Eight high strength concrete (HSC) prisms strengthened with continuous carbon fiber sheet(CFS)were tested.As a result of the confinement provided by CFS,the concrete would fail at a greater strain than the unconfined ...Eight high strength concrete (HSC) prisms strengthened with continuous carbon fiber sheet(CFS)were tested.As a result of the confinement provided by CFS,the concrete would fail at a greater strain than the unconfined and then a significant increase in ductility can be achieved.The lateral pressure exerted by CFS would increase the compressive strength of the concrete,resulting in higher load bearing capacity.This paper proposes the stress strain curve of this kind of hybrid specimen,which agrees well with the test results.Based on the stress strain relationship and the assumptions proposed in this paper,a computer program was developed to analyze HSC columns,confined by CFS,which were subjected to axial compression and biaxial bending.The results shown in this paper indicate that the ductility of HSC column is significantly improved and the strength is also increased by some degree.展开更多
This paper discusses the method of determining the tensile strength and modulus of elasticity of continuous carbon fiber sheet.Five simply supported beams strengthened by CFS were tested.Based on th experiment,a compu...This paper discusses the method of determining the tensile strength and modulus of elasticity of continuous carbon fiber sheet.Five simply supported beams strengthened by CFS were tested.Based on th experiment,a computer analysis program is developed and a simplified formula is proposed.The calculated results agree well with the experimental results.The design method suggested by this paper can meet the engineering requirements.展开更多
To improve the manufacture efficiency and promote the application of composites in the automobile industry, a new composite forming method, thermal stamping, was discussed to form composite parts directly. Experiments...To improve the manufacture efficiency and promote the application of composites in the automobile industry, a new composite forming method, thermal stamping, was discussed to form composite parts directly. Experiments on two typical stamping processes, thermal bending and thermal deep drawing, were conducted to investigate the forming behavior of composite sheets and analyze the influence of forming temperature on the formed composite part. Experimental results show that the locking angle for woven composite is about 30°. The bending load is smaller than 5 N in the stamping process and decreases with the increase of temperature. The optimal temperature to form the carbon fiber composite is 170 ℃. The die temperature distribution and the deformation of composite sheet were simulated by FEA software ABAQUS. To investigate the fiber movement of carbon woven fabric during stamping, the two-node three-dimension linear Truss unit T2D3 was chosen as the fiber element. The simulation results have a good agreement to the experimental results.展开更多
In order to study the fatigue failure mode and fatigue life laws of basalt-aramid and basalt-carbon hybrid fiber reinforced polymer （ FRP ） sheets, fatigue experiments are carried out, considering two hybrid ratios ...In order to study the fatigue failure mode and fatigue life laws of basalt-aramid and basalt-carbon hybrid fiber reinforced polymer （ FRP ） sheets, fatigue experiments are carried out, considering two hybrid ratios of 1 ： 1 and 2：1 under different stress levels from 0.6 to 0.95. The results show that fractures occur first in carbon fibers or aramid fibers for the specimens with hybrid ratio of 1： 1, namely B1A1 and B1C1, while a fracture occurs first in basalt fibers for the specimens with a hybrid ratio of 2： 1, namely B2A1 and B2C1. The fatigue lives of the hybrid FRP sheets increase with the improvement of the content of carbon fibers or aramid fibers, and the influence of the carbon fibers content improvement to fatigue life is more significant. The fatigue performance of B2A1 is relatively worse, while the fatigue performance of B1C1 and B2C1 is relatively better. Finally, a new fatigue stiffness degradation model with dual variables and double inflection points is presented, which is applicable to both hybrid and normal FRP sheets.展开更多
A novel porous metal fiber sintered sheet （PMFSS） with a three-dimensional reticulated structure was fabricated by multi-tooth cutting and high-temperature solid-phase sintering process with copper fibers. A uniaxia...A novel porous metal fiber sintered sheet （PMFSS） with a three-dimensional reticulated structure was fabricated by multi-tooth cutting and high-temperature solid-phase sintering process with copper fibers. A uniaxial tensile test was conducted to investigate the effect of fiber length and natural aging factor on the tensile properties of the PMFSS. Results indicated that, under given stress, the increase of fiber length helped reinforce the tensile strength. The elongation of the PMFSS with medium length fiber of 15 mm exhibited the optimal performance, reaching about 13.5%. After natural aging treatment for a month, the tensile strength of PMFSS significantly decreased, but the change of elongation was negligible except for the one with the shortest fiber length of 5 mm, whose elongation was effectively improved. The morphological fracture features of PMFSSs were also characterized.展开更多
