In this study, several kinds of flexible protective materials sprayed with polyurea elastomers （hereinafter referred to as polyurea elastomer protective material） were adopted to meet the abrasion resistance require...In this study, several kinds of flexible protective materials sprayed with polyurea elastomers （hereinafter referred to as polyurea elastomer protective material） were adopted to meet the abrasion resistance requirement of hydraulic structures, and their abrasion resistances against the water flow with suspended load or bed load were studied systematically through tests. Natural basalt stones were adopted as the abrasive for simulation of the abrasion effect of the water flow with bed load, and test results indicate that the basalt stone is suitable for use in the abrasion resistance test of the flexible protective material. The wear process of the polyurea elastomer protective material is stable, and the wear loss is linear with the time of abrasion. If the wear thickness is regarded as the abrasion resistance evaluation factor, the abrasion resistance of the 351 pure polyurea is about twice those of pure polyurea with a high level of hardness and aliphatic polyurea, and over five times that of high-performance abrasion-resistant concrete under the abrasion of the water flow with suspended load. It is also about 50 times that of high-performance abrasion-resistant concrete under the abrasion of the water flow with bed load. Overall, the abrasion resistance of pure polyurea presented a decreasing trend with increasing hardness. Pure polyurea with a Shore hardness of D30 has the best abrasion resistance, which is 60 to 70 times that of high-performance abrasion-resistant concrete under the abrasion of the water flow with bed load, and has been recommended, among the five kinds of pure polyurea materials with different hardness, in anti-abrasion protection of hydraulic structures.展开更多
Public health events caused by viruses pose a significant risk to humans worldwide.From December 2019 till now,the rampant novel 2019 coronavirus(SAR-CoV-2)has hugely impacted China and over world.Regarding a commenda...Public health events caused by viruses pose a significant risk to humans worldwide.From December 2019 till now,the rampant novel 2019 coronavirus(SAR-CoV-2)has hugely impacted China and over world.Regarding a commendable means of protection,mask technology is relatively mature,though most of the masks cannot effectively resist the viral infections.The key material of the mask is a non-woven material,which makes the barrier of virus through filtration.Due to the lack of the ability to kill the viruses,masks are prone to cross-infection and become an additional source of infection after being discarded.If the filteration and antiviral effects can be simultaneously integrated into the mask,it will be more effcient,work for a longer time and create less difficulty in post-treatment.This mini-review presents the advances in antiviral materials,different mechanisms of their activity,and their potential applications in personal protective fabrics.Furthermore,the article addresses the future challenges and directions of mask technology.展开更多
NATO standards"AEP-2920 Procedures for the Evaluation and Classification of Personal Armor"and NIJ Standard-0101.06,indicate the method to statistically assess the resistance of personal ballistic protection...NATO standards"AEP-2920 Procedures for the Evaluation and Classification of Personal Armor"and NIJ Standard-0101.06,indicate the method to statistically assess the resistance of personal ballistic protection materials.To be validated and accepted through these procedures,a personal ballistic protection material should withstand an impact of a specific projectile with a probability of a partial penetration confidence level higher than 90%.The present study introduces an energy equilibrium method to assess the confidence level for the probability of partial penetration of ductile and brittle materials.The experiments performed in the Ballistics laboratory of the Royal Military Academy in Belgium,use a modified pendulum method that allowed the quantification of the energy balance before and after the ballistic impact.The results were then compared with the ones obtained using the method specified by the NATO standard and NIJ 0101.06,mentioned above.The outcome of this comparison shows the tendency of the values obtained by the pendulum method to faithfully follow the values obtained according to NATO and NIJ specifications.The presented method is not based on statistical estimations,but instead,an exact method,of computing the energy absorbed by the tested material.This is an advantage for the cases when the material to be evaluated is expensive or it is in the development phase and mass production is not possible.展开更多
