The paper presented the results regarding the decomposition of gaseous CF_2ClB_r by cold plasma method.After two minutes discharge,the maximum decomposition rate of 2660 Pa CF_2ClB_r pure and 2660 Pa CF_2ClBr plus 798...The paper presented the results regarding the decomposition of gaseous CF_2ClB_r by cold plasma method.After two minutes discharge,the maximum decomposition rate of 2660 Pa CF_2ClB_r pure and 2660 Pa CF_2ClBr plus 7980 Pa O_2 reached 60% and 80%,respectively.The pa- per also studied the cold plasma gas phase chemistry reaction mechanism of CF_2ClBr at low pres- sure,and the pressure effects of CF_2ClBr and added gas(He,N_2,O_2 and dry air)on the CF_2ClBr decomposition respectively by cold plasma method.These studies will be helpful to application of cold plasma method in the treatment of hazardous gaseous wastes.展开更多
Quantitative level evaluation of cold-rolled strip was significant for the shape control and the product structure optimization. Based on the probability statistics method and the shape pattern recognition method, the...Quantitative level evaluation of cold-rolled strip was significant for the shape control and the product structure optimization. Based on the probability statistics method and the shape pattern recognition method, the shape evaluation model of cold-rolled strip was established to evaluate real-time shape of the online strip. The model was embedded in the shape control system, and the online strip shape state was real-time observed whether to meet the technical indicators, so the shape level could be identified and evaluated. Based on the shape evaluation indicators, the shape component could be well controlled to improve the shape hit rate and the control stability, so that the rolled strip shape could meet the technical requirements. At a 1050 cold strip mill, the shape data of the scene typical specifications strip were online collected and real-time evaluated, and the hit of macro shape in less than 8 I was 68.44%, indicating that the mill shape control had considerable room for improvement, as well as the evaluation method was feasible and practical for quantitative evaluation of the strip shape. So the new evaluation model has important guiding significance to increase value-added and reduce product quality objection.展开更多
In the pathological changes of psoriasis vulgaris,excessive proliferation of keratinocytes,proliferation of microvessels,infiltration of a large number of inflammatory cells,and great shortening of epidermal replaceme...In the pathological changes of psoriasis vulgaris,excessive proliferation of keratinocytes,proliferation of microvessels,infiltration of a large number of inflammatory cells,and great shortening of epidermal replacement time,are the manifestations of Qi and Yin depletion,and they all correspond with pathological changes of nutrient Qi and blood deficiency caused by excessive loss.The treatment of psoriasis should focus on cold straight fire,convergence and fixation.Therefore,it is feasible to treat psoriasis with hoop in theory,and it is found that"cold hoop confining medicine"may be more suitable for the treatment of psoriasis vulgaris in the gradual progress of the experiment.The research could provide theoretical basis for the application of cold hoop confining medicine represented by brusatol in psoriasis vulgaris and related diseases.展开更多
This paper presents the elastic and plastic deformation of the steel helmet with coldextrusion moulding. The plastic streamline of the plastic mould-making process for ellipse thinplate is described. The distribution ...This paper presents the elastic and plastic deformation of the steel helmet with coldextrusion moulding. The plastic streamline of the plastic mould-making process for ellipse thinplate is described. The distribution of slip-line is established based on the plastic streamline. Theextrusion force of plastic moulding of the steel helmet is calculated by using of slip-line method.Furthermore, an applied example is given.展开更多
Oily cold rolling mill （CRM） sludge is one of the pollutants emitted by iron and steel plants. Recycling oily CRM sludge can not only reduce pollution but also bring social and environmental benefits. In this study,...Oily cold rolling mill （CRM） sludge is one of the pollutants emitted by iron and steel plants. Recycling oily CRM sludge can not only reduce pollution but also bring social and environmental benefits. In this study, using oily CRM sludge as sources of iron oxide, the strontium ferrite powders were synthesized in multiple steps including vacuum distillation, magnetic separation, oxidizing roasting, and solidstate reaction. The optimal technological conditions of vacuum distillation and oxidizing roasting were studied carefully. To consider the effects of Fe203/ SrCO3 tool ratio, calcination temperature, milling time and calcination time on magnetic properties of prepared strontium ferrite powders, the orthogonal experimental method was adopted. The maximum saturation magneti- zation （62.6 mA-m2.g-1） of the synthesized strontium ferrite powders was achieved at the Fe203/SrCO3 mol ratio of 6, 5 h milling time, 1250 ~C calcination temperature, and 1 h calcination time. Strontium ferrite powders syn- thesis method not only provides a cheap, high quality raw material for the production of strontium ferrite powders, but also effectively prevents the environmental pollution.展开更多
