We study the strength and texture of tantalum （Ta） under uniaxiM compression up to 80 GPa using an angle-dispersive radial x-ray diffraction technique together with the lattice strain theory in a diamond anvil cell ...We study the strength and texture of tantalum （Ta） under uniaxiM compression up to 80 GPa using an angle-dispersive radial x-ray diffraction technique together with the lattice strain theory in a diamond anvil cell at ambient temperature. The ratio of differential stress to shear modulus （t/G） is found to remain constant above -60GPa, indicating that the Ta starts to experience macro yield with plastic deformation at this pressure.Combined with independent constraints on the high-pressure shear modulus, we find that the Ta sample could support a differential stress of -4.67 GPa when it starts to yield with plastic deformation at -60 CPa under unlaxial compression. The differential stress in Ta ranges from 0.216 GPa to 4.67CPa with pressure increasing from 1 GPa to 60GPa and can be expressed as t=0.199（33）＋0.075（1）P, where P is the pressure in GPa. A maximum differential stress as high as -5.37 GPa can be supported by Ta at the high pressure of -80 GPa. In addition, we investigate the texture of Ta under nonhydrostatic compression to 80 GPa using the software package material analysis using diffraction. It is proven that the plastic deformation due to stress under high pressures is responsible for the development of texture.展开更多
The behaviour of marine risers is investigated under the forces produced by selfweight, wave and current and quasistatic motion of the top vessel. The parameters include the applied tension, geometric nonlinearity, ma...The behaviour of marine risers is investigated under the forces produced by selfweight, wave and current and quasistatic motion of the top vessel. The parameters include the applied tension, geometric nonlinearity, magnitude of surge, heave and pitch motion of the top vessel and wave height. The study shows that the above parameters have considerable influence on the riser response.展开更多
基金Supported by the National Natural Science Foundation of China under Grant Nos 10875142 and 11079040the Chinese Academy of Sciences under Grant Nos KJCX2-SW-N03 and KJCX2-SW-N20
文摘We study the strength and texture of tantalum （Ta） under uniaxiM compression up to 80 GPa using an angle-dispersive radial x-ray diffraction technique together with the lattice strain theory in a diamond anvil cell at ambient temperature. The ratio of differential stress to shear modulus （t/G） is found to remain constant above -60GPa, indicating that the Ta starts to experience macro yield with plastic deformation at this pressure.Combined with independent constraints on the high-pressure shear modulus, we find that the Ta sample could support a differential stress of -4.67 GPa when it starts to yield with plastic deformation at -60 CPa under unlaxial compression. The differential stress in Ta ranges from 0.216 GPa to 4.67CPa with pressure increasing from 1 GPa to 60GPa and can be expressed as t=0.199（33）＋0.075（1）P, where P is the pressure in GPa. A maximum differential stress as high as -5.37 GPa can be supported by Ta at the high pressure of -80 GPa. In addition, we investigate the texture of Ta under nonhydrostatic compression to 80 GPa using the software package material analysis using diffraction. It is proven that the plastic deformation due to stress under high pressures is responsible for the development of texture.
文摘The behaviour of marine risers is investigated under the forces produced by selfweight, wave and current and quasistatic motion of the top vessel. The parameters include the applied tension, geometric nonlinearity, magnitude of surge, heave and pitch motion of the top vessel and wave height. The study shows that the above parameters have considerable influence on the riser response.
