Pretreatment technology is deeply discussed to explain its importance in guaranteeing properties and formability of aluminum alloy automotive sheet. Some typical applications of aluminum alloy automotive sheet to auto...Pretreatment technology is deeply discussed to explain its importance in guaranteeing properties and formability of aluminum alloy automotive sheet. Some typical applications of aluminum alloy automotive sheet to automotive industry are listed. Based on the author's knowledge and recognition and research progress presently, the important research contents about aluminum alloy automotive sheet are emphasized. Reducing cost and price of sheet and going deeply into application research are the main work for expending the application of aluminum alloy automotive sheet in the automobile.展开更多
For large-scale in-service electric vehicles(EVs)that undergo potential maintenance,second-hand transactions,and retirement,it is crucial to rapidly evaluate the health status of their battery packs.However,existing m...For large-scale in-service electric vehicles(EVs)that undergo potential maintenance,second-hand transactions,and retirement,it is crucial to rapidly evaluate the health status of their battery packs.However,existing methods often rely on lengthy battery charging/discharging data or extensive training samples,which hinders their implementation in practical scenarios.To address this issue,a rapid health estimation method based on short-time charging data and limited labels for in-service battery packs is proposed in this paper.First,a digital twin of battery pack is established to emulate its dynamic behavior across various aging levels and inconsistency degrees.Then,increment capacity sequences(△Q)within a short voltage span are extracted from charging process to indicate battery health.Furthermore,data-driven models based on deep convolutional neural network(DCNN)are constructed to estimate battery state of health(SOH),where the synthetic data is employed to pre-train the models,and transfer learning strategies by using fine-tuning and domain adaptation are utilized to enhance the model adaptability.Finally,field data of 10 EVs exhibiting different SOHs are used to verify the proposed methods.By using the△Q with 100 m V voltage change,the SOH of battery packs can be accurately estimated with an error around 3.2%.展开更多
In this article,current application,materials,key equipments,finite element(FE) simulation and parts properties of hot stamping are introduced.The investigations of all processes and further excellent processes are de...In this article,current application,materials,key equipments,finite element(FE) simulation and parts properties of hot stamping are introduced.The investigations of all processes and further excellent processes are described.The survey of existing works,especially key equipments has revealed several gaps.Some new ideas and programs are proposed on the basis of traditional process.This article aims at providing an insight into a whole process backgrounds and pointing out the great potential for further investigations and innovations of hot stamping.展开更多
The light weight heat treated B-grade bulletproof steel was developed through composition design and optimization based on multiplex alloying,multiplex micro-alloying design ideas and complex phase structure strengthe...The light weight heat treated B-grade bulletproof steel was developed through composition design and optimization based on multiplex alloying,multiplex micro-alloying design ideas and complex phase structure strengthening theory.The puzzle how to avoid the quenching deformation problem of super high strength thin sheet was solved through heat treatment in a die with a set of cooling system.Such B-grade bulletproof steel plate has fine tempered lath martensite structure.The shooting and certification test results showed that the shoot resistance of B-grade bulletproof steel plate can meet the protection demand of Protection specification for cash carrying vehicles(GA 164—2005).In comparison with B-grade bulletproof steel plate made by one of the companies in Sweden,the weight of the developed B-grade bulletproof steel plate can be decreased by 8 %under the same shoot resistance condition.It will be meaningful for cash truck and anti-hijacking vehicle to realize light weight,energy conservation and emission reduction.展开更多
Automotive lightweight and safety performance come into play as key technologies to promote competiveness, and average applied amount of automotive plastics has become a significant sign for automotive industrial deve...Automotive lightweight and safety performance come into play as key technologies to promote competiveness, and average applied amount of automotive plastics has become a significant sign for automotive industrial development level of a country.Various performances of a vehicle with plastic automotive fenders are analyzed in the paper.The research is emphasized on sinking-resistance and pedestrian protection performance of the plastic fenders by studying plastics characteristics and simulation analysis.It offers references for engineering design in which both automotive lightweight and safety performance are achieved and well balanced.展开更多
