In today’s rapidly developing modern society,automobiles,as an important part of transportation and industrial fields,play a pivotal role.With the improvement of people’s living standards and the increase in traffic...In today’s rapidly developing modern society,automobiles,as an important part of transportation and industrial fields,play a pivotal role.With the improvement of people’s living standards and the increase in traffic demand,the automobile manufacturing industry has been continuously developing and growing globally.However,to cope with increasingly fierce market competition and ever-changing consumer demands,the automobile manufacturing industry is also facing the challenges of improving production efficiency,reducing costs,and improving product quality.In this context,automation technology has gradually become a major trend in the automobile manufacturing industry.As an important support of modern industry,automation technology has shown great application potential in many fields.From industrial production to daily life,automation technology can be seen everywhere.In the field of manufacturing,especially in automobile manufacturing,the application of automation technology is getting more and more attention.Automated production lines,intelligent robots,and automated warehousing systems have all changed the face of automobile manufacturing to varying degrees,bringing companies higher efficiency,more stable quality,and greater competitive advantages.The application trend of this automation technology in various fields not only meets the needs of modern industry for efficient,precise,and sustainable development but also provides new ideas and paths for the future development of the automobile manufacturing industry.展开更多
Mechanical metamaterials can be defined as a class of architected materials that exhibit unprecedented mechanical properties derived from designed artificial architectures rather than their constituent materials.While...Mechanical metamaterials can be defined as a class of architected materials that exhibit unprecedented mechanical properties derived from designed artificial architectures rather than their constituent materials.While macroscale and simple layouts can be realized by conventional top-down manufacturing approaches,many of the sophisticated designs at various length scales remain elusive,due to the lack of adequate manufacturing methods.Recent progress in additive manufacturing(AM)has led to the realization of a myriad of novel metamaterial concepts.AM methods capable of fabricating microscale architectures with high resolution,arbitrary complexity,and high feature fidelity have enabled the rapid development of architected meta materials and drastically reduced the design-computation and experimental-validation cycle.This paper first provides a detailed review of various topologies based on the desired mechanical properties,including stiff,strong,and auxetic(negative Poisson’s ratio)metamaterials,followed by a discussion of the AM technologies capable of fabricating these metamaterials.Finally,we discuss current challenges and recommend future directions for AM and mechanical metamaterials.展开更多
Multistable mechanical metamaterials are a type of mechanical metamaterials with special features,such as reusability,energy storage and absorption capabilities,rapid deformation,and amplified output forces.These meta...Multistable mechanical metamaterials are a type of mechanical metamaterials with special features,such as reusability,energy storage and absorption capabilities,rapid deformation,and amplified output forces.These metamaterials are usually realized by series and/or parallel of bistable units.They can exhibit multiple stable configurations under external loads and can be switched reversely among each other,thereby realizing the reusability of mechanical metamaterials and offering broad engineering applications.This paper reviews the latest research progress in the design strategy,manufacture and application of multistable mechanical metamaterials.We divide bistable structures into three categories based on their basic element types and provide the criterion of their bistability.Various manufacturing techniques to fabricate these multistable mechanical metamaterials are introduced,including mold casting,cutting,folding and three-dimensional/4D printing.Furthermore,the prospects of multistable mechanical metamaterials for applications in soft driving,mechanical computing,energy absorption and wave controlling are discussed.Finally,this paper highlights possible challenges and opportunities for future investigations.The review aims to provide insights into the research and development of multistable mechanical metamaterials.展开更多
