Mixed mode Ⅰ/Ⅱ fracture erperiments of LC4-CS aluminum alloy were conductedby using tension--shear specimens with thicknesses of 2, 4, 8 and 14mm. Fracturemechanisms of thickness effect on mixed mode Ⅰ/Ⅱ fracture ...Mixed mode Ⅰ/Ⅱ fracture erperiments of LC4-CS aluminum alloy were conductedby using tension--shear specimens with thicknesses of 2, 4, 8 and 14mm. Fracturemechanisms of thickness effect on mixed mode Ⅰ/Ⅱ fracture were first examined fromfracture surface morphology to correlate with the macroscopic fracture behavior andstress state. It is found that specimen thickness has a strong influence on mixed modefracture. As thickness varies from thin to thick the macroscopic fracture surfacesappear the characteristics of plane stress state (2mm, 4mm--thick specimen), three--dimensional stress state (8mm--thick specimens), and plane strain state (14mm--thickspecimens), respectively. The specimens of all kinds of thicknesses are typical of ten-sile type failure under mode Ⅰ loading condition and shear type failure under mode Ⅱloading condition. Two distinct features coexist on the fracture surfaces under mixedmode loading conditions, and the corresponding proportion varies with loading mix-ity. Void--growth processes are the failure mechanism in both predominately tensile-and shears--type fractures. The size and depth of dimples on the fracture surface varygreatly with thickness. Therefore, it is extraordinary necessary to take into accountthe thickness effect when a mixed mode fracture criterion is being established.展开更多
This paper presents a mixed grade magnet model for surface-inset machines considering the magnet thickness. In the polar coordinates, on the basis of the Laplace/quasi-Poisson equations and boundary conditions, the co...This paper presents a mixed grade magnet model for surface-inset machines considering the magnet thickness. In the polar coordinates, on the basis of the Laplace/quasi-Poisson equations and boundary conditions, the constructed matrix equations are solved and the air gap magnetic field in the machine is derived. Taking an 8-pole/12-slot surface-inset motor as an example, through the presented optimization process, the air gap field is optimized considering the magnet thickness, remanence and magnetization angle. In addition, the back-EMF and electromagnetic torque are analytically obtained. The optimized results show that the proposed mixed grade magnet model has larger electromagnetic torque and smaller torque ripple than the conventional one. Finally, the analytical predictions are evaluated by finite element analysis(FEA).展开更多
A theoretical model for mixed lubrication with more accurate contact length has been developed based on the average volume flow model and asperity flattening model,and the lubricant volume flow rate and outlet speed r...A theoretical model for mixed lubrication with more accurate contact length has been developed based on the average volume flow model and asperity flattening model,and the lubricant volume flow rate and outlet speed ratio are determined by integrating differential equations based on rolling parameters.The lubrication characteristics at the roll-strip interface with different surface roughness,rolling speed,reduction and lubricant viscosity are analyzed respectively.Additionally,the average volume flow rates of lubricant under different rolling conditions are calculated and used to explain the change rule of lubrication characteristics.The developed scheme is able to determine the total pressure,lubricant pressure,film thickness and real contact area at any point within the work zone.The prediction and analysis of mixed lubrication characteristics at the interface is meaningful to better control the surface quality and optimize the rolling process.展开更多
We investigated the effects of monsoon onset vortex(MOV)on the mixed layer heat budget in the Bay of Bengal(BOB)in spring 2003 using the reanalysis datasets.The results suggest that the solar radiation flux penetratin...We investigated the effects of monsoon onset vortex(MOV)on the mixed layer heat budget in the Bay of Bengal(BOB)in spring 2003 using the reanalysis datasets.The results suggest that the solar radiation flux penetrating the mixed layer and the existence of barrier layer are both able to modulate the effects of MOV on the evolution of sea surface temperature(SST)in the BOB.Prior to the formation of BOB MOV,the local SST raised quickly due to mass of solar radiation reaching the sea surface under the clear-sky condition.Meanwhile,since the mixed layer was shallow before the onset of the Asian summer monsoon(ASM),some solar radiation flux could penetrate to directly heat the deeper water,which partly offset the warming effect of shortwave radiation.On the other hand,the in-situ SST started to cool due to the upwelling of cold water when the MOV generated over the BOB,along with the rapidly increased surface wind speed and its resultant deeper mixed layer.As the MOV developed and moved northward,the SST tended to decrease remarkably because of the strong upward surface latent heat flux over the BOB ascribed to the wind-evaporation mechanism.However,the MOV-related precipitation brought more fresh water into the upper ocean to produce a thicker barrier layer,whose thermal barrier effect damped the cooling effect of entrainment upwelling on the decrease tendency of the BOB SST.In other words,the thermal barrier effect could slow down the decreasing trend of the BOB SST even after the onset of ASM,which facilitated the further enhancement of the MOV.展开更多
By using “the method of modified two-variable”,“the method of mixing perturbation” and introducing four small parameters,the problem of the nonlinear unsymmetrical bending for orthotropic rectangular thin plate wi...By using “the method of modified two-variable”,“the method of mixing perturbation” and introducing four small parameters,the problem of the nonlinear unsymmetrical bending for orthotropic rectangular thin plate with linear variable thickness is studied.And the uniformly valid asymptotic solution of Nth-order for ε_1 and Mth-order for ε_2 of the deflection functions and stress function are obtained.展开更多
