1997 Vol. 14, No. 4
1997, 14(4): 6-9.
Abstract:
This paper studies the technology of preparing isotropical NdFeB magnetic composites through compression molding process.The result shows that the characteristics of the NdFeB magnetic composites are remarkably affected by different kinds of magnetic powders and adhesives.Increasing the filler level of magnetic composites will dogood to improve the magnetic characteristics of the magnetic within a certain limit.
This paper studies the technology of preparing isotropical NdFeB magnetic composites through compression molding process.The result shows that the characteristics of the NdFeB magnetic composites are remarkably affected by different kinds of magnetic powders and adhesives.Increasing the filler level of magnetic composites will dogood to improve the magnetic characteristics of the magnetic within a certain limit.
1997, 14(4): 10-13.
Abstract:
The basic principle for the on-line ultrasonic detection of wall-thickness of large glass-fiber products,the composition of the system and the probe make-up and the soft ware design were expounded.The results show that it is a high detective precision,high speed test method and advanced technology,and that the method is suitable for the on-line automatic detection of wall-thickness of all large glass-fiber products.
The basic principle for the on-line ultrasonic detection of wall-thickness of large glass-fiber products,the composition of the system and the probe make-up and the soft ware design were expounded.The results show that it is a high detective precision,high speed test method and advanced technology,and that the method is suitable for the on-line automatic detection of wall-thickness of all large glass-fiber products.
1997, 14(4): 14-18.
Abstract:
Five kinds of bisphenol-A diglycidyl ethers made in China were characterized by Matrix-ssisted Laser Desorption Ionization Time of Flight Mass Spectrometry(MALDITOF-MS).The information of their degrees of polymerization was obtained,and the moleculcer structures of different degrees of polymerization components were suggested.Some polymers of chloromethyl oxirane itself were found in these epoxy resins.
Five kinds of bisphenol-A diglycidyl ethers made in China were characterized by Matrix-ssisted Laser Desorption Ionization Time of Flight Mass Spectrometry(MALDITOF-MS).The information of their degrees of polymerization was obtained,and the moleculcer structures of different degrees of polymerization components were suggested.Some polymers of chloromethyl oxirane itself were found in these epoxy resins.
STUDY ON THE MECHANICAL AND TRIBOLOGICAL PROPERTIES OF GLASSFIBER REINFORCED POLYETHYLENE COMPOSITES
1997, 14(4): 19-25.
Abstract:
Tribological behavior of glass fiber reinforced HDPE(GF/HDPE) composites was studied,focusing on the effects of the content and orientation of glassfibre on the mechanical and tribological properties of the polyethylene based composites.Experimental resups showed that fiber content and orientation have great influences on the tribological behavior of the composite.The wear loss is the least in the direction vertical to fibers orientation,and the fiction coefficient is lower in the direction parallel with fibers orientation.HDPE composite reinforced by 30% glassfiber has good comprehensive mechanical and tribological properties,which can be a good candidatefor the tribological applications under severe conditions.
Tribological behavior of glass fiber reinforced HDPE(GF/HDPE) composites was studied,focusing on the effects of the content and orientation of glassfibre on the mechanical and tribological properties of the polyethylene based composites.Experimental resups showed that fiber content and orientation have great influences on the tribological behavior of the composite.The wear loss is the least in the direction vertical to fibers orientation,and the fiction coefficient is lower in the direction parallel with fibers orientation.HDPE composite reinforced by 30% glassfiber has good comprehensive mechanical and tribological properties,which can be a good candidatefor the tribological applications under severe conditions.
1997, 14(4): 26-32.
Abstract:
The thickening agent of phenolic sheet molding compound and its thickening mechanism were studied in this paper.The thickening agent of phenolic sheet molding is investigated by the viscosity tests.The results show that the mixture of B2O3 and ZnO is the proper thickening agent of phenolic sheet molding compound and the suitable thickening effect can be achieved when 4 portion B2O3 and 1 portion ZnO are added into 100 portion phenolic resin.And at the same time,the infrared analysis is used to analyze the thickening mechanism of B2O3 and ZnO to the Phenolic resin,respectively.It is found that B2O3 has fine effect of thickening on the phenolic resin and ZnO not only has no effect on the resin but also delays the effect of B2O3 thickening on the resin.