Ti−Al−V−Nb alloys with the cluster formula,12[Al−Ti_(12)](AlTi_(2))+5[Al−Ti1_(4)](V,Nb)2Ti,were designed by replacing V with Nb based on the Ti−6Al−4V alloy.Single-track cladding layers and bulk samples of the alloys ...Ti−Al−V−Nb alloys with the cluster formula,12[Al−Ti_(12)](AlTi_(2))+5[Al−Ti1_(4)](V,Nb)2Ti,were designed by replacing V with Nb based on the Ti−6Al−4V alloy.Single-track cladding layers and bulk samples of the alloys with Nb contents ranging from 0 to 6.96 wt.%were prepared by laser additive manufacturing to examine their formability,microstructure,and mechanical properties.For single-track cladding layers,the addition of Nb increased the surface roughness slightly and decreased the molten pool height to improve its spreadability.The alloy,Ti−5.96Al−1.94V−3.54Nb(wt.%),exhibited better geometrical accuracy than the other alloys because its molten pool height was consistent with the spread layer thickness of the powder.The microstructures of the bulk samples contained similar columnar β-phase grains,regardless of Nb content.These grains grew epitaxially from the Ti substrate along the deposition direction,with basket-weaveα-phase laths within the columnar grains.Theα-phase size increased with increasing Nb contents,but its uniformity decreased.Along the deposition direction,the Vickers hardness increased from the substrate to the surface.The Ti−5.96Al−1.94V−3.54Nb alloy exhibited the highest Vickers hardness regardless of deposition position because of the optimal matching relationship between theα-phase size and its content among the designed alloys.展开更多
In this study,α+βTi-Al-V-Mo-Nb alloys with the addition of multiple elements that are suitable for laser additive manufacturing(LAM)were designed according to a Ti-6Al-4V cluster formula.This formula can be expresse...In this study,α+βTi-Al-V-Mo-Nb alloys with the addition of multiple elements that are suitable for laser additive manufacturing(LAM)were designed according to a Ti-6Al-4V cluster formula.This formula can be expressed as 12[Al-Ti12](AlTi2)+5[Al-Ti14]((Mo,V,Nb)2Ti),in which Mo and Nb were added into the alloys partially instead of V to give alloys with nominal compositions of Ti-6.01Al-3.13V-1.43Nb,Ti-5.97Al-2.33V-2.93Mo,and Ti-5.97Al-2.33V-2.20Mo-0.71Nb(wt.%).The microstructures and mechanical properties of the as-deposited and heat-treated samples prepared via LAM were examined.The sizes of theβcolumnar grains andαlaths in the Nb-containing samples are found to be larger than those of the Ti-6Al-4V alloy,whereas Mo-or Mo/Nb-added alloys contain finer grains.It indicates that Nb gives rise to coarsenedβcolumnar grains andαlaths,while Mo significantly refines them.Furthermore,the single addition of Nb improves the elongation,whereas the single addition of Mo enhances the strength of the alloys.The simultaneous addition of Mo/Nb significantly improves the comprehensive mechanical properties of the alloys,leading to the best properties with an ultimate tensile strength of 1,070 MPa,a yield strength of 1,004 MPa,an elongation of 9%,and micro-hardness of 355 HV.The fracture modes of all the alloys are ductile-brittle mixed fracture.展开更多
Industry 4.0 as referred to a fourth industrial revolution has endorsed in several national manufacturing development plans such as in Germany, the UK, and China. A set of important pervasive and secondary technologie...Industry 4.0 as referred to a fourth industrial revolution has endorsed in several national manufacturing development plans such as in Germany, the UK, and China. A set of important pervasive and secondary technologies for future manufacturing activities have been identified such as additive manufacturing, sensor technology, big data analytics, Internet of things, robotics, cloud computing, and nanotechnology.展开更多
With the development of the times, undergraduate colleges and universities begin to transform and develop to adapt to the changing society, and put forward new requirements for practical teaching strategies, especiall...With the development of the times, undergraduate colleges and universities begin to transform and develop to adapt to the changing society, and put forward new requirements for practical teaching strategies, especially for applied undergraduate colleges. The reform of practical teaching is particularly important. Under the development of education transformation, the reform of mechanical design and manufacture and the practice teaching of automation specialty also occupy a very important position. Through the understanding of the reform of the practical teaching of this specialty, the effect of the reform is observed, and a reasonable teaching scheme is put forward to promote the steps of the transformation of the practical teaching.展开更多
The advanced manufacturing technology of mechanical products features interaction, and high simulation, etc. In this paper, a digital geometry model for the processing is established with the aid of computer technolog...The advanced manufacturing technology of mechanical products features interaction, and high simulation, etc. In this paper, a digital geometry model for the processing is established with the aid of computer technology, so that the needs of machinery manufacturing production and precision machining can be fulfilled, and also the simulation, validation, comparison, and optimization of many plans can be implemented for ultimately finding out an optimal processing method and realizing the benefit of low cost and high quality. From two different levels of activity and parts, the configuration principle of mechanical products' advanced manufacturing technology is defined. Therefore, the advanced manufacturing technology for customizing different products can be derived, and also the reuse of different types of parts is realized. Finally, this is verified with an example.展开更多
