When heavy machines and large scaled receiver system of communication equipment are manufactured, it always needs to produce large-sized steel castings, aluminum castings and etc. Some defects of hot cracking by therm...When heavy machines and large scaled receiver system of communication equipment are manufactured, it always needs to produce large-sized steel castings, aluminum castings and etc. Some defects of hot cracking by thermal stress often appear during solidification process as these castings are produced, which results in failure of castings. Therefore predicting the effects of technological parameters for production of castings on the thermal stress during solidification process becomes an important means. In this paper, the mathematical models have been established and numerical calculation of temperature fields by using finite difference method (FDM) and then thermal stress fields by using finite element method (FEM) during solidification process of castings have been carried out. The technological parameters of production have been optimized by the results of calculation and the defects of hot cracking have been eliminated. Modeling and simulation of 3D thermal stress during solidification processes of large-sized castings provided a scientific basis, which promoted further development of advanced manufacturing technique.展开更多
To decrease thermal stress during laser metal deposition shaping(LMDS)process,it is of great importance to learn the transient thermal stress distribution regularities.Based on the“element life and death”technique o...To decrease thermal stress during laser metal deposition shaping(LMDS)process,it is of great importance to learn the transient thermal stress distribution regularities.Based on the“element life and death”technique of finite element analy- sis(FEA),a three-dimensional multi-track and multi-layer numerical simulation model for LMDS is developed with ANSYS parametric design language(APDL)for the first time,in which long-edge parallel reciprocating scanning paths is introduced. Through the model,detailed simulations of thermal stress during whole metal cladding process are conducted,the generation and distribution regularities of thermal stress are also discussed in detail.Using the same process parameters,the simulation results show good agreement with the features of samples which fabricated by LMDS.展开更多
The physical model of temperature field and thermal stress field are established in this paper, on which the numerical simulation with the assuming physical and laser milling parameters have been finished. The laser m...The physical model of temperature field and thermal stress field are established in this paper, on which the numerical simulation with the assuming physical and laser milling parameters have been finished. The laser milling process can be explained.展开更多
A system for the numerical simulation of 3D temperature and stress fields during casting process was studied, developed and practiced based on finite difference method (FDM) in this paper. An approach where the stress...A system for the numerical simulation of 3D temperature and stress fields during casting process was studied, developed and practiced based on finite difference method (FDM) in this paper. An approach where the stress/strain and the heat transfer analysis use the same computational domain was presented, which avoided transferring temperature data between FDM and FEM nodes and elements. A slot-board steel casting was simulated and the calculated results are in agreements with those obtained from practical producing.展开更多
The professional modeling software package CrysVUn was employed to study the process of a large sapphire single crystal growth using Kyropoulos method. The influence of gas pressure on thermal field, solid-liquid inte...The professional modeling software package CrysVUn was employed to study the process of a large sapphire single crystal growth using Kyropoulos method. The influence of gas pressure on thermal field, solid-liquid interface shape, gas velocity field and von Mises stress were studied for the first time. It is found that the root of the seed melt when gas pressure equals to one atmosphere or more than one atmosphere, especially during the seeding period, this result is consistent with the experimental observation, and this paper presents three ways to solve this problem. The temperature gradient and stress decreases significantly as the gas pressure increases. The convexity of the solid-liquid interface slightly increases when the gas pressure increases. Numerical analysis was used to optimize the hot zone design.展开更多
