Light-weight magnesium -aluminate spinel materi- als were prepared by foaming-gel process with polyalumi- nium chloride （PAC） as gel. Effect of solid loading in initial slurry on microstructure, porosity, pore size ...Light-weight magnesium -aluminate spinel materi- als were prepared by foaming-gel process with polyalumi- nium chloride （PAC） as gel. Effect of solid loading in initial slurry on microstructure, porosity, pore size distri- bution, thermal conductivity and mechanical properties was investigated. The results show that the bulk density of the light-weight magnesium -aluminate spinel mate- rials is in the range of O. 7 1.2 g cm-3 ; pore size distribution curves show single-peak characteristics and the mean pore size is in the range of 30. 83 - 61.37 μm ; with the increase of solid loading, the linear shrinkage of the green body during firing and the permanent change in dimensions on heating at l 600 ℃ for 3 h de- crease, but the bulk density increases, the mechanical properties increase obviously; the maximum compressive strength and bending strength reach 35. 25 MPa and 9. 92 MPa, respectively, while the bulk density is 1. 16 g · cm ; and the thermal conductivity at 1 000 ℃ tea- ches 0. 371 W · m-1 . K-1 while the bulk density is O. 7 -3 g · cm展开更多
Ultra-large aluminum shape castings have been increasingly used in automotive vehicles,particularly in electric vehicles for light-weighting and vehicle manufacturing cost reduction.As most of them are structural comp...Ultra-large aluminum shape castings have been increasingly used in automotive vehicles,particularly in electric vehicles for light-weighting and vehicle manufacturing cost reduction.As most of them are structural components subject to both quasi-static,dynamic and cyclic loading,the quality and quantifiable performance of the ultra-large aluminum shape castings is critical to their success in both design and manufacturing.This paper briefly reviews some application examples of ultra-large aluminum castings in automotive industry and outlines their advantages and benefits.Factors affecting quality,microstructure and mechanical properties of ultra-large aluminum castings are evaluated and discussed as aluminum shape casting processing is very complex and often involves many competing mechanisms,multi-physics phenomena,and potentially large uncertainties that significantly influence the casting quality and performance.Metallurgical analysis and mechanical property assessment of an ultra-large aluminum shape casting are presented.Challenges are highlighted and suggestions are made for robust design and manufacturing of ultra-large aluminum castings.展开更多
Dynastes tityus(D.tityus)is a typical beetle whose elytra are light and strong.The primary function of elytra is to protect beetle's hindwings.In this paper,D.tityus elytra were selected as the biological prototyp...Dynastes tityus(D.tityus)is a typical beetle whose elytra are light and strong.The primary function of elytra is to protect beetle's hindwings.In this paper,D.tityus elytra were selected as the biological prototype for the investigation to obtain bio-inspirations for the design and development of light materials with high ratio of strength to mass.Firstly,the microstructure investigation and quasi-static nanoindentation tests have been carried out on the ten samples of the selected elytra ofD.tityus to reveal their mechanical properties and microstructures.Secondly,based on the fmdings from the microstructure investigation and nanoindentation tests,three models of bio-inspired materials have been proposed for further study to gain the deep understanding of the relationships between the special mechanical characteristics and microstructures.Then Finite Element Analysis(FEA)simulations have been performed on the three models for harvesting the bio-inspirations for the initial design of light materials.Finally,through comparative analysis of the findings from the microstructure investigation,the nanoindentation tests and the simulations,some meaningful bio-inspirations have been reaped for the future optimization of the design and development of light materials with high ratio of strength to mass.展开更多