Twenty-one square concrete columns were constructed and tested. The testing results indicate that bonded carbon fiber reinforced plastics(CFRP) sheets can be used to increase the strength and improve the serviceabilit...Twenty-one square concrete columns were constructed and tested. The testing results indicate that bonded carbon fiber reinforced plastics(CFRP) sheets can be used to increase the strength and improve the serviceability of damaged concrete columns at low temperatures. The failure of the specimens,in most cases,takes place within the middle half of the columns. And the failure of strengthened columns is sudden and explosive. The CFRP sheets increase both the axial load capacity and the ultimate concrete compressive strain of the columns. The ultimate loads of strengthened columns at-10,0 and 10 ℃ increase averagely by 9.09%,6.63% and 17.83%,respectively,as compared with those of the control specimens. The axial compressive strength of strengthened columns is related to the curing temperatures. The improvement of axial compressive strength decreases with reducing temperature,and when the temperature drops to a certain value,the improvement increases with falling temperature.展开更多
The problems on the non-uniqueness and stability of a two-family fiber- reinforced anisotropic incompressible hyper-elastic square sheet under equibiaxial tensile dead loading are examined within the framework of fini...The problems on the non-uniqueness and stability of a two-family fiber- reinforced anisotropic incompressible hyper-elastic square sheet under equibiaxial tensile dead loading are examined within the framework of finite elasticity. For a two-family fiber-reinforced square sheet, which is in-plane symmetric and subjected to the in-plane symmetric tension in dead loading on the edges, three symmetrically deformed configu- rations and six asymmetrically deformed configurations are possible for any values of the loading. Moreover, another four bifurcated asymmetrically deformed configurations are possible for the loading beyond a certain criticM value. The stability of all the solutions is discussed in comparison with the energy of the sheet. It is shown that only one of the symmetric solutions is stable when the loading is less than the critical value. However, this symmetric solution will become unstable when the loading is larger than the critical value, while one of the four bifurcated asymmetric solutions will be stable.展开更多
This study focuses on the thermophysical characterizations of composite materials made from polypropylene reinforced with residues and fibers from Borassus wood from Chad. These properties are experimentally determine...This study focuses on the thermophysical characterizations of composite materials made from polypropylene reinforced with residues and fibers from Borassus wood from Chad. These properties are experimentally determined at different temperatures using the hot wire method of the “FP2C” machine, where the hot wire probe is inserted between two specimens. The values of the thermal conductivity in powdered Borassus wood range from 0.170 W/mK to 0.182 W/mK for female wood (FNTF) and from 0.169 W/mK to 0.173 W/mK for male wood. For the female and male fibers, the thermal conductivity values range from 0.137 W/mK to 0.157 W/mK for the female and from 0.138 W/mK to 0.168 W/mK for the male. The thermal effusivity of the residues and fibers of Borassus wood varies from: 509.6 Ws1/2/m2K to 543 Ws1/2/m2K for the powder of female wood and from 524.6 Ws1/2/m2K to 547 Ws1/2/m2K for the powder of male wood. For the fibers of Borassus wood, the values range from 410.6 Ws1/2/m2K to 523.6 Ws1/2/m2K for the female wood fibers and from 420.3 Ws1/2/m2K to 480.3 Ws1/2/m2K for the male wood fibers. These results are important for the applications of Borassus wood residues and fibers in construction works regarding the thermal insulation of habitats.展开更多
In this investigation, the secondary fibers from old book papers were treated with a kind of commercial cellulase. The modifying conditions that cellulase works best as enzyme dosage, temperature, pH value, pulp consi...In this investigation, the secondary fibers from old book papers were treated with a kind of commercial cellulase. The modifying conditions that cellulase works best as enzyme dosage, temperature, pH value, pulp consistency, the reaction time and the primary freeness of pulp were optimized. Investigative work showed that the better drainage of the pulp was obtained, and the physical strengths were improved in different degrees, including the breaking length and density, when the fibers were treated with adequate enzyme preparations. The enzyme treatment effects were evidenced by means of SEM technology.展开更多
We report on the generation of conventional and dissipative solitons in erbium-doped fiber lasers by the evanescent field interaction between the propagating light and a multilayer molybdenum disulfide（MoS_2） thin f...We report on the generation of conventional and dissipative solitons in erbium-doped fiber lasers by the evanescent field interaction between the propagating light and a multilayer molybdenum disulfide（MoS_2） thin film. The MoS_2 film is fabricated by depositing the MoS_2 water–ethanol mixture on a D-shape-fiber（DF） repetitively. The measured nonsaturable loss, saturable optical intensity, and the modulation depth of this device are 13.3%, 110 MW/cm^2, and 3.4% respectively.Owing to the very low nonsaturable loss, the laser threshold of conventional soliton is as low as 4.8 mW. The further increase of net cavity dispersion to normal regime, stable dissipation soliton pulse trains with a spectral bandwidth of 11.7 nm and pulse duration of 116 ps are successfully generated. Our experiment demonstrates that the MoS_2-DF device can indeed be used as a high performance saturable absorber for further applications in ultrafast photonics.展开更多