Low-tempemture stress is a major abiotic stress influencing plant growth, economic yield and quality worldwide. Precise and reliable identification and test of plant cold resistance is a foundation for exploring low-t...Low-tempemture stress is a major abiotic stress influencing plant growth, economic yield and quality worldwide. Precise and reliable identification and test of plant cold resistance is a foundation for exploring low-temperature damages, cold resistance mechanism of plants, cultivating and innovating quality cold-re- sistant germplasm resources, which is rather important for woody plants because their perennial and large-sized characteristics. Generally, most researches on plant cold-resistant physiology focused on identification and utilization of cold resistance worldwide, and a few on test methods of cold resistance, but cold resistance mechanism has been less reported. Therefore, researches on methods of identifying and testing plant resistance have achieved considerable progress, accumulated much experience and formed characteristics gradually in terms of methodology. Current methods of identifying plant cold resistance include open field/outdoor culti- vation evaluation, cold and frost damage investigation, simulated cold weather, and mathematical model forecast. And the methods of testing plant cold resistance include growth condition test, frozen index investigation, electrolyte leakage, bioelectrical impedance mapping and so on. Synthesizing the methods of identifying and testing plant cold resistance should be a key matter in the present and future researches and application of plant cold resistance physiology, improvement and in- novation of the identification and test will be an important direction of the future researches. Identification and test of plant cold resistance based on genomies, meta- bonomics and proteomics should be the new trend of the researches on physiology and ecology of plant cold resistance.展开更多
A mixed method which combines the recent developed finite analytical method and the boundary fitting coordinate transformation method was used first to calculate the temperature field and thermal stress field of the c...A mixed method which combines the recent developed finite analytical method and the boundary fitting coordinate transformation method was used first to calculate the temperature field and thermal stress field of the cold roller in this paper. The following results are obtained by the calculation: thermal stresses σr=0, σθ=σz are maximum tension stress on the inner surface of the cold roller and σr=0, |σθ|=|σz| are maximum compression stress on the outer surface of the cold roller in the steady and unsteady case. Effectiveness and validity of the mixed method are checked with steady coil roller problems having theoretical solutions. The results show that good agreement is achived between the calculated value and theoretical solution,and the mixed method used in the paper is very workable. The mixed method is also useful in solving the steady and unsteady thermal stress field proplems of the hot -rolled for the reversing rolling mill and the continous rolling mill.展开更多
Under low temperature stress,theplasmamembrane and chloroplast of plant cellsare impaired,resulting in electrolyte leakage and al-teration of chlorophyll fluorescence which can bemeasured with conductometer and fluore...Under low temperature stress,theplasmamembrane and chloroplast of plant cellsare impaired,resulting in electrolyte leakage and al-teration of chlorophyll fluorescence which can bemeasured with conductometer and fluoremeter.The cold tolerance of excised leaves of several ricevarieties were determined with these two instru-ments at seedling and heading stages to compare展开更多
Cold atmospheric plasmas(CAPs)have attracted considerable interest in the field of plasma medicine.Generated reactive species such as hydroxyl(OH)species play an important role in applications of CAPs.Transportation o...Cold atmospheric plasmas(CAPs)have attracted considerable interest in the field of plasma medicine.Generated reactive species such as hydroxyl(OH)species play an important role in applications of CAPs.Transportation of OH species towards the target and distribution of these OH species in the plasma plume play an important role in the applications of plasma medicine.In the present work,a computational model was built to simulate the transportation and distribution of OH species in CAP discharges,which was based on the level set method to dynamically track the propagation of plasma carrier gas in air.A reaction term was incorporated for the OH species.The OH species tended to diffuse around the main stream of the carrier gas,and thus covered larger radial and axial distances.A CAP discharge onto a skin layer led to the largest accumulation of OH species at the central part of the exposed area.The distribution of OH species on the skin was asymmetric,which agreed with experiments.The computational model itself and the obtained results would be useful for future development of plasma medicine.展开更多
