Strong impact does serious harm to the military industries so it is necessary to choose reasonable cushioning material and design effective buffers to prevent the impact of equipment.Based on the capillary property en...Strong impact does serious harm to the military industries so it is necessary to choose reasonable cushioning material and design effective buffers to prevent the impact of equipment.Based on the capillary property entangled porous metallic wire materials(EPMWM),this paper designed a composite buffer which uses EPMWM and viscous fluid as cushioning materials under the low-speed impact of the recoil force device of weapon equipment(such as artillery,mortar,etc.).Combined with the capillary model,porosity,hydraulic diameter,maximum pore diameter and pore distribution were used to characterize the pore structure characteristics of EPMWM.The calculation model of the damping force of the composite buffer was established.The low-speed impact test of the composite buffer was conducted.The parameters of the buffer under low-speed impact were identified according to the model,and the nonlinear model of damping force was obtained.The test results show that the composite buffer with EPMWM and viscous fluid can absorb the impact energy from the recoil movement effectively,and provide a new method for the buffer design of weapon equipment(such as artillery,mortar,etc.).展开更多
To improve the defense capability of military equipment under extreme conditions,impact-resistant and high-energy-consuming materials have to be developed.The damping characteristic of entangled porous metallic wire m...To improve the defense capability of military equipment under extreme conditions,impact-resistant and high-energy-consuming materials have to be developed.The damping characteristic of entangled porous metallic wire materials(EPMWM)for vibration isolation was previously investigated.In this paper,a study focusing on the impact-resistance of EPMWM with the consideration of ambient temperature is presented.The quasi-static and low-velocity impact mechanical behavior of EPMWM under different temperatures(25℃-300℃)are systematically studied.The results of the static compression test show that the damping energy dissipation of EPMWM increases with temperature while the nonlinear damping characteristics are gradually enhanced.During the impact experiments,the impact energy loss rate of EPMWM was between 65%and 85%,while the temperatures increased from 25℃to 300℃.Moreover,under the same drop impact conditions,the overall deformation of EPMWM decreases in the temperature range of 100℃-200℃.On the other hand,the impact stiffness,energy dissipation,and impact loss factor of EPMWM significantly increase with temperature.This can be attributed to an increase in temperature,which changes the thermal expansion coefficient and contact state of the internal wire helixes.Consequently,the energy dissipation mode(dry friction,air damping,and plastic deformation)of EPMWM is also altered.Therefore,the EPMWM may act as a potential candidate material for superior energy absorption applications.展开更多
Entangled porous metallic wire material(EPMWM)has the potential as a thermal insulation material in defence and engineering.In order to optimize its thermophysical properties at the design stage,it is of great signifi...Entangled porous metallic wire material(EPMWM)has the potential as a thermal insulation material in defence and engineering.In order to optimize its thermophysical properties at the design stage,it is of great significance to reveal the thermal response mechanism of EPMWM based on its complex structural effects.In the present work,virtual manufacturing technology(VMT)was developed to restore the physics-based 3D model of EPMWM.On this basis,the transient thermal analysis is carried out to explore the contact-relevant thermal behavior of EPMWM,and then the spiral unit containing unique structural information are further extracted and counted.In particular,the thermal resistance network is numerically constructed based on the spiral unit through the thermoelectric analogy method to accurately predict the effective thermal conductivity(ETC)of EPMWM.Finally,the thermal diffusivity and specific heat of the samples were obtained by the laser thermal analyzer to calculate the ETC and thermal insulation factor of interest.The results show that the ETC of EPMWM increases with increasing temperature or reducing density under the experimental conditions.The numerical prediction is consistent with the experimental result and the average error is less than 4%.展开更多
The FeCrA1 fiber was used to prepare porous metal materials with air-laid technology, and then followed by sintering at 1300 ℃ for a holding period of 2 h in the vacuum. In addition, a novel fractal soft, which was d...The FeCrA1 fiber was used to prepare porous metal materials with air-laid technology, and then followed by sintering at 1300 ℃ for a holding period of 2 h in the vacuum. In addition, a novel fractal soft, which was developed based on the fractal theory and the computer image processing technology, was explored to describe the pore structure of porous metal materials. Furthermore, the fractal dimension of pore structure was calculated by the soft and the effects of magnification and porosity on ffactal dimension were also discussed. The results show that the fractal dimension decreases with increase in the magnification, while it increases continuously with the porosity enhancing. The interrelationship between the fractal dimension and the magnification or porosity can be presented by the equation of D=α_0exp(-x/α_1)+α_2和D=k_2-(k_1-k_2)/[1+exp((θ-k_0)/k_3)], respectively.展开更多
The effect of deformation of porous material on infiltrative performance is investigated. Based on Darcy theory and Boit principle, the Reynolds equation and mathematical expression of deformable metal rubber (MR) m...The effect of deformation of porous material on infiltrative performance is investigated. Based on Darcy theory and Boit principle, the Reynolds equation and mathematical expression of deformable metal rubber (MR) material under laminar flow are obtained according to the change of porosity of metal rubber. It is shown that the throttle of MR material is dependent on its porosity and diameter of metal wires. It will be of great value for the application of MR in throttle field.展开更多