The capability of pulping for the solid waste of leather was investigated. The properties of paper that made up of collagenous fiber and plant fiber were also analyzed. The result showed that by proper treatment, soli...The capability of pulping for the solid waste of leather was investigated. The properties of paper that made up of collagenous fiber and plant fiber were also analyzed. The result showed that by proper treatment, solid waste of leather could be made into collagen fiber for papermaking. The physical strength of paper can be enhanced by appending collagenous fiber in a proper propriety.展开更多
Experiments were carried out to design polyvinyl alcohol （PVA） fiber reinforced cementitous composites （PVA-FRCCs） holding high ductility and energy consumption ability. Besides, the properties of each ingredients...Experiments were carried out to design polyvinyl alcohol （PVA） fiber reinforced cementitous composites （PVA-FRCCs） holding high ductility and energy consumption ability. Besides, the properties of each ingredients in composites, mixing method and technology for fresh mixture were described in detail. Then, the pseudo-strain-hardening （PSH） behavior was investigated in uniaxial tension test. As a result, the maximum ultimate tensile strain can reach 0.7 percent. On the other hand, the single edge notch （SEN） thin sheet specimens were employed to gain the normal tensile load via crack mouth opening displacement （CMOD） curves, which can show obvious PSH behavior. In addition, the curves can be divided into four zones whose fracture toughness calculation methods were discussed. The wedge splitting （WS） test method can be applied to discuss the fracture toughness. Moreover, fracture energy of SEN and WS specimens were both approximately evaluated.展开更多
Low pressure sheet molding compound （LPMC,1.0-3.0 MPa,95-103 ℃） is a new kind of thermosetting material with crystalline polyester as a physical thickenner.LPMC is different from conventional SMC using an earth oxi...Low pressure sheet molding compound （LPMC,1.0-3.0 MPa,95-103 ℃） is a new kind of thermosetting material with crystalline polyester as a physical thickenner.LPMC is different from conventional SMC using an earth oxide thickening agent （e.g.MgO） as chemical thickenner,it relies on the physical thickening of crystalline polyester.Crystalline polyester resin is the key material to mold LPMC parts.Currently there was no report about the thickening mechanism of crystalline polyester in LPMC.In this article,crystalline polyester resins,whose melting points were between 45 ℃ and 89 ℃,were synthesized by a two-step esterification.The melt points of crystalline polyesters are controlled by regulating the mol ratio of the two glycols and the two acids.And by means of varying the content of crystalline polyester resin,the thickening effect on resin paste is investigated.In addition,the thickening mechanism of crystalline polyester in LPMC was investigated by FTIR and DSC analysis.The effects of the diameters and viscosity of crystalline polyester on the rheological property and fiber distribution of LPMC sheets were studied,too.Results show that the thickening effect is excellent when the weight content of crystalline polyester resin is 3%.And there exists three kinds of functions acting in the process of thickening：swelling,hydrogen bonds and induction crystallization.During the preparing process of resin paste in LPMC,the temperature of resin paste must be kept at 90 ℃.In addition,crystalline polyester make LPMC have a perfect fluid property.When the viscosity of LPMC sheet is beyond 1 kPa s,the fiber orientation is not obvious.But when the viscosity of LPMC sheet is about 500 Pa s,the fiber shows a certain degree of orientation.Moreover the study of physical and chemical thickening mechanism of crystalline polyester and the rheological discipline of LPMC sheets in the hot mould will provide the researchers and enterprises with theory guidance.展开更多
文摘Eight high strength concrete (HSC) prisms strengthened with continuous carbon fiber sheet(CFS)were tested.As a result of the confinement provided by CFS,the concrete would fail at a greater strain than the unconfined and then a significant increase in ductility can be achieved.The lateral pressure exerted by CFS would increase the compressive strength of the concrete,resulting in higher load bearing capacity.This paper proposes the stress strain curve of this kind of hybrid specimen,which agrees well with the test results.Based on the stress strain relationship and the assumptions proposed in this paper,a computer program was developed to analyze HSC columns,confined by CFS,which were subjected to axial compression and biaxial bending.The results shown in this paper indicate that the ductility of HSC column is significantly improved and the strength is also increased by some degree.