To investigate the spring-back behavior of dual-phase(DP) steel,V-shape spring-back experiments with different bending angles,relative bending radii and blank holding forces were carried out in this paper.It is conclu...To investigate the spring-back behavior of dual-phase(DP) steel,V-shape spring-back experiments with different bending angles,relative bending radii and blank holding forces were carried out in this paper.It is concluded that with the increase of V-shape angle or blank holding force,the spring-back of DP steel sheets decreases;while raising fillet radius of punch,which has the most apparent effects on spring- back,advances spring-back angle.Among DP590,DP780 and DP980,higher strength yields more notable spring-back due to larger elastic deformation.The difference of spring-back among these materials is relevant with the microstructure and mechanical properties.The total elastic deformation approximately equals the ratio of the strength corresponding to the applied load to the modulus of elasticity.展开更多
This paper gives analysis of application status and prospect of plastic materials from the aspects of applied material amount comparison,development of new materials & new technologies,lightweight,design conceptio...This paper gives analysis of application status and prospect of plastic materials from the aspects of applied material amount comparison,development of new materials & new technologies,lightweight,design conception of new components,recyclability,simplification and diversity of materials,standardization of material specification and presents corresponding conclusions and suggestions.展开更多
The rapid development of China’s automobile industry has brought ever-increasing impact on resources,energy and environment,the energy-saving and new energy vehicles come into being accordingly.This article firstly s...The rapid development of China’s automobile industry has brought ever-increasing impact on resources,energy and environment,the energy-saving and new energy vehicles come into being accordingly.This article firstly systematically introduces the technical route of energy-saving and new energy vehicles of China,focusing on the key bottleneck problems arising from the construction process of current assessment system of the technical route for energy-saving and new energy vehicles,establishes the energy-saving and new energy vehicle business model assessment index system afterward based on the comparative analysis on energy-saving and new energy vehicle business assessment model and the full life cycle theory,and finally makes prospects and forecasts on vital problems of system boundary,dynamic optimization,simulation system of full life cycle assessment of energy-saving and new energy vehicle.展开更多
Dent resistance of automobile body panels is an important property for automobile design and manufacture, but the study on this aspect is not still profound. This study is to summarize the testing methods and physical...Dent resistance of automobile body panels is an important property for automobile design and manufacture, but the study on this aspect is not still profound. This study is to summarize the testing methods and physical significations of static and dynamic dent resistance of automobile body panels combined with the author's study, and to analyze the dent behaviors in the round. Several influence factors on dent resistance are expatiated including the mechanical properties of materials, stress states after forming, bake hardening ability, modulus, methods of testing, and structure of specimens and so on. The automotive lightweight and application of high strength steel sheets and aluminum alloys sheets are analyzed, and the significance of testing of dent resistance, especially for dynamic dent resistance of auto-panels, and the finite element simulation analysis are emphasized. To explain the physical phenomenon of dent behaviors, the latest and concerned study results are also discussed. According to this study, a dent resistance test and evaluation standard of Society of Automotive Engineers of China for automotive body panel is presented and is being carried out, and an industry conference is hold to discuss the working-out of the standard, a primary schedule of this standard is confirmed now. The study can guide the further testing and study of dent resistant of auto-panels.展开更多
The formation cause of orange peel of aluminum-alloy automotive sheet after tensile deformation was analysed by using X-ray diffraction and electron back-scattered diffraction(EBSD).The test results showed that format...The formation cause of orange peel of aluminum-alloy automotive sheet after tensile deformation was analysed by using X-ray diffraction and electron back-scattered diffraction(EBSD).The test results showed that formation cause of surface orange peel after tensile deformation related to product texture and nonuniform deformation during the tensile process.The grain size has significant effect on deformation uniform and texture formation.Coarse grains were easy to produce nonuniform deformation and texture,which would produce surface orange peel after tensile deformation.展开更多
