A three-dimensional finite element simulation was carried out to investigate the effects of tunnel construction on nearby pile foundation.The displacement controlled model (DCM) was used to simulate the tunneling-indu...A three-dimensional finite element simulation was carried out to investigate the effects of tunnel construction on nearby pile foundation.The displacement controlled model (DCM) was used to simulate the tunneling-induced volume loss effects.The numerical model was verified based on the results of a centrifuge test and a set of parametric studies was implemented based on this model.There is good agreement between the trend of the results of the centrifuge test and the present model.The results of parametric studies show that the tunnelling-induced pile internal force and deformation depend mainly on the pile?tunnel distance,the pile length to tunnel depth ratio and the volume loss.Two different zones are separated by a 45° line projected from the tunnel springline.Within the zone of influence,the pile is subjected to tensile force and large settlement;whereas outside the zone of influence,dragload and small settlement are induced.It is also established that the impact of tunnelling on a pile group is substantially smaller as compared with a single pile in the same location with the rear pile in a group,demonstrating a positive pile group effect.展开更多
The interaction between pile and soft soil of the passive pile group subjected to soil movement was analyzed with three-dimensional finite element model by using ANSYS software. The soil was assumed to be elastic-plas...The interaction between pile and soft soil of the passive pile group subjected to soil movement was analyzed with three-dimensional finite element model by using ANSYS software. The soil was assumed to be elastic-plastic complying with the Drucker-Prager yield criterion in the analysis. The large displacement of soil was considered and contact elements were used to evaluate the interaction between pile and soil. The influences of soil depth of layer and number of piles on the lateral pressure of the pile were investigated, and the lateral pressure distributions on the (2×1) pile group and on the (2×2) pile group were compared. The results show that the adjacent surcharge may result in significant lateral movement of the soft soil and considerable pressure on the pile. The pressure acting on the row near the surcharge is higher than that on the other row, due to the "barrier" and arching effects in pile groups. The passive load and its distribution should be taken into account in the design of the passive piles.展开更多
Based on the principle of energy conservation,the applicable technique for drained cell retrofitted from conventional one was analyzed with 2D finite element model. The model employed a 1D heat transfer scheme to comp...Based on the principle of energy conservation,the applicable technique for drained cell retrofitted from conventional one was analyzed with 2D finite element model. The model employed a 1D heat transfer scheme to compute iteratively the freeze profile until the thickness variable reached the terminating requirement. The calculated 2D heat dissipation from the cell surfaces was converted into the overall 3D heat loss. The potential drop of the system, freeze profile and heat balance were analyzed to evaluate their variation with technical parameters when designing the 150 kA conventional cell based drained cell. The simulation results show that the retrofitted drained cell is able to keep thermal balance under the conditions that the current is 190 kA, the anodic current density is 0.96 A/cm2, the anode-cathode distance is 2.5 cm, the alumina cover is 16 cm thick with a thermal conductivity of 0.20 W/(m·℃ ) and the electrolysis temperature is 946 ℃ .展开更多
A nonlinear finite element model of the nut post reinforced concrete （RC） structure of the safety mechanism in the Three Gorges Project （TGP） ship lift was built by ANSYS software. Some irregular structures such a...A nonlinear finite element model of the nut post reinforced concrete （RC） structure of the safety mechanism in the Three Gorges Project （TGP） ship lift was built by ANSYS software. Some irregular structures such as the nut post and the rotary rod were divided by curved surface into a series of regular parts, and the structures were all meshed to hexahedron. Constraint equations were defined between two interfaces with different element sizes and mesh patterns. PRETS179 elements were used to simulate the preload in the tendons and the pre-stressed screws, and the loss of prestressing force was calculated. Five extreme load cases were analyzed. The stress of each part in the structure was obtained. The results indicate that the maximum compressive stress of concrete C35 is 24.13 MPa, so the concrete may be partially crushed; the maximum tensile stress of the grouting motar is 6.73 MPa, so the grouting motar may partially fracture; the maximum yon Mises stress of the rotary rod is 648.70 MPa, therefore the rotary rod may partially yield.展开更多
Due to the variation of the blade cross-section, the deformation stress and strain of the workpiece keep changing during the rolling process and the conventional rolling theory is no longer valid. The complexity and d...Due to the variation of the blade cross-section, the deformation stress and strain of the workpiece keep changing during the rolling process and the conventional rolling theory is no longer valid. The complexity and diversity of the blade cross-section determine it impossible to establish an universal theoretical model for the rolling process. Finite element analysis(FEA) provides a perspective solution to the prediction. The FEA software DEFORM was applied to discovering the deformation, stress, strain and velocity field of the variable cross-section workpiece, and the effects of friction coefficient and rolling speed during the rolling process. which indicates that the average rolling force at friction coefficient of 0.4 is 6.5% higher than that at 0.12, and the rolling velocity has less effect on the equivalent stress and strain distribution, which would confer instructive significance on the theoretical study as well as the engineering practice.展开更多
