2000 Vol. 17, No. 1
2000, 17(1): 1-4.
Abstract:
In the present article, the developmental course of composite materials in china wasreviewed briefly, and then some prospective oppor tunities and challenges were delivered. Finally,a number of measures were also suggested.
In the present article, the developmental course of composite materials in china wasreviewed briefly, and then some prospective oppor tunities and challenges were delivered. Finally,a number of measures were also suggested.
2000, 17(1): 5-10.
Abstract:
The wo rldw ide p rogress and p resen t statu s of SHS research w ere in t roduced.Impo rtan t SHS techno logies w ere analyzed. The new est research wo rk s in the wo rld and theimpo rtan t resu lt s ob tained by the Ch inese scien Tist s w ere review ed.
The wo rldw ide p rogress and p resen t statu s of SHS research w ere in t roduced.Impo rtan t SHS techno logies w ere analyzed. The new est research wo rk s in the wo rld and theimpo rtan t resu lt s ob tained by the Ch inese scien Tist s w ere review ed.
2000, 17(1): 11-14.
Abstract:
Combining the micro structure and the interaction between two particles in an electrorheological fluid thaTis calculated by the modified dipolemodel and the conductivity model respecTively, the shear stress-strain relationships of the electrorheological fluid were set up. On this basis, and considering the fracture and reconfiguration process in the post-yield state of this material, its dynamic yield stress was obtained. The calculation indicates that the dynamic yieldst ress low er than staTic yield st ress by abou t 25%. In addiTion, the dynam ic yield st ress of theelect ro rheo logical f lu id increases nearly linearly w ith the vo lume f racTion at the small vo lumef racTion and get s their max imum s at rather large vo lume f racTion s, 0. 4～ 0. 5.
Combining the micro structure and the interaction between two particles in an electrorheological fluid thaTis calculated by the modified dipolemodel and the conductivity model respecTively, the shear stress-strain relationships of the electrorheological fluid were set up. On this basis, and considering the fracture and reconfiguration process in the post-yield state of this material, its dynamic yield stress was obtained. The calculation indicates that the dynamic yieldst ress low er than staTic yield st ress by abou t 25%. In addiTion, the dynam ic yield st ress of theelect ro rheo logical f lu id increases nearly linearly w ith the vo lume f racTion at the small vo lumef racTion and get s their max imum s at rather large vo lume f racTion s, 0. 4～ 0. 5.
2000, 17(1): 15-18.
Abstract:
The structures of epoxy resins of E 51(bisphenol A diglycidyl ether),AG 80(tetraglycidyldiaminodiphenylmethane), TDE 85(cycloaliphatic aromatic glycidle ester) were characterized by 1H and 13 C NMR, and assignments of the peaks were made by means of 1 H 1H homo nuclear shift correlation(COSY) 1 H 13 C chemical shift correlation(HETCOR).
The structures of epoxy resins of E 51(bisphenol A diglycidyl ether),AG 80(tetraglycidyldiaminodiphenylmethane), TDE 85(cycloaliphatic aromatic glycidle ester) were characterized by 1H and 13 C NMR, and assignments of the peaks were made by means of 1 H 1H homo nuclear shift correlation(COSY) 1 H 13 C chemical shift correlation(HETCOR).
2000, 17(1): 19-22.
Abstract:
The effects of the content and surface treatment of glass beads on the tensile properties of the filled low density polyethylene (LDPE)composites were investigated at room temperature using an Instron materials tester. The results show that the elastic modulus ( Ec) of the composites increases with the addition of the volume fraction of glass beads and the yield strength ( σ yR ) does not vary much. On the contrary, the tensile stress at break ( σ bR ), fracture strain ( ε bR ) and fracture energy ( E bR ) decrease. At the same test conditions the values of E c, σ yR and σ bR of the composite with glass bead surface pretreated with a silane coupling agent are slightly higher than those of the untreated one, and the difference in ε bR and E bR between both the filled systems is very insignificant.
The effects of the content and surface treatment of glass beads on the tensile properties of the filled low density polyethylene (LDPE)composites were investigated at room temperature using an Instron materials tester. The results show that the elastic modulus ( Ec) of the composites increases with the addition of the volume fraction of glass beads and the yield strength ( σ yR ) does not vary much. On the contrary, the tensile stress at break ( σ bR ), fracture strain ( ε bR ) and fracture energy ( E bR ) decrease. At the same test conditions the values of E c, σ yR and σ bR of the composite with glass bead surface pretreated with a silane coupling agent are slightly higher than those of the untreated one, and the difference in ε bR and E bR between both the filled systems is very insignificant.