基金Supported by Ministry of Education,Science,Sports and Culture ofJapan under constract No.1 0 0 4 50 55
文摘This paper discusses the method of determining the tensile strength and modulus of elasticity of continuous carbon fiber sheet.Five simply supported beams strengthened by CFS were tested.Based on th experiment,a computer analysis program is developed and a simplified formula is proposed.The calculated results agree well with the experimental results.The design method suggested by this paper can meet the engineering requirements.
基金Project(51375369)supported by the National Natural Science Foundation of ChinaProject(SYG201137)supported by the Science and Technology Development Program of Suzhou,China
文摘To improve the manufacture efficiency and promote the application of composites in the automobile industry, a new composite forming method, thermal stamping, was discussed to form composite parts directly. Experiments on two typical stamping processes, thermal bending and thermal deep drawing, were conducted to investigate the forming behavior of composite sheets and analyze the influence of forming temperature on the formed composite part. Experimental results show that the locking angle for woven composite is about 30°. The bending load is smaller than 5 N in the stamping process and decreases with the increase of temperature. The optimal temperature to form the carbon fiber composite is 170 ℃. The die temperature distribution and the deformation of composite sheet were simulated by FEA software ABAQUS. To investigate the fiber movement of carbon woven fabric during stamping, the two-node three-dimension linear Truss unit T2D3 was chosen as the fiber element. The simulation results have a good agreement to the experimental results.
基金The National Natural Science Foundation of China(No.51108238)
文摘In order to study the fatigue failure mode and fatigue life laws of basalt-aramid and basalt-carbon hybrid fiber reinforced polymer （ FRP ） sheets, fatigue experiments are carried out, considering two hybrid ratios of 1 ： 1 and 2：1 under different stress levels from 0.6 to 0.95. The results show that fractures occur first in carbon fibers or aramid fibers for the specimens with hybrid ratio of 1： 1, namely B1A1 and B1C1, while a fracture occurs first in basalt fibers for the specimens with a hybrid ratio of 2： 1, namely B2A1 and B2C1. The fatigue lives of the hybrid FRP sheets increase with the improvement of the content of carbon fibers or aramid fibers, and the influence of the carbon fibers content improvement to fatigue life is more significant. The fatigue performance of B2A1 is relatively worse, while the fatigue performance of B1C1 and B2C1 is relatively better. Finally, a new fatigue stiffness degradation model with dual variables and double inflection points is presented, which is applicable to both hybrid and normal FRP sheets.
基金Projects(51475172,51275180,51375177) supported by the National Natural Science Foundation of ChinaProject(S2013040016899) supported by the Natural Science Foundation of Guangdong Province,ChinaProjects(2013ZM0003,2013ZZ017) supported by the Fundamental Research Funds for the Central Universities,South China University of Technology,China
文摘A novel porous metal fiber sintered sheet （PMFSS） with a three-dimensional reticulated structure was fabricated by multi-tooth cutting and high-temperature solid-phase sintering process with copper fibers. A uniaxial tensile test was conducted to investigate the effect of fiber length and natural aging factor on the tensile properties of the PMFSS. Results indicated that, under given stress, the increase of fiber length helped reinforce the tensile strength. The elongation of the PMFSS with medium length fiber of 15 mm exhibited the optimal performance, reaching about 13.5%. After natural aging treatment for a month, the tensile strength of PMFSS significantly decreased, but the change of elongation was negligible except for the one with the shortest fiber length of 5 mm, whose elongation was effectively improved. The morphological fracture features of PMFSSs were also characterized.
