Variable-diameter deployable carbon fiber reinforced polymer(CFRP)composites possess deformation and load-bearing functions and are composed of stiff-flexible coupled preforms and matrix.The stiff-flexible coupled pre...Variable-diameter deployable carbon fiber reinforced polymer(CFRP)composites possess deformation and load-bearing functions and are composed of stiff-flexible coupled preforms and matrix.The stiff-flexible coupled preform,serving as the reinforcing structure,directly determines the deployable properties,and its forming technology is currently a research challenge.This paper designs a braiding and needle-punching(BNP)composite preform forming technology suitable for stiff-flexible coupled preforms.Before forming,the preform is partitioned into flexible and rigid zones,with braiding and needle-punching performed layer by layer in the respective zones.A retractable rotating device is developed to form the stiff-flexible coupled preform,achieving a diameter variation rate of up to 26.6%for the BNP preform.A structural parameter model is also established to describe the geometric parameter changes in the deformation and load-bearing areas of the preform during deployment as a function of the braiding angle.Based on experiments,this paper explains the performance changes of BNP composites concerning the structural parameters of the preform.Experimental analysis shows that as the braiding angle increases,the tensile performance of BNP composites significantly decreases,with the change rate of tensile strength first decreasing and then increasing.Additionally,when the braiding angle is less than 21.89°,the impact toughness of BNP composites remains within the range of 83.66±2 kJ/m^(2).However,when the braiding angle exceeds 21.89°,the impact toughness of BNP composites gradually decreases with increasing braiding angle.Furthermore,a hybrid agent model based on Latin hypercube sampling and error back-propagation neural network is developed to predict the tensile and impact properties of BNP composites with different structural parameters,with maximum test relative errors of 1.89%for tensile strength and 2.37%for impact toughness.展开更多
The isothermal compression tests were carried out on Gleeble-3500 thermal-mechanical simulation machine in a temperature range of 298-473 K and strain rate range of 0.001-10 s^-1. The experimental results show that th...The isothermal compression tests were carried out on Gleeble-3500 thermal-mechanical simulation machine in a temperature range of 298-473 K and strain rate range of 0.001-10 s^-1. The experimental results show that the flow stress data are negatively correlated with temperature for temperature softening, and the strain rates sensitivity of this composite increases with elevating temperature. Based on the experimental data, Johnson-Cook, modified Johnson-Cook and Arrhenius constitutive models were established. The accuracy of these three constitutive models was analyzed and compared. The results show that the values predicted by Johnson-Cook model could not agree well with the experimental values. The prediction accuracy of Arrhenius model is higher than that of Johnson-Cook model but lower than that of the Modified Johnson-Cook model.展开更多
Three-dimensional（3 D）braided composites are a kind of advanced ones and are used in the aeronautical and astronautical fields more widely. The advantages, usages, shortages and disadvantages of 3D braided composite...Three-dimensional（3 D）braided composites are a kind of advanced ones and are used in the aeronautical and astronautical fields more widely. The advantages, usages, shortages and disadvantages of 3D braided composites are analyzed, and the possible approach of improving the properties of the materials is presented, that is, a new type of 3D full 5-directional braided composites is developed. The methods of making this type of preform are proposed. It is pointed out that the four-step braiding which is the most possible to realize industrialized production almost has no effect on the composites＇ properties. By analyzing the simulation model,the advantages of the material compared with the 3D 4-directional and 5-directional materials are presented. Finally, a microstructural model is analyzed to lay the foundation for the future theoretical analysis of these composites.展开更多
The effect of Mg and Si additon to Al matrix on infiltration kinetics and rates of Al alloys pressureless infiltration into porous SiCp preform was investigated by observing the change of infiltration distance with ti...The effect of Mg and Si additon to Al matrix on infiltration kinetics and rates of Al alloys pressureless infiltration into porous SiCp preform was investigated by observing the change of infiltration distance with time as the Al alloys infiltrate into SiCp preforms at different temperatures.The results show that infiltration of SiCp preforms by Al melt is a thermal activation process and there is an incubation period before the infiltration becomes stable.With the increase of Mg content in the Al alloys from 0wt% to 8wt%,the infiltration will become much easier,the incubation period becomes shorter and the infiltration rate is faster,but these effects are not obvious when the Mg content is higher than 8wt%.As for Si addition to the Al alloys,it has no obvious effect on the incubation period,but the infiltration rate increases markedly with the increase of Si content from 0wt% to 12wt% and the rate has no obvious change when the content is bigger than 12wt%.The effect of Mg and Si on the incubation period is related to the infiltration mechanism of Al pressureless infiltration into SiCp preforms and their impact on the infiltration rate is a combined result from viscosity and surface tension of Al melt and SiC-Al wetting ability.展开更多