In order to study bearing characteristics of bridge pile at steep slope under complex loads in mountians, according to double pile-column bridge piers engineering at steep slope and test models in laboratory, finite e...In order to study bearing characteristics of bridge pile at steep slope under complex loads in mountians, according to double pile-column bridge piers engineering at steep slope and test models in laboratory, finite element analysis of pile-column bridge piers was carried out using software ADINA under different loadings, such as horizontal loading in the longitudinal direction along bridge, vertical loadings, slope top loadings and complex loadings. The numerical simulation results show that displacements of front pile pier top and back pile pier top are different under horizontal loadings in the longitudinal direction along bridge or vertical loadings, the displacements of front pile pier top are higher than those of back pile pier top, and its difference increases with the increase of loadings. Vertical displacements will also appear under slope top loadings, and displacements of front pier top are higher than those of back pier top too, while its difference reduces with the increase of loadings. Displacements of both front pile pier top and back pile pier top under comlex loading are larger than those under single loading.展开更多
The aim of this study is to address the issues associated with traditional magnetorheological fluid(MRF)dampers,such as insufficient damping force after power failure and susceptibility to settlement.In order to achie...The aim of this study is to address the issues associated with traditional magnetorheological fluid(MRF)dampers,such as insufficient damping force after power failure and susceptibility to settlement.In order to achieve this,a bidirectional adjustable MRF damper was designed and developed.Magnetic field simulation analysis was conducted on the damper,along with simulation analysis on its dynamic characteristics.The dynamic characteristics were ultimately validated through experimental testing on the material testing machine,thereby corroborating the theoretical simulation results.Concurrently,this process generated valuable test data for subsequent implementation of the semi-active vibration control system.The simulation and test results demonstrate that the integrated permanent magnet effectively accomplishes bidirectional regulation.The magnetic induction intensity of the damping channel is 0.2 T in the absence of current,increases to 0.5 T when a maximum forward current of 4 A is applied,and becomes 0 T when a maximum reverse current of 3.8 A is applied.When the excitation amplitude is 8 mm and the frequency is 2 Hz,with the applied currents varying,the maximum damping force reaches 8 kN,while the minimum damping force measures at 511 N.Additionally,at zero current,the damping force stands at 2 kN,which aligns closely with simulation results.The present paper can serve as a valuable reference for the design and research of semi-active MRF dampers.展开更多
Silicon wafers are the most widely used substrates for semiconductors. The falling price of silicon wafers has created tremendous pressure on silicon wafer manufacturers to develop cost-effective manufacturing process...Silicon wafers are the most widely used substrates for semiconductors. The falling price of silicon wafers has created tremendous pressure on silicon wafer manufacturers to develop cost-effective manufacturing processes. A critical issue in wafer production is the waviness induced by wire sawing. If this waviness is not removed, it will affect wafer flatness and semiconductor performance. In practice, both lapping and grinding have been used to flatten wire-sawn wafers. Although grinding is not as effective as lapping in removing waviness, it has many other advantages over lapping (such as higher throughput, fully automatic, and more benign to environment) and has great potential to reduce manufacturing cost of silicon wafers. This paper presents a finite element analysis (FEA) study on grinding and lapping of wire-sawn silicon wafers. An FEA model is first developed to simulate the waviness deformation of wire-sawn wafers in grinding and lapping processes. It is then used to explain how the waviness is removed or reduced by lapping and grinding and why the effectiveness of grinding in removing waviness is different from that of lapping. Furthermore, the model is used to study the effects of various parameters including active-grinding-zone orientation, grinding force, waviness wavelength, and waviness height on the reduction and elimination of waviness. Finally, the results of pilot experiments to verify the model are discussed.展开更多
The theoretical model of residual stress of ceramics grinding has been established applying thermal elastoplastic mechanics theory. While grinding at the course of grinding wheel moved along workpiece surface the dist...The theoretical model of residual stress of ceramics grinding has been established applying thermal elastoplastic mechanics theory. While grinding at the course of grinding wheel moved along workpiece surface the distributing regulation of residual stress can be simplified into thermal elastioplastic mechanical issue, under the action of the both moving centralized force and heat source. Calculating and evaluating of surface residual stress using current procedure of finite element analysis which has been reformed is successful. Comparing with X-ray diffraction experiment method, satisfactory precision has been acquired. The results of experiment show the changing regularity of residual stresses after grinding Al 2O 3 using diamond wheel, on condition that alter grinding parameters. The values of residual compress stress are taken place changing at key certain critical point on their figure as follow: When grinding depth a p is lower than 50 μm, the residual compress stresses are increased with grinding depth increasing, on the contrary as a p>50 μm. At V w<8 m/min, the residual compress stresses increased rapidly with feed speed of workpiece increasing, on the contrary at V w>8 m/min.When V s<25 m/s the residual stress increased with wheel speed increasing and keep stable in value at V s>25 m/s.According to grinding mechanism the cause of residual stress transform has been explained.展开更多