The radial multiple jets-in-crossflow mixing structure(RMJCMS) is extensively used in industrial manufacture. In this research, the effects of thickness of injection ring on mixing performance and factors influencing ...The radial multiple jets-in-crossflow mixing structure(RMJCMS) is extensively used in industrial manufacture. In this research, the effects of thickness of injection ring on mixing performance and factors influencing the mixing performance of RMJCMS were discussed based on the results of computational fluid dynamics. The simulation results showed that the dimensionless mixing distance, with the increase of the thickness of injection ring, drops from 1.1 to 0.18 first and then increases to 0.27 while the uniformity of flux monotonously improves, manifesting that the consistency of flux is not the single element determining the mixing performance. Analyzing the simulation results, a conclusion was drawn that the consistency of flux, penetration mode and interaction among injection flows which can be altered by adjusting the thickness of injection ring, determine the mixing performance of RMJCMS jointly. That is to say, in RMJCMS an injection ring with a suitable thickness can realize the function of injection and rectification simultaneously, which not only improves the mixing performance but also reduces the complexity of RMJCMS as well.展开更多
With the benefit fierce competition in the steel industry market in recent years,double cold reduction products have been developed towards strength improvement and thickness reduction.The traditional cold-rolling lub...With the benefit fierce competition in the steel industry market in recent years,double cold reduction products have been developed towards strength improvement and thickness reduction.The traditional cold-rolling lubrication process with a fixed flow rate and concentration cannot solve the problems,which are uncontrollable plate shape and the excessive consumption of lubricating oil.Moreover,based on the analysis of the traditional direct aplication lubrication system of double cold reduction mill,a set of design scheme suitable for the emulsion pipeline direct mixing lubrication system of double cold reduction mill unit was proposed.The design completed the selection of key components,which included the static mixer and atomization nozzle selection,pump and oil pump design selection,pipeline design selection,flow type selection,pressure gauge selection,electronic control cabinet design selection and other eight aspects.Equipment of the emulsion pipeline direct mixing lubrication system of double cold reduction has been developed.Comparing with characteristics of the traditional direct aplication lubrication system,the emulsion pipeline direct mixing lubrication system was better applied to the production practice of a 1220 double cold reduction mill.The consumption of ton of steel was reduced by 9.6%.The rolling energy consumption and fuel consumption comprehensive costs decreased by 10.7%,and the strip steel section thickness difference was reduced by 19.3%.In addition,the plate shape quality defect rate decreased by 25.6%,otherwise creating a large economic benefit for the unit and promoting the application value.展开更多
A high-performance concrete （HPC） is required to have superior performance in various aspects such as workability,strength, durability, dimensional stability, segregation stability, and passing ability. The mix desi...A high-performance concrete （HPC） is required to have superior performance in various aspects such as workability,strength, durability, dimensional stability, segregation stability, and passing ability. The mix design of HPC is rather complicatedbecause the number of ingredients in HPC is usually more than those in conventional concrete and some of the required propertiesare conflicting with each other in the sense that improvement in one property would at the same time cause impairment of anotherproperty. However, there is still lack of understanding regarding how the various mix parameters should be optimised forachieving best overall performance. Most practitioners are still conducting mix design primarily through trial concrete mixing,which is laborious, ineffective, and often unable to timely respond to fluctuations in the properties of raw materials. To addressthese issues, the authors have been developing the packing and film thickness theories of concrete materials, in order to revamp themix design philosophy of HPC in terms of the water film thickness （WFT）, paste film thickness （PFT）, and mortar film thickness（MFT） in the concrete. Based on the findings from an extensive experimental programme, suitable ranges ofWFT, PFT, and MFThave been recommended.展开更多
文摘Mixed mode Ⅰ/Ⅱ fracture erperiments of LC4-CS aluminum alloy were conductedby using tension--shear specimens with thicknesses of 2, 4, 8 and 14mm. Fracturemechanisms of thickness effect on mixed mode Ⅰ/Ⅱ fracture were first examined fromfracture surface morphology to correlate with the macroscopic fracture behavior andstress state. It is found that specimen thickness has a strong influence on mixed modefracture. As thickness varies from thin to thick the macroscopic fracture surfacesappear the characteristics of plane stress state (2mm, 4mm--thick specimen), three--dimensional stress state (8mm--thick specimens), and plane strain state (14mm--thickspecimens), respectively. The specimens of all kinds of thicknesses are typical of ten-sile type failure under mode Ⅰ loading condition and shear type failure under mode Ⅱloading condition. Two distinct features coexist on the fracture surfaces under mixedmode loading conditions, and the corresponding proportion varies with loading mix-ity. Void--growth processes are the failure mechanism in both predominately tensile-and shears--type fractures. The size and depth of dimples on the fracture surface varygreatly with thickness. Therefore, it is extraordinary necessary to take into accountthe thickness effect when a mixed mode fracture criterion is being established.