The Shangzhuang altered-rock type gold ore deposit is located in the middle segment of and controlled by the Wang'ershan fault zone in the northwestern part of the Jiaodong gold province, China. The deformation evolu...The Shangzhuang altered-rock type gold ore deposit is located in the middle segment of and controlled by the Wang'ershan fault zone in the northwestern part of the Jiaodong gold province, China. The deformation evolution, the structure of strain and stress fields and its ore-controlling effect in the Shangzhuang deposit are discussed in this paper. It is revealed that the deformation evolution has mainly undergone four phases: the early ductile deformation, the second NE-striking horizontal simple shear, the third NE-striking compression-shear and the final NW-striking compression. The mineralization happened during the third stage in which the maximum principal stress gradually transited from NE to NW. The 3-D numerical simulations of the stress field show that, on the condition that the maximum principal stress is NE-striking, the fracture development in the fault zone is favored, while when the maximum principal stress is NW-striking, the fault zone is relatively extensional and it is suitable for the influx and emplacement of ore-forming fluids. The compression-shear strain field during the mineralization is characterized by the λ-type structure, the positive flower structure, etc. Orebodies are mostly equidistantly located in the dilatational spaces, which are distributed in the integral compressional circumstances. And the dilatational spaces are developed where the fault attitude changes or shear joint systems develop. In the overall compression-shear stress field, the strain field bears self-similarity at multiple scales, including the orebody, ore deposit and orefield. The selfsimilarity of the structure comprises the subequidistant distribution of fractures at the same scale and the similar shape of the fractures at various scales. Yet, due to the special geological structure, the orebodies are mostly located in the hanging wall in the Shangzhuang deposit, which is different from most deposits in the Jiaodong gold province. Analyses of the ore-controlling stress and strain fields in the deposit provide an important basis for deposit seeking.展开更多
A numerical method is presented that simulates 3D explosive field problems. A code MMIC3D using this method can be used to simulate the propagation and reflected effects of all kinds of rigid boundaries to shock waves...A numerical method is presented that simulates 3D explosive field problems. A code MMIC3D using this method can be used to simulate the propagation and reflected effects of all kinds of rigid boundaries to shock waves produced by an explosive source. These numerical results indicate that the code MMIC3D has the ability in computing cases such as 3D shock waves produced by air explosion, vortex region of the shock wave, the Mach wave, and reflected waves behind rigid boundaries.展开更多
The heat flow in crust and the thermal stress generated by the flow play a very important role in earthquake occurrence. Different crustal structure has different effect on heat distribution and associated thermal str...The heat flow in crust and the thermal stress generated by the flow play a very important role in earthquake occurrence. Different crustal structure has different effect on heat distribution and associated thermal stress. In all of typical seismogenic crustal structure models, including the bulge of Moho surface, the deep-large fault in the mid-lower crust, low-velocity and high-conductive layer in the middle crust, and the typical crustal structure in mid-upper crust, the thermal stress produced by deep heat disturbance may move up to the mid-upper crest. This leads to upper brittle part of crust break and hence, strong earthquakes. This result is constructive in enhancing our understanding of the role of deep fieat flow in curst in development of earthquake and its generation, as well as the generation mechanism of the shallow flowing fluid.展开更多
Based on the 2D horizontal plane numerical model, a quasi-3D numerical model is established for coastal regions of shallow water. The characteristics of this model are that the velocity profiles;can be obtained at the...Based on the 2D horizontal plane numerical model, a quasi-3D numerical model is established for coastal regions of shallow water. The characteristics of this model are that the velocity profiles;can be obtained at the same time when the equations of the value of difference between the horizontal current velocity and its depth-averaged velocity in the vertical direction are solved and the results obtained are consistent with the results of the 2D, model. The circulating flow in the rectangular area induced by wind is simulated and applied to the tidal flow field of the radial sandbanks in the South Yellow Sea. The computational results from this quasi-3D model are in good agreement with analytical results and observed data. The solution of the finite difference equations has been found to be stable, and the model is simple, effective and practical.展开更多
DSS data of the last twenty years and more in the northern part of North China are further interpreted, and combined with other geological and geophysical data, the crustal model for the 3 D finite element method is ...DSS data of the last twenty years and more in the northern part of North China are further interpreted, and combined with other geological and geophysical data, the crustal model for the 3 D finite element method is built after straticulate crustal structure and elastic mechanics parameters are obtained. Referring to regional tectonic stress field and taking the effect of gravity into account, the paper constrains properly the model boundary and then computes the displacement of each nodal point and the strain and stress of each element by using the program from the 3 D linear elastic finite method. The relationship between the distribution feature of the crustal stress field and seismicity is discussed on the basis of analyzing contour maps of maximum principal compressive stress in the upper, middle and lower crusts.展开更多