The FEM analysis of stress and deformation of steel base of the special diamond saw blades are carried out.The small carbide round segments are welded on the side of blades in order to increase the side wear re sistan...The FEM analysis of stress and deformation of steel base of the special diamond saw blades are carried out.The small carbide round segments are welded on the side of blades in order to increase the side wear re sistance of blade.Comparing with conventional saw blade,the maximum stress val ues of reasonable special saw blade are reduced respectively about 17%20% 33%,and the maximum deformation values are reduced respectively about 26%22 %44.7%in thetangential(X),radial(Y)and axial(Z)direction.The stress conce ntration zone is decreased for the special structure diamond saw blade.The stru ctures of diamond saw blade with different number of hard material pellet are an alyzed and optimized.展开更多
Precisely quantifying the strength of the proximal femur and accurately assessing hip fracture risk would enable those at high risk to be identified so that preventive interventions could be taken.Development of bette...Precisely quantifying the strength of the proximal femur and accurately assessing hip fracture risk would enable those at high risk to be identified so that preventive interventions could be taken.Development of better measures of femoral strength using the clinically展开更多
Articular cartilage is a layer of low-friction,load-bearing soft hydrated tissue covering bone-ends in diarthrosis,which plays an important role in spreading the load,reducing the joint contact stress,joint friction a...Articular cartilage is a layer of low-friction,load-bearing soft hydrated tissue covering bone-ends in diarthrosis,which plays an important role in spreading the load,reducing the joint contact stress,joint friction and wear during exercise.The vital mechanical function展开更多
The finite element analysis （FEA） software Ansys was employed to study the stress state of the dies of both plane and non-plane parting face structures with uniform interference and the die of plane parting face str...The finite element analysis （FEA） software Ansys was employed to study the stress state of the dies of both plane and non-plane parting face structures with uniform interference and the die of plane parting face structure with non-uniform interference. Considering the symmetry of the die, a half gear tooth model of the two-ring assembled die with 2.5 GPa inner pressure was constructed. Four paths were defined to investigate the stress state at the bottom comer of the die where stress concentration was serious. FEA results show that the change of parting face from non-plane to plane can greatly reduce the stress at the teeth tips of the die so that the tip fracture is avoided. The interference structure of the die is the most important influencing factor for the stress concentration at the bottom comer. When non-uniform interference is adopted the first principal stress at the comer on the defined paths of the die is much lower than that with uniform interference. The bottom hole radius is another important influencing factor for the comer stress concentration. The first principal stress at the comer of the plane parting face die with non-uniform interference is reduced from 2.3 to 1.9 GPa when the hole radius increases from 12.5 to 16.0 mm. The optimization of the die structure increases the life of the die from 100 to 6 000 hits.展开更多
A new finite element model for single-layered strand was investigated for accurate and efficient mechanical behavior analysis.Mathematical model was created by sectional path-nodes sweeping and dynamic node-beam mappi...A new finite element model for single-layered strand was investigated for accurate and efficient mechanical behavior analysis.Mathematical model was created by sectional path-nodes sweeping and dynamic node-beam mapping.Geometric relations between nodes in center core wire and helical wires were deduced in tension and bending incorporating material elasticity theory and deformation geometrical compatibility.Based on Timoshenko beam theory,strand of a pitch length was modeled with specific material,geometric parameters and synthesized constraint equations defined in ANSYS software,and predetermined load cases were performed.The obtained results show that discrepancies between suggested method and Costello theory do not exceed 1.51% in tension and 6.21% in bending,which verifies the correctness and accuracy of the suggested finite element model in predicting mechanical behavior of single-layered wire strand.展开更多
The finite element model is established according to the experimental results,and then the experimental results are verified by simulation calculation.In terms of the combination of finite element analysis and experim...The finite element model is established according to the experimental results,and then the experimental results are verified by simulation calculation.In terms of the combination of finite element analysis and experiment,the effect of particle size of CuO and SnO_(2) on the stress,strain and microstructure of AgCuOSnO_(2) composite during hot extrusion was studied.The results illustrate that with the decrease of particle size,the dispersion of the second phase increases gradually,while the possibility of“tail shrinkage”of the billet decreases continuously;cubic CuO will evolve to fibrosis,and the degree of fibrosis will increase with the decrease of the particle size and ring clusters.Specifically,the degree of fibrosis at the middle end of the billet is higher than that at the front end,the degree of fibrosis at the front end is higher than that at the back end,and the degree of fibrosis on the surface is higher than that in the core;part of CuO fibers will bend,and the degree of buckling strength is positively correlated with the size of particles and their annular clusters.Additionally,there is fiber CuO in the front and back end of the billet that are inconsistent with the extrusion direction,and the degree of difference was negatively correlated with the particle size.展开更多