The thickening agent of phenolic sheet molding compound and its thickening mechanism were studied in this paper.The thickening agent of phenolic sheet molding is investigated by the viscosity tests.The results show that the mixture of B2O3 and ZnO is the proper thickening agent of phenolic sheet molding compound and the suitable thickening effect can be achieved when 4 portion B2O3 and 1 portion ZnO are added into 100 portion phenolic resin.And at the same time,the infrared analysis is used to analyze the thickening mechanism of B2O3 and ZnO to the Phenolic resin,respectively.It is found that B2O3 has fine effect of thickening on the phenolic resin and ZnO not only has no effect on the resin but also delays the effect of B2O3 thickening on the resin.
1997, 14(4): 33-37.
Abstract:
The latent curing acceleration of the rare-earth organometallic compound (MrAn) for the anhydride/epoxy resin system was studied by DSC,TG and rotation viscometer,etc,and commparisons were made with the curing efficiency of terriary amine (DMP 30) in this paper.The results showed that the rare-earth compound served,an ideal latent accelerator for anhydride/epoxy resin systems,the overall curing process followed quasi-first order kinetics,and all total properties of the MrAn catalyzed/anhydride/epoxy resin system were better than those of a DMP-30 catalyzed one.
The latent curing acceleration of the rare-earth organometallic compound (MrAn) for the anhydride/epoxy resin system was studied by DSC,TG and rotation viscometer,etc,and commparisons were made with the curing efficiency of terriary amine (DMP 30) in this paper.The results showed that the rare-earth compound served,an ideal latent accelerator for anhydride/epoxy resin systems,the overall curing process followed quasi-first order kinetics,and all total properties of the MrAn catalyzed/anhydride/epoxy resin system were better than those of a DMP-30 catalyzed one.
1997, 14(4): 38-41.
Abstract:
The relationship between the flexural strength,fracture toughness and TiC particle sizein TiCP/SiC composite was investigated.The effects of cool treatmemt on the properties of TiCY/SiC composite were studied.The results obtained show that the addition of TiC particle can enhance the strength and toughness of the composite,but there is only a very narrow particle size range of enhancing strength and toughness simultaneously.Cool treatment not only increases further the toughness and strength but also changes the toughening extent of TiC particle size,making wider the overlapped particle size extent of strengthening and toughening.Thereby,a strengthening and toughening region is formed.It provides the basis for designing the strengthening and toughening of materials and for formulating the corresnonding technological process.
The relationship between the flexural strength,fracture toughness and TiC particle sizein TiCP/SiC composite was investigated.The effects of cool treatmemt on the properties of TiCY/SiC composite were studied.The results obtained show that the addition of TiC particle can enhance the strength and toughness of the composite,but there is only a very narrow particle size range of enhancing strength and toughness simultaneously.Cool treatment not only increases further the toughness and strength but also changes the toughening extent of TiC particle size,making wider the overlapped particle size extent of strengthening and toughening.Thereby,a strengthening and toughening region is formed.It provides the basis for designing the strengthening and toughening of materials and for formulating the corresnonding technological process.
1997, 14(4): 42-47.
Abstract:
The chemical states of both the original surface of SiC particles and the interface of SiCP/Al composite made by powder metallurgy were investigated by means of XPS and AES.It was found that there are SiC,SiO2,free carbon,absorption oxygen and Fe2O3 on the original surface of SiC particles and segregated Mg and oxygen element in the interface of SiCP/Al composite.According to thermodynamichs,it is possible that Mg element segregated on the interface reacts with oxygen,yielding MgO.
The chemical states of both the original surface of SiC particles and the interface of SiCP/Al composite made by powder metallurgy were investigated by means of XPS and AES.It was found that there are SiC,SiO2,free carbon,absorption oxygen and Fe2O3 on the original surface of SiC particles and segregated Mg and oxygen element in the interface of SiCP/Al composite.According to thermodynamichs,it is possible that Mg element segregated on the interface reacts with oxygen,yielding MgO.
1997, 14(4): 48-51.
Abstract:
An Al2O3 short fibre reinforced Al-12Si matrix composite was prepared using sqeeze cast method.T he process of fracture and crack nucleation of the composite were studied by in-situ observation in transmission electron microscope.The results show that the fihre matrix interface is one of the fracture courses of the composite.Also thefailure of the fihre resulting from crack initiation and propagation in it was observed in the experiment.
An Al2O3 short fibre reinforced Al-12Si matrix composite was prepared using sqeeze cast method.T he process of fracture and crack nucleation of the composite were studied by in-situ observation in transmission electron microscope.The results show that the fihre matrix interface is one of the fracture courses of the composite.Also thefailure of the fihre resulting from crack initiation and propagation in it was observed in the experiment.
1997, 14(4): 52-56.
