Carbon fiber-reinforced polymer(CFRP)is widely used in aerospace applications.This kind of material may face the threat of high-velocity impact in the process of dedicated service,and the relevant research mainly cons...Carbon fiber-reinforced polymer(CFRP)is widely used in aerospace applications.This kind of material may face the threat of high-velocity impact in the process of dedicated service,and the relevant research mainly considers the impact resistance of the material,and lacks the high-velocity impact damage monitoring research of CFRP.To solve this problem,a real high-velocity impact damage experiment and structural health monitoring(SHM)method of CFRP plate based on piezoelectric guided wave is proposed.The results show that CFRP has obvious perforation damage and fiber breakage when high-velocity impact occurs.It is also proved that guided wave SHM technology can be effectively used in the monitoring of such damage,and the damage can be reflected by quantifying the signal changes and damage index(DI).It provides a reference for further research on guided wave structure monitoring of high/hyper-velocity impact damage of CFRP.展开更多
The construction controlling elements,including construction performance at low ambient temperatures,reserved time ranges,and the strength increasing rule,for locally developed epoxy asphalt mixture（LDEAM） are studi...The construction controlling elements,including construction performance at low ambient temperatures,reserved time ranges,and the strength increasing rule,for locally developed epoxy asphalt mixture（LDEAM） are studied through laboratory tests.Air void and Marshall stability are chosen as the performance measures for evaluating the construction quality.The wheel rolling test is used to simulate the actual construction situations,while the Marshall test and the Brookfield viscosity test are adopted to study the strength increasing rule.The experimental results reveal that the LDEAM can be constructed under a low ambient temperature condition of 10℃,and its longest reserved time is 70 min at a reserved temperature of 120℃.Test also shows that the strength of the LDEAM increases with time and temperature before cured.Finally,the theoretical reason for the strength increasing rule is analyzed on the basis of the organic chemistry theory.展开更多
The present study investigates the effect of the addition of nanoparticles into epoxy resins as the matrix on the impact absorbed energy of CFRP （carbon fiber reinforced polymer）. Impact absorbed energy is one of th...The present study investigates the effect of the addition of nanoparticles into epoxy resins as the matrix on the impact absorbed energy of CFRP （carbon fiber reinforced polymer）. Impact absorbed energy is one of the main properties to evaluate the CFRP＇s performance for transportation and aerospace structures. Two types of nanoparticle, namely nanofibers and nano-silica beads, were added into the epoxy resin to improve the impact absorption capacity of the CFRP. Two modified additives and conventional epoxy resins were quantitatively compared. The impact test results showed that impact absorbed energy for nanofibers was higher than nano-silica beads, and nanofibers as the additive promoted about 11% of impact absorbed energy compared with neat epoxy resin.展开更多
Since the introduction of＂green tyres＂ in the early 90＇s, the use of silica as a reinforcing filler, along with a silane coupling agent, has spread and grown worldwide. The greatest advantage of using silica over c...Since the introduction of＂green tyres＂ in the early 90＇s, the use of silica as a reinforcing filler, along with a silane coupling agent, has spread and grown worldwide. The greatest advantage of using silica over carbon black as reinforcing filler in a tyre tread compound is that a lower rolling resistance is achieved, while maintaining good wet traction. However, a previous study has shown that the wear resistance of a silica filled ENR （epoxidised natural rubber） compound was not as high as those of conventional OESBR （oil extended styrene butadiene rubber） and NR/BR compounds used in passenger car and truck tyre treads. In this work, with the aim of improving abrasion resistance, the effect of blending BR （butadiene rubber） into a silica filled ENR compound was studied. Blends with 0 to 30 phr BR were prepared in a Polylab Haake internal mixer. The rheological properties of the compounds were measured using a Mooney viscometer and oscillating-disc rheometer. The hardness, tensile strength and DIN abrasion resistance were also measured. The results showed that the ENR/silica compound properties such as tensile strength and hardness were as good as those of the conventional compounds. However, the most important finding was that abrasion resistance increased significantly with BR content, exceeding that of the conventional compound at BR： ENR ratios of greater than 20：80.展开更多