2000, 17(1): 23-27.
Abstract:
The hydroxy and chlorine contents of a four functional epoxy resin, N,N,N',N' teraglycidy 4,4' diaminodiphenyl methane(AG 80), were determined by chemical analysis. According to the experimental results of the chemical analysis and the HPLC results reported in the literature, the concentrations of various impurities in AG 80 could be quantitatively given. ITis shown that the hydroxy and chorine contents especially the hydroxy contenTin AG 80 are higher , and the contents of epoxy group as well as TGDDM monomer in AG 80 are lower than those contents in other TGDDM epoxy resins in the world market. The experimental results show also that the main way to enhance the epoxy group contenTin AG 80 is to avoid the hydrolysis of the resin during its production process, and the measurements of the contents of hydroxy and chlorine in different forms in the resins are useful for the quantitative determination of various impurities in TGDDM epoxy resins.
The hydroxy and chlorine contents of a four functional epoxy resin, N,N,N',N' teraglycidy 4,4' diaminodiphenyl methane(AG 80), were determined by chemical analysis. According to the experimental results of the chemical analysis and the HPLC results reported in the literature, the concentrations of various impurities in AG 80 could be quantitatively given. ITis shown that the hydroxy and chorine contents especially the hydroxy contenTin AG 80 are higher , and the contents of epoxy group as well as TGDDM monomer in AG 80 are lower than those contents in other TGDDM epoxy resins in the world market. The experimental results show also that the main way to enhance the epoxy group contenTin AG 80 is to avoid the hydrolysis of the resin during its production process, and the measurements of the contents of hydroxy and chlorine in different forms in the resins are useful for the quantitative determination of various impurities in TGDDM epoxy resins.
2000, 17(1): 28-31.
Abstract:
By adding carbon black, ferrite and metal powders, polyacrylonitrile(PAN) based carbon fiber felts and epoxy resin were used to make a new kind of structural material for the application of radar microwave absorption. The material with area density of 5.2 kg/m2 achieved maximum absorbing value of -13.37 dB, and minimum value of -10 dB over the whole frequency range (8～18 GHz). The absorbing mechanisms were discussed using theory of electromagnetic scattering
By adding carbon black, ferrite and metal powders, polyacrylonitrile(PAN) based carbon fiber felts and epoxy resin were used to make a new kind of structural material for the application of radar microwave absorption. The material with area density of 5.2 kg/m2 achieved maximum absorbing value of -13.37 dB, and minimum value of -10 dB over the whole frequency range (8～18 GHz). The absorbing mechanisms were discussed using theory of electromagnetic scattering
2000, 17(1): 32-36.
Abstract:
Nylon 6 shows low impact strength values. By adding thermoplastic polyamide elastomers(TPAE), Nylon 6 alloy can obtain high impact strength values. PLM and SEM observations of the fracture surfaces and deformed regions beneath the fracture surfaces revealed that the fracture process of Nylon 6 was brittle, which was originated from the plastic constraint at the notch tip. The fracture of the alloy was also caused by the plastic constraint at the notch tip. However, the plastic deformation zone at the notch tip was composed of many voids and partially elongated fibrils, and this absorbed the impact energy. The plastic deformation was enhanced by the transition of the stress state from plane strain to plane stress. The final fracture occurred from the notch tip connecting voids in the plastic deformation zone.
Nylon 6 shows low impact strength values. By adding thermoplastic polyamide elastomers(TPAE), Nylon 6 alloy can obtain high impact strength values. PLM and SEM observations of the fracture surfaces and deformed regions beneath the fracture surfaces revealed that the fracture process of Nylon 6 was brittle, which was originated from the plastic constraint at the notch tip. The fracture of the alloy was also caused by the plastic constraint at the notch tip. However, the plastic deformation zone at the notch tip was composed of many voids and partially elongated fibrils, and this absorbed the impact energy. The plastic deformation was enhanced by the transition of the stress state from plane strain to plane stress. The final fracture occurred from the notch tip connecting voids in the plastic deformation zone.
2000, 17(1): 37-41.