The quantitative characterization of the full-field stress and displacement is significant for analyzing the failure and instability of engineering materials.Various optical measurement techniques such as photoelastic...The quantitative characterization of the full-field stress and displacement is significant for analyzing the failure and instability of engineering materials.Various optical measurement techniques such as photoelasticity,moiréand digital image correlation methods have been developed to achieve this goal.However,these methods are difficult to incorporate to determine the stress and displacement fields simultaneously because the tested models must contain particles and grating for displacement measurement;however,these elements will disturb the light passing through the tested models using photoelasticity.In this study,by combining photoelasticity and the sampling moirémethod,we developed a method to determine the stress and displacement fields simultaneously in a three-dimensional(3D)-printed photoelastic model with orthogonal grating.Then,the full-field stress was determined by analyzing 10 photoelastic patterns,and the displacement fields were calculated using the sampling moirémethod.The results indicate that the developed method can simultaneously determine the stress and displacement fields.展开更多
Based on data of fault movement surveying, we simulate the evolution process of three dimensional stress field in North China by three dimensional finite element method. Evolutional patterns in one-year time scale fro...Based on data of fault movement surveying, we simulate the evolution process of three dimensional stress field in North China by three dimensional finite element method. Evolutional patterns in one-year time scale from 1986 to 1997 have been illustrated and the evolution characteristics of stress field have been analyzed. In comparison with the seismic activity among that time interval in North China, we have primarily discussed the relationship between the evolution of stress field and seismic activity.展开更多
In the initial phase of the physics experiment, the double-null divertor plates used consist of graphite armor tiles, Mo-alloy intermediate layers and Cu-alloy coolant tubes. In the later operating phase, tungsten wil...In the initial phase of the physics experiment, the double-null divertor plates used consist of graphite armor tiles, Mo-alloy intermediate layers and Cu-alloy coolant tubes. In the later operating phase, tungsten will be used as armor tiles. A multi-physical field numerical analysis method is used in this paper. Its analysis model reflects more realistically the real divertor structure than other models. Two-dimensional (2D) and three-dimensional (3D) fluid flow field, temperature distribution and thermal stress analyses of the divertor plates are carried out by the ANSYS code. During the physics experimental phase with a heat flux of 1 MW/m2, a coolant velocity of 5.48 m/s, and a thermal stress of 750 kg/cm2, the graphite armor tiles successfully meet the requirements of temperature, thermal stress and sputtering erosion. The tungsten armor will be considered as a second candidate. The result of simulation can be used for upgrading the design parameters of the HL-2A poloidal divertor.展开更多
The paper proposes a simulated 3D Finite Element Model(FEM)for drilling of Nickel based super alloy known as Nimonic C-263.The Lagrangian finite element model-based simulations were performed to determine the thrust f...The paper proposes a simulated 3D Finite Element Model(FEM)for drilling of Nickel based super alloy known as Nimonic C-263.The Lagrangian finite element model-based simulations were performed to determine the thrust force,temperature generation,effective stress,and effective strain.The simulations were performed according to the L27 orthogonal array.A perfect plastic work piece was assumed,and the shape is considered to be cylindrical.The spindle speed,feed rate,and point angle were considered as the input parameters.The work piece was modeled by Johnson-Cook(JC)material model and tungsten carbide(WC)was chosen as the drill bit and the body was assumed to be rigid.The demonstrative results of the thrust force and the temperature at drill bit cutting edge were substantiated with the simulated results and a percentage error was observed within 10%.Further,simulated results of effective stress and strain were also observed.展开更多