基金Project(04043076) supported by the Outstanding Youth Foundation for Scientific and Technological Research of Anhui Province, ChinaProject(2007jq1035) supported by the Scientific Research Projects for Young College Teachers of Anhui Province, China
文摘Twenty-one square concrete columns were constructed and tested. The testing results indicate that bonded carbon fiber reinforced plastics(CFRP) sheets can be used to increase the strength and improve the serviceability of damaged concrete columns at low temperatures. The failure of the specimens,in most cases,takes place within the middle half of the columns. And the failure of strengthened columns is sudden and explosive. The CFRP sheets increase both the axial load capacity and the ultimate concrete compressive strain of the columns. The ultimate loads of strengthened columns at-10,0 and 10 ℃ increase averagely by 9.09%,6.63% and 17.83%,respectively,as compared with those of the control specimens. The axial compressive strength of strengthened columns is related to the curing temperatures. The improvement of axial compressive strength decreases with reducing temperature,and when the temperature drops to a certain value,the improvement increases with falling temperature.
基金supported by the National Natural Science Foundation of China(No.10772104)the Shanghai Leading Academic Discipline Project(No.S30106)
文摘The problems on the non-uniqueness and stability of a two-family fiber- reinforced anisotropic incompressible hyper-elastic square sheet under equibiaxial tensile dead loading are examined within the framework of finite elasticity. For a two-family fiber-reinforced square sheet, which is in-plane symmetric and subjected to the in-plane symmetric tension in dead loading on the edges, three symmetrically deformed configu- rations and six asymmetrically deformed configurations are possible for any values of the loading. Moreover, another four bifurcated asymmetrically deformed configurations are possible for the loading beyond a certain criticM value. The stability of all the solutions is discussed in comparison with the energy of the sheet. It is shown that only one of the symmetric solutions is stable when the loading is less than the critical value. However, this symmetric solution will become unstable when the loading is larger than the critical value, while one of the four bifurcated asymmetric solutions will be stable.
文摘This study focuses on the thermophysical characterizations of composite materials made from polypropylene reinforced with residues and fibers from Borassus wood from Chad. These properties are experimentally determined at different temperatures using the hot wire method of the “FP2C” machine, where the hot wire probe is inserted between two specimens. The values of the thermal conductivity in powdered Borassus wood range from 0.170 W/mK to 0.182 W/mK for female wood (FNTF) and from 0.169 W/mK to 0.173 W/mK for male wood. For the female and male fibers, the thermal conductivity values range from 0.137 W/mK to 0.157 W/mK for the female and from 0.138 W/mK to 0.168 W/mK for the male. The thermal effusivity of the residues and fibers of Borassus wood varies from: 509.6 Ws1/2/m2K to 543 Ws1/2/m2K for the powder of female wood and from 524.6 Ws1/2/m2K to 547 Ws1/2/m2K for the powder of male wood. For the fibers of Borassus wood, the values range from 410.6 Ws1/2/m2K to 523.6 Ws1/2/m2K for the female wood fibers and from 420.3 Ws1/2/m2K to 480.3 Ws1/2/m2K for the male wood fibers. These results are important for the applications of Borassus wood residues and fibers in construction works regarding the thermal insulation of habitats.
文摘In this investigation, the secondary fibers from old book papers were treated with a kind of commercial cellulase. The modifying conditions that cellulase works best as enzyme dosage, temperature, pH value, pulp consistency, the reaction time and the primary freeness of pulp were optimized. Investigative work showed that the better drainage of the pulp was obtained, and the physical strengths were improved in different degrees, including the breaking length and density, when the fibers were treated with adequate enzyme preparations. The enzyme treatment effects were evidenced by means of SEM technology.