Abstract:
In this paper iTis proposed to measure the change of viscosity of composite resin using fiber optic microbend attenuation. Proper optical fibers were selected and processed to increase sensitivities. Experiments of viscosity measurement for different lay up conditions were accomplished and the results were compared to dielectric measurement. ITis found that fiber optic attenuation is sensitive to composite cure monitoring in autoclave with good reliability which can indicate the gel point and the end point of the cure processing. The sensitivity is found to be related to the cross angle of optical fiber to reinforced fiber and the pressure in cure process. Embedded optical fibers which can accomplish cure monitoring and maintain optical wave guide performance are developed to be two sorts of vibration sensors based on the statistic mode of fiber optic vibration sensing mechanism.
In this paper iTis proposed to measure the change of viscosity of composite resin using fiber optic microbend attenuation. Proper optical fibers were selected and processed to increase sensitivities. Experiments of viscosity measurement for different lay up conditions were accomplished and the results were compared to dielectric measurement. ITis found that fiber optic attenuation is sensitive to composite cure monitoring in autoclave with good reliability which can indicate the gel point and the end point of the cure processing. The sensitivity is found to be related to the cross angle of optical fiber to reinforced fiber and the pressure in cure process. Embedded optical fibers which can accomplish cure monitoring and maintain optical wave guide performance are developed to be two sorts of vibration sensors based on the statistic mode of fiber optic vibration sensing mechanism.
2000, 17(1): 42-45.
Abstract:
The relationship between the phase structure of PSF/epoxy blend system and brittle/ductile transition was investigated, and the toughening mechanism was analyzed by studying the peeling strength of PSF/epoxy system, DMA and SEM fracture morphology. The results show that the blend system demonstrates good toughness when dispersed epoxy particles are covered by the continuous PSF network film homogeneously, and the thickness of the film is less than 0.04μm. Meanwhile the plastic strain produced in the ductile PSF film on fracture makes the system more flexible, and a toughened structure and toughening mechanism are different from that of traditional “sea island” structure. This resulTis of significance to develop resin matrix with excellent toughness of advanced composites and structural adhesives.
The relationship between the phase structure of PSF/epoxy blend system and brittle/ductile transition was investigated, and the toughening mechanism was analyzed by studying the peeling strength of PSF/epoxy system, DMA and SEM fracture morphology. The results show that the blend system demonstrates good toughness when dispersed epoxy particles are covered by the continuous PSF network film homogeneously, and the thickness of the film is less than 0.04μm. Meanwhile the plastic strain produced in the ductile PSF film on fracture makes the system more flexible, and a toughened structure and toughening mechanism are different from that of traditional “sea island” structure. This resulTis of significance to develop resin matrix with excellent toughness of advanced composites and structural adhesives.
2000, 17(1): 45-50.
Abstract:
Thermal residual stresses and their effects on the stress distributions under the applied tensile and compressive loadings were studied by using the deformation model proposed in paper[1]. It was demonstrated that the residual stresses in the matrix and the fiber can reach considerably high magnitudes and resulTin asymmetrical stress distributions and matrix plasticity under the applied tensile and compressive loadings. Thermal residual stresses reduce the stress transfer in tension and enhance the stress transfer in compression.
Thermal residual stresses and their effects on the stress distributions under the applied tensile and compressive loadings were studied by using the deformation model proposed in paper[1]. It was demonstrated that the residual stresses in the matrix and the fiber can reach considerably high magnitudes and resulTin asymmetrical stress distributions and matrix plasticity under the applied tensile and compressive loadings. Thermal residual stresses reduce the stress transfer in tension and enhance the stress transfer in compression.
2000, 17(1): 51-55.
Abstract:
By using the deformation model proposed in paper [1] and the calculated results of the stresses, the expressions of tensile and compressive elastic moduli and yield strengths in the absence of thermal residual stresses were derived, which exhibit good agreement with the experimental results. It was shown that the asymmetry in the elastic modulus results from the compressive residual stress in the fiber root and the asymmetry in the yield strength results from the tensile residual stress in the matrix and compressive residual stress in the fiber.
By using the deformation model proposed in paper [1] and the calculated results of the stresses, the expressions of tensile and compressive elastic moduli and yield strengths in the absence of thermal residual stresses were derived, which exhibit good agreement with the experimental results. It was shown that the asymmetry in the elastic modulus results from the compressive residual stress in the fiber root and the asymmetry in the yield strength results from the tensile residual stress in the matrix and compressive residual stress in the fiber.
2000, 17(1): 56-59.