The temperature response calculation of thermal protection materials,especially ablative thermal protection materials,usually adopts the ablation model,which is complicated in process and requires a large amount of ca...The temperature response calculation of thermal protection materials,especially ablative thermal protection materials,usually adopts the ablation model,which is complicated in process and requires a large amount of calculation.Especially in the process of optimization calculation and parameter identification,the ablation model needs to be called many times,so it is necessary to construct an ablation surrogate model to improve the computational efficiency under the premise of ensuring the accuracy.In this paper,the Gaussian process model method is used to construct a thermal protection material ablation surrogate model,and the prediction accuracy of the surrogate model is improved through optimization.展开更多
The thermal protection materials and structures are widely used in hypersonic vehicles for the purpose of thermal insulation, and their mechanical behavior is one of the key issues in design and manufacture of hyperso...The thermal protection materials and structures are widely used in hypersonic vehicles for the purpose of thermal insulation, and their mechanical behavior is one of the key issues in design and manufacture of hypersonic vehicles. It is our great pleasure to present the seven papers in this special subject of Theoretical ＆ Applied Mechanics Letters （TAML） and introduce the recent progresses on the mechanical behavior of thermal protection materials and structures by the authors.展开更多
Effect of isobutyl-triethoxy-silane penetrative protective agent on the carbonation resistance of the concrete was studied.The concrete specimens for the 28 d accelerated carbonation process were manufactured with w/c...Effect of isobutyl-triethoxy-silane penetrative protective agent on the carbonation resistance of the concrete was studied.The concrete specimens for the 28 d accelerated carbonation process were manufactured with w/c of 0.49 and 0.64,both in the presence and absence of silane and mineral admixture.The penetration of isobutyl-triethoxy-silane and the carbonation of concrete were investigated by penetration depth,carbonation depth,XRD,SEM,and pore size distribution.The results showed that concrete compactness played an important role in the silane penetration and carbonation resistance.Penetration depth of silane-treated concrete mainly depended on the compactness of the concrete,and could not remarkably change through the accelerated carbonation process.In the accelerated carbonation process,penetrative protective agent improved the carbonation resistance of the higher compactness concretes but accelerated the carbonization process of the lower compactness concretes.As penetrative protective agent penetrated along the external connectivity pores into concrete not filling the entire surface area,the inorganic film could not fully protect the Ca（OH）_2 phase from carbonation.After 28 d accelerated carbonation,fibrous hydration products disappeared and the surface holes decreased.Due to the formation of carbonized products,the porosity of the concrete surface decreased,especially in high-strength concrete.展开更多
Hybrid nanoSiO_(2) (HNS) modified cement pastes were explored as a kind of surface protection material (SPM).The carbonation resistance and mechanical properties of SPMs coated samples were tested.Thermogravimetric an...Hybrid nanoSiO_(2) (HNS) modified cement pastes were explored as a kind of surface protection material (SPM).The carbonation resistance and mechanical properties of SPMs coated samples were tested.Thermogravimetric analysis (TGA),X-ray diffraction (XRD),scanning electron microscope (SEM),and mercury intrusion porosimetry (MIP) were further employed to evaluate the chemical composition and microstructure characteristics of SPM.Besides,thermodynamic modeling was adopted to simulate the changes in the phase assemblages of SPM under the carbonation process.The results showed that SPM with 1 wt% HNS could effectively enhance the carbonation resistance.The incorporation of HNS could densify the microstructure and refine the pore structure.Moreover,the thaumasite can be stable at ambient temperature with the addition of HNS,which is beneficial to maintain alkalinity under the carbonation process.展开更多
A time-resolved numerical computational approach, involving the combustion of double-base propellant is performed on thermal protection material for SRM nozzle. An implicit Navier-Stokes Solver is selected to simulate...A time-resolved numerical computational approach, involving the combustion of double-base propellant is performed on thermal protection material for SRM nozzle. An implicit Navier-Stokes Solver is selected to simulate two-dimensional axial-symmetric unsteady turbulent flow of compressible fluid. The governing equations are discredited by using the finite Volume method. S-A turbulence model is employed. CFD scheme is implemented to investigate the temperature distribution causes at nozzle throat inserts composite material. Different parameters have been selected for the analysis to validate the temperature variation in the throat inserts and baking material of SRM nozzle. The advanced SRM nozzle composite material is also characterized for the high thermo stability and high thermo mechanical capabilities to make it more reliable, simpler and lighter.展开更多