The microbially cemented sand(MCS)material is a new building material with a broad research prospect,although the nationwide cold wave affects the mechanical properties of the material in the practical application.The...The microbially cemented sand(MCS)material is a new building material with a broad research prospect,although the nationwide cold wave affects the mechanical properties of the material in the practical application.The microstructure of MCS is obtained by computed tomography(CT)and scanning electron microscope(SEM);the thermodynamic mathematical model is established by considering the particle shapes and bonding state based on direct element method(DEM).By studying the damage of temperature drop amplitude and cooling duration to MCS material under the effect of cold wave,the following conclusions are drawn.For a given temperature drop range,an increased cooling time can aggravate the material damage.In addition,a rapid drop in temperature can cause serious damage to the material.The cracks generated by the temperature stress propagate in the direction of the weaker component of the material.The DEM model can be better used to analyze the damage of the MCS structure induced by cold wave.展开更多
An analytic model based on ANSYS/LS-DYNA has been developed on the cold rolling process for Q235 steel rebar with 12 mm in diameter. The elastic-plastic finite element method (FEM) and the cold deformation resistance ...An analytic model based on ANSYS/LS-DYNA has been developed on the cold rolling process for Q235 steel rebar with 12 mm in diameter. The elastic-plastic finite element method (FEM) and the cold deformation resistance model of Q235 steel were adopted in this model. Deformation uniformity of the final product has been analyzed using this model. The results indicate that the uniformity of the final product is obtained only as the centerline of the bending rolls is vertical to the centerline of the driven roll and parallel to the centerline of the drive roll in the whole rolling process. Besides, the number of the bending rolls must even realize the continuous bending and reverse bending process. Also, the number of the bending rolls must match the deformation degree of the workpiece in the cold rolling process. The validity of this finite element model was verified by the size and distribution of grains from the billet to the rebar in a practical cold rolling process.展开更多
The aerodynamic aspects of indirect thrust measurement by the impulse method have been studied both experimentally and numerically. The underlying basic aerodynamic principle is outlined, the phenomena in subsonic, su...The aerodynamic aspects of indirect thrust measurement by the impulse method have been studied both experimentally and numerically. The underlying basic aerodynamic principle is outlined, the phenomena in subsonic, supersonic and arc-heated jets are explored, and factors affecting the accuracy of the method are studied and discussed. Results show that the impulse method is reliable for indirect thrust measurement if certain basic requirements are met, and a simple guideline for its proper application is given.展开更多
Double-skin facades(DSF)are a technique developed for colder climates,so few people think about whether or not it can also be used for hot-summer and cold-winter zones in China.After analyzing the problems of using DS...Double-skin facades(DSF)are a technique developed for colder climates,so few people think about whether or not it can also be used for hot-summer and cold-winter zones in China.After analyzing the problems of using DSF for hot-summer zones,this paper explored on the possibility of applying DSF in hot-summer and cold-winter zones in China.The main existing research methods for DSF were also collected and commented.If properly managed,the ventilated DSF with controlled shading devices can be used even in hot summer in China.展开更多
The present study deals with the effect of cold deformation and subsequent aging on the microstructure and mechanical properties of AI-Cu-Si-Mg alloy. Differential scanning calorimetry indicates that precipitation occ...The present study deals with the effect of cold deformation and subsequent aging on the microstructure and mechanical properties of AI-Cu-Si-Mg alloy. Differential scanning calorimetry indicates that precipitation occurs in the temperature range of 258-272℃ for the as quenched wrought alloy. The activation energy value estimated by Kissinger method for the aforesaid precipitation reaction is obtained as 106 kJ/mol. 45% cold deformation prior to aging indicates the first dissolution reaction at about 50℃ and the precipitation reaction at a temperature of about 82℃. Microstructural investigations have revealed the formation of fine precipitates within the matrix after aging of the cold deformed sample. As-quenched alloy reveals prominently the aging response, The increase in hardness, yield and tensile strength with simultaneous decrease in elongation in the deformed alloy is found to be primarily due to the deformation strengthening and not due to the precipitation hardening.展开更多