Abstract:
To study the different graded interfacial characteristics of fiber/matrix and fiber bundle/matrix for carbon/carbon composites, two sets of push ouTinstruments for evaluating the interfacial bonding properties were designed and established respectively. Meanwhile, by using the push out techniques, the relationship between the bonding strength of these two graded interfaces under different processing parameters of C/C composites was investigated and their effects on the tensile properties of C/C composites were discussed. ITis found that the fiber and fiber bundle push out test techniques established in this paper can be used to evaluate the different graded interfacial bonding properties of C/C composites quantitatively. The results reveal that the different graded interfacial bonding status provides different contributions to the macro mechanical properties of C/C composites to some extent.
To study the different graded interfacial characteristics of fiber/matrix and fiber bundle/matrix for carbon/carbon composites, two sets of push ouTinstruments for evaluating the interfacial bonding properties were designed and established respectively. Meanwhile, by using the push out techniques, the relationship between the bonding strength of these two graded interfaces under different processing parameters of C/C composites was investigated and their effects on the tensile properties of C/C composites were discussed. ITis found that the fiber and fiber bundle push out test techniques established in this paper can be used to evaluate the different graded interfacial bonding properties of C/C composites quantitatively. The results reveal that the different graded interfacial bonding status provides different contributions to the macro mechanical properties of C/C composites to some extent.
2000, 17(1): 60-64.
Abstract:
Dry friction and wear behavior of Al matrix composites including those hybridizedly reinforced with 20 vol%SiC and 9 vol%Gr particles, and those separately reinforced with 20 vol%SiC and 9 vol%Gr particles were investigated. The wear tests were performed using a pin on disk wear machine under dry sliding condition, at a speed of 0.6 m/s within a load of 10 N to 120 N. At low loads (<30 N), the friction coefficient and wear rate of hybrid composites were all lower than those of composites reinforced respectively with SiC P and Gr P, because of cooperation of load bearing of SiC P and self lubrication of Gr P. At higher loads (30~120 N), the wear rate of hybrid composite was higher than that of SiC P/Al because of surface delamination of hybrid composite, but was greatly lower than Gr P/Al. The friction coefficient of hybrid coompisite was less than that of SiC P/Al. The wear rate of counterface which mated with pin of hybrid composite was largely lower than that of SiC P/Al at all loads.
Dry friction and wear behavior of Al matrix composites including those hybridizedly reinforced with 20 vol%SiC and 9 vol%Gr particles, and those separately reinforced with 20 vol%SiC and 9 vol%Gr particles were investigated. The wear tests were performed using a pin on disk wear machine under dry sliding condition, at a speed of 0.6 m/s within a load of 10 N to 120 N. At low loads (<30 N), the friction coefficient and wear rate of hybrid composites were all lower than those of composites reinforced respectively with SiC P and Gr P, because of cooperation of load bearing of SiC P and self lubrication of Gr P. At higher loads (30~120 N), the wear rate of hybrid composite was higher than that of SiC P/Al because of surface delamination of hybrid composite, but was greatly lower than Gr P/Al. The friction coefficient of hybrid coompisite was less than that of SiC P/Al. The wear rate of counterface which mated with pin of hybrid composite was largely lower than that of SiC P/Al at all loads.
2000, 17(1): 65-70.
Abstract:
SiC P/ZL109 composites fabricated by centrifugal casting and squeeze casting were characterized by conventional TEM. The leading phase Si in the (Al+Si) eutectic tended to nucleate and grow preferentially at the SiC surface(facets), thus forming the characteristic “interfacial Si” and the SiC/Si interfaces. A “subgrain Al layer” was usually observed at the Al side of a SiC/Al interface, which was less than 1μm thick with high density of dislocation generated in it. Measurements of crystallographic orientation relationship between SiC and Al and between SiC and Si were made at tens of SiC/Si and SiC/Al interfaces. ITis shown that no fixed and unique orientation relationships were determined, though the following preferential ones were observed: (1103)SiC //(111) Al ,[1120] SiC //[110] Al ; (1101) SiC //(111) Si ,[1120] SiC //[112] Si .