We have introduced a polymer precursor into molten magnesium and then in-situ pyrolyzed to produce castings of metal matrix composites(P-MMCs)containing silicon-carbonitride(SiCNO)ceramic particles.Stress-rupture meas...We have introduced a polymer precursor into molten magnesium and then in-situ pyrolyzed to produce castings of metal matrix composites(P-MMCs)containing silicon-carbonitride(SiCNO)ceramic particles.Stress-rupture measurements of as-cast P-MMCs was performed at 350 ℃(0.69TM)to 450 ℃(0.78TM)under dead load condition corresponding to tensile stress of 2.5 MPa to 20 MPa.The time-to-fracture data were analyzed using the classical Monkman–Grant equation.The time-to-fracture is thermally activated and follows a power-law stress exponent exhibiting dislocation creep.Fractography analysis revealed that while pure magnesium appears to fracture by dislocation slip,the P-MMCs fail from the nucleation and growth of voids at the grain boundaries.展开更多
Experiments were conducted to investigate bed forms and flow resistance of light-weight sediment in an open channel flow. Three different synthetic materials of specific gravity 1. 055, 1. 46, each with uniform sizes ...Experiments were conducted to investigate bed forms and flow resistance of light-weight sediment in an open channel flow. Three different synthetic materials of specific gravity 1. 055, 1. 46, each with uniform sizes D50 for 1. 25mm, 1. 05mm, 1. 40mm were used. Some conclusions were obtained from the resultS of these experiments and the data of other reliable sources[1, 2, 3, 4]. They indicate that the grain resistence is greatly affected by D50, and bed form resistances is the function of the downstream slope and the height of the dune. As well as natural sand, Y is not only the function of Y', but also affected by the relative roughness Rb/D50 and the size of the sediment.展开更多
为解决船舶产品设计(Ship Product Design,SPD)软件在舾装件制作图出图及物料清单(Bill of Material,BOM)输出方面经常需要设计师大量手动干预、设计效率低下的问题,开发舾装快速出图系统。基于SPD二次开发接口,实现舾装标准件数量和材...为解决船舶产品设计(Ship Product Design,SPD)软件在舾装件制作图出图及物料清单(Bill of Material,BOM)输出方面经常需要设计师大量手动干预、设计效率低下的问题,开发舾装快速出图系统。基于SPD二次开发接口,实现舾装标准件数量和材料的快速抽取,1∶1制作图的批量生成,材料明细表和部件列表的自由增删改,图名、图号和页码的自动批处理,各类BOM数据定制化表格的自动输出等功能。该系统成功应用于实船舾装设计,大幅提升舾装件制作图和BOM表的绘制效率,为后续舾装件的自动化和智能化生产提供数据支撑。展开更多
基金supported by the National Basic Research Program of China(973 Program,No.2010CB735810)
文摘Light-weight magnesium -aluminate spinel materi- als were prepared by foaming-gel process with polyalumi- nium chloride （PAC） as gel. Effect of solid loading in initial slurry on microstructure, porosity, pore size distri- bution, thermal conductivity and mechanical properties was investigated. The results show that the bulk density of the light-weight magnesium -aluminate spinel mate- rials is in the range of O. 7 1.2 g cm-3 ; pore size distribution curves show single-peak characteristics and the mean pore size is in the range of 30. 83 - 61.37 μm ; with the increase of solid loading, the linear shrinkage of the green body during firing and the permanent change in dimensions on heating at l 600 ℃ for 3 h de- crease, but the bulk density increases, the mechanical properties increase obviously; the maximum compressive strength and bending strength reach 35. 25 MPa and 9. 92 MPa, respectively, while the bulk density is 1. 16 g · cm ; and the thermal conductivity at 1 000 ℃ tea- ches 0. 371 W · m-1 . K-1 while the bulk density is O. 7 -3 g · cm
文摘Ultra-large aluminum shape castings have been increasingly used in automotive vehicles,particularly in electric vehicles for light-weighting and vehicle manufacturing cost reduction.As most of them are structural components subject to both quasi-static,dynamic and cyclic loading,the quality and quantifiable performance of the ultra-large aluminum shape castings is critical to their success in both design and manufacturing.This paper briefly reviews some application examples of ultra-large aluminum castings in automotive industry and outlines their advantages and benefits.Factors affecting quality,microstructure and mechanical properties of ultra-large aluminum castings are evaluated and discussed as aluminum shape casting processing is very complex and often involves many competing mechanisms,multi-physics phenomena,and potentially large uncertainties that significantly influence the casting quality and performance.Metallurgical analysis and mechanical property assessment of an ultra-large aluminum shape casting are presented.Challenges are highlighted and suggestions are made for robust design and manufacturing of ultra-large aluminum castings.