Ls-DYNA software is adopted to conduct research of numerical simulation on hot stamping of side impact beam to calculate the temperature field distribution,stress field distribution,forming limit diagram(FLD) figure,e...Ls-DYNA software is adopted to conduct research of numerical simulation on hot stamping of side impact beam to calculate the temperature field distribution,stress field distribution,forming limit diagram(FLD) figure,etc.in the course of hot stamping so as to predict and analyze the formability of parts.ProCAST software is employed to conduct research of numerical simulation on solid quenching course concerning hot stamping to calculate temperature field distribution of tools and component of multiple stamping cycles.The results obtained from numerical simulation can provide significant reference value to hot stamping part design,formability predication and tools cooling system design.展开更多
The tension property of aluminum-alloy sheet with different microstructures is measured,and the surface and tension fracture morphology of tension sample with and without orange peel are observed by using scanning ele...The tension property of aluminum-alloy sheet with different microstructures is measured,and the surface and tension fracture morphology of tension sample with and without orange peel are observed by using scanning electron microscope(SEM).Surface roughness and nano hardness of tension sample are measured.The results show that the average elongation of the samples with orange peel is lower than that without orange peel;especially the r value of perpendicular to the rolling direction is much lower than that without orange peel.The tension surface of the orange peel samples is very rough;various parameters of surface roughness are higher.Under the observation of SEM,a wider sliding band with a micro crack on the surface of orange peel sample can be found.The various parameters of surface roughness without orange peel sample are near to zero,the sliding band is narrow and without micro cracks.The dimple width in tensile fracture of orange peel sample is larger than that without orange peel sample,but shear lip is narrower.The nano hardness testing results show that samples with orange peel behave high elastic modulus,high hardness,and high maximum load,but low plastic deformation depth.These mentioned features can completely describe surface and fracture morphology of tension samples with orange peel.展开更多
For Lightweight body,sound radiation and sound insulation performance have negative effects on interior noise by the deterioration of local stiffness and modality.So the research on the active control of vibration and...For Lightweight body,sound radiation and sound insulation performance have negative effects on interior noise by the deterioration of local stiffness and modality.So the research on the active control of vibration and noise for car body panels is useful for engineering.Analysis and active control of booming noise in car is researched by using a new active damping vibration reduction technology named smart constrained layer damping(SCLD).According to the vibration characters of body roof,an optimal placement of actuators is distributed.Based on dSPACE hardware in loop environment,an adaptive active control system is designed.Selecting vibration signals of engine mounting point as the reference input of adaptive controller,an active control experiment of booming noise for mini-car is carried out.Experimental results show that,when the engine speed is at 3700 RPM and4250RPM,the interior booming noise decreases 4.2dB(A),and 3.5dB(A) separately.It proposes new methods and techniques for intelligent control of car body NVH in the future.展开更多
<正>This article summarizes the comparison between the preparation,structure and mechanical properties of long fiber reinforced thermoplastics(LFT) and short fiber reinforced thermoplastics(SFT).Both of the expe...<正>This article summarizes the comparison between the preparation,structure and mechanical properties of long fiber reinforced thermoplastics(LFT) and short fiber reinforced thermoplastics(SFT).Both of the experiment and theory results showed that the mechanical properties of long glass fiber reinforced thermoplastics pellets(LGFRT) have been enhanced better than that of short glass fiber reinforced thermoplastics pellets(SGFRT) manufactured by molding procession.After regulation of the relative humidity by 50%,the mechanical properties of 30%(weight percent) short glass fiber content in SFT(SFT-PA6-SGF30) are similar to that of 40%long glass fiber content in LFT.However, the density of the latter is about 17%lower than that of the former.Thus,the corresponding weight of products is reduced by 13%;output rate is increased by 21%,and the cost is therefore significantly lowered.And it has the following advantages;impact strength is increased by 87%;the proportion is reduced by 20%;molding cycle is shortened by 10%;materials cost is saved by 20%~ 30%and the final total cost is saved by 30%~ 40%.So LFT (LFT-PP-LGF40 ) can replace SFT(SFT-PA6-SGF30) with the similar basic mechanical properties under normal temperature or 160℃lower.展开更多