Pretrcatment technology is deeply discussed to explain its importance in guaranteeing properties and form- ability of aluminum alloy automotive sheet. Some typical applications of aluminum alloy automotive sheet to au...Pretrcatment technology is deeply discussed to explain its importance in guaranteeing properties and form- ability 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 re- search 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
The Schwarz primitive triply periodic minimal surface(P-type TPMS)lattice structures are widely used.However,these lattice structures have weak load-bearing capacity compared with other cellular structures.In this pap...The Schwarz primitive triply periodic minimal surface(P-type TPMS)lattice structures are widely used.However,these lattice structures have weak load-bearing capacity compared with other cellular structures.In this paper,an adaptive enhancement design method based on the non-uniform stress distribution in structures with uniform thickness is proposed to design the P-type TPMS lattice structures with higher mechanical properties.Two types of structures are designed by adjusting the adaptive thickness distribution in the TPMS.One keeps the same relative density,and the other keeps the same of non-enhanced region thickness.Compared with the uniform lattice structure,the elastic modulus for the structure with the same relative density increases by more than 17%,and the yield strength increases by more than 10.2%.Three kinds of TPMS lattice structures are fabricated by laser powder bed fusion(L-PBF)with 316L stainless steel to verify the proposed enhanced design.The manufacture-induced geometric deviation between the as-design and as-printed models is measured by micro X-ray computed tomography(μ-CT)scans.The quasi-static compression experimental results of P-type TPMS lattice structures show that the reinforced structures have stronger elastic moduli,ultimate strengths,and energy absorption capabilities than the homogeneous P-TPMS lattice structure.展开更多
Based on the traditional re-entrant honeycomb,a novel re-entrant octagon honeycomb(ROH)is proposed.The deformation mode of the honeycomb under quasi-static compression is analyzed by numerical simulation,and the resul...Based on the traditional re-entrant honeycomb,a novel re-entrant octagon honeycomb(ROH)is proposed.The deformation mode of the honeycomb under quasi-static compression is analyzed by numerical simulation,and the results are in good agreement with the experimental ones.The deformation modes,mechanical properties,and energy absorption characteristics of ROH along the impact and perpendicular directions gradient design are investigated under different velocities.The results indicated that the deformation mode of ROH is affected by gradient design along the direction of impact and impact speed.In addition,gradient design along the direction of impact can increase the initial peak stress of ROH and accelerate its densification phase.Gradient design perpendicular to the impact direction can enhance the energy absorption performance of ROH,especially for ROH,with wall thickness increasing from the inside outwards.Compared to ROH with uniform wall thickness at the same relative density,ROH with a gradient design can increase the plateau stress by over half.With the elevation of impact velocity,the plateau stress and specific energy absorption exhibit an upward trend,aligning with the dynamic performance pattern observed in conventional honeycombs.The results can be used as a reference for the design and application of honeycomb and provide a new idea for developing more efficient and reliable energy-absorbing materials.展开更多
As the IC manufacturing enter sub 20nm tech nodes,DFM become more and more important to make sure more stable yield and lower cost.However,by introducing newly designed hardware(1980i etc.)process chemical(NTD)and Con...As the IC manufacturing enter sub 20nm tech nodes,DFM become more and more important to make sure more stable yield and lower cost.However,by introducing newly designed hardware(1980i etc.)process chemical(NTD)and Control Algorithm(Focus APC)into the mature tech nodes such as 14nm/12nm,more process window and less process variations are expected for latecomer wafer fabs(Tier-2/3 companies)who just started the competition with Tier-1 companies.With improved weapons,latecomer companies are able to review their DFM strategy one more time to see whether the benefit from hardware/process/control algorithm improvement can be shared with designers.In this paper,we use OPC simulation tools from different EDA suppliers to see the feasibility of transferring the benefits of hardware/process/control algorithm improvement to more relaxed design limitation through source mask optimization(SMO):1)Better hardware:scanner(better focus/exposure variation),CMP(intrafield topo),Mask CD variation(relaxed MEEF spec),etc.2) New process:from positive tone development to negative tone development.3)Better control schemes:holistic focus feedback,feedback/forward overlay control,high order CD uniformity improvement.Simulations show all those gains in hardware and process can be transferred into more relaxed design such as sub design rule structure process window include forbidden pitches(1D)and smaller E2E gaps(2D weak points).展开更多