The title compounds 1-（4,5-dihydro-3-phenyl pyridine-1-yl）-2-（1H-1,2,4-triazole-1-yl） ethyl ketones were studied as a corrosion inhibitor in a mild steel in 1 mol /L hydrochloric acid solution using weight loss me...The title compounds 1-（4,5-dihydro-3-phenyl pyridine-1-yl）-2-（1H-1,2,4-triazole-1-yl） ethyl ketones were studied as a corrosion inhibitor in a mild steel in 1 mol /L hydrochloric acid solution using weight loss measurement, potentiodynamic polarization, and electrochemical impedance spectroscopy （EIS）. Results indicated that these compounds had excellent inhibition properties. Polarization curves indicated that the inhibitor behaved mainly as mixed-type inhibitor. The EIS results showed that the charge transfer controlled the corrosion process in the uninhibited and inhibited solutions. Adsorption of the inhibitor on the mild steel surface followed Langmuir＇s adsorption isotherm with negative value of the free energy of adsorption ΔGads^o. The thermodynamic parameters of adsorption were determined and discussed.展开更多
Aerogel materials possess a wide variety of excellent functions,hence a striking number of applications have developed for them.In this paper,we present a historic review of the aerogel materials,showing the main conc...Aerogel materials possess a wide variety of excellent functions,hence a striking number of applications have developed for them.In this paper,we present a historic review of the aerogel materials,showing the main concepts,research methods,important scientific problems,formation mechanism,structure characteristics and essence of aerogel.More applications are evolving as the scientific and engineering community,which becomes familiar with the unusual and exceptional physical properties of aerogels.In addition,we also discuss the huge development potential and prospect of polysaccharide aerogels as the research trend in the future.展开更多
The inhibition effects of sodium vanadate along with inorganic coolantinhibitors were examined on corrosion of AZ91D in ASTM D1384-80 corrosive water by polarizationmeasurements. The galvanic corrosion of AZ91D couple...The inhibition effects of sodium vanadate along with inorganic coolantinhibitors were examined on corrosion of AZ91D in ASTM D1384-80 corrosive water by polarizationmeasurements. The galvanic corrosion of AZ91D coupled to 3003, 6063, and 356 Al alloys were alsotested. An effective combination of inhibitors containing (but not limited to) sodium vanadate,silicate, and nitrate was proposed for inhibition of AZ91D and prevention of galvanic corrosion.展开更多
Multi-phase flow effect generated from the combustion of aluminum based composite propellant was performed on the thermal protection material of solid rocket motor(SRM) nozzle.Injection of alumina(Al2O3) particles fro...Multi-phase flow effect generated from the combustion of aluminum based composite propellant was performed on the thermal protection material of solid rocket motor(SRM) nozzle.Injection of alumina(Al2O3) particles from 5% to 10% was tried on SRM nozzle flow field to see the influence of multiphase flow on heat transfer computations.A coupled,time resolved CFD(computational fluid dynamics) approach was adopted to solve the conjugate problem of multi-phase fluid flow and heat transfer in the solid rocket motor nozzle.The governing equations are discretized by using the finite volume method.Spalart-Allmaras(S-A) turbulence model was employed.The computation was executed on the different models selected for the analysis to validate the temperature variation in the throat inserts and baking material of SRM nozzle.Comparison for temperatures variations were also carried out at different expansion ratios of nozzle.This paper also characterized the advanced SRM nozzle composites material for their high thermo stability and their high thermo mechanical capabilities to make it more reliable simpler and lighter.展开更多
The non-metallic lightning strike protection film covering carbon fiber reinforced polymers(NM-LSP covering CFRP)can reduce the weight and thus the fuel consumption of aircraft by replacing the traditional lightning s...The non-metallic lightning strike protection film covering carbon fiber reinforced polymers(NM-LSP covering CFRP)can reduce the weight and thus the fuel consumption of aircraft by replacing the traditional lightning strike protection(LSP)materials.In the present study,in order to study the environmental influence of utilizing NM-LSP covering CFRP in an aircraft elevator,a new elevator was designed and manufactured,replacing the aluminium net and glass fiber reinforced polymers(GFRP)with NM-LSP covering CFRP,with the same mechanical and LSP abilities.A comparative life cycle assessment was conducted between the two kinds of aircraft elevators,including material extraction,transportation,elevator manufacturing phase,service phase,and end-of-life procedures.Additionally,the environmental impacts of producing two LSP materials were compared by considering the environmental effects of different buy-to-fly ratios and recycling