Two kinds of rosin derivatives, （2-hydroxy-3-（methacryloyloxy）propyl 7-isopropyl-1,4a-dimethyl-1,2,3,4,4a,4b,5,6,10,10a- decahydrophenanthrene-1-carboxylate） （HMPIDDC） and （（（7-isopropyl-1,4a-dimethyl-1,2,3,4...Two kinds of rosin derivatives, （2-hydroxy-3-（methacryloyloxy）propyl 7-isopropyl-1,4a-dimethyl-1,2,3,4,4a,4b,5,6,10,10a- decahydrophenanthrene-1-carboxylate） （HMPIDDC） and （（（7-isopropyl-1,4a-dimethyl-1,2,3,4,4a,9,10,10a-octahydrophenan- thren-1-yl）methyl）azanediyl）bis（2-hydroxypropane-3,1-diyl）bis（2-methylacrylate） （IDOMAHM） were synthesized under mild and easy to implement conditions. The two derivatives were employed as the rigid monomers to copolymerize with acrylated epoxidized soybean oil （AESO）, as so to improve the performance of the cured resins. The chemical structures of HMPIDDC and IDOMAHM were confirmed by nuclear magnetic resonance （NMR） and Fourier Transform Infrared （FT-IR） before copolymerization. The curing behaviors of pristine AESO, AESO/HMPIDDC blend, and AESO/IDOMAHM blend were monitored by differential scanning calorimetry （DSC）. Moreover, the thermal and mechanical properties of the cured resins were evaluated by universal mechanical testing, dynamic mechanical analysis （DMA） and thermogravimetric analysis （TGA）. The results demonstrated that after the introduction of HMPIDDC and IDOMAHM, the glass transition temperature and mechanical properties of the copolymerized resin were significantly increased. In one word, HMPIDDC and IDOMAHM showed dramatic potential to be used as bio-based compounds to improve the properties of soybean-oil based thermosets.展开更多
基金supported by the National Natural Science Foundation of China(Nos.51921003,52275153)the Fundamental Research Funds for the Central Universities(No.NI2023001)+2 种基金the Research Fund of State Key Laboratory of Mechanics and Control for Aero-space Structures(No.MCAS-I-0423G01)the Fund of Pro-spective Layout of Scientific Research for Nanjing University of Aeronautics and Astronauticsthe Priority Academic Program Development of Jiangsu Higher Education Institu-tions of China.
文摘Carbon fiber-reinforced polymer(CFRP)is widely used in aerospace applications.This kind of material may face the threat of high-velocity impact in the process of dedicated service,and the relevant research mainly considers the impact resistance of the material,and lacks the high-velocity impact damage monitoring research of CFRP.To solve this problem,a real high-velocity impact damage experiment and structural health monitoring(SHM)method of CFRP plate based on piezoelectric guided wave is proposed.The results show that CFRP has obvious perforation damage and fiber breakage when high-velocity impact occurs.It is also proved that guided wave SHM technology can be effectively used in the monitoring of such damage,and the damage can be reflected by quantifying the signal changes and damage index(DI).It provides a reference for further research on guided wave structure monitoring of high/hyper-velocity impact damage of CFRP.
基金The National Natural Science Foundation of China (No.50578038)the National Key Technology R& D Program of China during the 11th Five-Year Plan Period (No. 2009BAG15B03)
文摘The construction controlling elements,including construction performance at low ambient temperatures,reserved time ranges,and the strength increasing rule,for locally developed epoxy asphalt mixture（LDEAM） are studied through laboratory tests.Air void and Marshall stability are chosen as the performance measures for evaluating the construction quality.The wheel rolling test is used to simulate the actual construction situations,while the Marshall test and the Brookfield viscosity test are adopted to study the strength increasing rule.The experimental results reveal that the LDEAM can be constructed under a low ambient temperature condition of 10℃,and its longest reserved time is 70 min at a reserved temperature of 120℃.Test also shows that the strength of the LDEAM increases with time and temperature before cured.Finally,the theoretical reason for the strength increasing rule is analyzed on the basis of the organic chemistry theory.