Modem technology and manufacturing methods often require engineers who understand the fundamental principles of vibration theory and who are also skilled in vibration applications. Simply processing, remembering and a...Modem technology and manufacturing methods often require engineers who understand the fundamental principles of vibration theory and who are also skilled in vibration applications. Simply processing, remembering and applying the material learned from lectures and laboratory experiments With artificial criteria are inadequate. Hands-on teaching techniques with real-world problems are needed to complete the engineering students' education. This paper demonstrates how hands-on experiments performed in industry support and increase the students' understanding of fundamental principles and skill in their applications. Graduates with both knowledge and skill are more competitive in today's job market. A one-quarter industry-based vibration course was developed and taught with a hands-on segment at the Manufacturing and Mechanical Engineering and Technology (MMET) program at Oregon Institute of Technology (OIT) - Portland Campus. This novel instructional approach provided students with the opportunity to immediately apply material, learned in class and laboratory, in real-world industry situations with real-world problems. This instructional approach is applicable in many engineering fields and the author found the mechanical vibrations class particularly well suited for this instructional design style. The hands-on approach, grounded in the vibration course curriculum, provided a direct link to the fundamentals of vibration in industry. Student comments are included to demonstrate the value perceived by the students. Although this curriculum experiment involved mechanical engineering technology students, it would benefit mechanical engineering students equally well. In addition, the paper provides a brief description of the industries that participated in this project. Industries were selected because they use vibration based manufacturing, perform extreme testing or design their products to avoid failure due to vibrations.展开更多
Surface mount technology product manufacturing grid(SMT-MG) is a typical application which grid technology was applied to SMT product manufacturing.In this paper,for SMT-MG system,conception and intension of SMT-MG we...Surface mount technology product manufacturing grid(SMT-MG) is a typical application which grid technology was applied to SMT product manufacturing.In this paper,for SMT-MG system,conception and intension of SMT-MG were analyzed.Then six-layer architecture of SMT-MG was constructed and mesh three-dimensional matrix organization mode of SMT-MG was studied.Operation mechanism of SMT-MG was discussed emphatically which include adaptive evolution mechanism,PUSH/PULL driving mechanism,cooperation game mechanism,feedback,regulation and control mechanism,coordination mechanism and impetus mechanism.The study of SMT-MG must be useful for developing of electronic product manufacturing.展开更多
Displacement damage effects on the charge-coupled device(CCD)induced by neutrons at the back-streaming white neutron source(Back-n)in the China Spallation Neutron Source(CSNS)are analyzed according to an online irradi...Displacement damage effects on the charge-coupled device(CCD)induced by neutrons at the back-streaming white neutron source(Back-n)in the China Spallation Neutron Source(CSNS)are analyzed according to an online irradiation experiment.The hot pixels,random telegraph signal(RTS),mean dark signal,dark current and dark signal non-uniformity(DSNU)induced by Back-n are presented.The dark current is calculated according to the mean dark signal at various integration times.The single-particle displacement damage and transient response are also observed based on the online measurement data.The trends of hot pixels,mean dark signal,DSNU and RTS degradation are related to the integration time and irradiation fluence.The mean dark signal,dark current and DSNU2 are nearly linear with neutron irradiation fluence when nearly all the pixels do not reach saturation.In addition,the mechanisms of the displacement damage effects on the CCD are demonstrated by combining the experimental results and technology computer-aided design(TCAD)simulation.Radiation-induced traps in the space charge region of the CCD will act as generation/recombination centers of electron-hole pairs,leading to an increase in the dark signal.展开更多
Nasal defects are facial defects caused by trauma,tumors,or congenital diseases that seriously damage a patient’s physical and mental health.Nasal defects,from skin defects to total nasal defects,require surgical rep...Nasal defects are facial defects caused by trauma,tumors,or congenital diseases that seriously damage a patient’s physical and mental health.Nasal defects,from skin defects to total nasal defects,require surgical repair and reconstruction to restore the appearance and function of the nose,which have always been challenges for rhinoplasty.The development of digital technology has increased the possibility of nasal reconstruction.Digital technology is involved in the preoperative,intraoperative,and postoperative stages of nasal construction and is of great significance in improving the effect of this surgery.This article reviews the application of major digital technologies,including three-dimensional(3D)imaging technology,computer-assisted surgical navigation,and 3D printing,in nasal reconstruction and discusses the shortcomings of the current application of digital technology.展开更多
