The dynamic fracture behaviors of Ti-6Al-4V alloy at high strain rate loading were investigated systemically through Taylor impact test, over the range of impact velocities from 145 m/s to 306 m/s. The critical impact...The dynamic fracture behaviors of Ti-6Al-4V alloy at high strain rate loading were investigated systemically through Taylor impact test, over the range of impact velocities from 145 m/s to 306 m/s. The critical impact velocity of fracture ranges from 217 m/s to 236 m/s. Smooth surfaces and ductile dimple areas were observed on the fracture surfaces. As the impact velocity reached 260 m/s, the serious melting regions were also observed on the fracture surfaces. Self-organization of cracks emerges when the impact velocity reaches 260 m/s, while some special cracks whose ＂tips＂ are not sharp but arc and smooth, and without any evidence of deformation or adiabatic shear band were also observed on the impact end surfaces. Examination of the sections of these special cracks reveals that the cracks expand along the two maximum shear stress directions respectively, and finally intersect as a tridimensional ＂stagger ridge＂ structure.展开更多
On the basis of analysis of the present roofbolter’s structures, the pneumatic vane motor roofbolter was proposed and researched. Structure principle of MFT 80Y type pneumatic vane motor roofbolter was expounded, a n...On the basis of analysis of the present roofbolter’s structures, the pneumatic vane motor roofbolter was proposed and researched. Structure principle of MFT 80Y type pneumatic vane motor roofbolter was expounded, a new project of the rotary shearing mechanism with integrating pneumatic vane motor with epicyclic reduction gear unit was carried out, the mathematical model for optimum design of the rotary shearing mechanism was set up, and the optimum design for the rotary shearing mechanism was made by MATLAB Optimization Toolbox. Finally, performance of MFT 80 type pneumatic vane motor roofbolter made with optimum method and the on site experiment were introduced.展开更多
基金Project (51001014) supported by the Young Scientists Fund of the National Natural Science Foundation of China
文摘The dynamic fracture behaviors of Ti-6Al-4V alloy at high strain rate loading were investigated systemically through Taylor impact test, over the range of impact velocities from 145 m/s to 306 m/s. The critical impact velocity of fracture ranges from 217 m/s to 236 m/s. Smooth surfaces and ductile dimple areas were observed on the fracture surfaces. As the impact velocity reached 260 m/s, the serious melting regions were also observed on the fracture surfaces. Self-organization of cracks emerges when the impact velocity reaches 260 m/s, while some special cracks whose ＂tips＂ are not sharp but arc and smooth, and without any evidence of deformation or adiabatic shear band were also observed on the impact end surfaces. Examination of the sections of these special cracks reveals that the cracks expand along the two maximum shear stress directions respectively, and finally intersect as a tridimensional ＂stagger ridge＂ structure.
文摘On the basis of analysis of the present roofbolter’s structures, the pneumatic vane motor roofbolter was proposed and researched. Structure principle of MFT 80Y type pneumatic vane motor roofbolter was expounded, a new project of the rotary shearing mechanism with integrating pneumatic vane motor with epicyclic reduction gear unit was carried out, the mathematical model for optimum design of the rotary shearing mechanism was set up, and the optimum design for the rotary shearing mechanism was made by MATLAB Optimization Toolbox. Finally, performance of MFT 80 type pneumatic vane motor roofbolter made with optimum method and the on site experiment were introduced.