strategies on the production of aluminium net.The analysis indicates that the new elevator achieved reduction for all the environmental impact categories used,such as human toxicity potential and marine aquatic ecotoxicity potential(3.83%and 3.20%reduction).Furthermore,it is found that the service phase makes the greatest contribution to the environmental impact of the elevators under investigation.When recycling is excluded,NM-LSP covering CFRP is more environmentally friendly than the traditional material.At the same time,CFRP prepreg and electricity from the production of NM-LSP covering CFRP contribute to a higher environmental impact compared to the NM-LSP film.From the sensitivity analysis,it is believed that NM-LSP covering CFRP can reduce environmental impact compared with traditional LSP materials.展开更多
Various thermal protection materials exhibit obviously different and complicated thermal response,oxidation and ablation behavior,which are very important for the appropriate design and selection.However,the relative ...Various thermal protection materials exhibit obviously different and complicated thermal response,oxidation and ablation behavior,which are very important for the appropriate design and selection.However,the relative researches are very few currently.In this work,the thermal response,oxidation and ablation behavior of representative thermal protection materials including ultra-high temperature ceramics,C/SiC,C/C, graphite and graphite-ceramic were investigated systematically in strong heat flux,high enthalpy and low-pressure environments.Thermal response of these materials was analyzed based on experimental results and thermal energy balance that accounts for all of the heat transfer processes transporting energy into and out of the surface.Many factors were playing important roles in the thermal response including thermal conductivity,volumetric heat capacity,catalytic efficiency,emissivity and oxidation characteristics of the materials.The importance of each factor not only depends on the material characteristics such as material composition and phase content but also environment parameters including heat flux,enthalpy,pressure and testing time.The comparisons and relationships of oxidation and ablation behaviors for these materials under extreme environments were also illustrated in detail.Furthermore,thermal response and ablation behaviors of pre-oxidized material or repeated tests were also performed to evaluate the effect of pre-treatment on the performance and reusability of thermal protection materials.This work offers guiding significance for the appropriate design and selection of thermal protection materials.展开更多
基金supported by the National Natural Science Foundation of China(Grants No.51109143 and 51209144)the Natural Science Foundation of Jiangsu Province(Grant No.BK2011109)the Foundation of Nanjing Hydraulic Research Institute(Grant No.Y113004)
文摘In this study, several kinds of flexible protective materials sprayed with polyurea elastomers （hereinafter referred to as polyurea elastomer protective material） were adopted to meet the abrasion resistance requirement of hydraulic structures, and their abrasion resistances against the water flow with suspended load or bed load were studied systematically through tests. Natural basalt stones were adopted as the abrasive for simulation of the abrasion effect of the water flow with bed load, and test results indicate that the basalt stone is suitable for use in the abrasion resistance test of the flexible protective material. The wear process of the polyurea elastomer protective material is stable, and the wear loss is linear with the time of abrasion. If the wear thickness is regarded as the abrasion resistance evaluation factor, the abrasion resistance of the 351 pure polyurea is about twice those of pure polyurea with a high level of hardness and aliphatic polyurea, and over five times that of high-performance abrasion-resistant concrete under the abrasion of the water flow with suspended load. It is also about 50 times that of high-performance abrasion-resistant concrete under the abrasion of the water flow with bed load. Overall, the abrasion resistance of pure polyurea presented a decreasing trend with increasing hardness. Pure polyurea with a Shore hardness of D30 has the best abrasion resistance, which is 60 to 70 times that of high-performance abrasion-resistant concrete under the abrasion of the water flow with bed load, and has been recommended, among the five kinds of pure polyurea materials with different hardness, in anti-abrasion protection of hydraulic structures.
基金This work was financially supported by the National Key Research and Development Program of China(2016YFA0201702 and 2016YFA0201700)the National Natural Science Foundation of China(51972056,51773036)+3 种基金Innovation Program of Shanghai Municipal Education Commission(2017-01-07-00-03-E00055)Shanghai Belt and Road Joint Laboratory of Advanced Fiber and Low-dimension Materials(18520750400)China Postdoctoral Science Foundation(2019M661323)the Fundamental Research Funds for the Central Universities.