文摘In today’s rapidly developing modern society,automobiles,as an important part of transportation and industrial fields,play a pivotal role.With the improvement of people’s living standards and the increase in traffic demand,the automobile manufacturing industry has been continuously developing and growing globally.However,to cope with increasingly fierce market competition and ever-changing consumer demands,the automobile manufacturing industry is also facing the challenges of improving production efficiency,reducing costs,and improving product quality.In this context,automation technology has gradually become a major trend in the automobile manufacturing industry.As an important support of modern industry,automation technology has shown great application potential in many fields.From industrial production to daily life,automation technology can be seen everywhere.In the field of manufacturing,especially in automobile manufacturing,the application of automation technology is getting more and more attention.Automated production lines,intelligent robots,and automated warehousing systems have all changed the face of automobile manufacturing to varying degrees,bringing companies higher efficiency,more stable quality,and greater competitive advantages.The application trend of this automation technology in various fields not only meets the needs of modern industry for efficient,precise,and sustainable development but also provides new ideas and paths for the future development of the automobile manufacturing industry.
基金supported by the Guangdong Major Project of Basic and Applied Basic Research(2021B0301030001)project supported by the Space Utilization System of China Manned Space Engineering(KJZ-YY-WCL03)+6 种基金National Key Laboratory Foundation of Science and Technology on Materials under Shock and Impact(6142902210109)National Key Research and Development Program of China(2018YFB0905600 and 2017YFB0310400)National Natural Science Foundation of China(51472188 and 51521001)Natural Research Funds of Hubei Province(2016CFB583)Natural Research Funds of Shenzhen,Fundamental Research Funds for the Central Universities China,State Key Laboratory of Advanced Electromagnetic Engineering and Technology(Huazhong University of Science and Technology)the Science and Technology Project of the Global Energy Interconnection Research Institute Co.,Ltd.(SGGR0000WLJS1801080)the 111 Project(B13035)。
文摘Mechanical metamaterials can be defined as a class of architected materials that exhibit unprecedented mechanical properties derived from designed artificial architectures rather than their constituent materials.While macroscale and simple layouts can be realized by conventional top-down manufacturing approaches,many of the sophisticated designs at various length scales remain elusive,due to the lack of adequate manufacturing methods.Recent progress in additive manufacturing(AM)has led to the realization of a myriad of novel metamaterial concepts.AM methods capable of fabricating microscale architectures with high resolution,arbitrary complexity,and high feature fidelity have enabled the rapid development of architected meta materials and drastically reduced the design-computation and experimental-validation cycle.This paper first provides a detailed review of various topologies based on the desired mechanical properties,including stiff,strong,and auxetic(negative Poisson’s ratio)metamaterials,followed by a discussion of the AM technologies capable of fabricating these metamaterials.Finally,we discuss current challenges and recommend future directions for AM and mechanical metamaterials.
基金supported by the National Natural Science Foundation of China(Grant Nos.12172164,52250363)the National Key R&D Program of China(Grant Nos.2021YFB3801800,2018YFA0306200)。
文摘Multistable mechanical metamaterials are a type of mechanical metamaterials with special features,such as reusability,energy storage and absorption capabilities,rapid deformation,and amplified output forces.These metamaterials are usually realized by series and/or parallel of bistable units.They can exhibit multiple stable configurations under external loads and can be switched reversely among each other,thereby realizing the reusability of mechanical metamaterials and offering broad engineering applications.This paper reviews the latest research progress in the design strategy,manufacture and application of multistable mechanical metamaterials.We divide bistable structures into three categories based on their basic element types and provide the criterion of their bistability.Various manufacturing techniques to fabricate these multistable mechanical metamaterials are introduced,including mold casting,cutting,folding and three-dimensional/4D printing.Furthermore,the prospects of multistable mechanical metamaterials for applications in soft driving,mechanical computing,energy absorption and wave controlling are discussed.Finally,this paper highlights possible challenges and opportunities for future investigations.The review aims to provide insights into the research and development of multistable mechanical metamaterials.