基金National Natural Science Foundation of China (No.31672348),National Key R&D Program of China (No.2016YFE0112100)China-EU H2020 FabSurfWAR project (No.644971)by 111 project (No.B16020)of China.
文摘Dynastes tityus(D.tityus)is a typical beetle whose elytra are light and strong.The primary function of elytra is to protect beetle's hindwings.In this paper,D.tityus elytra were selected as the biological prototype for the investigation to obtain bio-inspirations for the design and development of light materials with high ratio of strength to mass.Firstly,the microstructure investigation and quasi-static nanoindentation tests have been carried out on the ten samples of the selected elytra ofD.tityus to reveal their mechanical properties and microstructures.Secondly,based on the fmdings from the microstructure investigation and nanoindentation tests,three models of bio-inspired materials have been proposed for further study to gain the deep understanding of the relationships between the special mechanical characteristics and microstructures.Then Finite Element Analysis(FEA)simulations have been performed on the three models for harvesting the bio-inspirations for the initial design of light materials.Finally,through comparative analysis of the findings from the microstructure investigation,the nanoindentation tests and the simulations,some meaningful bio-inspirations have been reaped for the future optimization of the design and development of light materials with high ratio of strength to mass.
基金the Metals and Nanomaterials program in the Division of Materials Research at the National Science Foundation under Grant No.DMR1105347.
文摘We have introduced a polymer precursor into molten magnesium and then in-situ pyrolyzed to produce castings of metal matrix composites(P-MMCs)containing silicon-carbonitride(SiCNO)ceramic particles.Stress-rupture measurements of as-cast P-MMCs was performed at 350 ℃(0.69TM)to 450 ℃(0.78TM)under dead load condition corresponding to tensile stress of 2.5 MPa to 20 MPa.The time-to-fracture data were analyzed using the classical Monkman–Grant equation.The time-to-fracture is thermally activated and follows a power-law stress exponent exhibiting dislocation creep.Fractography analysis revealed that while pure magnesium appears to fracture by dislocation slip,the P-MMCs fail from the nucleation and growth of voids at the grain boundaries.
文摘Experiments were conducted to investigate bed forms and flow resistance of light-weight sediment in an open channel flow. Three different synthetic materials of specific gravity 1. 055, 1. 46, each with uniform sizes D50 for 1. 25mm, 1. 05mm, 1. 40mm were used. Some conclusions were obtained from the resultS of these experiments and the data of other reliable sources[1, 2, 3, 4]. They indicate that the grain resistence is greatly affected by D50, and bed form resistances is the function of the downstream slope and the height of the dune. As well as natural sand, Y is not only the function of Y', but also affected by the relative roughness Rb/D50 and the size of the sediment.
文摘为解决船舶产品设计(Ship Product Design,SPD)软件在舾装件制作图出图及物料清单(Bill of Material,BOM)输出方面经常需要设计师大量手动干预、设计效率低下的问题,开发舾装快速出图系统。基于SPD二次开发接口,实现舾装标准件数量和材料的快速抽取,1∶1制作图的批量生成,材料明细表和部件列表的自由增删改,图名、图号和页码的自动批处理,各类BOM数据定制化表格的自动输出等功能。该系统成功应用于实船舾装设计,大幅提升舾装件制作图和BOM表的绘制效率,为后续舾装件的自动化和智能化生产提供数据支撑。
