7075 aluminum alloy and Ti - 1300 titanium alloy fracture mechanism of adiabatic shear injury
|School||Central South University|
|Course||Materials Processing Engineering|
|Keywords||Shear zone Self-organization Gap Spallation Adiabatic shear sensitivity|
The collapse of the thick-walled cylinder experiments and finite element method to study the impact of different radius of curvature gap of more than 7075 of the shear zone self-organizing behavior . The results show that : the vast majority of the shear zone in the gap in the state-of-the-art nucleation and showed a spiral pattern clockwise ( or counterclockwise) , notched specimens shear zone than unnotched specimen in shear with a number of much smaller . Simulation and experimental results are basically the same. Notch tip stress concentration is obvious. Disturbance of the stress and strain of the shear zone in the notch tip first nucleation , and the larger area of the gap near the shielding effect . Sharp notch local equivalent strain is about an order of magnitude than the macro equivalent strain and the local equivalent strain . The gap is more acute , the stronger the shielding effect of the shear zone self-organizing behavior . Use of a light gas gun as a means of loading , loaded 7075 damage and spallation . Soft recovery 7075 sample metallographic and scanning electron microscopy (SEM) , the results showed that : 7075 aluminum alloy target reflected tensile wave plate impact experiments , the spall fracture mode to intergranular brittle fracture ; the fracture behavior of the penetration process is complex and includes several fracture mode dynamic fracture behavior . Projectile penetrating into 7075 aluminum alloy target process into three stages : the plugging stage inside the material crack initiation stage and the final tensile fracture stage , the fracture mode to intergranular brittle fracture and ductile fracture mode of the mixed fracture and brittle fracture from major role. The split Hopkinson pressure bar Ti - 1300 alloy cap -shaped specimen dynamic loading, the organizational structure of the Ti - 1300 alloy adiabatic shear behavior . in forced dynamic shear experiments , the the alpha beta lamellar structure and the p -phase structure of the sample are the shear zone. Organizational structure has a great influence on the Ti - 1300 alloy adiabatic shear behavior . The alpha beta lamellar structure of adiabatic shear critical strain is lower than the critical strain of the p -phase structure . The alpha beta sheet organization microscopic serious injury . Therefore , in the same strain rate , the alpha - beta lamellar structure of Ti - 1300 alloy phase structure than beta Ti - 1300 alloy adiabatic shear sensitivity .