基金the National Key Research and Development Program of China(No.2016YFB1100103)。
文摘Ti−Al−V−Nb alloys with the cluster formula,12[Al−Ti_(12)](AlTi_(2))+5[Al−Ti1_(4)](V,Nb)2Ti,were designed by replacing V with Nb based on the Ti−6Al−4V alloy.Single-track cladding layers and bulk samples of the alloys with Nb contents ranging from 0 to 6.96 wt.%were prepared by laser additive manufacturing to examine their formability,microstructure,and mechanical properties.For single-track cladding layers,the addition of Nb increased the surface roughness slightly and decreased the molten pool height to improve its spreadability.The alloy,Ti−5.96Al−1.94V−3.54Nb(wt.%),exhibited better geometrical accuracy than the other alloys because its molten pool height was consistent with the spread layer thickness of the powder.The microstructures of the bulk samples contained similar columnar β-phase grains,regardless of Nb content.These grains grew epitaxially from the Ti substrate along the deposition direction,with basket-weaveα-phase laths within the columnar grains.Theα-phase size increased with increasing Nb contents,but its uniformity decreased.Along the deposition direction,the Vickers hardness increased from the substrate to the surface.The Ti−5.96Al−1.94V−3.54Nb alloy exhibited the highest Vickers hardness regardless of deposition position because of the optimal matching relationship between theα-phase size and its content among the designed alloys.
基金the National Key Research and Development Program of China(No.2016YFB1100103)the Key Discipline and Major Project of Dalian Science and Technology Innovation Foundation(No.2020JJ25CY004)。
文摘In this study,α+βTi-Al-V-Mo-Nb alloys with the addition of multiple elements that are suitable for laser additive manufacturing(LAM)were designed according to a Ti-6Al-4V cluster formula.This formula can be expressed as 12[Al-Ti12](AlTi2)+5[Al-Ti14]((Mo,V,Nb)2Ti),in which Mo and Nb were added into the alloys partially instead of V to give alloys with nominal compositions of Ti-6.01Al-3.13V-1.43Nb,Ti-5.97Al-2.33V-2.93Mo,and Ti-5.97Al-2.33V-2.20Mo-0.71Nb(wt.%).The microstructures and mechanical properties of the as-deposited and heat-treated samples prepared via LAM were examined.The sizes of theβcolumnar grains andαlaths in the Nb-containing samples are found to be larger than those of the Ti-6Al-4V alloy,whereas Mo-or Mo/Nb-added alloys contain finer grains.It indicates that Nb gives rise to coarsenedβcolumnar grains andαlaths,while Mo significantly refines them.Furthermore,the single addition of Nb improves the elongation,whereas the single addition of Mo enhances the strength of the alloys.The simultaneous addition of Mo/Nb significantly improves the comprehensive mechanical properties of the alloys,leading to the best properties with an ultimate tensile strength of 1,070 MPa,a yield strength of 1,004 MPa,an elongation of 9%,and micro-hardness of 355 HV.The fracture modes of all the alloys are ductile-brittle mixed fracture.
文摘Industry 4.0 as referred to a fourth industrial revolution has endorsed in several national manufacturing development plans such as in Germany, the UK, and China. A set of important pervasive and secondary technologies for future manufacturing activities have been identified such as additive manufacturing, sensor technology, big data analytics, Internet of things, robotics, cloud computing, and nanotechnology.
文摘With the development of the times, undergraduate colleges and universities begin to transform and develop to adapt to the changing society, and put forward new requirements for practical teaching strategies, especially for applied undergraduate colleges. The reform of practical teaching is particularly important. Under the development of education transformation, the reform of mechanical design and manufacture and the practice teaching of automation specialty also occupy a very important position. Through the understanding of the reform of the practical teaching of this specialty, the effect of the reform is observed, and a reasonable teaching scheme is put forward to promote the steps of the transformation of the practical teaching.