Magnesia-chrome porous purging plugs are crucial functional components to remove inclusions and stabilize the flow field during iron and steel smelting.However,practical applications of magnesia-chrome porous purging ...Magnesia-chrome porous purging plugs are crucial functional components to remove inclusions and stabilize the flow field during iron and steel smelting.However,practical applications of magnesia-chrome porous purging materials are stil hampered by the poor scouring resistance to molten steel and unstable air permeability owing to their low mechanical properties and uncontrollable pore structure.Therefore,the particle-packing type magnesiachrome porous purging materials reinforced by in situ formed spinel were prepared using fused magnesia-chrome particles and Al powders as major raw materials.The results show that in situ formed spinel solid solutions in bonding phase led to the decreased median pore size and increased pore surface fractal dimension from the reactions between Al powders and magnesia-chrome particles and along with high-temperature sintering,bonding between magnesia-chrome particles and the resultant mechanical properties of materials were greatly elevated.Besides,the results of air permeability tests and polynomial ftting indicated that the formation of spinel solid solutions was the main contributing factor for controllable air permeability,and pressure drop of porous purging materials was positively correlated with surface fractal dimension of pores.Moreover,the as-prepared porous purging materials added with 6 wt.%Al powders obtained the maximum cold crushing strength(54.2 MPa)and hot modulus of rupture(12.9 MPa)with median pore size of 24.06μm and ftting non-Darcian permeability coefficient of 0.97×10^(-6)m.展开更多
Among various gas sensing materials, metal oxide semiconductors have shown great potential as resistive type sensors. The ordered porous structural metal oxide semiconductors with well-defined meso- or macro-pores che...Among various gas sensing materials, metal oxide semiconductors have shown great potential as resistive type sensors. The ordered porous structural metal oxide semiconductors with well-defined meso- or macro-pores chemically synthesized via soft-templating method and nanocasting strategy have high porosity, highly interconnected pore channels and high surface area with enormous active sites for interacting with gaseous molecules. These features enable them good performance in gas sensing, including high sensitivity, fast response and recovery, good selectivity. This review gives a comprehensive summary about the porous metal oxides with focus on the synthesis methods, structure related properties, as well as the modification strategies for gas sensing improved performances.展开更多
基金supported by the National Natural Science Foundation of China (Grant No.51805086)。
文摘Strong impact does serious harm to the military industries so it is necessary to choose reasonable cushioning material and design effective buffers to prevent the impact of equipment.Based on the capillary property entangled porous metallic wire materials(EPMWM),this paper designed a composite buffer which uses EPMWM and viscous fluid as cushioning materials under the low-speed impact of the recoil force device of weapon equipment(such as artillery,mortar,etc.).Combined with the capillary model,porosity,hydraulic diameter,maximum pore diameter and pore distribution were used to characterize the pore structure characteristics of EPMWM.The calculation model of the damping force of the composite buffer was established.The low-speed impact test of the composite buffer was conducted.The parameters of the buffer under low-speed impact were identified according to the model,and the nonlinear model of damping force was obtained.The test results show that the composite buffer with EPMWM and viscous fluid can absorb the impact energy from the recoil movement effectively,and provide a new method for the buffer design of weapon equipment(such as artillery,mortar,etc.).
基金supported by the National Natural Science Foundation of China(grant number 51805086)the Natural Science Foundation of Fujian Province,China(grant number 2018J01763)。
文摘To improve the defense capability of military equipment under extreme conditions,impact-resistant and high-energy-consuming materials have to be developed.The damping characteristic of entangled porous metallic wire materials(EPMWM)for vibration isolation was previously investigated.In this paper,a study focusing on the impact-resistance of EPMWM with the consideration of ambient temperature is presented.The quasi-static and low-velocity impact mechanical behavior of EPMWM under different temperatures(25℃-300℃)are systematically studied.The results of the static compression test show that the damping energy dissipation of EPMWM increases with temperature while the nonlinear damping characteristics are gradually enhanced.During the impact experiments,the impact energy loss rate of EPMWM was between 65%and 85%,while the temperatures increased from 25℃to 300℃.Moreover,under the same drop impact conditions,the overall deformation of EPMWM decreases in the temperature range of 100℃-200℃.On the other hand,the impact stiffness,energy dissipation,and impact loss factor of EPMWM significantly increase with temperature.This can be attributed to an increase in temperature,which changes the thermal expansion coefficient and contact state of the internal wire helixes.Consequently,the energy dissipation mode(dry friction,air damping,and plastic deformation)of EPMWM is also altered.Therefore,the EPMWM may act as a potential candidate material for superior energy absorption applications.
基金National Natural Science Foundation of China(Grant Nos.52175162,51805086 and 51975123)Natural Science Foundation of Fujian Province,China(Grant No.2019J01210)Health Education Joint Project of Fujian Province,China(Grant No.2019-WJ-01).
