrete Element Method

A driving technical concern for the automobile industry is their assurance that developed windshield products meet Federal safety standards. Besides conducting innumerable glass breakage experiments, product developers also have the option of utilizing numerical approaches that can provide further insight into glass impact breakage, fracture, and fragmentation. The combined finite-discrete element method (FDEM) is one such tool and was used in this study to investigate 3D impact glass fracture processes. To enable this analysis, a generalized traction-separation model, which defines the constitutive relationship between the traction and separation in FDEM cohesive zone models, was introduced. The mechanical responses of a laminated glass and a glass plate under impact were then analyzed. For laminated glass, an impact fracture process was investigated and results were compared against corresponding experiments. Correspondingly, two glass plate impact fracture patterns, i.e., concentric fractures and radial fractures, were simulated. The results show that for both cases, FDEM simulated fracture processes and fracture patterns are in good agreement with the experimental observations. The work demonstrates that FDEM is an effective tool for modeling of fracture and fragmentation in glass.