Achieving the spin-exchange relaxation-free(SERF)state in atomic comagnetometers(ACMs)necessitates a stable and weak magnetic environment.This paper presents the design of a miniaturized permalloy magnetic shielding s...Achieving the spin-exchange relaxation-free(SERF)state in atomic comagnetometers(ACMs)necessitates a stable and weak magnetic environment.This paper presents the design of a miniaturized permalloy magnetic shielding spherical shell(MSSS)with minimal apertures,tailored to meet these requirements.By employing a combination of analytical solutions and finite element analysis(FEA),we achieved superior magnetic shielding while maintaining a compact form factor.The analytical solution for the shielding factor indicated that a four-layer permalloy sphere shell with optimized air gaps was necessary.A numerical analysis model of the MSSS was developed and validated using COMSOL software,confirming the suitability of the air gaps.The size,shape,and orientation of the openings in the perforated sphere shell were meticulously designed and optimized to minimize residual magnetism.The optimal structure was fabricated,resulting in triaxial shielding factors of 47619,52631,and 21739,meeting the anticipated requirements.A comparison of simulation results with experimental tests demonstrated the efficacy of the design methodology.This study has significant implications for ultrasensitive magnetic field detection devices requiring weak magnetic field environments,such as atomic gyroscopes,magnetometers,atomic interferometers,and atomic clocks.展开更多
A new structure design method of elastic composite cylindrical roller bearing is proposed, in which PTFE is embedded into a hollow cylindrical rolling element, according to the principle of creative combinations and t...A new structure design method of elastic composite cylindrical roller bearing is proposed, in which PTFE is embedded into a hollow cylindrical rolling element, according to the principle of creative combinations and through innovation research on cylindrical roller bearing structure. In order to systematically investigate the inner wall bending stress of the rolling element in elastic composite cylindrical roller bearing, finite element analysis on different elastic composite cylindrical rolling elements was conducted. The results show that, the bending stress of the elastic composite cylindrical rolling increases along with the increase of hollowness with the same filling material. The bending stress of the elastic composite cylindrical rolling element decreases along with the increase of the elasticity modulus of the material under the same physical dimension. Under the same load, on hollow cylindrical rolling element, the maximum bending tensile stress values of the elastic composite cylindrical rolling element after material filling at 0° and 180° are 8.2% and 9.5%, respectively, lower than those of the deep cavity hollow cylindrical rolling element. In addition, the maximum bending-compressive stress value at 90° is decreased by 6.1%.展开更多
In order to avoid the curing effects of paraffin on the transport process and reduce the transport difficulty,usually high temperature and high pressure are used in the transportation of oil and gas.The differences of...In order to avoid the curing effects of paraffin on the transport process and reduce the transport difficulty,usually high temperature and high pressure are used in the transportation of oil and gas.The differences of temperature and pressure cause additional stress along the pipeline,due to the constraint of the foundation soil,the additional stress can not release freely,when the additional stress is large enough to motivate the submarine pipelines buckle.In this work,the energy method is introduced to deduce the analytical solution which is suitable for the global buckling modes of idealized subsea pipeline and analyze the relationship between the critical buckling temperature,buckling length and amplitude under different high-order global lateral buckling modes.To obtain a consistent formulation of the problem,the principles of virtual displacements and the variation calculus for variable matching points are applied.The finite element method based on elasto-plastic theory is used to simulate the lateral global buckling of the pipelines under high temperature and pressure.The factors influencing the lateral buckling of pipelines are further studied.Based upon some actual engineering projects,the finite element results are compared with the analytical ones,and then the influence of thermal stress,the section rigidity of pipeline,the soil properties and the trigging force to the high order lateral buckling are discussed.The method of applying the small trigging force on pipeline is reliable in global buckling numerical analysis.In practice,increasing the section rigidity of a pipeline is an effective measure to improve the ability to resist the global buckling.展开更多
A finite element model was established for analyzing the geometric errors in turning operations and a two-step analyzing process was proposed. In the first analyzing step, the cutting force and the cutting heat for th...A finite element model was established for analyzing the geometric errors in turning operations and a two-step analyzing process was proposed. In the first analyzing step, the cutting force and the cutting heat for the cutting conditions were obtained using the AdvantEdge. Also, the deformation of a workpiece was estimated in the second step using the ANSYS. The deformation was analyzed for a 150 mm-long workpiece at three different measuring points, such as 10, 70 and 130 mm from a reference point, and the amounts of the deformation were compared through experiments. /n the results of the comparison and analysis, the values obtained from these comparison and analysis represent similar tendencies. Also, it is verified that their geometric errors increase with the increase in temperature. In addition, regarding the factors that affect the deformation of a workpiecc, it can be seen that the geometric error in the lathe is about 15%, the error caused by the cutting force is about 10%, and the deformation caused by the heat is about 75%.展开更多