文摘Public health events caused by viruses pose a significant risk to humans worldwide.From December 2019 till now,the rampant novel 2019 coronavirus(SAR-CoV-2)has hugely impacted China and over world.Regarding a commendable means of protection,mask technology is relatively mature,though most of the masks cannot effectively resist the viral infections.The key material of the mask is a non-woven material,which makes the barrier of virus through filtration.Due to the lack of the ability to kill the viruses,masks are prone to cross-infection and become an additional source of infection after being discarded.If the filteration and antiviral effects can be simultaneously integrated into the mask,it will be more effcient,work for a longer time and create less difficulty in post-treatment.This mini-review presents the advances in antiviral materials,different mechanisms of their activity,and their potential applications in personal protective fabrics.Furthermore,the article addresses the future challenges and directions of mask technology.
文摘NATO standards"AEP-2920 Procedures for the Evaluation and Classification of Personal Armor"and NIJ Standard-0101.06,indicate the method to statistically assess the resistance of personal ballistic protection materials.To be validated and accepted through these procedures,a personal ballistic protection material should withstand an impact of a specific projectile with a probability of a partial penetration confidence level higher than 90%.The present study introduces an energy equilibrium method to assess the confidence level for the probability of partial penetration of ductile and brittle materials.The experiments performed in the Ballistics laboratory of the Royal Military Academy in Belgium,use a modified pendulum method that allowed the quantification of the energy balance before and after the ballistic impact.The results were then compared with the ones obtained using the method specified by the NATO standard and NIJ 0101.06,mentioned above.The outcome of this comparison shows the tendency of the values obtained by the pendulum method to faithfully follow the values obtained according to NATO and NIJ specifications.The presented method is not based on statistical estimations,but instead,an exact method,of computing the energy absorbed by the tested material.This is an advantage for the cases when the material to be evaluated is expensive or it is in the development phase and mass production is not possible.
基金supported by Independent Research and Development Project of CASC(YF-ZZYF-2022-132)。
文摘The temperature response calculation of thermal protection materials,especially ablative thermal protection materials,usually adopts the ablation model,which is complicated in process and requires a large amount of calculation.Especially in the process of optimization calculation and parameter identification,the ablation model needs to be called many times,so it is necessary to construct an ablation surrogate model to improve the computational efficiency under the premise of ensuring the accuracy.In this paper,the Gaussian process model method is used to construct a thermal protection material ablation surrogate model,and the prediction accuracy of the surrogate model is improved through optimization.
基金support from the Natural Science Foundation of China(91016029,91216302,and 91216301)
文摘The thermal protection materials and structures are widely used in hypersonic vehicles for the purpose of thermal insulation, and their mechanical behavior is one of the key issues in design and manufacture of hypersonic vehicles. It is our great pleasure to present the seven papers in this special subject of Theoretical ＆ Applied Mechanics Letters （TAML） and introduce the recent progresses on the mechanical behavior of thermal protection materials and structures by the authors.
基金Funded by the National Sci-Tech Support Plan of China(No.2013BAJ10B05)Marine Interdisciplinary Research Guide Fund of Zhejiang University(No.2012HY003B)
文摘Effect of isobutyl-triethoxy-silane penetrative protective agent on the carbonation resistance of the concrete was studied.The concrete specimens for the 28 d accelerated carbonation process were manufactured with w/c of 0.49 and 0.64,both in the presence and absence of silane and mineral admixture.The penetration of isobutyl-triethoxy-silane and the carbonation of concrete were investigated by penetration depth,carbonation depth,XRD,SEM,and pore size distribution.The results showed that concrete compactness played an important role in the silane penetration and carbonation resistance.Penetration depth of silane-treated concrete mainly depended on the compactness of the concrete,and could not remarkably change through the accelerated carbonation process.In the accelerated carbonation process,penetrative protective agent improved the carbonation resistance of the higher compactness concretes but accelerated the carbonization process of the lower compactness concretes.As penetrative protective agent penetrated along the external connectivity pores into concrete not filling the entire surface area,the inorganic film could not fully protect the Ca（OH）_2 phase from carbonation.After 28 d accelerated carbonation,fibrous hydration products disappeared and the surface holes decreased.Due to the formation of carbonized products,the porosity of the concrete surface decreased,especially in high-strength concrete.