基金supported by the Anhui Provincial Natural Science Foundation under Grant 2008085ME179Anhui Province Key Laboratory of Renewable Energy Utilization and Energy Savingthe 111 Project under Grant BP0719039。
文摘This paper presents a mixed grade magnet model for surface-inset machines considering the magnet thickness. In the polar coordinates, on the basis of the Laplace/quasi-Poisson equations and boundary conditions, the constructed matrix equations are solved and the air gap magnetic field in the machine is derived. Taking an 8-pole/12-slot surface-inset motor as an example, through the presented optimization process, the air gap field is optimized considering the magnet thickness, remanence and magnetization angle. In addition, the back-EMF and electromagnetic torque are analytically obtained. The optimized results show that the proposed mixed grade magnet model has larger electromagnetic torque and smaller torque ripple than the conventional one. Finally, the analytical predictions are evaluated by finite element analysis(FEA).
基金Project(2012BAF09B04)supported by the National Key Technology Research and Development Program of China
文摘A theoretical model for mixed lubrication with more accurate contact length has been developed based on the average volume flow model and asperity flattening model,and the lubricant volume flow rate and outlet speed ratio are determined by integrating differential equations based on rolling parameters.The lubrication characteristics at the roll-strip interface with different surface roughness,rolling speed,reduction and lubricant viscosity are analyzed respectively.Additionally,the average volume flow rates of lubricant under different rolling conditions are calculated and used to explain the change rule of lubrication characteristics.The developed scheme is able to determine the total pressure,lubricant pressure,film thickness and real contact area at any point within the work zone.The prediction and analysis of mixed lubrication characteristics at the interface is meaningful to better control the surface quality and optimize the rolling process.
基金Supported by the Strategic Priority Research Program of Chinese Academy of Sciences(No.XDA20060502)the Key Special Project for Introduced Talents Team of Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou)(No.GML2019ZD0306)+4 种基金the National Natural Science Foundation of China(Nos.41776023,41731173,41521005,41676013,41775052,41506003)the Rising Star Foundation of the South China Sea Institute of Oceanology(No.NHXX2018WL0201)the Innovation Academy of South China Sea Ecology and Environmental Engineering,Chinese Academy of Sciences(No.ISEE2018PY06)the Independent Research Project Program of State Key Laboratory of Tropical Oceanography(No.LTOZZ1802)the Basic Scientifi c Research and Operation Foundation of the CAMS(Nos.2018Z006,2017R001)。
文摘We investigated the effects of monsoon onset vortex(MOV)on the mixed layer heat budget in the Bay of Bengal(BOB)in spring 2003 using the reanalysis datasets.The results suggest that the solar radiation flux penetrating the mixed layer and the existence of barrier layer are both able to modulate the effects of MOV on the evolution of sea surface temperature(SST)in the BOB.Prior to the formation of BOB MOV,the local SST raised quickly due to mass of solar radiation reaching the sea surface under the clear-sky condition.Meanwhile,since the mixed layer was shallow before the onset of the Asian summer monsoon(ASM),some solar radiation flux could penetrate to directly heat the deeper water,which partly offset the warming effect of shortwave radiation.On the other hand,the in-situ SST started to cool due to the upwelling of cold water when the MOV generated over the BOB,along with the rapidly increased surface wind speed and its resultant deeper mixed layer.As the MOV developed and moved northward,the SST tended to decrease remarkably because of the strong upward surface latent heat flux over the BOB ascribed to the wind-evaporation mechanism.However,the MOV-related precipitation brought more fresh water into the upper ocean to produce a thicker barrier layer,whose thermal barrier effect damped the cooling effect of entrainment upwelling on the decrease tendency of the BOB SST.In other words,the thermal barrier effect could slow down the decreasing trend of the BOB SST even after the onset of ASM,which facilitated the further enhancement of the MOV.