SiC P/ZL109 composites fabricated by centrifugal casting and squeeze casting were characterized by conventional TEM. The leading phase Si in the (Al+Si) eutectic tended to nucleate and grow preferentially at the SiC surface(facets), thus forming the characteristic “interfacial Si” and the SiC/Si interfaces. A “subgrain Al layer” was usually observed at the Al side of a SiC/Al interface, which was less than 1μm thick with high density of dislocation generated in it. Measurements of crystallographic orientation relationship between SiC and Al and between SiC and Si were made at tens of SiC/Si and SiC/Al interfaces. ITis shown that no fixed and unique orientation relationships were determined, though the following preferential ones were observed: (1103)SiC //(111) Al ,[1120] SiC //[110] Al ; (1101) SiC //(111) Si ,[1120] SiC //[112] Si .
2000, 17(1): 71-75.
Abstract:
Using liquid surface reaction technique, Fe VC surface composites with thickness of 3～4 mm were produced on casting steel. The microstructure and phase of Fe VC surface composite were studied by light microscope, SEM and XRD. The distribution of alloy elements in this surface composite was analysed by Electron probe with wave spectrum. Under condition of dry sliding with heavy loads, Fe VC surface composite holds great wear resistance.
Using liquid surface reaction technique, Fe VC surface composites with thickness of 3～4 mm were produced on casting steel. The microstructure and phase of Fe VC surface composite were studied by light microscope, SEM and XRD. The distribution of alloy elements in this surface composite was analysed by Electron probe with wave spectrum. Under condition of dry sliding with heavy loads, Fe VC surface composite holds great wear resistance.
2000, 17(1): 76-80.
Abstract:
A novel in situ reaction synthesis process, reaction technique in melt, was developed. An in situ particle reinforced Al 4.5 Cu/TiB2 composite was fabricated with low cost TiO2, H3BO3, Na3AlF6 powders and Al Cu alloy. TiB2 particle is very small, about 0.93 μm in size, and it has spheric shape in the solidification microstructure of the composite. The distribution of TiB2 particle in the matrix is uniform. The interface between TiB2 particle and the matrix is combining well. The tensile strength, yield strength and elongation of the composite are 416.7 MPa, 316.9 MPa and 3.3%, respectively, when TiB2 particle contenTin the matrix is 10 vol%.
A novel in situ reaction synthesis process, reaction technique in melt, was developed. An in situ particle reinforced Al 4.5 Cu/TiB2 composite was fabricated with low cost TiO2, H3BO3, Na3AlF6 powders and Al Cu alloy. TiB2 particle is very small, about 0.93 μm in size, and it has spheric shape in the solidification microstructure of the composite. The distribution of TiB2 particle in the matrix is uniform. The interface between TiB2 particle and the matrix is combining well. The tensile strength, yield strength and elongation of the composite are 416.7 MPa, 316.9 MPa and 3.3%, respectively, when TiB2 particle contenTin the matrix is 10 vol%.
2000, 17(1): 81-85.
Abstract:
In this paper, a kinetics model for martensitic transformation in shape memory alloys(SMAs) is established on the fact that the partial derivative of martensite fraction with respect to temperature is in linear relationship with the partial derivative of free energy difference with respect to temperature. The model is compared with Tanaka's model and Liang's model. All the models are implanted in the SMAs reinforced composite model and the result shows that the model established in this paper agrees well with experimental observations.
In this paper, a kinetics model for martensitic transformation in shape memory alloys(SMAs) is established on the fact that the partial derivative of martensite fraction with respect to temperature is in linear relationship with the partial derivative of free energy difference with respect to temperature. The model is compared with Tanaka's model and Liang's model. All the models are implanted in the SMAs reinforced composite model and the result shows that the model established in this paper agrees well with experimental observations.
2000, 17(1): 86-88.
Abstract:
The study on the energy release rate for cracks propagating of particle and matrix interface in Functionally Gradient Materials (FGM) was carried out. The thermal stress for the matrix particle interface was calculated using Double Layer Embedment model, also the relation between the stress and metal volume fraction was obtained,and then the energy release rate and the change of critical particle size(radius) in the graded layers were given.
The study on the energy release rate for cracks propagating of particle and matrix interface in Functionally Gradient Materials (FGM) was carried out. The thermal stress for the matrix particle interface was calculated using Double Layer Embedment model, also the relation between the stress and metal volume fraction was obtained,and then the energy release rate and the change of critical particle size(radius) in the graded layers were given.
2000, 17(1): 89-92.