This paper creates 3D solid model and assembly of U RJ 92-6 oil tank and analyses its strength by integrated CAD/CAE/CAM software I-D EAS. Through integrated simulation in computer, design efficiency and quality of oi...This paper creates 3D solid model and assembly of U RJ 92-6 oil tank and analyses its strength by integrated CAD/CAE/CAM software I-D EAS. Through integrated simulation in computer, design efficiency and quality of oil tank is greatly improved. Adopting integrated CAD/CAE/CAM software to carry out integrated research to equ ipment and products, we will be able to take overall analysis in aspects of 3-D solid modeling, pre-assembly and strength, etc., to realize non-paper designi ng and parallel designing. Problems can be found and settled during designing, w hich will increase designing efficiency and one-time success rate and realize o ptimum designing for products.展开更多
文摘A three-dimensional finite element simulation was carried out to investigate the effects of tunnel construction on nearby pile foundation.The displacement controlled model (DCM) was used to simulate the tunneling-induced volume loss effects.The numerical model was verified based on the results of a centrifuge test and a set of parametric studies was implemented based on this model.There is good agreement between the trend of the results of the centrifuge test and the present model.The results of parametric studies show that the tunnelling-induced pile internal force and deformation depend mainly on the pile?tunnel distance,the pile length to tunnel depth ratio and the volume loss.Two different zones are separated by a 45° line projected from the tunnel springline.Within the zone of influence,the pile is subjected to tensile force and large settlement;whereas outside the zone of influence,dragload and small settlement are induced.It is also established that the impact of tunnelling on a pile group is substantially smaller as compared with a single pile in the same location with the rear pile in a group,demonstrating a positive pile group effect.
基金Project(50378036) supported by the National Natural Science Foundation of China
文摘The interaction between pile and soft soil of the passive pile group subjected to soil movement was analyzed with three-dimensional finite element model by using ANSYS software. The soil was assumed to be elastic-plastic complying with the Drucker-Prager yield criterion in the analysis. The large displacement of soil was considered and contact elements were used to evaluate the interaction between pile and soil. The influences of soil depth of layer and number of piles on the lateral pressure of the pile were investigated, and the lateral pressure distributions on the (2×1) pile group and on the (2×2) pile group were compared. The results show that the adjacent surcharge may result in significant lateral movement of the soft soil and considerable pressure on the pile. The pressure acting on the row near the surcharge is higher than that on the other row, due to the "barrier" and arching effects in pile groups. The passive load and its distribution should be taken into account in the design of the passive piles.
基金Projects(50374081 60634020) supported by the National Natural Science Foundation of China
文摘Based on the principle of energy conservation,the applicable technique for drained cell retrofitted from conventional one was analyzed with 2D finite element model. The model employed a 1D heat transfer scheme to compute iteratively the freeze profile until the thickness variable reached the terminating requirement. The calculated 2D heat dissipation from the cell surfaces was converted into the overall 3D heat loss. The potential drop of the system, freeze profile and heat balance were analyzed to evaluate their variation with technical parameters when designing the 150 kA conventional cell based drained cell. The simulation results show that the retrofitted drained cell is able to keep thermal balance under the conditions that the current is 190 kA, the anodic current density is 0.96 A/cm2, the anode-cathode distance is 2.5 cm, the alumina cover is 16 cm thick with a thermal conductivity of 0.20 W/(m·℃ ) and the electrolysis temperature is 946 ℃ .
基金Project (SPKJ 016-06) supported by the Key Research Project of State Power CorporationProject (2004AC101D31) supported the Key Scientific Research Project of Hubei Province, China
文摘A nonlinear finite element model of the nut post reinforced concrete （RC） structure of the safety mechanism in the Three Gorges Project （TGP） ship lift was built by ANSYS software. Some irregular structures such as the nut post and the rotary rod were divided by curved surface into a series of regular parts, and the structures were all meshed to hexahedron. Constraint equations were defined between two interfaces with different element sizes and mesh patterns. PRETS179 elements were used to simulate the preload in the tendons and the pre-stressed screws, and the loss of prestressing force was calculated. Five extreme load cases were analyzed. The stress of each part in the structure was obtained. The results indicate that the maximum compressive stress of concrete C35 is 24.13 MPa, so the concrete may be partially crushed; the maximum tensile stress of the grouting motar is 6.73 MPa, so the grouting motar may partially fracture; the maximum yon Mises stress of the rotary rod is 648.70 MPa, therefore the rotary rod may partially yield.
基金Project(F12-256-1-00)supported by the Key Laboratory Program of Shenyang City,ChinaProject(N090403006)supported by the Seed Cultivation Fund,ChinaProject supported by the Research Innovation Fund for Young Teachers,China
文摘Due to the variation of the blade cross-section, the deformation stress and strain of the workpiece keep changing during the rolling process and the conventional rolling theory is no longer valid. The complexity and diversity of the blade cross-section determine it impossible to establish an universal theoretical model for the rolling process. Finite element analysis(FEA) provides a perspective solution to the prediction. The FEA software DEFORM was applied to discovering the deformation, stress, strain and velocity field of the variable cross-section workpiece, and the effects of friction coefficient and rolling speed during the rolling process. which indicates that the average rolling force at friction coefficient of 0.4 is 6.5% higher than that at 0.12, and the rolling velocity has less effect on the equivalent stress and strain distribution, which would confer instructive significance on the theoretical study as well as the engineering practice.