Numerical simulation combined with experimental test was carried out to analyze the pre-stretching process of the 7075 aluminum alloy sheet,from which the stress variation curves and residual stress of aluminum alloy ...Numerical simulation combined with experimental test was carried out to analyze the pre-stretching process of the 7075 aluminum alloy sheet,from which the stress variation curves and residual stress of aluminum alloy sheet in different stretch rates were obtained.The results show that the residual stress in length direction is released after unloading the stretch force,while the residual stress in width direction is released during the stretching process.The study of residual stress elimination is beneficial for optimizing stretch rate on the basis of residual stress distribution law.By comparing the variation principle of residual stress in length direction,the size range of three deformation areas and elimination percentage of residual stress were obtained.The residual stresses of clamping area and transition area are not eliminated effectively,so sawing quantity should be the sum of both the areas.The elimination rate of residual stress in even deformation area could reach 90% after choosing a proper stretch rate,which is verified by both simulation and experiment.展开更多
The process characteristics of heat treatment of aluminum alloy auto body sheet and the working principle of air cushion furnace were introduced.The process position and irreplaceable role of air cushion furnace in th...The process characteristics of heat treatment of aluminum alloy auto body sheet and the working principle of air cushion furnace were introduced.The process position and irreplaceable role of air cushion furnace in the aluminum alloy auto body sheet production was pointed out after the difficulty and key points in the whole production process of auto body sheet were studied.Then the development process of air cushion furnace line of aluminum alloy sheet was reviewed,summarized and divided to two stages.Based on the research of air cushion furnace,the key technology of it was analyzed,then the key points on process,equipment and control models of air cushion furnace for aluminum alloy auto body sheet in future were put forward.With the rapid development of automotive industry,there will be certainly a new upsurge of research and application of air cushion furnace for heat treatment of aluminum alloy auto body sheet.展开更多
In this paper,the spot welding technology of a new kind of 22 MnMoB hot stamping quenched steel sheet was systematically studied by power frequency spot welder.Through a series of technology and test experiments,we ha...In this paper,the spot welding technology of a new kind of 22 MnMoB hot stamping quenched steel sheet was systematically studied by power frequency spot welder.Through a series of technology and test experiments,we have obtained the optimal spot welding technological parameter condition.According to the results,the relations among spot welding technological parameter,welding nugget,mechanical property and fracture mode were discussed.The effects of all the welding parameters such as welding current,welding time and electrode force on the quality of joint can be boiled down to one thing—the diameter of welding nugget.The experimental results showed that welding nugget diameter determines the mechanical property of spot welding joint and the relation between welding nugget diameter and the mechanical property of joint presents a kind of linear mathematic representation.There are two typical fracture models of 22 MnMoB hot stamping quenched steel sheet,i.e.,interfacial fracture and nugget pullout.Other than mild steel or normal high strength steel,in the shearing tensile test,hot stamping quenched steel has a great tendency to fail in interfacial mode due to the effects of high strength matrix structure,welding soft zone and the porosity level of fusion zone.展开更多
Bulletproof steel plates are widely used for the safety of special vehicles.This paper mainly researches on the shoot resistance of heat treated light weight B-grade bulletproof steel plates through numerical analysis...Bulletproof steel plates are widely used for the safety of special vehicles.This paper mainly researches on the shoot resistance of heat treated light weight B-grade bulletproof steel plates through numerical analysis.Based on the flow behavior of bulletproof steel plates and bullet at various high strain rates,finite element(FE) model has been set up using ANSYS/LS-DYNA software.The simulation results are compared with the shooting results,which show a good consistency and a high reliability.Therefore,the simulation results are efficient approaches and strategies to decide and select the mechanical property and thickness of bulletproof steel plates,saving a lot of work and the cost of experiments.展开更多