文摘By using “the method of modified two-variable”,“the method of mixing perturbation” and introducing four small parameters,the problem of the nonlinear unsymmetrical bending for orthotropic rectangular thin plate with linear variable thickness is studied.And the uniformly valid asymptotic solution of Nth-order for ε_1 and Mth-order for ε_2 of the deflection functions and stress function are obtained.
基金Supported by the National Natural Science Foundation of China,China(21522602,21776092,91534202,91534122,51673063,51672082)Basic Research Program of Shanghai,China(15JC1401300,17JC1402300)+2 种基金Social Development Program of Shanghai,China(17DZ1200900)Innovation Program of Shanghai Municipal Education Commission,ChinaFundamental Research Funds for the Central Universities,China(222201718002).
文摘The radial multiple jets-in-crossflow mixing structure(RMJCMS) is extensively used in industrial manufacture. In this research, the effects of thickness of injection ring on mixing performance and factors influencing the mixing performance of RMJCMS were discussed based on the results of computational fluid dynamics. The simulation results showed that the dimensionless mixing distance, with the increase of the thickness of injection ring, drops from 1.1 to 0.18 first and then increases to 0.27 while the uniformity of flux monotonously improves, manifesting that the consistency of flux is not the single element determining the mixing performance. Analyzing the simulation results, a conclusion was drawn that the consistency of flux, penetration mode and interaction among injection flows which can be altered by adjusting the thickness of injection ring, determine the mixing performance of RMJCMS jointly. That is to say, in RMJCMS an injection ring with a suitable thickness can realize the function of injection and rectification simultaneously, which not only improves the mixing performance but also reduces the complexity of RMJCMS as well.
基金This work is supported by the Natural Science Foundation of Hebei Province(Grant No.E20160203385)the Heavy Machinery Collaborative Innovation Program(Grant No.ZX01-20140400-05)。
文摘With the benefit fierce competition in the steel industry market in recent years,double cold reduction products have been developed towards strength improvement and thickness reduction.The traditional cold-rolling lubrication process with a fixed flow rate and concentration cannot solve the problems,which are uncontrollable plate shape and the excessive consumption of lubricating oil.Moreover,based on the analysis of the traditional direct aplication lubrication system of double cold reduction mill,a set of design scheme suitable for the emulsion pipeline direct mixing lubrication system of double cold reduction mill unit was proposed.The design completed the selection of key components,which included the static mixer and atomization nozzle selection,pump and oil pump design selection,pipeline design selection,flow type selection,pressure gauge selection,electronic control cabinet design selection and other eight aspects.Equipment of the emulsion pipeline direct mixing lubrication system of double cold reduction has been developed.Comparing with characteristics of the traditional direct aplication lubrication system,the emulsion pipeline direct mixing lubrication system was better applied to the production practice of a 1220 double cold reduction mill.The consumption of ton of steel was reduced by 9.6%.The rolling energy consumption and fuel consumption comprehensive costs decreased by 10.7%,and the strip steel section thickness difference was reduced by 19.3%.In addition,the plate shape quality defect rate decreased by 25.6%,otherwise creating a large economic benefit for the unit and promoting the application value.
基金supported by the Research Grants Council of the Hong Kong Special Administrative Region,China(No.17203514)the Guangdong Provincial Natural Science Foundation(No.2015A030310282)the Guangzhou Science(Technology)Research Project of China(No.20160701329)
文摘A high-performance concrete （HPC） is required to have superior performance in various aspects such as workability,strength, durability, dimensional stability, segregation stability, and passing ability. The mix design of HPC is rather complicatedbecause the number of ingredients in HPC is usually more than those in conventional concrete and some of the required propertiesare conflicting with each other in the sense that improvement in one property would at the same time cause impairment of anotherproperty. However, there is still lack of understanding regarding how the various mix parameters should be optimised forachieving best overall performance. Most practitioners are still conducting mix design primarily through trial concrete mixing,which is laborious, ineffective, and often unable to timely respond to fluctuations in the properties of raw materials. To addressthese issues, the authors have been developing the packing and film thickness theories of concrete materials, in order to revamp themix design philosophy of HPC in terms of the water film thickness （WFT）, paste film thickness （PFT）, and mortar film thickness（MFT） in the concrete. Based on the findings from an extensive experimental programme, suitable ranges ofWFT, PFT, and MFThave been recommended.