The analysis of the impulse voltage on the internal electric field of the cable joint plays a key role in studying the breakdown of the joint. Based on the finite element method, a three-dimensional electromagnetic fi...The analysis of the impulse voltage on the internal electric field of the cable joint plays a key role in studying the breakdown of the joint. Based on the finite element method, a three-dimensional electromagnetic field simulation model of the cable joint is established in this paper. Simulation results show that the voltage at the head of the cable joint reaches about twice the impulse voltage. The increase of the conductivity of semi-conductive material also leads to the increase of electric field intensity. Then, several points and curves at different positions are selected for further analysis in this paper. Among them, the electric field distortion at the edge of the high voltage shield is the most serious and the electric field in the air gap is the least.展开更多
In this paper, we investigate the performance of the bulk fin field effect transistor (FinFET) through a three- dimensional (3D) full band Monte Carlo simulator with quantum correction. Several scattering mechanis...In this paper, we investigate the performance of the bulk fin field effect transistor (FinFET) through a three- dimensional (3D) full band Monte Carlo simulator with quantum correction. Several scattering mechanisms, such as the acoustic and optical phonon scattering, the ionized impurity scattering, the impact ionization scattering and the surface roughness scattering are considered in our simulator. The effects of the substrate bias and the surface roughness scattering near the Si/SiO2 interface on the performance of bulk FinFET are mainly discussed in our work. Our results show that the on-current of bulk FinFET is sensitive to the surface roughness and that we can reduce the substrate leakage current by modulating the substrate bias voltage.展开更多
文摘When heavy machines and large scaled receiver system of communication equipment are manufactured, it always needs to produce large-sized steel castings, aluminum castings and etc. Some defects of hot cracking by thermal stress often appear during solidification process as these castings are produced, which results in failure of castings. Therefore predicting the effects of technological parameters for production of castings on the thermal stress during solidification process becomes an important means. In this paper, the mathematical models have been established and numerical calculation of temperature fields by using finite difference method (FDM) and then thermal stress fields by using finite element method (FEM) during solidification process of castings have been carried out. The technological parameters of production have been optimized by the results of calculation and the defects of hot cracking have been eliminated. Modeling and simulation of 3D thermal stress during solidification processes of large-sized castings provided a scientific basis, which promoted further development of advanced manufacturing technique.
文摘To decrease thermal stress during laser metal deposition shaping(LMDS)process,it is of great importance to learn the transient thermal stress distribution regularities.Based on the“element life and death”technique of finite element analy- sis(FEA),a three-dimensional multi-track and multi-layer numerical simulation model for LMDS is developed with ANSYS parametric design language(APDL)for the first time,in which long-edge parallel reciprocating scanning paths is introduced. Through the model,detailed simulations of thermal stress during whole metal cladding process are conducted,the generation and distribution regularities of thermal stress are also discussed in detail.Using the same process parameters,the simulation results show good agreement with the features of samples which fabricated by LMDS.
文摘The physical model of temperature field and thermal stress field are established in this paper, on which the numerical simulation with the assuming physical and laser milling parameters have been finished. The laser milling process can be explained.
文摘A system for the numerical simulation of 3D temperature and stress fields during casting process was studied, developed and practiced based on finite difference method (FDM) in this paper. An approach where the stress/strain and the heat transfer analysis use the same computational domain was presented, which avoided transferring temperature data between FDM and FEM nodes and elements. A slot-board steel casting was simulated and the calculated results are in agreements with those obtained from practical producing.
文摘The professional modeling software package CrysVUn was employed to study the process of a large sapphire single crystal growth using Kyropoulos method. The influence of gas pressure on thermal field, solid-liquid interface shape, gas velocity field and von Mises stress were studied for the first time. It is found that the root of the seed melt when gas pressure equals to one atmosphere or more than one atmosphere, especially during the seeding period, this result is consistent with the experimental observation, and this paper presents three ways to solve this problem. The temperature gradient and stress decreases significantly as the gas pressure increases. The convexity of the solid-liquid interface slightly increases when the gas pressure increases. Numerical analysis was used to optimize the hot zone design.
基金This paper is supported by the National Natural Science Foundation of China (Grant Nos. 40572063 and 40272051);the Fostering Plan Fund for Trans-Century Excellent Talents and the Project 111 (No. B07011).