Abstract:
In plasma sprayed ZrO2 NiCoCrAlY graded coating, the amount of ZrO2 increases gradually along the coating thickness from TC4 substrate to coating surface, while that of NiCoCrAlY changes oppositely, and the macro interface between ZrO2 and NiCoCrAlY which exists in duplex coating is eliminated. With the increasing of the amount of ZrO2, the density of ZrO2 NiCoCrAlY composite coating decreases gradually, and the hardness decreases firstly and then improves ; the 60 vol% ZrO2 Ni CoCrAlY coating has the lowest hardness, and the porosity in the rich NiCoCrAlY coatings is slightly lower than thaTin the rich ZrO2 coating. The gradual distribution of composition improves the adherent strength of coating and the coherent strength between coating and substrate. The interface between coating and TC4 substrate is the weakest zone in the graded coating.
In plasma sprayed ZrO2 NiCoCrAlY graded coating, the amount of ZrO2 increases gradually along the coating thickness from TC4 substrate to coating surface, while that of NiCoCrAlY changes oppositely, and the macro interface between ZrO2 and NiCoCrAlY which exists in duplex coating is eliminated. With the increasing of the amount of ZrO2, the density of ZrO2 NiCoCrAlY composite coating decreases gradually, and the hardness decreases firstly and then improves ; the 60 vol% ZrO2 Ni CoCrAlY coating has the lowest hardness, and the porosity in the rich NiCoCrAlY coatings is slightly lower than thaTin the rich ZrO2 coating. The gradual distribution of composition improves the adherent strength of coating and the coherent strength between coating and substrate. The interface between coating and TC4 substrate is the weakest zone in the graded coating.
2000, 17(1): 93-97.
Abstract:
The approximate expression of the fluid force between a floating laminated composite plate and liquid surface is obtained in this paper. Nonlinear dynamic equations including the effects of transverse shear deformation and solid fluid interaction are established by Hamilton's principle. The nonlinear dynamic solid fluid interaction response is solved by means of a difference method. The effects of non linearity and fluid depth under different loading forms on dynamic response are discussed.
The approximate expression of the fluid force between a floating laminated composite plate and liquid surface is obtained in this paper. Nonlinear dynamic equations including the effects of transverse shear deformation and solid fluid interaction are established by Hamilton's principle. The nonlinear dynamic solid fluid interaction response is solved by means of a difference method. The effects of non linearity and fluid depth under different loading forms on dynamic response are discussed.
2000, 17(1): 98-101.
Abstract:
Based on the geometric model of a unit cell and meso scopic computational mechanics, the present paper predicts the nonlinear behavior of constitutive relation for three dimensional multi directional braided composites. Meso scopic damage behavior is simulated by introducing Murakami's damage theory and using finite element method. Numerical examples are given and compared with experimental results. to demonstrate the nonlinear constitutive relation of four directional braided carbon/epoxy composites.
Based on the geometric model of a unit cell and meso scopic computational mechanics, the present paper predicts the nonlinear behavior of constitutive relation for three dimensional multi directional braided composites. Meso scopic damage behavior is simulated by introducing Murakami's damage theory and using finite element method. Numerical examples are given and compared with experimental results. to demonstrate the nonlinear constitutive relation of four directional braided carbon/epoxy composites.
2000, 17(1): 103-107.
Abstract:
Two new equations of the S N curve equation and the E N curve equation are presented in this paper. These equations are with four parameters, therefore they have better physical properties than those with two or three parameters. By means of the optimization method of correlation coefficient the parameter estimation formulas and numerical solutions of these equations are established. Finally, two examples of these equations application are given. From these examples, iTis shown that the equations are not only of excellent fitting effect, but also convenient for application.
Two new equations of the S N curve equation and the E N curve equation are presented in this paper. These equations are with four parameters, therefore they have better physical properties than those with two or three parameters. By means of the optimization method of correlation coefficient the parameter estimation formulas and numerical solutions of these equations are established. Finally, two examples of these equations application are given. From these examples, iTis shown that the equations are not only of excellent fitting effect, but also convenient for application.
2000, 17(1): 108-110.
Abstract:
A new methodology is presented for composite plate stiffness identification. The orthotropic plate stiffness coefficients are identified from its dynamic properties (eigenvalues and eigenvectors) through a backward propagation neural network, which is constructed by three layer subnets. An example is used to demonstrate the effectiveness of the method.
A new methodology is presented for composite plate stiffness identification. The orthotropic plate stiffness coefficients are identified from its dynamic properties (eigenvalues and eigenvectors) through a backward propagation neural network, which is constructed by three layer subnets. An example is used to demonstrate the effectiveness of the method.