基金Funded by the National Natural Science Foundation of China (Nos.51808188, 52178202, 52108206)the Fundamental Research Funds for the Central Universities (No.B210201041)。
文摘Hybrid nanoSiO_(2) (HNS) modified cement pastes were explored as a kind of surface protection material (SPM).The carbonation resistance and mechanical properties of SPMs coated samples were tested.Thermogravimetric analysis (TGA),X-ray diffraction (XRD),scanning electron microscope (SEM),and mercury intrusion porosimetry (MIP) were further employed to evaluate the chemical composition and microstructure characteristics of SPM.Besides,thermodynamic modeling was adopted to simulate the changes in the phase assemblages of SPM under the carbonation process.The results showed that SPM with 1 wt% HNS could effectively enhance the carbonation resistance.The incorporation of HNS could densify the microstructure and refine the pore structure.Moreover,the thaumasite can be stable at ambient temperature with the addition of HNS,which is beneficial to maintain alkalinity under the carbonation process.
文摘A time-resolved numerical computational approach, involving the combustion of double-base propellant is performed on thermal protection material for SRM nozzle. An implicit Navier-Stokes Solver is selected to simulate two-dimensional axial-symmetric unsteady turbulent flow of compressible fluid. The governing equations are discredited by using the finite Volume method. S-A turbulence model is employed. CFD scheme is implemented to investigate the temperature distribution causes at nozzle throat inserts composite material. Different parameters have been selected for the analysis to validate the temperature variation in the throat inserts and baking material of SRM nozzle. The advanced SRM nozzle composite material is also characterized for the high thermo stability and high thermo mechanical capabilities to make it more reliable, simpler and lighter.
基金the financial of the Knowledge Innovation Program of the Chinese Academy of Sciences as a major guiding project(KZCX2-YW-210)as well as "Eleventh Five-Year" National Scientific and Technological Support Project(2007BAB27B00)
文摘The title compounds 1-（4,5-dihydro-3-phenyl pyridine-1-yl）-2-（1H-1,2,4-triazole-1-yl） ethyl ketones were studied as a corrosion inhibitor in a mild steel in 1 mol /L hydrochloric acid solution using weight loss measurement, potentiodynamic polarization, and electrochemical impedance spectroscopy （EIS）. Results indicated that these compounds had excellent inhibition properties. Polarization curves indicated that the inhibitor behaved mainly as mixed-type inhibitor. The EIS results showed that the charge transfer controlled the corrosion process in the uninhibited and inhibited solutions. Adsorption of the inhibitor on the mild steel surface followed Langmuir＇s adsorption isotherm with negative value of the free energy of adsorption ΔGads^o. The thermodynamic parameters of adsorption were determined and discussed.
基金supported by the National Natural Science Foundation of China(31471704 and 31271837)Major Project of the Department of Science and Technology of Fujian Province(2013N5003)
文摘Aerogel materials possess a wide variety of excellent functions,hence a striking number of applications have developed for them.In this paper,we present a historic review of the aerogel materials,showing the main concepts,research methods,important scientific problems,formation mechanism,structure characteristics and essence of aerogel.More applications are evolving as the scientific and engineering community,which becomes familiar with the unusual and exceptional physical properties of aerogels.In addition,we also discuss the huge development potential and prospect of polysaccharide aerogels as the research trend in the future.
基金This work was financially supported by the National Natural Science Foundation of China (No. 50122118)
文摘The inhibition effects of sodium vanadate along with inorganic coolantinhibitors were examined on corrosion of AZ91D in ASTM D1384-80 corrosive water by polarizationmeasurements. The galvanic corrosion of AZ91D coupled to 3003, 6063, and 356 Al alloys were alsotested. An effective combination of inhibitors containing (but not limited to) sodium vanadate,silicate, and nitrate was proposed for inhibition of AZ91D and prevention of galvanic corrosion.