文摘The Shangzhuang altered-rock type gold ore deposit is located in the middle segment of and controlled by the Wang'ershan fault zone in the northwestern part of the Jiaodong gold province, China. The deformation evolution, the structure of strain and stress fields and its ore-controlling effect in the Shangzhuang deposit are discussed in this paper. It is revealed that the deformation evolution has mainly undergone four phases: the early ductile deformation, the second NE-striking horizontal simple shear, the third NE-striking compression-shear and the final NW-striking compression. The mineralization happened during the third stage in which the maximum principal stress gradually transited from NE to NW. The 3-D numerical simulations of the stress field show that, on the condition that the maximum principal stress is NE-striking, the fracture development in the fault zone is favored, while when the maximum principal stress is NW-striking, the fault zone is relatively extensional and it is suitable for the influx and emplacement of ore-forming fluids. The compression-shear strain field during the mineralization is characterized by the λ-type structure, the positive flower structure, etc. Orebodies are mostly equidistantly located in the dilatational spaces, which are distributed in the integral compressional circumstances. And the dilatational spaces are developed where the fault attitude changes or shear joint systems develop. In the overall compression-shear stress field, the strain field bears self-similarity at multiple scales, including the orebody, ore deposit and orefield. The selfsimilarity of the structure comprises the subequidistant distribution of fractures at the same scale and the similar shape of the fractures at various scales. Yet, due to the special geological structure, the orebodies are mostly located in the hanging wall in the Shangzhuang deposit, which is different from most deposits in the Jiaodong gold province. Analyses of the ore-controlling stress and strain fields in the deposit provide an important basis for deposit seeking.
文摘A numerical method is presented that simulates 3D explosive field problems. A code MMIC3D using this method can be used to simulate the propagation and reflected effects of all kinds of rigid boundaries to shock waves produced by an explosive source. These numerical results indicate that the code MMIC3D has the ability in computing cases such as 3D shock waves produced by air explosion, vortex region of the shock wave, the Mach wave, and reflected waves behind rigid boundaries.
基金National Eleventh Five-year Science and Technology Development Foundation (2006BAC01B02-03-01).
文摘The heat flow in crust and the thermal stress generated by the flow play a very important role in earthquake occurrence. Different crustal structure has different effect on heat distribution and associated thermal stress. In all of typical seismogenic crustal structure models, including the bulge of Moho surface, the deep-large fault in the mid-lower crust, low-velocity and high-conductive layer in the middle crust, and the typical crustal structure in mid-upper crust, the thermal stress produced by deep heat disturbance may move up to the mid-upper crest. This leads to upper brittle part of crust break and hence, strong earthquakes. This result is constructive in enhancing our understanding of the role of deep fieat flow in curst in development of earthquake and its generation, as well as the generation mechanism of the shallow flowing fluid.
基金National Natural Science Foundation of China(Grant No.49236120)
文摘Based on the 2D horizontal plane numerical model, a quasi-3D numerical model is established for coastal regions of shallow water. The characteristics of this model are that the velocity profiles;can be obtained at the same time when the equations of the value of difference between the horizontal current velocity and its depth-averaged velocity in the vertical direction are solved and the results obtained are consistent with the results of the 2D, model. The circulating flow in the rectangular area induced by wind is simulated and applied to the tidal flow field of the radial sandbanks in the South Yellow Sea. The computational results from this quasi-3D model are in good agreement with analytical results and observed data. The solution of the finite difference equations has been found to be stable, and the model is simple, effective and practical.
文摘DSS data of the last twenty years and more in the northern part of North China are further interpreted, and combined with other geological and geophysical data, the crustal model for the 3 D finite element method is built after straticulate crustal structure and elastic mechanics parameters are obtained. Referring to regional tectonic stress field and taking the effect of gravity into account, the paper constrains properly the model boundary and then computes the displacement of each nodal point and the strain and stress of each element by using the program from the 3 D linear elastic finite method. The relationship between the distribution feature of the crustal stress field and seismicity is discussed on the basis of analyzing contour maps of maximum principal compressive stress in the upper, middle and lower crusts.