Bumper beam is one of the key structural parts,which plays an important role in the frontal crashes of automobile.With the global trend of light-weighted automotive parts,the light weight of bumper beam attracts exten...Bumper beam is one of the key structural parts,which plays an important role in the frontal crashes of automobile.With the global trend of light-weighted automotive parts,the light weight of bumper beam attracts extensive attention of automobile manufacturers,and hot stamping technology with significant weight advantage has become one of the main light weight measures for bumper beam.The quasi-static press,low speed crash and frontal crash simulation models of bumper beam were established according to its actual working conditions in the automobile crashes.The feasibility of replacing normal steel bumper beam with hot stamping bumper beam was analyzed.Meanwhile,the stiffeners in the front face of hot stamping bumper beam were optimized with topography optimization in order to further improve its performances.展开更多
Using high strength steel and ultra-high strength steel in hot stamping and automobile parts is one of the most important ways of the automobile lightweight,which is the development trend of automobiles currently.In t...Using high strength steel and ultra-high strength steel in hot stamping and automobile parts is one of the most important ways of the automobile lightweight,which is the development trend of automobiles currently.In this paper, the development of test device for heat friction coefficient by high strength steel can provide important technical parameters for hot stamping process,making the right selection of equipment types,mold design,technology optimization,and research and development of lubrication medium of press forming.At the same time,the experiments indicate that the instrument has not only accurate test result but also good repeatability.展开更多
文摘Pretreatment technology is deeply discussed to explain its importance in guaranteeing properties and formability of aluminum alloy automotive sheet. Some typical applications of aluminum alloy automotive sheet to automotive industry are listed. Based on the author's knowledge and recognition and research progress presently, the important research contents about aluminum alloy automotive sheet are emphasized. Reducing cost and price of sheet and going deeply into application research are the main work for expending the application of aluminum alloy automotive sheet in the automobile.
基金supported in part by the National Natural Science Foundation of China,China(Grant No.52102420)the National Key Research and Development Program of China,China(Grant No.2022YFE0102700)the China Postdoctoral Science Foundation,China(Grant No.2023T160085)。
文摘For large-scale in-service electric vehicles(EVs)that undergo potential maintenance,second-hand transactions,and retirement,it is crucial to rapidly evaluate the health status of their battery packs.However,existing methods often rely on lengthy battery charging/discharging data or extensive training samples,which hinders their implementation in practical scenarios.To address this issue,a rapid health estimation method based on short-time charging data and limited labels for in-service battery packs is proposed in this paper.First,a digital twin of battery pack is established to emulate its dynamic behavior across various aging levels and inconsistency degrees.Then,increment capacity sequences(△Q)within a short voltage span are extracted from charging process to indicate battery health.Furthermore,data-driven models based on deep convolutional neural network(DCNN)are constructed to estimate battery state of health(SOH),where the synthetic data is employed to pre-train the models,and transfer learning strategies by using fine-tuning and domain adaptation are utilized to enhance the model adaptability.Finally,field data of 10 EVs exhibiting different SOHs are used to verify the proposed methods.By using the△Q with 100 m V voltage change,the SOH of battery packs can be accurately estimated with an error around 3.2%.
基金National Science and Technology Supporting Program of China(No.2011BAG03B02)
文摘In this article,current application,materials,key equipments,finite element(FE) simulation and parts properties of hot stamping are introduced.The investigations of all processes and further excellent processes are described.The survey of existing works,especially key equipments has revealed several gaps.Some new ideas and programs are proposed on the basis of traditional process.This article aims at providing an insight into a whole process backgrounds and pointing out the great potential for further investigations and innovations of hot stamping.
文摘The light weight heat treated B-grade bulletproof steel was developed through composition design and optimization based on multiplex alloying,multiplex micro-alloying design ideas and complex phase structure strengthening theory.The puzzle how to avoid the quenching deformation problem of super high strength thin sheet was solved through heat treatment in a die with a set of cooling system.Such B-grade bulletproof steel plate has fine tempered lath martensite structure.The shooting and certification test results showed that the shoot resistance of B-grade bulletproof steel plate can meet the protection demand of Protection specification for cash carrying vehicles(GA 164—2005).In comparison with B-grade bulletproof steel plate made by one of the companies in Sweden,the weight of the developed B-grade bulletproof steel plate can be decreased by 8 %under the same shoot resistance condition.It will be meaningful for cash truck and anti-hijacking vehicle to realize light weight,energy conservation and emission reduction.