文摘Entangled porous metallic wire material(EPMWM)has the potential as a thermal insulation material in defence and engineering.In order to optimize its thermophysical properties at the design stage,it is of great significance to reveal the thermal response mechanism of EPMWM based on its complex structural effects.In the present work,virtual manufacturing technology(VMT)was developed to restore the physics-based 3D model of EPMWM.On this basis,the transient thermal analysis is carried out to explore the contact-relevant thermal behavior of EPMWM,and then the spiral unit containing unique structural information are further extracted and counted.In particular,the thermal resistance network is numerically constructed based on the spiral unit through the thermoelectric analogy method to accurately predict the effective thermal conductivity(ETC)of EPMWM.Finally,the thermal diffusivity and specific heat of the samples were obtained by the laser thermal analyzer to calculate the ETC and thermal insulation factor of interest.The results show that the ETC of EPMWM increases with increasing temperature or reducing density under the experimental conditions.The numerical prediction is consistent with the experimental result and the average error is less than 4%.
基金Project(2011CB610302) supported by the National Basic Research Program of ChinaProjects(51074130,51134003) supported by the National Natural Science Foundation of ChinaProject(20110491699) supported by the National Science Foundation for Post-doctoral Scientists of China
文摘The FeCrA1 fiber was used to prepare porous metal materials with air-laid technology, and then followed by sintering at 1300 ℃ for a holding period of 2 h in the vacuum. In addition, a novel fractal soft, which was developed based on the fractal theory and the computer image processing technology, was explored to describe the pore structure of porous metal materials. Furthermore, the fractal dimension of pore structure was calculated by the soft and the effects of magnification and porosity on ffactal dimension were also discussed. The results show that the fractal dimension decreases with increase in the magnification, while it increases continuously with the porosity enhancing. The interrelationship between the fractal dimension and the magnification or porosity can be presented by the equation of D=α_0exp(-x/α_1)+α_2和D=k_2-(k_1-k_2)/[1+exp((θ-k_0)/k_3)], respectively.
基金This project is supported by National Natural Science Foundation of China (No.50075017)Municipal Youth Foundation of Harbin, China(No.2003AFQXJ035).
文摘The effect of deformation of porous material on infiltrative performance is investigated. Based on Darcy theory and Boit principle, the Reynolds equation and mathematical expression of deformable metal rubber (MR) material under laminar flow are obtained according to the change of porosity of metal rubber. It is shown that the throttle of MR material is dependent on its porosity and diameter of metal wires. It will be of great value for the application of MR in throttle field.
基金the National Natural Science Foundation of China(U21A2057)the Key Research and Development Project of Hubei Province,China(2022BAA032).
文摘Magnesia-chrome porous purging plugs are crucial functional components to remove inclusions and stabilize the flow field during iron and steel smelting.However,practical applications of magnesia-chrome porous purging materials are stil hampered by the poor scouring resistance to molten steel and unstable air permeability owing to their low mechanical properties and uncontrollable pore structure.Therefore,the particle-packing type magnesiachrome porous purging materials reinforced by in situ formed spinel were prepared using fused magnesia-chrome particles and Al powders as major raw materials.The results show that in situ formed spinel solid solutions in bonding phase led to the decreased median pore size and increased pore surface fractal dimension from the reactions between Al powders and magnesia-chrome particles and along with high-temperature sintering,bonding between magnesia-chrome particles and the resultant mechanical properties of materials were greatly elevated.Besides,the results of air permeability tests and polynomial ftting indicated that the formation of spinel solid solutions was the main contributing factor for controllable air permeability,and pressure drop of porous purging materials was positively correlated with surface fractal dimension of pores.Moreover,the as-prepared porous purging materials added with 6 wt.%Al powders obtained the maximum cold crushing strength(54.2 MPa)and hot modulus of rupture(12.9 MPa)with median pore size of 24.06μm and ftting non-Darcian permeability coefficient of 0.97×10^(-6)m.
基金supported by the National Natural Science Foundation of China(Nos.51372041,51422202, and 21673048)the "Shu Guang" Project(No. 13SG02)supported by Shanghai Municipal Education Commission and Shanghai Education Development Foundation+3 种基金the National Youth Top-notch Talent Support Program in China, China Postdoctoral Science Foundation(No. KLH1615138)Shanghai Nature Science Foundation of China(Nos. 14ZR1416600 and 15ZR1402000)Shanghai Pujiang Program, China(No.16PJ1401100)the International Scientific Partnership Program ISPP at King Saud University for funding this research work through ISPP# 0094
文摘Among various gas sensing materials, metal oxide semiconductors have shown great potential as resistive type sensors. The ordered porous structural metal oxide semiconductors with well-defined meso- or macro-pores chemically synthesized via soft-templating method and nanocasting strategy have high porosity, highly interconnected pore channels and high surface area with enormous active sites for interacting with gaseous molecules. These features enable them good performance in gas sensing, including high sensitivity, fast response and recovery, good selectivity. This review gives a comprehensive summary about the porous metal oxides with focus on the synthesis methods, structure related properties, as well as the modification strategies for gas sensing improved performances.