文摘Multi-phase flow effect generated from the combustion of aluminum based composite propellant was performed on the thermal protection material of solid rocket motor(SRM) nozzle.Injection of alumina(Al2O3) particles from 5% to 10% was tried on SRM nozzle flow field to see the influence of multiphase flow on heat transfer computations.A coupled,time resolved CFD(computational fluid dynamics) approach was adopted to solve the conjugate problem of multi-phase fluid flow and heat transfer in the solid rocket motor nozzle.The governing equations are discretized by using the finite volume method.Spalart-Allmaras(S-A) turbulence model was employed.The computation was executed on the different models selected for the analysis to validate the temperature variation in the throat inserts and baking material of SRM nozzle.Comparison for temperatures variations were also carried out at different expansion ratios of nozzle.This paper also characterized the advanced SRM nozzle composites material for their high thermo stability and their high thermo mechanical capabilities to make it more reliable simpler and lighter.
基金supported by the National Key Research and Development Program of China(No.2017YFC0703007)the Chinese MIIT Special Research Plan on Civil Aircraft(No.MJ-2015-H-G-103)+1 种基金the National Natural Science Foundation of China(No.52008137)the China Postdoctoral Science Foundation(Nos.2019TQ0079 and 2019M661288)。
文摘The non-metallic lightning strike protection film covering carbon fiber reinforced polymers(NM-LSP covering CFRP)can reduce the weight and thus the fuel consumption of aircraft by replacing the traditional lightning strike protection(LSP)materials.In the present study,in order to study the environmental influence of utilizing NM-LSP covering CFRP in an aircraft elevator,a new elevator was designed and manufactured,replacing the aluminium net and glass fiber reinforced polymers(GFRP)with NM-LSP covering CFRP,with the same mechanical and LSP abilities.A comparative life cycle assessment was conducted between the two kinds of aircraft elevators,including material extraction,transportation,elevator manufacturing phase,service phase,and end-of-life procedures.Additionally,the environmental impacts of producing two LSP materials were compared by considering the environmental effects of different buy-to-fly ratios and recycling strategies on the production of aluminium net.The analysis indicates that the new elevator achieved reduction for all the environmental impact categories used,such as human toxicity potential and marine aquatic ecotoxicity potential(3.83%and 3.20%reduction).Furthermore,it is found that the service phase makes the greatest contribution to the environmental impact of the elevators under investigation.When recycling is excluded,NM-LSP covering CFRP is more environmentally friendly than the traditional material.At the same time,CFRP prepreg and electricity from the production of NM-LSP covering CFRP contribute to a higher environmental impact compared to the NM-LSP film.From the sensitivity analysis,it is believed that NM-LSP covering CFRP can reduce environmental impact compared with traditional LSP materials.
基金supported by Key Program of National Natural Science Foundation of China (No. 52032003)National Natural Science for Youth Foundation of China (No. 52102093)+2 种基金National Natural Science Foundation of China (No. 51872059),National Natural Science Foundation of China (No. 51772061)China Postdoctoral Science Foundation (No. 2021M690817)Heilongjiang Provincial Postdoctoral Science Foundation (No. LBH-Z20144)。
文摘Various thermal protection materials exhibit obviously different and complicated thermal response,oxidation and ablation behavior,which are very important for the appropriate design and selection.However,the relative researches are very few currently.In this work,the thermal response,oxidation and ablation behavior of representative thermal protection materials including ultra-high temperature ceramics,C/SiC,C/C, graphite and graphite-ceramic were investigated systematically in strong heat flux,high enthalpy and low-pressure environments.Thermal response of these materials was analyzed based on experimental results and thermal energy balance that accounts for all of the heat transfer processes transporting energy into and out of the surface.Many factors were playing important roles in the thermal response including thermal conductivity,volumetric heat capacity,catalytic efficiency,emissivity and oxidation characteristics of the materials.The importance of each factor not only depends on the material characteristics such as material composition and phase content but also environment parameters including heat flux,enthalpy,pressure and testing time.The comparisons and relationships of oxidation and ablation behaviors for these materials under extreme environments were also illustrated in detail.Furthermore,thermal response and ablation behaviors of pre-oxidized material or repeated tests were also performed to evaluate the effect of pre-treatment on the performance and reusability of thermal protection materials.This work offers guiding significance for the appropriate design and selection of thermal protection materials.
