It is of great practical importance to analyze the shakedown of shell structures under cyclic loading, especially of those made of strain hardening materials.In this paper, same further understanding of the shakedown ...It is of great practical importance to analyze the shakedown of shell structures under cyclic loading, especially of those made of strain hardening materials.In this paper, same further understanding of the shakedown theorem for kinematic hardening materials has been made, and it is applied to analyze the shakedown of shell structures Though the residual stress of a real stale is related to plastic strain, the time-independent residual stress field as we will show in the theorem may be unrelated to the time-independent kinematically admissible plastic strain field For the engineering application, it will lie much more convenient to point this out clearly and definitely, otherwise it will be very difficult. Also, we have proposed a new method of proving this theorem.The above theorem is applied to the shakedown analysis of a cylindrical shell with hemispherical ends. According to the elastic solution, various possible residual sfcss and plastic strain Jlelds, the shakedown analysis of the structure can be reduced to a mathematical programming problem.The results of calculation show that the shakedown load oj strain hardening materials is about 30-40% higher than that of ideal plastic materials. So it is very important to consider the hardening of materials in the shakedown analysis,for it can greatly increase the structure design capacity, and meanwhile provide ascicntific basis to improve the design of shell structures.展开更多
This study focuses on a 60 V trench MOSFET device designed for operation in space radiation environments.By increasing the bulk region concentration and placing the etched gate trench after the P+implantation process,...This study focuses on a 60 V trench MOSFET device designed for operation in space radiation environments.By increasing the bulk region concentration and placing the etched gate trench after the P+implantation process,we successfully reduced the threshold voltage shift from 6.5 to 2.2 V under a total dose of 400 krad(Si)^(60)Co,allowing the device to operate normally.Structurally,by embedding the source metal in the active and terminal regions,the device demonstrated current degradation without experiencing single-event burnout when subjected to a drain voltage of 60 V and a linear energy transfer value of 75.4 MeV·cm^(2)∕mg from tantalum-ion incidence.TCAD simulations verified that the embedded source metal effectively suppressed parasitic transistor conduction and eliminated the base-region expansion effect,thereby lowering the maximum temperature from 8000 to 1400 K.The irradiation effects of the embedded source metal in the terminal region were also investigated,which can improve the reverse recovery and ensure that the terminal metal does not melt prematurely,thereby significantly enhancing the radiation hardness of the device.展开更多
文摘It is of great practical importance to analyze the shakedown of shell structures under cyclic loading, especially of those made of strain hardening materials.In this paper, same further understanding of the shakedown theorem for kinematic hardening materials has been made, and it is applied to analyze the shakedown of shell structures Though the residual stress of a real stale is related to plastic strain, the time-independent residual stress field as we will show in the theorem may be unrelated to the time-independent kinematically admissible plastic strain field For the engineering application, it will lie much more convenient to point this out clearly and definitely, otherwise it will be very difficult. Also, we have proposed a new method of proving this theorem.The above theorem is applied to the shakedown analysis of a cylindrical shell with hemispherical ends. According to the elastic solution, various possible residual sfcss and plastic strain Jlelds, the shakedown analysis of the structure can be reduced to a mathematical programming problem.The results of calculation show that the shakedown load oj strain hardening materials is about 30-40% higher than that of ideal plastic materials. So it is very important to consider the hardening of materials in the shakedown analysis,for it can greatly increase the structure design capacity, and meanwhile provide ascicntific basis to improve the design of shell structures.
基金supported in part by National R&D Program for Major Research Instruments of China(No.62027814)。
文摘This study focuses on a 60 V trench MOSFET device designed for operation in space radiation environments.By increasing the bulk region concentration and placing the etched gate trench after the P+implantation process,we successfully reduced the threshold voltage shift from 6.5 to 2.2 V under a total dose of 400 krad(Si)^(60)Co,allowing the device to operate normally.Structurally,by embedding the source metal in the active and terminal regions,the device demonstrated current degradation without experiencing single-event burnout when subjected to a drain voltage of 60 V and a linear energy transfer value of 75.4 MeV·cm^(2)∕mg from tantalum-ion incidence.TCAD simulations verified that the embedded source metal effectively suppressed parasitic transistor conduction and eliminated the base-region expansion effect,thereby lowering the maximum temperature from 8000 to 1400 K.The irradiation effects of the embedded source metal in the terminal region were also investigated,which can improve the reverse recovery and ensure that the terminal metal does not melt prematurely,thereby significantly enhancing the radiation hardness of the device.
