The status and the variation of electrical resistance of impacted carbon fiber/epoxy-matrix composites were studied by ultrasonic F-scan and electrical resistance measurement The experimental results shows that impact...The status and the variation of electrical resistance of impacted carbon fiber/epoxy-matrix composites were studied by ultrasonic F-scan and electrical resistance measurement The experimental results shows that impact damage energy threshold value of carbon fabric/epoxy-matrix composites can determine by using ultrasonic F-scan. When the impact energy exceeds the threshold value, damage is generated in composites. Electrical resistance of impacted composites is changed owing to the contact of each carbon fiber unit in composites, which cause a change of the series-parallel in conductors. The veracity of detecting impact damage in composites can be improved in this case.展开更多
Impact damage tolerance is provided in intensity design on composites. The compression intensity of impacted composites requires more than 60% of its original intensity. The influence of impact on compressive intensit...Impact damage tolerance is provided in intensity design on composites. The compression intensity of impacted composites requires more than 60% of its original intensity. The influence of impact on compressive intensity and electrical resistance of carbon fabric/epoxy-matrix composites was studied in this paper. The experimental results shows that impact can cause damage in composites, degenerate compressive intensity, and increase resistance. The electrical resistance change rate was used as an evaluation indicator of impact damage tolerance of composites. Impact damage, which results from the applying process of composites, can be identified in time by electrical resistance measurement. So, the safety performance of composites can also be improved.展开更多
The effects of fibre/matrix bonding, fabric density, fibre volume fraction and bundle size on microstructure, mechanical properties and failure mechanisms in carbon fibre reinforced composites （plastic and carbon mat...The effects of fibre/matrix bonding, fabric density, fibre volume fraction and bundle size on microstructure, mechanical properties and failure mechanisms in carbon fibre reinforced composites （plastic and carbon matrix） have been investigated. The microstructure of unloaded and cracked samples was studied by optical microscopy and scanning electron microscopy （SEM）, respectively whereas the mechanical behaviour was examined by 3- point bending experiments. Exclusively one type of experimental resole type phenolic resin was applied. A strong fibre/matrix bonding, which is needed for high strength of carbon fibre reinforced plastic （CFRP） materials leads to severe composite damages during the pyrolysis resulting in low strength, brittle failure and a very low utilisation of the fibres strain to failure in C/C composites. Inherent fabric parameters such as an increasing fabric density or bundle size or a reduced fibre volume fraction introduce inhomogenities to the CFRP＇s microstructure. Results are lower strength and stiffness whereas the strain to failure increases or remains unchanged. Toughness is almost not affected. In C/C composites inhomogenities due to a reduced bundle size reduce strain to failure, strength, stiffness and toughness. Vice versa a declining fibre volume fraction leads to exactly the opposite behaviour. Increasing the fabric density （weight per unit area） causes similar effects as in CFRPs.展开更多
The main problems with the liquid-phase technology of carbon fiber/aluminum matrix composites include poor wetting of the fiber with liquid aluminum and formation of aluminum carbide on the fibers’surface.This paper ...The main problems with the liquid-phase technology of carbon fiber/aluminum matrix composites include poor wetting of the fiber with liquid aluminum and formation of aluminum carbide on the fibers’surface.This paper aims to solve these problems.The theoretical and experimental dependence of porosity on the applied pressure were determined.The possibility of obtaining a carbon fiber/aluminum matrix composite wire with a strength value of about 1500 MPa was shown.The correlation among the strength of the carbon fiber reinforced aluminum matrix composite,the fracture surface,and the degradation of the carbon fiber surface was discussed.展开更多
In the light of the mapping between[0,1]matrixes of fab-ric weaves,we establish in this paper a mathematical modelfor fabric weave design- One type of non- associative al-gebra composed of 7 basic transformations in a...In the light of the mapping between[0,1]matrixes of fab-ric weaves,we establish in this paper a mathematical modelfor fabric weave design- One type of non- associative al-gebra composed of 7 basic transformations in a 2- elementfield.In view of practice,we expand the generative set ofmapping of this matematical model to cover the generaltransformation methods in traditional weave design.Takingthe algorethm of" Kronecker product" as an example,wefurthermore illustrate applied potentialities of the generativeset of mapping in the CAD of fabic weaves.展开更多
Composites are materials that are made up of two or more chemically dissimilar phases. In this project aluminum was chosen as matrix material because it was inexpensive, light-weight, strong, tough and corrosion resis...Composites are materials that are made up of two or more chemically dissimilar phases. In this project aluminum was chosen as matrix material because it was inexpensive, light-weight, strong, tough and corrosion resistant. For the main load bearing phase it was hard, corrosion resistant at room temperature and thermally stable. The stir casting method was used because it was cost-effective and easy, and the particulate reinforcement (nickel) was uniformly distributed throughout the matrix phase. Sand moulding was used to cast the specimens. Specimens with 10, 20, 30 and 40 percentage Nickel were tested and the optimal specimen contained 20% Nickel. The Brinell hardness of Al + 20% Ni increased by 14.80%, Rockwell hardness increased by 2.43%, ultimate tensile strength increased by 1.003% and thermal conductivity of Al + 20% Ni decreased by 24.98% with respect to Aluminum.展开更多
The correct rate of detection for fabric defect is affected by low contrast of images. Aiming at the problem,frequencytuned salient map is used to detect the fabric defect. Firstly,the images of fabric defect are divi...The correct rate of detection for fabric defect is affected by low contrast of images. Aiming at the problem,frequencytuned salient map is used to detect the fabric defect. Firstly,the images of fabric defect are divided into blocks. Then,the blocks are highlighted by frequency-tuned salient algorithm. Simultaneously,gray-level co-occurrence matrix is used to extract the characteristic value of each rectangular patch. Finally,PNN is used to detect the defect on the fabric image. The performance of proposed algorithm is estimated off-line by two sets of fabric defect images. The theoretical argument is supported by experimental results.展开更多
基金Funded by the Key Laboratory of Nondestructive Testing (Nanchang Hangkong University), Ministry of Education, China(No.ZD200829001)
文摘The status and the variation of electrical resistance of impacted carbon fiber/epoxy-matrix composites were studied by ultrasonic F-scan and electrical resistance measurement The experimental results shows that impact damage energy threshold value of carbon fabric/epoxy-matrix composites can determine by using ultrasonic F-scan. When the impact energy exceeds the threshold value, damage is generated in composites. Electrical resistance of impacted composites is changed owing to the contact of each carbon fiber unit in composites, which cause a change of the series-parallel in conductors. The veracity of detecting impact damage in composites can be improved in this case.