文摘The present study investigates the effect of the addition of nanoparticles into epoxy resins as the matrix on the impact absorbed energy of CFRP （carbon fiber reinforced polymer）. Impact absorbed energy is one of the main properties to evaluate the CFRP＇s performance for transportation and aerospace structures. Two types of nanoparticle, namely nanofibers and nano-silica beads, were added into the epoxy resin to improve the impact absorption capacity of the CFRP. Two modified additives and conventional epoxy resins were quantitatively compared. The impact test results showed that impact absorbed energy for nanofibers was higher than nano-silica beads, and nanofibers as the additive promoted about 11% of impact absorbed energy compared with neat epoxy resin.
文摘Since the introduction of＂green tyres＂ in the early 90＇s, the use of silica as a reinforcing filler, along with a silane coupling agent, has spread and grown worldwide. The greatest advantage of using silica over carbon black as reinforcing filler in a tyre tread compound is that a lower rolling resistance is achieved, while maintaining good wet traction. However, a previous study has shown that the wear resistance of a silica filled ENR （epoxidised natural rubber） compound was not as high as those of conventional OESBR （oil extended styrene butadiene rubber） and NR/BR compounds used in passenger car and truck tyre treads. In this work, with the aim of improving abrasion resistance, the effect of blending BR （butadiene rubber） into a silica filled ENR compound was studied. Blends with 0 to 30 phr BR were prepared in a Polylab Haake internal mixer. The rheological properties of the compounds were measured using a Mooney viscometer and oscillating-disc rheometer. The hardness, tensile strength and DIN abrasion resistance were also measured. The results showed that the ENR/silica compound properties such as tensile strength and hardness were as good as those of the conventional compounds. However, the most important finding was that abrasion resistance increased significantly with BR content, exceeding that of the conventional compound at BR： ENR ratios of greater than 20：80.
基金supported by the Youth Innovation Promotion Association of the Chinese Academy of Sciences(Grant No.2012229)Natural Sciences Foundation of Ningbo City(Grant No.2014A610110)+1 种基金Research Project of Technology Application for Public Welfare of Zhejiang Province(Grant No.2014C31143)National Natural Science Foundation of China(Grant Nos.51373194,51203176)
文摘Two kinds of rosin derivatives, （2-hydroxy-3-（methacryloyloxy）propyl 7-isopropyl-1,4a-dimethyl-1,2,3,4,4a,4b,5,6,10,10a- decahydrophenanthrene-1-carboxylate） （HMPIDDC） and （（（7-isopropyl-1,4a-dimethyl-1,2,3,4,4a,9,10,10a-octahydrophenan- thren-1-yl）methyl）azanediyl）bis（2-hydroxypropane-3,1-diyl）bis（2-methylacrylate） （IDOMAHM） were synthesized under mild and easy to implement conditions. The two derivatives were employed as the rigid monomers to copolymerize with acrylated epoxidized soybean oil （AESO）, as so to improve the performance of the cured resins. The chemical structures of HMPIDDC and IDOMAHM were confirmed by nuclear magnetic resonance （NMR） and Fourier Transform Infrared （FT-IR） before copolymerization. The curing behaviors of pristine AESO, AESO/HMPIDDC blend, and AESO/IDOMAHM blend were monitored by differential scanning calorimetry （DSC）. Moreover, the thermal and mechanical properties of the cured resins were evaluated by universal mechanical testing, dynamic mechanical analysis （DMA） and thermogravimetric analysis （TGA）. The results demonstrated that after the introduction of HMPIDDC and IDOMAHM, the glass transition temperature and mechanical properties of the copolymerized resin were significantly increased. In one word, HMPIDDC and IDOMAHM showed dramatic potential to be used as bio-based compounds to improve the properties of soybean-oil based thermosets.
