A new technology—the thixoforging of ceramics/metal composites in pseudo-semi-solid state was proposed based on the powder metallurgy technology combined with semi-solid metal forming process, and the cup shell of au...A new technology—the thixoforging of ceramics/metal composites in pseudo-semi-solid state was proposed based on the powder metallurgy technology combined with semi-solid metal forming process, and the cup shell of automobile piston with Al2O3/Al composites was prepared. It is proved through metallographic analyses and three-point bending tests that the technology is feasible for the ceramics/metal composites forming. The results show that the tough strength and the degree of hardness of the samples with certain plasticity are high. It will play a very large role in accelerating the ceramics composites and high melt point materials use in more fields and tamp the foundation for further studies of this technology.展开更多
The dynamic buckling of elasto-plastic cylindrical shells under axial fluid-solid impact is investigated theoretically. A simplified liquid- gas- structure model is given to approximately imitate the problem. The basi...The dynamic buckling of elasto-plastic cylindrical shells under axial fluid-solid impact is investigated theoretically. A simplified liquid- gas- structure model is given to approximately imitate the problem. The basic equation of the structure is derived from a minimum principle in dynamics of elasto-plastic continua at finite deformation, and the flow theory of plasticity is employed. The liquid is incompressible and the gas is compressed adiabatically. A number of numerical results are presented and the characteristics of the buckling behavior under fluid-solid impact are illustrated.展开更多
In this paper, the axisymmetric problems of arbitrary thick spherical shell and solid sphere are studied directly from equilibrium equations of three-dimensional problem, and the general solutions informs of Legendre ...In this paper, the axisymmetric problems of arbitrary thick spherical shell and solid sphere are studied directly from equilibrium equations of three-dimensional problem, and the general solutions informs of Legendre serifs for thick spherical shell and solid sphere are given by using the method of weighted residuals.展开更多
To fabricate electronic packaging shell of coppermatrix composite with characteristics of high ther mal conductivity and low thermal expansion coefficient, semisolid forming technology, and powder metallurgy was combi...To fabricate electronic packaging shell of coppermatrix composite with characteristics of high ther mal conductivity and low thermal expansion coefficient, semisolid forming technology, and powder metallurgy was combined. Conventional mechanical mixing of Cu and SiC could have insufficient wettability, and a new method of semisolid processing was introduced for billets preparation. The SiC/Cu composites were first prepared by PM, and then, semisolid reheating was performed for the successive semisolid forging. Composite billets with SiC 35 % vol ume fraction were compacted and sintered pressurelessly, microstructure analysis showed that the composites pre pared by PM had high density, and the combination between SiC particles and Cualloy was good. Semisolid reheating was the crucial factor in determining the micro structure and thixotropic property of the billet. An opti mised reheating strategy was proposed： temperature 1,025 ℃and holding time 5 min.展开更多
The dynamic behaviors of rotating shells coupled with liquid areshown. The shell under con- sideration has arbitrary boundaryconditions and a complex shape. A modified boundary element methodand finite strip technique...The dynamic behaviors of rotating shells coupled with liquid areshown. The shell under con- sideration has arbitrary boundaryconditions and a complex shape. A modified boundary element methodand finite strip technique are used to improve the computingefficiency and to guarantee the continuity conditions on theliquid-shell interaction plane. The effects of various parameterssuch as shell's thickness and liquid depth are investigated. Dynamicsimulations are applied to several typical shell-liquid systems, andthe natu- ral frequencies, mode shapes and response of vibration arecalculated numerically.展开更多
基金Project(50375035) supported by the National Natural Science Foundation of China
文摘A new technology—the thixoforging of ceramics/metal composites in pseudo-semi-solid state was proposed based on the powder metallurgy technology combined with semi-solid metal forming process, and the cup shell of automobile piston with Al2O3/Al composites was prepared. It is proved through metallographic analyses and three-point bending tests that the technology is feasible for the ceramics/metal composites forming. The results show that the tough strength and the degree of hardness of the samples with certain plasticity are high. It will play a very large role in accelerating the ceramics composites and high melt point materials use in more fields and tamp the foundation for further studies of this technology.
文摘The dynamic buckling of elasto-plastic cylindrical shells under axial fluid-solid impact is investigated theoretically. A simplified liquid- gas- structure model is given to approximately imitate the problem. The basic equation of the structure is derived from a minimum principle in dynamics of elasto-plastic continua at finite deformation, and the flow theory of plasticity is employed. The liquid is incompressible and the gas is compressed adiabatically. A number of numerical results are presented and the characteristics of the buckling behavior under fluid-solid impact are illustrated.
文摘In this paper, the axisymmetric problems of arbitrary thick spherical shell and solid sphere are studied directly from equilibrium equations of three-dimensional problem, and the general solutions informs of Legendre serifs for thick spherical shell and solid sphere are given by using the method of weighted residuals.
基金supported by the National Natural Science Foundation of China(No.51174028)the Beijing Natural Science Foundation(No.2102029)
文摘To fabricate electronic packaging shell of coppermatrix composite with characteristics of high ther mal conductivity and low thermal expansion coefficient, semisolid forming technology, and powder metallurgy was combined. Conventional mechanical mixing of Cu and SiC could have insufficient wettability, and a new method of semisolid processing was introduced for billets preparation. The SiC/Cu composites were first prepared by PM, and then, semisolid reheating was performed for the successive semisolid forging. Composite billets with SiC 35 % vol ume fraction were compacted and sintered pressurelessly, microstructure analysis showed that the composites pre pared by PM had high density, and the combination between SiC particles and Cualloy was good. Semisolid reheating was the crucial factor in determining the micro structure and thixotropic property of the billet. An opti mised reheating strategy was proposed： temperature 1,025 ℃and holding time 5 min.
基金the National Natural Science Foundation of China(No.19702004)
文摘The dynamic behaviors of rotating shells coupled with liquid areshown. The shell under con- sideration has arbitrary boundaryconditions and a complex shape. A modified boundary element methodand finite strip technique are used to improve the computingefficiency and to guarantee the continuity conditions on theliquid-shell interaction plane. The effects of various parameterssuch as shell's thickness and liquid depth are investigated. Dynamicsimulations are applied to several typical shell-liquid systems, andthe natu- ral frequencies, mode shapes and response of vibration arecalculated numerically.