基金financial support from the National Natural Science Foundation of China(Nos.52004137,52121003,51727807,12032013 and 11972209)Fundamental Research Funds for the Central Universities(No.2022XJAQ01)。
文摘The quantitative characterization of the full-field stress and displacement is significant for analyzing the failure and instability of engineering materials.Various optical measurement techniques such as photoelasticity,moiréand digital image correlation methods have been developed to achieve this goal.However,these methods are difficult to incorporate to determine the stress and displacement fields simultaneously because the tested models must contain particles and grating for displacement measurement;however,these elements will disturb the light passing through the tested models using photoelasticity.In this study,by combining photoelasticity and the sampling moirémethod,we developed a method to determine the stress and displacement fields simultaneously in a three-dimensional(3D)-printed photoelastic model with orthogonal grating.Then,the full-field stress was determined by analyzing 10 photoelastic patterns,and the displacement fields were calculated using the sampling moirémethod.The results indicate that the developed method can simultaneously determine the stress and displacement fields.
基金State Natural Science Foundation of China (49574223)Key Project (95-04-04-03-01) from China Seismological Bureau under (Nint
文摘Based on data of fault movement surveying, we simulate the evolution process of three dimensional stress field in North China by three dimensional finite element method. Evolutional patterns in one-year time scale from 1986 to 1997 have been illustrated and the evolution characteristics of stress field have been analyzed. In comparison with the seismic activity among that time interval in North China, we have primarily discussed the relationship between the evolution of stress field and seismic activity.
文摘In the initial phase of the physics experiment, the double-null divertor plates used consist of graphite armor tiles, Mo-alloy intermediate layers and Cu-alloy coolant tubes. In the later operating phase, tungsten will be used as armor tiles. A multi-physical field numerical analysis method is used in this paper. Its analysis model reflects more realistically the real divertor structure than other models. Two-dimensional (2D) and three-dimensional (3D) fluid flow field, temperature distribution and thermal stress analyses of the divertor plates are carried out by the ANSYS code. During the physics experimental phase with a heat flux of 1 MW/m2, a coolant velocity of 5.48 m/s, and a thermal stress of 750 kg/cm2, the graphite armor tiles successfully meet the requirements of temperature, thermal stress and sputtering erosion. The tungsten armor will be considered as a second candidate. The result of simulation can be used for upgrading the design parameters of the HL-2A poloidal divertor.
文摘The paper proposes a simulated 3D Finite Element Model(FEM)for drilling of Nickel based super alloy known as Nimonic C-263.The Lagrangian finite element model-based simulations were performed to determine the thrust force,temperature generation,effective stress,and effective strain.The simulations were performed according to the L27 orthogonal array.A perfect plastic work piece was assumed,and the shape is considered to be cylindrical.The spindle speed,feed rate,and point angle were considered as the input parameters.The work piece was modeled by Johnson-Cook(JC)material model and tungsten carbide(WC)was chosen as the drill bit and the body was assumed to be rigid.The demonstrative results of the thrust force and the temperature at drill bit cutting edge were substantiated with the simulated results and a percentage error was observed within 10%.Further,simulated results of effective stress and strain were also observed.
文摘The analysis of the impulse voltage on the internal electric field of the cable joint plays a key role in studying the breakdown of the joint. Based on the finite element method, a three-dimensional electromagnetic field simulation model of the cable joint is established in this paper. Simulation results show that the voltage at the head of the cable joint reaches about twice the impulse voltage. The increase of the conductivity of semi-conductive material also leads to the increase of electric field intensity. Then, several points and curves at different positions are selected for further analysis in this paper. Among them, the electric field distortion at the edge of the high voltage shield is the most serious and the electric field in the air gap is the least.
基金Project supported by the National Basic Research Program of China (Grant No. 2011CBA00604)
文摘In this paper, we investigate the performance of the bulk fin field effect transistor (FinFET) through a three- dimensional (3D) full band Monte Carlo simulator with quantum correction. Several scattering mechanisms, such as the acoustic and optical phonon scattering, the ionized impurity scattering, the impact ionization scattering and the surface roughness scattering are considered in our simulator. The effects of the substrate bias and the surface roughness scattering near the Si/SiO2 interface on the performance of bulk FinFET are mainly discussed in our work. Our results show that the on-current of bulk FinFET is sensitive to the surface roughness and that we can reduce the substrate leakage current by modulating the substrate bias voltage.