基金Projects(50878083,50578060)supported by the National Natural Science Foundation of ChinaProject(200831878531)supported by the Ministry of Transportation of China
文摘In order to study bearing characteristics of bridge pile at steep slope under complex loads in mountians, according to double pile-column bridge piers engineering at steep slope and test models in laboratory, finite element analysis of pile-column bridge piers was carried out using software ADINA under different loadings, such as horizontal loading in the longitudinal direction along bridge, vertical loadings, slope top loadings and complex loadings. The numerical simulation results show that displacements of front pile pier top and back pile pier top are different under horizontal loadings in the longitudinal direction along bridge or vertical loadings, the displacements of front pile pier top are higher than those of back pile pier top, and its difference increases with the increase of loadings. Vertical displacements will also appear under slope top loadings, and displacements of front pier top are higher than those of back pier top too, while its difference reduces with the increase of loadings. Displacements of both front pile pier top and back pile pier top under comlex loading are larger than those under single loading.
文摘The aim of this study is to address the issues associated with traditional magnetorheological fluid(MRF)dampers,such as insufficient damping force after power failure and susceptibility to settlement.In order to achieve this,a bidirectional adjustable MRF damper was designed and developed.Magnetic field simulation analysis was conducted on the damper,along with simulation analysis on its dynamic characteristics.The dynamic characteristics were ultimately validated through experimental testing on the material testing machine,thereby corroborating the theoretical simulation results.Concurrently,this process generated valuable test data for subsequent implementation of the semi-active vibration control system.The simulation and test results demonstrate that the integrated permanent magnet effectively accomplishes bidirectional regulation.The magnetic induction intensity of the damping channel is 0.2 T in the absence of current,increases to 0.5 T when a maximum forward current of 4 A is applied,and becomes 0 T when a maximum reverse current of 3.8 A is applied.When the excitation amplitude is 8 mm and the frequency is 2 Hz,with the applied currents varying,the maximum damping force reaches 8 kN,while the minimum damping force measures at 511 N.Additionally,at zero current,the damping force stands at 2 kN,which aligns closely with simulation results.The present paper can serve as a valuable reference for the design and research of semi-active MRF dampers.
文摘Silicon wafers are the most widely used substrates for semiconductors. The falling price of silicon wafers has created tremendous pressure on silicon wafer manufacturers to develop cost-effective manufacturing processes. A critical issue in wafer production is the waviness induced by wire sawing. If this waviness is not removed, it will affect wafer flatness and semiconductor performance. In practice, both lapping and grinding have been used to flatten wire-sawn wafers. Although grinding is not as effective as lapping in removing waviness, it has many other advantages over lapping (such as higher throughput, fully automatic, and more benign to environment) and has great potential to reduce manufacturing cost of silicon wafers. This paper presents a finite element analysis (FEA) study on grinding and lapping of wire-sawn silicon wafers. An FEA model is first developed to simulate the waviness deformation of wire-sawn wafers in grinding and lapping processes. It is then used to explain how the waviness is removed or reduced by lapping and grinding and why the effectiveness of grinding in removing waviness is different from that of lapping. Furthermore, the model is used to study the effects of various parameters including active-grinding-zone orientation, grinding force, waviness wavelength, and waviness height on the reduction and elimination of waviness. Finally, the results of pilot experiments to verify the model are discussed.
文摘The theoretical model of residual stress of ceramics grinding has been established applying thermal elastoplastic mechanics theory. While grinding at the course of grinding wheel moved along workpiece surface the distributing regulation of residual stress can be simplified into thermal elastioplastic mechanical issue, under the action of the both moving centralized force and heat source. Calculating and evaluating of surface residual stress using current procedure of finite element analysis which has been reformed is successful. Comparing with X-ray diffraction experiment method, satisfactory precision has been acquired. The results of experiment show the changing regularity of residual stresses after grinding Al 2O 3 using diamond wheel, on condition that alter grinding parameters. The values of residual compress stress are taken place changing at key certain critical point on their figure as follow: When grinding depth a p is lower than 50 μm, the residual compress stresses are increased with grinding depth increasing, on the contrary as a p>50 μm. At V w<8 m/min, the residual compress stresses increased rapidly with feed speed of workpiece increasing, on the contrary at V w>8 m/min.When V s<25 m/s the residual stress increased with wheel speed increasing and keep stable in value at V s>25 m/s.According to grinding mechanism the cause of residual stress transform has been explained.