To simulate the process of cold roll-forming process, a new method isadopted. The theoretical foundation of this method is an elastic-plastic large deformation splinefinite strip method based on object-oriented progra...To simulate the process of cold roll-forming process, a new method isadopted. The theoretical foundation of this method is an elastic-plastic large deformation splinefinite strip method based on object-oriented programming. Combined with the computer graphicstechnology, the visual simulation of cold roll-forming is completed and the system is established.By analyzing common channel steel, the process is shown and explained including theory method, modeland result display. So the simulation system is already a kind of mature and effective tool toanalyze the process of cold roll forming.展开更多
Cold spraying is a new coating process and manufacturing technology. The coating quality is upgraded with dense layers, higher bonding force and lower oxidation comparing with thermal spraying. Bonding of particles on...Cold spraying is a new coating process and manufacturing technology. The coating quality is upgraded with dense layers, higher bonding force and lower oxidation comparing with thermal spraying. Bonding of particles onto substrate is a result of extensive plastic deformation and related phenomena at the interface. The cold-sprayed copper and aluminum deposits on aluminum and steel substrates were prepared, and the features of interface were observed by using scanning electron microscope (SEM). Then the particle/substrate impact process was modeling through finite-element methods (ANSYS/LS-DYNA software). Numerical results show that the high plastic strain at the interface can result in an adiabatic shear instability at the interface. Due to these extremely high pressure and strain rate, it may be more appropriate to treat the material adjacent to the particle/substrate interface as a viscous ‘fluid-like’ material, various fluid-based phenomena, such as interfacial instabilities and roll-ups and vortices, can lead to interface material mixing. In numerical simulation, adiabatic shear instability both in the particle and the substrate at contact interface is regarded as a criterion for predicting the optimal process parameters and the bonding feature.展开更多
文摘The paper presented the results regarding the decomposition of gaseous CF_2ClB_r by cold plasma method.After two minutes discharge,the maximum decomposition rate of 2660 Pa CF_2ClB_r pure and 2660 Pa CF_2ClBr plus 7980 Pa O_2 reached 60% and 80%,respectively.The pa- per also studied the cold plasma gas phase chemistry reaction mechanism of CF_2ClBr at low pres- sure,and the pressure effects of CF_2ClBr and added gas(He,N_2,O_2 and dry air)on the CF_2ClBr decomposition respectively by cold plasma method.These studies will be helpful to application of cold plasma method in the treatment of hazardous gaseous wastes.
基金Item Sponsored by the National Science and Technology Support Plan of China(2011BAF15B03)National Natural Science Foundation of China(51305387)Hebei Province Colleges and Universities Natural Science Research Youth Foundation of China(Q2012104)
文摘Quantitative level evaluation of cold-rolled strip was significant for the shape control and the product structure optimization. Based on the probability statistics method and the shape pattern recognition method, the shape evaluation model of cold-rolled strip was established to evaluate real-time shape of the online strip. The model was embedded in the shape control system, and the online strip shape state was real-time observed whether to meet the technical indicators, so the shape level could be identified and evaluated. Based on the shape evaluation indicators, the shape component could be well controlled to improve the shape hit rate and the control stability, so that the rolled strip shape could meet the technical requirements. At a 1050 cold strip mill, the shape data of the scene typical specifications strip were online collected and real-time evaluated, and the hit of macro shape in less than 8 I was 68.44%, indicating that the mill shape control had considerable room for improvement, as well as the evaluation method was feasible and practical for quantitative evaluation of the strip shape. So the new evaluation model has important guiding significance to increase value-added and reduce product quality objection.