基金Supporting Program of the"Twelfth Five-year Plan"for Sci & Tech Research of China(No. 2011BAG03B02No.2011BAG03B06)
文摘Automotive lightweight and safety performance come into play as key technologies to promote competiveness, and average applied amount of automotive plastics has become a significant sign for automotive industrial development level of a country.Various performances of a vehicle with plastic automotive fenders are analyzed in the paper.The research is emphasized on sinking-resistance and pedestrian protection performance of the plastic fenders by studying plastics characteristics and simulation analysis.It offers references for engineering design in which both automotive lightweight and safety performance are achieved and well balanced.
文摘To investigate the spring-back behavior of dual-phase(DP) steel,V-shape spring-back experiments with different bending angles,relative bending radii and blank holding forces were carried out in this paper.It is concluded that with the increase of V-shape angle or blank holding force,the spring-back of DP steel sheets decreases;while raising fillet radius of punch,which has the most apparent effects on spring- back,advances spring-back angle.Among DP590,DP780 and DP980,higher strength yields more notable spring-back due to larger elastic deformation.The difference of spring-back among these materials is relevant with the microstructure and mechanical properties.The total elastic deformation approximately equals the ratio of the strength corresponding to the applied load to the modulus of elasticity.
基金"Twelfth Five-year Plan"for Sci & Tech Research of China(No.2011BAG03B02No.2011BAG03B06)
文摘This paper gives analysis of application status and prospect of plastic materials from the aspects of applied material amount comparison,development of new materials & new technologies,lightweight,design conception of new components,recyclability,simplification and diversity of materials,standardization of material specification and presents corresponding conclusions and suggestions.
文摘The rapid development of China’s automobile industry has brought ever-increasing impact on resources,energy and environment,the energy-saving and new energy vehicles come into being accordingly.This article firstly systematically introduces the technical route of energy-saving and new energy vehicles of China,focusing on the key bottleneck problems arising from the construction process of current assessment system of the technical route for energy-saving and new energy vehicles,establishes the energy-saving and new energy vehicle business model assessment index system afterward based on the comparative analysis on energy-saving and new energy vehicle business assessment model and the full life cycle theory,and finally makes prospects and forecasts on vital problems of system boundary,dynamic optimization,simulation system of full life cycle assessment of energy-saving and new energy vehicle.
基金supported by National Hi-tech Research and Development Program of China(863 Program, Grant No. 2007AA03z551)Chongqing Municipal Technology Project of China (Grant No. 2007AA4008-4-4)
文摘Dent resistance of automobile body panels is an important property for automobile design and manufacture, but the study on this aspect is not still profound. This study is to summarize the testing methods and physical significations of static and dynamic dent resistance of automobile body panels combined with the author's study, and to analyze the dent behaviors in the round. Several influence factors on dent resistance are expatiated including the mechanical properties of materials, stress states after forming, bake hardening ability, modulus, methods of testing, and structure of specimens and so on. The automotive lightweight and application of high strength steel sheets and aluminum alloys sheets are analyzed, and the significance of testing of dent resistance, especially for dynamic dent resistance of auto-panels, and the finite element simulation analysis are emphasized. To explain the physical phenomenon of dent behaviors, the latest and concerned study results are also discussed. According to this study, a dent resistance test and evaluation standard of Society of Automotive Engineers of China for automotive body panel is presented and is being carried out, and an industry conference is hold to discuss the working-out of the standard, a primary schedule of this standard is confirmed now. The study can guide the further testing and study of dent resistant of auto-panels.
文摘The formation cause of orange peel of aluminum-alloy automotive sheet after tensile deformation was analysed by using X-ray diffraction and electron back-scattered diffraction(EBSD).The test results showed that formation cause of surface orange peel after tensile deformation related to product texture and nonuniform deformation during the tensile process.The grain size has significant effect on deformation uniform and texture formation.Coarse grains were easy to produce nonuniform deformation and texture,which would produce surface orange peel after tensile deformation.