2000, 17(1): 111-114.
Abstract:
This paper describes a control system with multi parameters and hish precision based on IBM PC, which is programmed by VB and VC computer language, including A/D converter, multi channels converter and I/O control. This system was designed for controlling the thermal curing of polymer matrix composites. It can also be applied to in other similar systems.
This paper describes a control system with multi parameters and hish precision based on IBM PC, which is programmed by VB and VC computer language, including A/D converter, multi channels converter and I/O control. This system was designed for controlling the thermal curing of polymer matrix composites. It can also be applied to in other similar systems.
2000, 17(1): 115-118.
Abstract:
The presenTinvestigation is aimed to understand the microstructure evolution of SiC P/Al Si composites, i.e. , particle distribution and matrix microstructure in rapid solidification. Microstructures of SiC P/A356 composite and the monolithic alloy were comparatively studied through laser re melting process. ITis observed that the particle remains its original distribution after re solidification, indicating that rejection of particles by rapid solidification interface does not occur. The presence of particles does not lead to any change in the phase constitution in the matrix, but has a great effect on crystal growth of primary phase. For the monolithic alloy, primary phase dendrites arrange themselves closer to the heat flux direction. Raising the scanning velocity, the dendrites become finer but remain the characteristic of regular columnar epitaxial re growth. However, the arrangement of primary α Al in laser treated composite is somewhat chaotic. These results, in addition to some evidence of unstable branching dendritic structure and dendrites terminating at a particle, indicate that the particle with a size larger than the length scale of the sub grain structure forms a complete barrier to the crystal growth.
The presenTinvestigation is aimed to understand the microstructure evolution of SiC P/Al Si composites, i.e. , particle distribution and matrix microstructure in rapid solidification. Microstructures of SiC P/A356 composite and the monolithic alloy were comparatively studied through laser re melting process. ITis observed that the particle remains its original distribution after re solidification, indicating that rejection of particles by rapid solidification interface does not occur. The presence of particles does not lead to any change in the phase constitution in the matrix, but has a great effect on crystal growth of primary phase. For the monolithic alloy, primary phase dendrites arrange themselves closer to the heat flux direction. Raising the scanning velocity, the dendrites become finer but remain the characteristic of regular columnar epitaxial re growth. However, the arrangement of primary α Al in laser treated composite is somewhat chaotic. These results, in addition to some evidence of unstable branching dendritic structure and dendrites terminating at a particle, indicate that the particle with a size larger than the length scale of the sub grain structure forms a complete barrier to the crystal growth.
2000, 17(1): 119-122.
Abstract:
By TEM, XRD and polarized optical microscope the structure of Al2O3 short fibre(Saffil fibre) was studied. ITis shown that the outer surface of the fibre consists of texture of θ Al2O3 with texture zone
[011], the center zone of the fibre consists of fine grain of δ Al2O3.
By TEM, XRD and polarized optical microscope the structure of Al2O3 short fibre(Saffil fibre) was studied. ITis shown that the outer surface of the fibre consists of texture of θ Al2O3 with texture zone
[011], the center zone of the fibre consists of fine grain of δ Al2O3.
2000, 17(1): 122-125.
Abstract:
The transverse elasto plastic mechanical properties of fiber bundle reinforced composites were studied by using the micro mechanical model and finite element method. ITis assumed that the elastic fiber bundle is evenly distributed in the elastoplastic powerlaw hardening matrix and the contact between fibers in the fiber bundle is smooth. The effect of fiber bundling on the overall elasto plastic properties of composite material was investigated by comparing the results of fiber bundle composites with that of the single fiber composites. The numerical results for the Boron/Aluminum composite show that the transvers plastic deformation and tangent stiffness are considerably influenced by the fiber bundling. While the elastic properties of composites are microstructure insensitive.
The transverse elasto plastic mechanical properties of fiber bundle reinforced composites were studied by using the micro mechanical model and finite element method. ITis assumed that the elastic fiber bundle is evenly distributed in the elastoplastic powerlaw hardening matrix and the contact between fibers in the fiber bundle is smooth. The effect of fiber bundling on the overall elasto plastic properties of composite material was investigated by comparing the results of fiber bundle composites with that of the single fiber composites. The numerical results for the Boron/Aluminum composite show that the transvers plastic deformation and tangent stiffness are considerably influenced by the fiber bundling. While the elastic properties of composites are microstructure insensitive.