基金Supported by National Science Foundation for Young Scholars(81704090)Key Projects of Chongqing Municipal Science and Technology Commission(cstc2017jcyjbx0044).
文摘In the pathological changes of psoriasis vulgaris,excessive proliferation of keratinocytes,proliferation of microvessels,infiltration of a large number of inflammatory cells,and great shortening of epidermal replacement time,are the manifestations of Qi and Yin depletion,and they all correspond with pathological changes of nutrient Qi and blood deficiency caused by excessive loss.The treatment of psoriasis should focus on cold straight fire,convergence and fixation.Therefore,it is feasible to treat psoriasis with hoop in theory,and it is found that"cold hoop confining medicine"may be more suitable for the treatment of psoriasis vulgaris in the gradual progress of the experiment.The research could provide theoretical basis for the application of cold hoop confining medicine represented by brusatol in psoriasis vulgaris and related diseases.
文摘This paper presents the elastic and plastic deformation of the steel helmet with coldextrusion moulding. The plastic streamline of the plastic mould-making process for ellipse thinplate is described. The distribution of slip-line is established based on the plastic streamline. Theextrusion force of plastic moulding of the steel helmet is calculated by using of slip-line method.Furthermore, an applied example is given.
基金supported by the National Key Technology R&D Program (Nos. 2012BAC02B01, 2012BAC12B05, 2011BAE13B07, and 2011BAC10B02)the National High Technology Research and Development Program of China (No. 2012AA063202)+2 种基金the National Natural Science Foundation of China (Nos. 51174247 and 51004011)the Science and Technology Program of Guangdong Province, China (No. 2010A030200003)the Ph.D. Programs Foundation of the Ministry of Education of China (No. 2010000612003)
文摘Oily cold rolling mill （CRM） sludge is one of the pollutants emitted by iron and steel plants. Recycling oily CRM sludge can not only reduce pollution but also bring social and environmental benefits. In this study, using oily CRM sludge as sources of iron oxide, the strontium ferrite powders were synthesized in multiple steps including vacuum distillation, magnetic separation, oxidizing roasting, and solidstate reaction. The optimal technological conditions of vacuum distillation and oxidizing roasting were studied carefully. To consider the effects of Fe203/ SrCO3 tool ratio, calcination temperature, milling time and calcination time on magnetic properties of prepared strontium ferrite powders, the orthogonal experimental method was adopted. The maximum saturation magneti- zation （62.6 mA-m2.g-1） of the synthesized strontium ferrite powders was achieved at the Fe203/SrCO3 mol ratio of 6, 5 h milling time, 1250 ~C calcination temperature, and 1 h calcination time. Strontium ferrite powders syn- thesis method not only provides a cheap, high quality raw material for the production of strontium ferrite powders, but also effectively prevents the environmental pollution.
基金Supported by the National Natural Science Fundation of China(No.31270674)
文摘Low-tempemture stress is a major abiotic stress influencing plant growth, economic yield and quality worldwide. Precise and reliable identification and test of plant cold resistance is a foundation for exploring low-temperature damages, cold resistance mechanism of plants, cultivating and innovating quality cold-re- sistant germplasm resources, which is rather important for woody plants because their perennial and large-sized characteristics. Generally, most researches on plant cold-resistant physiology focused on identification and utilization of cold resistance worldwide, and a few on test methods of cold resistance, but cold resistance mechanism has been less reported. Therefore, researches on methods of identifying and testing plant resistance have achieved considerable progress, accumulated much experience and formed characteristics gradually in terms of methodology. Current methods of identifying plant cold resistance include open field/outdoor culti- vation evaluation, cold and frost damage investigation, simulated cold weather, and mathematical model forecast. And the methods of testing plant cold resistance include growth condition test, frozen index investigation, electrolyte leakage, bioelectrical impedance mapping and so on. Synthesizing the methods of identifying and testing plant cold resistance should be a key matter in the present and future researches and application of plant cold resistance physiology, improvement and in- novation of the identification and test will be an important direction of the future researches. Identification and test of plant cold resistance based on genomies, meta- bonomics and proteomics should be the new trend of the researches on physiology and ecology of plant cold resistance.