Abstract:
Composites reinforced with Shape Memory Alloy(SMA)wires employ the SMA wires as distributed actuators to achieve adaptive functions while in service.This paper presents at heoretical study on the thermo-mechanical characteristics of composites reinforced with SMA wires,based on the one-dimensional constitutive relation of SMA.Experimental results derived from tension,free recovery and rest rained recovery of composites reinforced with SMA wires are also presented and compared with the simulated results.
Composites reinforced with Shape Memory Alloy(SMA)wires employ the SMA wires as distributed actuators to achieve adaptive functions while in service.This paper presents at heoretical study on the thermo-mechanical characteristics of composites reinforced with SMA wires,based on the one-dimensional constitutive relation of SMA.Experimental results derived from tension,free recovery and rest rained recovery of composites reinforced with SMA wires are also presented and compared with the simulated results.
1997, 14(4): 57-60.
Abstract:
LaB6-ZrB2 eutectic in-situ composites with LaB6 as matrix and ZrB2 whiskers uniformly distributed in the matrix were prepared by the method of electron beam zone melting.The averag ediameter of the ZrB2 whiskers is 0.2～1.1m,and the number of ZrB2 whiskers perunitarea can be up to 108/cm2.
LaB6-ZrB2 eutectic in-situ composites with LaB6 as matrix and ZrB2 whiskers uniformly distributed in the matrix were prepared by the method of electron beam zone melting.The averag ediameter of the ZrB2 whiskers is 0.2～1.1m,and the number of ZrB2 whiskers perunitarea can be up to 108/cm2.
1997, 14(4): 61-64.
Abstract:
After remelted by laser,the pulse discharge coating was studied by TEM,XRD and hardness measurement for microstructure and microhardness.The results shiwed that the hardness of the coating was up to HV0.11600 and even higher,which was due to the superfine structure,high density dislocations and carbonides and the coating.
After remelted by laser,the pulse discharge coating was studied by TEM,XRD and hardness measurement for microstructure and microhardness.The results shiwed that the hardness of the coating was up to HV0.11600 and even higher,which was due to the superfine structure,high density dislocations and carbonides and the coating.
1997, 14(4): 65-69.
Abstract:
The effect of fibre arrangement direction on friction and wear properties of C/C composite was studied.The results of microstructure analysis and brake tests showed that for the 2D C/C composite,sometimes a single fibre and sometimes a bunch of fibres are surrounded by deposition carbon,the initial peak value of the brake moment and friction coeffident is smaller,but thewear rate is bigger; while for the 3D C/C composite,every single fibre is surrounded by the deposition carbon,the curve of moment of brake force is stable,the friction coefficient is bigger,but the wear rate is smaller.
The effect of fibre arrangement direction on friction and wear properties of C/C composite was studied.The results of microstructure analysis and brake tests showed that for the 2D C/C composite,sometimes a single fibre and sometimes a bunch of fibres are surrounded by deposition carbon,the initial peak value of the brake moment and friction coeffident is smaller,but thewear rate is bigger; while for the 3D C/C composite,every single fibre is surrounded by the deposition carbon,the curve of moment of brake force is stable,the friction coefficient is bigger,but the wear rate is smaller.
1997, 14(4): 70-74.
Abstract:
Anodic oxidative surface treatment of graphite fibers in four anolytes of ammonium was studied.Mechanical properties including tensile strength and modulus of anodic treated monofilament were determined and surficial morphology and chemical composition were characterized by SEM and XPS.The adhesion between graphite fibers and epoxy matrix was evaluated in terms of interlaminar shear strength(ILSS).
Anodic oxidative surface treatment of graphite fibers in four anolytes of ammonium was studied.Mechanical properties including tensile strength and modulus of anodic treated monofilament were determined and surficial morphology and chemical composition were characterized by SEM and XPS.The adhesion between graphite fibers and epoxy matrix was evaluated in terms of interlaminar shear strength(ILSS).
1997, 14(4): 75-80.
Abstract:
Composites were fabricated by squeeze casting.By means of a statistical method,the effects of fibre orientation on wear properties of composites were studied under condition of lubricated sliding at load of 600N and velocity of 1.05ms-1.The results show that wear volumes of both fibre parallel-and normal-oriented composites acxeord with the same normal distribution of probability density f(x)(formulal).Wear propeties of composites are independent of fibre orientation.Wear mechanisms of fibre parallel-and normal-oriented composites are fibre fracture and abrasive.