文摘The advanced manufacturing technology of mechanical products features interaction, and high simulation, etc. In this paper, a digital geometry model for the processing is established with the aid of computer technology, so that the needs of machinery manufacturing production and precision machining can be fulfilled, and also the simulation, validation, comparison, and optimization of many plans can be implemented for ultimately finding out an optimal processing method and realizing the benefit of low cost and high quality. From two different levels of activity and parts, the configuration principle of mechanical products' advanced manufacturing technology is defined. Therefore, the advanced manufacturing technology for customizing different products can be derived, and also the reuse of different types of parts is realized. Finally, this is verified with an example.
文摘Pretrcatment technology is deeply discussed to explain its importance in guaranteeing properties and form- ability 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 re- search 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 by the National Natural Science Foundation of China(Nos.12002031,12122202U22B2083)+1 种基金the China Postdoctoral Science Foundation(Nos.BX2021038 and 2021M700428)the National Key Research and Development of China(No.2022YFB4601901)。
文摘The Schwarz primitive triply periodic minimal surface(P-type TPMS)lattice structures are widely used.However,these lattice structures have weak load-bearing capacity compared with other cellular structures.In this paper,an adaptive enhancement design method based on the non-uniform stress distribution in structures with uniform thickness is proposed to design the P-type TPMS lattice structures with higher mechanical properties.Two types of structures are designed by adjusting the adaptive thickness distribution in the TPMS.One keeps the same relative density,and the other keeps the same of non-enhanced region thickness.Compared with the uniform lattice structure,the elastic modulus for the structure with the same relative density increases by more than 17%,and the yield strength increases by more than 10.2%.Three kinds of TPMS lattice structures are fabricated by laser powder bed fusion(L-PBF)with 316L stainless steel to verify the proposed enhanced design.The manufacture-induced geometric deviation between the as-design and as-printed models is measured by micro X-ray computed tomography(μ-CT)scans.The quasi-static compression experimental results of P-type TPMS lattice structures show that the reinforced structures have stronger elastic moduli,ultimate strengths,and energy absorption capabilities than the homogeneous P-TPMS lattice structure.
基金This work is supported by the National Natural Science Foundation of China(No.11902232).
文摘Based on the traditional re-entrant honeycomb,a novel re-entrant octagon honeycomb(ROH)is proposed.The deformation mode of the honeycomb under quasi-static compression is analyzed by numerical simulation,and the results are in good agreement with the experimental ones.The deformation modes,mechanical properties,and energy absorption characteristics of ROH along the impact and perpendicular directions gradient design are investigated under different velocities.The results indicated that the deformation mode of ROH is affected by gradient design along the direction of impact and impact speed.In addition,gradient design along the direction of impact can increase the initial peak stress of ROH and accelerate its densification phase.Gradient design perpendicular to the impact direction can enhance the energy absorption performance of ROH,especially for ROH,with wall thickness increasing from the inside outwards.Compared to ROH with uniform wall thickness at the same relative density,ROH with a gradient design can increase the plateau stress by over half.With the elevation of impact velocity,the plateau stress and specific energy absorption exhibit an upward trend,aligning with the dynamic performance pattern observed in conventional honeycombs.The results can be used as a reference for the design and application of honeycomb and provide a new idea for developing more efficient and reliable energy-absorbing materials.
文摘As the IC manufacturing enter sub 20nm tech nodes,DFM become more and more important to make sure more stable yield and lower cost.However,by introducing newly designed hardware(1980i etc.)process chemical(NTD)and Control Algorithm(Focus APC)into the mature tech nodes such as 14nm/12nm,more process window and less process variations are expected for latecomer wafer fabs(Tier-2/3 companies)who just started the competition with Tier-1 companies.With improved weapons,latecomer companies are able to review their DFM strategy one more time to see whether the benefit from hardware/process/control algorithm improvement can be shared with designers.In this paper,we use OPC simulation tools from different EDA suppliers to see the feasibility of transferring the benefits of hardware/process/control algorithm improvement to more relaxed design limitation through source mask optimization(SMO):1)Better hardware:scanner(better focus/exposure variation),CMP(intrafield topo),Mask CD variation(relaxed MEEF spec),etc.2) New process:from positive tone development to negative tone development.3)Better control schemes:holistic focus feedback,feedback/forward overlay control,high order CD uniformity improvement.Simulations show all those gains in hardware and process can be transferred into more relaxed design such as sub design rule structure process window include forbidden pitches(1D)and smaller E2E gaps(2D weak points).