基金Funded by Key Laboratory of Nondestructive Testing (Nanchang Hangkong University)Ministry of Education, China(No. ZD200829001)Department of Education of Jiangxi Province, China(No. GJJ10531)
文摘Impact damage tolerance is provided in intensity design on composites. The compression intensity of impacted composites requires more than 60% of its original intensity. The influence of impact on compressive intensity and electrical resistance of carbon fabric/epoxy-matrix composites was studied in this paper. The experimental results shows that impact can cause damage in composites, degenerate compressive intensity, and increase resistance. The electrical resistance change rate was used as an evaluation indicator of impact damage tolerance of composites. Impact damage, which results from the applying process of composites, can be identified in time by electrical resistance measurement. So, the safety performance of composites can also be improved.
文摘The effects of fibre/matrix bonding, fabric density, fibre volume fraction and bundle size on microstructure, mechanical properties and failure mechanisms in carbon fibre reinforced composites （plastic and carbon matrix） have been investigated. The microstructure of unloaded and cracked samples was studied by optical microscopy and scanning electron microscopy （SEM）, respectively whereas the mechanical behaviour was examined by 3- point bending experiments. Exclusively one type of experimental resole type phenolic resin was applied. A strong fibre/matrix bonding, which is needed for high strength of carbon fibre reinforced plastic （CFRP） materials leads to severe composite damages during the pyrolysis resulting in low strength, brittle failure and a very low utilisation of the fibres strain to failure in C/C composites. Inherent fabric parameters such as an increasing fabric density or bundle size or a reduced fibre volume fraction introduce inhomogenities to the CFRP＇s microstructure. Results are lower strength and stiffness whereas the strain to failure increases or remains unchanged. Toughness is almost not affected. In C/C composites inhomogenities due to a reduced bundle size reduce strain to failure, strength, stiffness and toughness. Vice versa a declining fibre volume fraction leads to exactly the opposite behaviour. Increasing the fabric density （weight per unit area） causes similar effects as in CFRPs.
基金financially supported by ISSP RAS-Russian Government contracts
文摘The main problems with the liquid-phase technology of carbon fiber/aluminum matrix composites include poor wetting of the fiber with liquid aluminum and formation of aluminum carbide on the fibers’surface.This paper aims to solve these problems.The theoretical and experimental dependence of porosity on the applied pressure were determined.The possibility of obtaining a carbon fiber/aluminum matrix composite wire with a strength value of about 1500 MPa was shown.The correlation among the strength of the carbon fiber reinforced aluminum matrix composite,the fracture surface,and the degradation of the carbon fiber surface was discussed.
文摘In the light of the mapping between[0,1]matrixes of fab-ric weaves,we establish in this paper a mathematical modelfor fabric weave design- One type of non- associative al-gebra composed of 7 basic transformations in a 2- elementfield.In view of practice,we expand the generative set ofmapping of this matematical model to cover the generaltransformation methods in traditional weave design.Takingthe algorethm of" Kronecker product" as an example,wefurthermore illustrate applied potentialities of the generativeset of mapping in the CAD of fabic weaves.
文摘Composites are materials that are made up of two or more chemically dissimilar phases. In this project aluminum was chosen as matrix material because it was inexpensive, light-weight, strong, tough and corrosion resistant. For the main load bearing phase it was hard, corrosion resistant at room temperature and thermally stable. The stir casting method was used because it was cost-effective and easy, and the particulate reinforcement (nickel) was uniformly distributed throughout the matrix phase. Sand moulding was used to cast the specimens. Specimens with 10, 20, 30 and 40 percentage Nickel were tested and the optimal specimen contained 20% Nickel. The Brinell hardness of Al + 20% Ni increased by 14.80%, Rockwell hardness increased by 2.43%, ultimate tensile strength increased by 1.003% and thermal conductivity of Al + 20% Ni decreased by 24.98% with respect to Aluminum.
文摘The correct rate of detection for fabric defect is affected by low contrast of images. Aiming at the problem,frequencytuned salient map is used to detect the fabric defect. Firstly,the images of fabric defect are divided into blocks. Then,the blocks are highlighted by frequency-tuned salient algorithm. Simultaneously,gray-level co-occurrence matrix is used to extract the characteristic value of each rectangular patch. Finally,PNN is used to detect the defect on the fabric image. The performance of proposed algorithm is estimated off-line by two sets of fabric defect images. The theoretical argument is supported by experimental results.