基金Supported by Jiangsu Provincial Frontier Leading Technology Basic Research Project(Grant No.BK20212007)Aero-Engine and Gas Turbine Basic Science Center(Grant No.P2022-B-IV-014-001)+1 种基金China Postdoctoral Program Fund(Grant No.1005/YBA23044)China Postdoctoral Assistance Fund(Grant No.1005/YBA23031)。
文摘Variable-diameter deployable carbon fiber reinforced polymer(CFRP)composites possess deformation and load-bearing functions and are composed of stiff-flexible coupled preforms and matrix.The stiff-flexible coupled preform,serving as the reinforcing structure,directly determines the deployable properties,and its forming technology is currently a research challenge.This paper designs a braiding and needle-punching(BNP)composite preform forming technology suitable for stiff-flexible coupled preforms.Before forming,the preform is partitioned into flexible and rigid zones,with braiding and needle-punching performed layer by layer in the respective zones.A retractable rotating device is developed to form the stiff-flexible coupled preform,achieving a diameter variation rate of up to 26.6%for the BNP preform.A structural parameter model is also established to describe the geometric parameter changes in the deformation and load-bearing areas of the preform during deployment as a function of the braiding angle.Based on experiments,this paper explains the performance changes of BNP composites concerning the structural parameters of the preform.Experimental analysis shows that as the braiding angle increases,the tensile performance of BNP composites significantly decreases,with the change rate of tensile strength first decreasing and then increasing.Additionally,when the braiding angle is less than 21.89°,the impact toughness of BNP composites remains within the range of 83.66±2 kJ/m^(2).However,when the braiding angle exceeds 21.89°,the impact toughness of BNP composites gradually decreases with increasing braiding angle.Furthermore,a hybrid agent model based on Latin hypercube sampling and error back-propagation neural network is developed to predict the tensile and impact properties of BNP composites with different structural parameters,with maximum test relative errors of 1.89%for tensile strength and 2.37%for impact toughness.
基金Funded by the Program of International S&T Cooperation(No.2013DFA51230)the Opening Subject Fund of Ningbo University(No.zj1226)
文摘The isothermal compression tests were carried out on Gleeble-3500 thermal-mechanical simulation machine in a temperature range of 298-473 K and strain rate range of 0.001-10 s^-1. The experimental results show that the flow stress data are negatively correlated with temperature for temperature softening, and the strain rates sensitivity of this composite increases with elevating temperature. Based on the experimental data, Johnson-Cook, modified Johnson-Cook and Arrhenius constitutive models were established. The accuracy of these three constitutive models was analyzed and compared. The results show that the values predicted by Johnson-Cook model could not agree well with the experimental values. The prediction accuracy of Arrhenius model is higher than that of Johnson-Cook model but lower than that of the Modified Johnson-Cook model.
文摘Three-dimensional（3 D）braided composites are a kind of advanced ones and are used in the aeronautical and astronautical fields more widely. The advantages, usages, shortages and disadvantages of 3D braided composites are analyzed, and the possible approach of improving the properties of the materials is presented, that is, a new type of 3D full 5-directional braided composites is developed. The methods of making this type of preform are proposed. It is pointed out that the four-step braiding which is the most possible to realize industrialized production almost has no effect on the composites＇ properties. By analyzing the simulation model,the advantages of the material compared with the 3D 4-directional and 5-directional materials are presented. Finally, a microstructural model is analyzed to lay the foundation for the future theoretical analysis of these composites.
基金supported by the National Natural Science Foundation of China (No.51004010)the Research Fund for the Doctoral Program of Higher Education of China (No.20090006120022)
文摘The effect of Mg and Si additon to Al matrix on infiltration kinetics and rates of Al alloys pressureless infiltration into porous SiCp preform was investigated by observing the change of infiltration distance with time as the Al alloys infiltrate into SiCp preforms at different temperatures.The results show that infiltration of SiCp preforms by Al melt is a thermal activation process and there is an incubation period before the infiltration becomes stable.With the increase of Mg content in the Al alloys from 0wt% to 8wt%,the infiltration will become much easier,the incubation period becomes shorter and the infiltration rate is faster,but these effects are not obvious when the Mg content is higher than 8wt%.As for Si addition to the Al alloys,it has no obvious effect on the incubation period,but the infiltration rate increases markedly with the increase of Si content from 0wt% to 12wt% and the rate has no obvious change when the content is bigger than 12wt%.The effect of Mg and Si on the incubation period is related to the infiltration mechanism of Al pressureless infiltration into SiCp preforms and their impact on the infiltration rate is a combined result from viscosity and surface tension of Al melt and SiC-Al wetting ability.