基金National Science and Technology Supporting Program of China(No.20 11BAG03B02)
文摘Ls-DYNA software is adopted to conduct research of numerical simulation on hot stamping of side impact beam to calculate the temperature field distribution,stress field distribution,forming limit diagram(FLD) figure,etc.in the course of hot stamping so as to predict and analyze the formability of parts.ProCAST software is employed to conduct research of numerical simulation on solid quenching course concerning hot stamping to calculate temperature field distribution of tools and component of multiple stamping cycles.The results obtained from numerical simulation can provide significant reference value to hot stamping part design,formability predication and tools cooling system design.
文摘The tension property of aluminum-alloy sheet with different microstructures is measured,and the surface and tension fracture morphology of tension sample with and without orange peel are observed by using scanning electron microscope(SEM).Surface roughness and nano hardness of tension sample are measured.The results show that the average elongation of the samples with orange peel is lower than that without orange peel;especially the r value of perpendicular to the rolling direction is much lower than that without orange peel.The tension surface of the orange peel samples is very rough;various parameters of surface roughness are higher.Under the observation of SEM,a wider sliding band with a micro crack on the surface of orange peel sample can be found.The various parameters of surface roughness without orange peel sample are near to zero,the sliding band is narrow and without micro cracks.The dimple width in tensile fracture of orange peel sample is larger than that without orange peel sample,but shear lip is narrower.The nano hardness testing results show that samples with orange peel behave high elastic modulus,high hardness,and high maximum load,but low plastic deformation depth.These mentioned features can completely describe surface and fracture morphology of tension samples with orange peel.
基金Supported by the State Key Development Program for Basic Research of China(No.2010CB736104)the National High Technology Research and Development Program of China(No.2012AA111803)
文摘For Lightweight body,sound radiation and sound insulation performance have negative effects on interior noise by the deterioration of local stiffness and modality.So the research on the active control of vibration and noise for car body panels is useful for engineering.Analysis and active control of booming noise in car is researched by using a new active damping vibration reduction technology named smart constrained layer damping(SCLD).According to the vibration characters of body roof,an optimal placement of actuators is distributed.Based on dSPACE hardware in loop environment,an adaptive active control system is designed.Selecting vibration signals of engine mounting point as the reference input of adaptive controller,an active control experiment of booming noise for mini-car is carried out.Experimental results show that,when the engine speed is at 3700 RPM and4250RPM,the interior booming noise decreases 4.2dB(A),and 3.5dB(A) separately.It proposes new methods and techniques for intelligent control of car body NVH in the future.
文摘<正>This article summarizes the comparison between the preparation,structure and mechanical properties of long fiber reinforced thermoplastics(LFT) and short fiber reinforced thermoplastics(SFT).Both of the experiment and theory results showed that the mechanical properties of long glass fiber reinforced thermoplastics pellets(LGFRT) have been enhanced better than that of short glass fiber reinforced thermoplastics pellets(SGFRT) manufactured by molding procession.After regulation of the relative humidity by 50%,the mechanical properties of 30%(weight percent) short glass fiber content in SFT(SFT-PA6-SGF30) are similar to that of 40%long glass fiber content in LFT.However, the density of the latter is about 17%lower than that of the former.Thus,the corresponding weight of products is reduced by 13%;output rate is increased by 21%,and the cost is therefore significantly lowered.And it has the following advantages;impact strength is increased by 87%;the proportion is reduced by 20%;molding cycle is shortened by 10%;materials cost is saved by 20%~ 30%and the final total cost is saved by 30%~ 40%.So LFT (LFT-PP-LGF40 ) can replace SFT(SFT-PA6-SGF30) with the similar basic mechanical properties under normal temperature or 160℃lower.