Composites were fabricated by squeeze casting.By means of a statistical method,the effects of fibre orientation on wear properties of composites were studied under condition of lubricated sliding at load of 600N and velocity of 1.05ms-1.The results show that wear volumes of both fibre parallel-and normal-oriented composites acxeord with the same normal distribution of probability density f(x)(formulal).Wear propeties of composites are independent of fibre orientation.Wear mechanisms of fibre parallel-and normal-oriented composites are fibre fracture and abrasive.
1997, 14(4): 81-84.
Abstract:
The typical model of neural network e.g.B-P algorithm was adopted to analyze as well as predict the mechanical properties of ZA22/Al2O3f composites.The results show that B-P model is not only suitable for the regression and prediction for the single variable output non-linear system,but also suitable for the multi-variables output non-linear system.Perfect fault tolerance ability was also found in the B-P model while it was used to analyze the mechanical properties of ZA22/Al2O3f composites.
The typical model of neural network e.g.B-P algorithm was adopted to analyze as well as predict the mechanical properties of ZA22/Al2O3f composites.The results show that B-P model is not only suitable for the regression and prediction for the single variable output non-linear system,but also suitable for the multi-variables output non-linear system.Perfect fault tolerance ability was also found in the B-P model while it was used to analyze the mechanical properties of ZA22/Al2O3f composites.
1997, 14(4): 85-89.
Abstract:
Based on Raghava yield criterion and the modified secant moduli method,cromethanicl model is proposed,which enables one to analyze the influence of matrix S-D effect and applied hydrostatic pressure on composite plastic behavior.
Based on Raghava yield criterion and the modified secant moduli method,cromethanicl model is proposed,which enables one to analyze the influence of matrix S-D effect and applied hydrostatic pressure on composite plastic behavior.
1997, 14(4): 90-94.
Abstract:
This paper is based on the one-Iimensional surface grating,which can be formed by means of parallel and equidistant lines that are marked on the specimen surface.The distance between two adjacent marked lines is the nominal grating constant d.When the specimen is irradiated by a laser beam,a clear row of diffraction spots equally spaced along on a straight line is formed.The spacing of spots is related to d,which,under stress,changes and so does the spacing of spots.In measuring the changes in spacing of spots,use is made of charge coupled device,driving circuits,A/D transformation and computer.The authors' apparatus is also equipped with necessary computer software for control and data processing.Thus the authors'apparato s allows high-peed,high-precision and automatic determination of surface deformation and residual stress fields.
This paper is based on the one-Iimensional surface grating,which can be formed by means of parallel and equidistant lines that are marked on the specimen surface.The distance between two adjacent marked lines is the nominal grating constant d.When the specimen is irradiated by a laser beam,a clear row of diffraction spots equally spaced along on a straight line is formed.The spacing of spots is related to d,which,under stress,changes and so does the spacing of spots.In measuring the changes in spacing of spots,use is made of charge coupled device,driving circuits,A/D transformation and computer.The authors' apparatus is also equipped with necessary computer software for control and data processing.Thus the authors'apparato s allows high-peed,high-precision and automatic determination of surface deformation and residual stress fields.
1997, 14(4): 95-100.
Abstract:
An approach to feature extraction and recognition of the characteristic signal in the field of the damage detection of the composite materials is studied by thewavelet packets that disintegrate the signal into different frequency bands.These features are fed into the wavelet neural network as the input patterns for training and classifying.The experiments are conducted to demonstrate the feasibility of the proposed method.
An approach to feature extraction and recognition of the characteristic signal in the field of the damage detection of the composite materials is studied by thewavelet packets that disintegrate the signal into different frequency bands.These features are fed into the wavelet neural network as the input patterns for training and classifying.The experiments are conducted to demonstrate the feasibility of the proposed method.
1997, 14(4): 101-107.
Abstract:
A two-dimensional elastic foundation model to analyze the buckling of elliptical face-core ddaminations in composite sandwich plates is established.A displacement function is found to properly describe the buckling shapes of ddaminations.The buckling loads and effcctivc boundary fixity coefficient C' of ddaminations are obtained by Raylcigh Ritz energy method.It is found thatthc film dclamination model can not reflect the effect of the core on delaminations by transverse elastic support,and can only give the upper critical buckling load of dclaminations.Also the relations between the parameters of the ddamination and the effctive boundary fixity coefficient C' arc analyzed.