文摘The FEM analysis of stress and deformation of steel base of the special diamond saw blades are carried out.The small carbide round segments are welded on the side of blades in order to increase the side wear re sistance of blade.Comparing with conventional saw blade,the maximum stress val ues of reasonable special saw blade are reduced respectively about 17%20% 33%,and the maximum deformation values are reduced respectively about 26%22 %44.7%in thetangential(X),radial(Y)and axial(Z)direction.The stress conce ntration zone is decreased for the special structure diamond saw blade.The stru ctures of diamond saw blade with different number of hard material pellet are an alyzed and optimized.
基金supported by The HongKong Polytechnic University Research Grants(No.1-BB81)grants from National Natural Science Foundation of China,Nos.10872078 and 10832012
文摘Precisely quantifying the strength of the proximal femur and accurately assessing hip fracture risk would enable those at high risk to be identified so that preventive interventions could be taken.Development of better measures of femoral strength using the clinically
基金National Natural Science Foundation of China,10872147Natural Science Foundation of Tianjin,09JCYBJC1400
文摘Articular cartilage is a layer of low-friction,load-bearing soft hydrated tissue covering bone-ends in diarthrosis,which plays an important role in spreading the load,reducing the joint contact stress,joint friction and wear during exercise.The vital mechanical function
基金Project(2006BAF04B06) supported by the National Key Technology R & D Program of ChinaProject(2005AA101B19) supported by the Key Technology R & D Program of Hubei Province, China
文摘The finite element analysis （FEA） software Ansys was employed to study the stress state of the dies of both plane and non-plane parting face structures with uniform interference and the die of plane parting face structure with non-uniform interference. Considering the symmetry of the die, a half gear tooth model of the two-ring assembled die with 2.5 GPa inner pressure was constructed. Four paths were defined to investigate the stress state at the bottom comer of the die where stress concentration was serious. FEA results show that the change of parting face from non-plane to plane can greatly reduce the stress at the teeth tips of the die so that the tip fracture is avoided. The interference structure of the die is the most important influencing factor for the stress concentration at the bottom comer. When non-uniform interference is adopted the first principal stress at the comer on the defined paths of the die is much lower than that with uniform interference. The bottom hole radius is another important influencing factor for the comer stress concentration. The first principal stress at the comer of the plane parting face die with non-uniform interference is reduced from 2.3 to 1.9 GPa when the hole radius increases from 12.5 to 16.0 mm. The optimization of the die structure increases the life of the die from 100 to 6 000 hits.
基金Project(2009J007)supported by Science and Technology Department of Railway Ministry of ChinaProject(U1134203)supported by Joint Fund of High-speed Railway Fundamental Research,China
文摘A new finite element model for single-layered strand was investigated for accurate and efficient mechanical behavior analysis.Mathematical model was created by sectional path-nodes sweeping and dynamic node-beam mapping.Geometric relations between nodes in center core wire and helical wires were deduced in tension and bending incorporating material elasticity theory and deformation geometrical compatibility.Based on Timoshenko beam theory,strand of a pitch length was modeled with specific material,geometric parameters and synthesized constraint equations defined in ANSYS software,and predetermined load cases were performed.The obtained results show that discrepancies between suggested method and Costello theory do not exceed 1.51% in tension and 6.21% in bending,which verifies the correctness and accuracy of the suggested finite element model in predicting mechanical behavior of single-layered wire strand.
基金Project(2017FA027)supported by the Key Project of Science and Technology of Yunnan Province,China。
文摘The finite element model is established according to the experimental results,and then the experimental results are verified by simulation calculation.In terms of the combination of finite element analysis and experiment,the effect of particle size of CuO and SnO_(2) on the stress,strain and microstructure of AgCuOSnO_(2) composite during hot extrusion was studied.The results illustrate that with the decrease of particle size,the dispersion of the second phase increases gradually,while the possibility of“tail shrinkage”of the billet decreases continuously;cubic CuO will evolve to fibrosis,and the degree of fibrosis will increase with the decrease of the particle size and ring clusters.Specifically,the degree of fibrosis at the middle end of the billet is higher than that at the front end,the degree of fibrosis at the front end is higher than that at the back end,and the degree of fibrosis on the surface is higher than that in the core;part of CuO fibers will bend,and the degree of buckling strength is positively correlated with the size of particles and their annular clusters.Additionally,there is fiber CuO in the front and back end of the billet that are inconsistent with the extrusion direction,and the degree of difference was negatively correlated with the particle size.
基金supported by Hefei National Laboratory,Innovation Program for Quantum Science and Technology(Grant Nos.2021ZD0300500 and 2021ZD0300503).