基金Project supported by the National Natural Science Foundation of China(Grant No.61378024)
文摘We report on the generation of conventional and dissipative solitons in erbium-doped fiber lasers by the evanescent field interaction between the propagating light and a multilayer molybdenum disulfide（MoS_2） thin film. The MoS_2 film is fabricated by depositing the MoS_2 water–ethanol mixture on a D-shape-fiber（DF） repetitively. The measured nonsaturable loss, saturable optical intensity, and the modulation depth of this device are 13.3%, 110 MW/cm^2, and 3.4% respectively.Owing to the very low nonsaturable loss, the laser threshold of conventional soliton is as low as 4.8 mW. The further increase of net cavity dispersion to normal regime, stable dissipation soliton pulse trains with a spectral bandwidth of 11.7 nm and pulse duration of 116 ps are successfully generated. Our experiment demonstrates that the MoS_2-DF device can indeed be used as a high performance saturable absorber for further applications in ultrafast photonics.
文摘The capability of pulping for the solid waste of leather was investigated. The properties of paper that made up of collagenous fiber and plant fiber were also analyzed. The result showed that by proper treatment, solid waste of leather could be made into collagen fiber for papermaking. The physical strength of paper can be enhanced by appending collagenous fiber in a proper propriety.
基金Committee on Science and Technology Foundation of China(No.50438010)The Research of Formation Progress and Control Technology of Concrete Structure Cracks
文摘Experiments were carried out to design polyvinyl alcohol （PVA） fiber reinforced cementitous composites （PVA-FRCCs） holding high ductility and energy consumption ability. Besides, the properties of each ingredients in composites, mixing method and technology for fresh mixture were described in detail. Then, the pseudo-strain-hardening （PSH） behavior was investigated in uniaxial tension test. As a result, the maximum ultimate tensile strain can reach 0.7 percent. On the other hand, the single edge notch （SEN） thin sheet specimens were employed to gain the normal tensile load via crack mouth opening displacement （CMOD） curves, which can show obvious PSH behavior. In addition, the curves can be divided into four zones whose fracture toughness calculation methods were discussed. The wedge splitting （WS） test method can be applied to discuss the fracture toughness. Moreover, fracture energy of SEN and WS specimens were both approximately evaluated.
基金supported by National Natural Science Foundation of China (Grant No. 50473013)National Hi-tech Research and Development Program of China (863 Program,Grant No. 2003AA333070)+1 种基金Hubei Provincial Natural Science Foundation of China (Grant No.2009CDA037)Researching Foundation of Hubei Automotive Industries Institute of China (Grant No. BK201001)
文摘Low pressure sheet molding compound （LPMC,1.0-3.0 MPa,95-103 ℃） is a new kind of thermosetting material with crystalline polyester as a physical thickenner.LPMC is different from conventional SMC using an earth oxide thickening agent （e.g.MgO） as chemical thickenner,it relies on the physical thickening of crystalline polyester.Crystalline polyester resin is the key material to mold LPMC parts.Currently there was no report about the thickening mechanism of crystalline polyester in LPMC.In this article,crystalline polyester resins,whose melting points were between 45 ℃ and 89 ℃,were synthesized by a two-step esterification.The melt points of crystalline polyesters are controlled by regulating the mol ratio of the two glycols and the two acids.And by means of varying the content of crystalline polyester resin,the thickening effect on resin paste is investigated.In addition,the thickening mechanism of crystalline polyester in LPMC was investigated by FTIR and DSC analysis.The effects of the diameters and viscosity of crystalline polyester on the rheological property and fiber distribution of LPMC sheets were studied,too.Results show that the thickening effect is excellent when the weight content of crystalline polyester resin is 3%.And there exists three kinds of functions acting in the process of thickening：swelling,hydrogen bonds and induction crystallization.During the preparing process of resin paste in LPMC,the temperature of resin paste must be kept at 90 ℃.In addition,crystalline polyester make LPMC have a perfect fluid property.When the viscosity of LPMC sheet is beyond 1 kPa s,the fiber orientation is not obvious.But when the viscosity of LPMC sheet is about 500 Pa s,the fiber shows a certain degree of orientation.Moreover the study of physical and chemical thickening mechanism of crystalline polyester and the rheological discipline of LPMC sheets in the hot mould will provide the researchers and enterprises with theory guidance.