A two-dimensional elastic foundation model to analyze the buckling of elliptical face-core ddaminations in composite sandwich plates is established.A displacement function is found to properly describe the buckling shapes of ddaminations.The buckling loads and effcctivc boundary fixity coefficient C' of ddaminations are obtained by Raylcigh Ritz energy method.It is found thatthc film dclamination model can not reflect the effect of the core on delaminations by transverse elastic support,and can only give the upper critical buckling load of dclaminations.Also the relations between the parameters of the ddamination and the effctive boundary fixity coefficient C' arc analyzed.
1997, 14(4): 108-113.
Abstract:
A higher order displacement mode is presented for sandwich shells including shear deformation in composite face layers.The mode satisfies the condition that the transverse shear stresses vanish on the sandwich shell top and bottom surfaces.From this mode the finite element equations are derived for free vibration of sandwich shells.The damping characteristics of the core and face layers are discussed.And the formula of damping matrix is given.The comparisons between numerical computed values and experimental data are carried on.Finally,the curves which the damping ratio Ψ varies with the core thickness hc,shear modulus G and damping loss factor β,are shown graphically.
A higher order displacement mode is presented for sandwich shells including shear deformation in composite face layers.The mode satisfies the condition that the transverse shear stresses vanish on the sandwich shell top and bottom surfaces.From this mode the finite element equations are derived for free vibration of sandwich shells.The damping characteristics of the core and face layers are discussed.And the formula of damping matrix is given.The comparisons between numerical computed values and experimental data are carried on.Finally,the curves which the damping ratio Ψ varies with the core thickness hc,shear modulus G and damping loss factor β,are shown graphically.
1997, 14(4): 114-118.
Abstract:
A kind of decoding method and genetic operators are presented in this paper,which are used in combinatorial optimization.The method of genetic algorithm is employed to solve the optimization problem of ply stacking sequence of composite laminates with given plies,to satisfy the requirement of natural frequencies of vibration.The results of the example indicate that the method proposed in this paper converges to optimum solutions by searching only a small fraction of the slolution space.
A kind of decoding method and genetic operators are presented in this paper,which are used in combinatorial optimization.The method of genetic algorithm is employed to solve the optimization problem of ply stacking sequence of composite laminates with given plies,to satisfy the requirement of natural frequencies of vibration.The results of the example indicate that the method proposed in this paper converges to optimum solutions by searching only a small fraction of the slolution space.
1997, 14(4): 119-124.
Abstract:
A model is developed to express the meso-damage,macro-damages(including debond,matrix crack and fiber break) and fracture process of composite laminates impacted by a projectile.It is assumed that the nonlinearity of composites is induced by the meso-damage produced in impact process,and is considered in constitutive equations.A maximum strain criterion is presented by the authors,and can be used to analyze the maoro-damages of composites.The process of the macro-damage is simulated by the nodal separate technique.
A model is developed to express the meso-damage,macro-damages(including debond,matrix crack and fiber break) and fracture process of composite laminates impacted by a projectile.It is assumed that the nonlinearity of composites is induced by the meso-damage produced in impact process,and is considered in constitutive equations.A maximum strain criterion is presented by the authors,and can be used to analyze the maoro-damages of composites.The process of the macro-damage is simulated by the nodal separate technique.
1997, 14(4): 125-131.
Abstract:
Based on a higher-order shear deformation theory of composite laminates,which fully satisfies the geometric and stress continuity conditions at interfaces,a refined finite element method and refined triangular element are proposed.The interelement C1 weak-continuity conditions can be satisfied,so that the convergence is insured.Numerical results show that the present element has higher computational efficiency and higher accuracy.
Based on a higher-order shear deformation theory of composite laminates,which fully satisfies the geometric and stress continuity conditions at interfaces,a refined finite element method and refined triangular element are proposed.The interelement C1 weak-continuity conditions can be satisfied,so that the convergence is insured.Numerical results show that the present element has higher computational efficiency and higher accuracy.
1997, 14(4): 132-137.
Abstract:
The moisture stability of the carbon fibre/PM R-15 matrix interface was studied.The results showed that ILSS and interfacial shear strength of composites increased in different degrees.CF/PM R-15 matrix interface had excellent moisture stability.And the effect and mechanism of boiling water on the inter face were discussed.Besides,the diffusion coefficient of composites decreased with the increase of interfacial adhesion.
The moisture stability of the carbon fibre/PM R-15 matrix interface was studied.The results showed that ILSS and interfacial shear strength of composites increased in different degrees.CF/PM R-15 matrix interface had excellent moisture stability.And the effect and mechanism of boiling water on the inter face were discussed.Besides,the diffusion coefficient of composites decreased with the increase of interfacial adhesion.