文摘A mixed method which combines the recent developed finite analytical method and the boundary fitting coordinate transformation method was used first to calculate the temperature field and thermal stress field of the cold roller in this paper. The following results are obtained by the calculation: thermal stresses σr=0, σθ=σz are maximum tension stress on the inner surface of the cold roller and σr=0, |σθ|=|σz| are maximum compression stress on the outer surface of the cold roller in the steady and unsteady case. Effectiveness and validity of the mixed method are checked with steady coil roller problems having theoretical solutions. The results show that good agreement is achived between the calculated value and theoretical solution,and the mixed method used in the paper is very workable. The mixed method is also useful in solving the steady and unsteady thermal stress field proplems of the hot -rolled for the reversing rolling mill and the continous rolling mill.
文摘Under low temperature stress,theplasmamembrane and chloroplast of plant cellsare impaired,resulting in electrolyte leakage and al-teration of chlorophyll fluorescence which can bemeasured with conductometer and fluoremeter.The cold tolerance of excised leaves of several ricevarieties were determined with these two instru-ments at seedling and heading stages to compare
基金funded by National Natural Science Foundation of China (Nos. U1632145, 81573093 and 81227902)funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD) and Jiangsu Provincial Key Laboratory of Radiation Medicine and Protection, China Postdoctoral Science Foundation (No. 2016M592584)Strategic Research Grant 7004641 from City University of Hong Kong
文摘Cold atmospheric plasmas(CAPs)have attracted considerable interest in the field of plasma medicine.Generated reactive species such as hydroxyl(OH)species play an important role in applications of CAPs.Transportation of OH species towards the target and distribution of these OH species in the plasma plume play an important role in the applications of plasma medicine.In the present work,a computational model was built to simulate the transportation and distribution of OH species in CAP discharges,which was based on the level set method to dynamically track the propagation of plasma carrier gas in air.A reaction term was incorporated for the OH species.The OH species tended to diffuse around the main stream of the carrier gas,and thus covered larger radial and axial distances.A CAP discharge onto a skin layer led to the largest accumulation of OH species at the central part of the exposed area.The distribution of OH species on the skin was asymmetric,which agreed with experiments.The computational model itself and the obtained results would be useful for future development of plasma medicine.
基金Foundation item:the National Natural Science Foundation of China(No.51621096)
文摘The microbially cemented sand(MCS)material is a new building material with a broad research prospect,although the nationwide cold wave affects the mechanical properties of the material in the practical application.The microstructure of MCS is obtained by computed tomography(CT)and scanning electron microscope(SEM);the thermodynamic mathematical model is established by considering the particle shapes and bonding state based on direct element method(DEM).By studying the damage of temperature drop amplitude and cooling duration to MCS material under the effect of cold wave,the following conclusions are drawn.For a given temperature drop range,an increased cooling time can aggravate the material damage.In addition,a rapid drop in temperature can cause serious damage to the material.The cracks generated by the temperature stress propagate in the direction of the weaker component of the material.The DEM model can be better used to analyze the damage of the MCS structure induced by cold wave.