文摘Modem technology and manufacturing methods often require engineers who understand the fundamental principles of vibration theory and who are also skilled in vibration applications. Simply processing, remembering and applying the material learned from lectures and laboratory experiments With artificial criteria are inadequate. Hands-on teaching techniques with real-world problems are needed to complete the engineering students' education. This paper demonstrates how hands-on experiments performed in industry support and increase the students' understanding of fundamental principles and skill in their applications. Graduates with both knowledge and skill are more competitive in today's job market. A one-quarter industry-based vibration course was developed and taught with a hands-on segment at the Manufacturing and Mechanical Engineering and Technology (MMET) program at Oregon Institute of Technology (OIT) - Portland Campus. This novel instructional approach provided students with the opportunity to immediately apply material, learned in class and laboratory, in real-world industry situations with real-world problems. This instructional approach is applicable in many engineering fields and the author found the mechanical vibrations class particularly well suited for this instructional design style. The hands-on approach, grounded in the vibration course curriculum, provided a direct link to the fundamentals of vibration in industry. Student comments are included to demonstrate the value perceived by the students. Although this curriculum experiment involved mechanical engineering technology students, it would benefit mechanical engineering students equally well. In addition, the paper provides a brief description of the industries that participated in this project. Industries were selected because they use vibration based manufacturing, perform extreme testing or design their products to avoid failure due to vibrations.
文摘Surface mount technology product manufacturing grid(SMT-MG) is a typical application which grid technology was applied to SMT product manufacturing.In this paper,for SMT-MG system,conception and intension of SMT-MG were analyzed.Then six-layer architecture of SMT-MG was constructed and mesh three-dimensional matrix organization mode of SMT-MG was studied.Operation mechanism of SMT-MG was discussed emphatically which include adaptive evolution mechanism,PUSH/PULL driving mechanism,cooperation game mechanism,feedback,regulation and control mechanism,coordination mechanism and impetus mechanism.The study of SMT-MG must be useful for developing of electronic product manufacturing.
基金Project supported by the Foundation of State Key Laboratory of China(Grant Nos.SKLIPR1903Z,1803)the National Natural Science Foundation of China(Grant Nos.U2167208 and 11875223).
文摘Displacement damage effects on the charge-coupled device(CCD)induced by neutrons at the back-streaming white neutron source(Back-n)in the China Spallation Neutron Source(CSNS)are analyzed according to an online irradiation experiment.The hot pixels,random telegraph signal(RTS),mean dark signal,dark current and dark signal non-uniformity(DSNU)induced by Back-n are presented.The dark current is calculated according to the mean dark signal at various integration times.The single-particle displacement damage and transient response are also observed based on the online measurement data.The trends of hot pixels,mean dark signal,DSNU and RTS degradation are related to the integration time and irradiation fluence.The mean dark signal,dark current and DSNU2 are nearly linear with neutron irradiation fluence when nearly all the pixels do not reach saturation.In addition,the mechanisms of the displacement damage effects on the CCD are demonstrated by combining the experimental results and technology computer-aided design(TCAD)simulation.Radiation-induced traps in the space charge region of the CCD will act as generation/recombination centers of electron-hole pairs,leading to an increase in the dark signal.
基金supported by the Clinical Key Project of the Peking University Third Hospital(grant no.BYSYFY2021005).
文摘Nasal defects are facial defects caused by trauma,tumors,or congenital diseases that seriously damage a patient’s physical and mental health.Nasal defects,from skin defects to total nasal defects,require surgical repair and reconstruction to restore the appearance and function of the nose,which have always been challenges for rhinoplasty.The development of digital technology has increased the possibility of nasal reconstruction.Digital technology is involved in the preoperative,intraoperative,and postoperative stages of nasal construction and is of great significance in improving the effect of this surgery.This article reviews the application of major digital technologies,including three-dimensional(3D)imaging technology,computer-assisted surgical navigation,and 3D printing,in nasal reconstruction and discusses the shortcomings of the current application of digital technology.