基金Project(2009GJF10028) supported by Technical Special Pilot Program of ChinaProject(CDJXS11110013) supported by the Fundamental Research Funds for the Central Universities of China
文摘Numerical simulation combined with experimental test was carried out to analyze the pre-stretching process of the 7075 aluminum alloy sheet,from which the stress variation curves and residual stress of aluminum alloy sheet in different stretch rates were obtained.The results show that the residual stress in length direction is released after unloading the stretch force,while the residual stress in width direction is released during the stretching process.The study of residual stress elimination is beneficial for optimizing stretch rate on the basis of residual stress distribution law.By comparing the variation principle of residual stress in length direction,the size range of three deformation areas and elimination percentage of residual stress were obtained.The residual stresses of clamping area and transition area are not eliminated effectively,so sawing quantity should be the sum of both the areas.The elimination rate of residual stress in even deformation area could reach 90% after choosing a proper stretch rate,which is verified by both simulation and experiment.
文摘The process characteristics of heat treatment of aluminum alloy auto body sheet and the working principle of air cushion furnace were introduced.The process position and irreplaceable role of air cushion furnace in the aluminum alloy auto body sheet production was pointed out after the difficulty and key points in the whole production process of auto body sheet were studied.Then the development process of air cushion furnace line of aluminum alloy sheet was reviewed,summarized and divided to two stages.Based on the research of air cushion furnace,the key technology of it was analyzed,then the key points on process,equipment and control models of air cushion furnace for aluminum alloy auto body sheet in future were put forward.With the rapid development of automotive industry,there will be certainly a new upsurge of research and application of air cushion furnace for heat treatment of aluminum alloy auto body sheet.
文摘In this paper,the spot welding technology of a new kind of 22 MnMoB hot stamping quenched steel sheet was systematically studied by power frequency spot welder.Through a series of technology and test experiments,we have obtained the optimal spot welding technological parameter condition.According to the results,the relations among spot welding technological parameter,welding nugget,mechanical property and fracture mode were discussed.The effects of all the welding parameters such as welding current,welding time and electrode force on the quality of joint can be boiled down to one thing—the diameter of welding nugget.The experimental results showed that welding nugget diameter determines the mechanical property of spot welding joint and the relation between welding nugget diameter and the mechanical property of joint presents a kind of linear mathematic representation.There are two typical fracture models of 22 MnMoB hot stamping quenched steel sheet,i.e.,interfacial fracture and nugget pullout.Other than mild steel or normal high strength steel,in the shearing tensile test,hot stamping quenched steel has a great tendency to fail in interfacial mode due to the effects of high strength matrix structure,welding soft zone and the porosity level of fusion zone.
文摘Bulletproof steel plates are widely used for the safety of special vehicles.This paper mainly researches on the shoot resistance of heat treated light weight B-grade bulletproof steel plates through numerical analysis.Based on the flow behavior of bulletproof steel plates and bullet at various high strain rates,finite element(FE) model has been set up using ANSYS/LS-DYNA software.The simulation results are compared with the shooting results,which show a good consistency and a high reliability.Therefore,the simulation results are efficient approaches and strategies to decide and select the mechanical property and thickness of bulletproof steel plates,saving a lot of work and the cost of experiments.
文摘Bumper beam is one of the key structural parts,which plays an important role in the frontal crashes of automobile.With the global trend of light-weighted automotive parts,the light weight of bumper beam attracts extensive attention of automobile manufacturers,and hot stamping technology with significant weight advantage has become one of the main light weight measures for bumper beam.The quasi-static press,low speed crash and frontal crash simulation models of bumper beam were established according to its actual working conditions in the automobile crashes.The feasibility of replacing normal steel bumper beam with hot stamping bumper beam was analyzed.Meanwhile,the stiffeners in the front face of hot stamping bumper beam were optimized with topography optimization in order to further improve its performances.
基金National Science and Technology Supporting Program of China(No.2011BAG03B02)
文摘Using high strength steel and ultra-high strength steel in hot stamping and automobile parts is one of the most important ways of the automobile lightweight,which is the development trend of automobiles currently.In this paper, the development of test device for heat friction coefficient by high strength steel can provide important technical parameters for hot stamping process,making the right selection of equipment types,mold design,technology optimization,and research and development of lubrication medium of press forming.At the same time,the experiments indicate that the instrument has not only accurate test result but also good repeatability.