基金Item Sponsored by Financial Supports From National Pillar Program of China(2007DAE30B02)
文摘An analytic model based on ANSYS/LS-DYNA has been developed on the cold rolling process for Q235 steel rebar with 12 mm in diameter. The elastic-plastic finite element method (FEM) and the cold deformation resistance model of Q235 steel were adopted in this model. Deformation uniformity of the final product has been analyzed using this model. The results indicate that the uniformity of the final product is obtained only as the centerline of the bending rolls is vertical to the centerline of the driven roll and parallel to the centerline of the drive roll in the whole rolling process. Besides, the number of the bending rolls must even realize the continuous bending and reverse bending process. Also, the number of the bending rolls must match the deformation degree of the workpiece in the cold rolling process. The validity of this finite element model was verified by the size and distribution of grains from the billet to the rebar in a practical cold rolling process.
基金supported by the National Natural Science Foundation of China (50836007, 10921062, 10772016)
文摘The aerodynamic aspects of indirect thrust measurement by the impulse method have been studied both experimentally and numerically. The underlying basic aerodynamic principle is outlined, the phenomena in subsonic, supersonic and arc-heated jets are explored, and factors affecting the accuracy of the method are studied and discussed. Results show that the impulse method is reliable for indirect thrust measurement if certain basic requirements are met, and a simple guideline for its proper application is given.
文摘Double-skin facades(DSF)are a technique developed for colder climates,so few people think about whether or not it can also be used for hot-summer and cold-winter zones in China.After analyzing the problems of using DSF for hot-summer zones,this paper explored on the possibility of applying DSF in hot-summer and cold-winter zones in China.The main existing research methods for DSF were also collected and commented.If properly managed,the ventilated DSF with controlled shading devices can be used even in hot summer in China.
文摘The present study deals with the effect of cold deformation and subsequent aging on the microstructure and mechanical properties of AI-Cu-Si-Mg alloy. Differential scanning calorimetry indicates that precipitation occurs in the temperature range of 258-272℃ for the as quenched wrought alloy. The activation energy value estimated by Kissinger method for the aforesaid precipitation reaction is obtained as 106 kJ/mol. 45% cold deformation prior to aging indicates the first dissolution reaction at about 50℃ and the precipitation reaction at a temperature of about 82℃. Microstructural investigations have revealed the formation of fine precipitates within the matrix after aging of the cold deformed sample. As-quenched alloy reveals prominently the aging response, The increase in hardness, yield and tensile strength with simultaneous decrease in elongation in the deformed alloy is found to be primarily due to the deformation strengthening and not due to the precipitation hardening.
基金This project is supported by Provincial Natural Science Foundation of Hebei (No.502214).
文摘To simulate the process of cold roll-forming process, a new method isadopted. The theoretical foundation of this method is an elastic-plastic large deformation splinefinite strip method based on object-oriented programming. Combined with the computer graphicstechnology, the visual simulation of cold roll-forming is completed and the system is established.By analyzing common channel steel, the process is shown and explained including theory method, modeland result display. So the simulation system is already a kind of mature and effective tool toanalyze the process of cold roll forming.
基金National Nature Science Foundation of China (50871019 and 50874009)
文摘Cold spraying is a new coating process and manufacturing technology. The coating quality is upgraded with dense layers, higher bonding force and lower oxidation comparing with thermal spraying. Bonding of particles onto substrate is a result of extensive plastic deformation and related phenomena at the interface. The cold-sprayed copper and aluminum deposits on aluminum and steel substrates were prepared, and the features of interface were observed by using scanning electron microscope (SEM). Then the particle/substrate impact process was modeling through finite-element methods (ANSYS/LS-DYNA software). Numerical results show that the high plastic strain at the interface can result in an adiabatic shear instability at the interface. Due to these extremely high pressure and strain rate, it may be more appropriate to treat the material adjacent to the particle/substrate interface as a viscous ‘fluid-like’ material, various fluid-based phenomena, such as interfacial instabilities and roll-ups and vortices, can lead to interface material mixing. In numerical simulation, adiabatic shear instability both in the particle and the substrate at contact interface is regarded as a criterion for predicting the optimal process parameters and the bonding feature.