文摘Achieving the spin-exchange relaxation-free(SERF)state in atomic comagnetometers(ACMs)necessitates a stable and weak magnetic environment.This paper presents the design of a miniaturized permalloy magnetic shielding spherical shell(MSSS)with minimal apertures,tailored to meet these requirements.By employing a combination of analytical solutions and finite element analysis(FEA),we achieved superior magnetic shielding while maintaining a compact form factor.The analytical solution for the shielding factor indicated that a four-layer permalloy sphere shell with optimized air gaps was necessary.A numerical analysis model of the MSSS was developed and validated using COMSOL software,confirming the suitability of the air gaps.The size,shape,and orientation of the openings in the perforated sphere shell were meticulously designed and optimized to minimize residual magnetism.The optimal structure was fabricated,resulting in triaxial shielding factors of 47619,52631,and 21739,meeting the anticipated requirements.A comparison of simulation results with experimental tests demonstrated the efficacy of the design methodology.This study has significant implications for ultrasensitive magnetic field detection devices requiring weak magnetic field environments,such as atomic gyroscopes,magnetometers,atomic interferometers,and atomic clocks.
基金Project(51175168)supported by the National Natural Science Foundation of ChinaProjects(2011GK3148,2012GK3092)supported by Science and Technology Program of Hunan Province,China
文摘A new structure design method of elastic composite cylindrical roller bearing is proposed, in which PTFE is embedded into a hollow cylindrical rolling element, according to the principle of creative combinations and through innovation research on cylindrical roller bearing structure. In order to systematically investigate the inner wall bending stress of the rolling element in elastic composite cylindrical roller bearing, finite element analysis on different elastic composite cylindrical rolling elements was conducted. The results show that, the bending stress of the elastic composite cylindrical rolling increases along with the increase of hollowness with the same filling material. The bending stress of the elastic composite cylindrical rolling element decreases along with the increase of the elasticity modulus of the material under the same physical dimension. Under the same load, on hollow cylindrical rolling element, the maximum bending tensile stress values of the elastic composite cylindrical rolling element after material filling at 0° and 180° are 8.2% and 9.5%, respectively, lower than those of the deep cavity hollow cylindrical rolling element. In addition, the maximum bending-compressive stress value at 90° is decreased by 6.1%.
基金Project(51021004)supported by Innovative Research Groups of the National Natural Science Foundation of ChinaProject(NCET-11-0370)supported by Program for New Century Excellent Talents in Universities of China+1 种基金Project(40776055)supported by the National Natural Science Foundation of ChinaProject(1002)supported by State Key Laboratory of Ocean Engineering Foundation,China
文摘In order to avoid the curing effects of paraffin on the transport process and reduce the transport difficulty,usually high temperature and high pressure are used in the transportation of oil and gas.The differences of temperature and pressure cause additional stress along the pipeline,due to the constraint of the foundation soil,the additional stress can not release freely,when the additional stress is large enough to motivate the submarine pipelines buckle.In this work,the energy method is introduced to deduce the analytical solution which is suitable for the global buckling modes of idealized subsea pipeline and analyze the relationship between the critical buckling temperature,buckling length and amplitude under different high-order global lateral buckling modes.To obtain a consistent formulation of the problem,the principles of virtual displacements and the variation calculus for variable matching points are applied.The finite element method based on elasto-plastic theory is used to simulate the lateral global buckling of the pipelines under high temperature and pressure.The factors influencing the lateral buckling of pipelines are further studied.Based upon some actual engineering projects,the finite element results are compared with the analytical ones,and then the influence of thermal stress,the section rigidity of pipeline,the soil properties and the trigging force to the high order lateral buckling are discussed.The method of applying the small trigging force on pipeline is reliable in global buckling numerical analysis.In practice,increasing the section rigidity of a pipeline is an effective measure to improve the ability to resist the global buckling.
基金Project(RTI04-01-03) supported by the Regional Technology Innovation Program of the Ministry of Knowledge Economy (MKE),Korea
文摘A finite element model was established for analyzing the geometric errors in turning operations and a two-step analyzing process was proposed. In the first analyzing step, the cutting force and the cutting heat for the cutting conditions were obtained using the AdvantEdge. Also, the deformation of a workpiece was estimated in the second step using the ANSYS. The deformation was analyzed for a 150 mm-long workpiece at three different measuring points, such as 10, 70 and 130 mm from a reference point, and the amounts of the deformation were compared through experiments. /n the results of the comparison and analysis, the values obtained from these comparison and analysis represent similar tendencies. Also, it is verified that their geometric errors increase with the increase in temperature. In addition, regarding the factors that affect the deformation of a workpiecc, it can be seen that the geometric error in the lathe is about 15%, the error caused by the cutting force is about 10%, and the deformation caused by the heat is about 75%.
文摘This paper creates 3D solid model and assembly of U RJ 92-6 oil tank and analyses its strength by integrated CAD/CAE/CAM software I-D EAS. Through integrated simulation in computer, design efficiency and quality of oil tank is greatly improved. Adopting integrated CAD/CAE/CAM software to carry out integrated research to equ ipment and products, we will be able to take overall analysis in aspects of 3-D solid modeling, pre-assembly and strength, etc., to realize non-paper designi ng and parallel designing. Problems can be found and settled during designing, w hich will increase designing efficiency and one-time success rate and realize o ptimum designing for products.
