1995 Vol. 12, No. 1
1995, 12(1): 1-5.
Abstract:
A new matrix resin for composite 4501I3 is introduced.the properties of the resin,cured resin and composites are studied,and the processability of the prepreg is also shown.
A new matrix resin for composite 4501I3 is introduced.the properties of the resin,cured resin and composites are studied,and the processability of the prepreg is also shown.
1995, 12(1): 6-10.
Abstract:
The rheology,the miscibility of TLCP and PES and the in-situ reinforcement of blends with injection moulding and twin screw blending extrusion drawing are studied. Results show that the viscosity of blends is lower than that of TLCP and PES,and flat the processing properties can be improved by adding TLCP. TLCP and PES in blends are almost immiscible. The viscosity of PES and its blends is so high that it is difficult to inject,and they are fit for blending extrusion drawing process with twin screw extruder. As the TLCP in blends increases the viscosity if blends decreases,but the tensile strength and the brittleness increase. With the increasing of drawing ratio,the tensile strength of composite fibres is enhanced greatly and good in-situ reinforcement can be obtained.
The rheology,the miscibility of TLCP and PES and the in-situ reinforcement of blends with injection moulding and twin screw blending extrusion drawing are studied. Results show that the viscosity of blends is lower than that of TLCP and PES,and flat the processing properties can be improved by adding TLCP. TLCP and PES in blends are almost immiscible. The viscosity of PES and its blends is so high that it is difficult to inject,and they are fit for blending extrusion drawing process with twin screw extruder. As the TLCP in blends increases the viscosity if blends decreases,but the tensile strength and the brittleness increase. With the increasing of drawing ratio,the tensile strength of composite fibres is enhanced greatly and good in-situ reinforcement can be obtained.
1995, 12(1): 11-17.
Abstract:
Air-drying-DCPD-type unsaturated polyester resin prepared by using modified hydrolysis addition method was proposed in the paper. By virtue of the theoretical analysis of IR and NMR,the mechanism of synthesis reaction and the optimal technological conditions were investigated. As a result,development was completed on the air drying unsaturated polyester resins,which have excellent properties such as shorter gelation time,higher cured velocity,higher mechanical strength,greater hardness,and better thermal and chemical resistances.
Air-drying-DCPD-type unsaturated polyester resin prepared by using modified hydrolysis addition method was proposed in the paper. By virtue of the theoretical analysis of IR and NMR,the mechanism of synthesis reaction and the optimal technological conditions were investigated. As a result,development was completed on the air drying unsaturated polyester resins,which have excellent properties such as shorter gelation time,higher cured velocity,higher mechanical strength,greater hardness,and better thermal and chemical resistances.
1995, 12(1): 18-25.
Abstract:
This paper reports on the fabrication of long-fiber jute/epoxy and random short-fiber jute/epoxy composites,as well as their mechanical properties under tensile, compressive,flexural,interlaminar shear and impact stresses. Microstructural aspects of these composite materials were investigated by using Scanning Electronic Microscopy. Apart from the good tensile strength of the raw jute fiber,composites fabricated in this study give good overall mechanical performance and indicate afar-reaching potential for development into useful products.
This paper reports on the fabrication of long-fiber jute/epoxy and random short-fiber jute/epoxy composites,as well as their mechanical properties under tensile, compressive,flexural,interlaminar shear and impact stresses. Microstructural aspects of these composite materials were investigated by using Scanning Electronic Microscopy. Apart from the good tensile strength of the raw jute fiber,composites fabricated in this study give good overall mechanical performance and indicate afar-reaching potential for development into useful products.
1995, 12(1): 26-31.
Abstract:
The microstrain of balanced laminate is calculated with finite element analysis and the maximum strain-concentration coefficient is obtained from the micromechanical results. The micromechanical criterion for the balanced laminate and the seepage criterion of GRP pipe are built up on the basis of criterion of resin breaking. The influence of fiber fractions, temperature difference and pipe diameters on seepage pressure of GRP pipe are discussed in this paper.
The microstrain of balanced laminate is calculated with finite element analysis and the maximum strain-concentration coefficient is obtained from the micromechanical results. The micromechanical criterion for the balanced laminate and the seepage criterion of GRP pipe are built up on the basis of criterion of resin breaking. The influence of fiber fractions, temperature difference and pipe diameters on seepage pressure of GRP pipe are discussed in this paper.
1995, 12(1): 32-37.
Abstract:
The twin roll casting of the SiCp/A356 aluminium matrix composite strips is investigated,with particular attention to the effects of the SiC volume fraction (3%-16%) and the casting speed (0.5-10m/min) on the SiC particulate distribution. A SiC-poor layer is found in the as-cast strips. When a higher casting speed is used,or there is a higher SiC volume fraction in the composites,the particulate-poor layer can be virtually eliminated. The results also show that the rapid solidification process of the twin roll casting can obviously refine aluminium-silicon eutectic structure and improve the SiC distribution in the matrix.
The twin roll casting of the SiCp/A356 aluminium matrix composite strips is investigated,with particular attention to the effects of the SiC volume fraction (3%-16%) and the casting speed (0.5-10m/min) on the SiC particulate distribution. A SiC-poor layer is found in the as-cast strips. When a higher casting speed is used,or there is a higher SiC volume fraction in the composites,the particulate-poor layer can be virtually eliminated. The results also show that the rapid solidification process of the twin roll casting can obviously refine aluminium-silicon eutectic structure and improve the SiC distribution in the matrix.
1995, 12(1): 38-42.
Abstract:
Liquid infiltration processing is advanced technique for the preparation of fiber reinforced metal matrix composites (FRM).The morphology and properties of FRM are influenced greatly by the infiltration and filling process. In this paper the resistance to the process and the filling form of FRM are studied. It is found that the filling form is determined by the distribution of fibers and the wettability between fibers and matrix. The way of controlling the infiltration and filling process to get perfect FRM was discussed by controlling the distribution of fibers,improving the wettability between fibers and matrix, and optimizing the parameters of the processing.
Liquid infiltration processing is advanced technique for the preparation of fiber reinforced metal matrix composites (FRM).The morphology and properties of FRM are influenced greatly by the infiltration and filling process. In this paper the resistance to the process and the filling form of FRM are studied. It is found that the filling form is determined by the distribution of fibers and the wettability between fibers and matrix. The way of controlling the infiltration and filling process to get perfect FRM was discussed by controlling the distribution of fibers,improving the wettability between fibers and matrix, and optimizing the parameters of the processing.
1995, 12(1): 43-49.
Abstract:
Two new methods to prepare in-situ whiskers reinforced Silicon Nitride matrix composites are proposed. When Si powders containing CaFz as catalyst are nitrided,in-situ β-Si3N4 whiskers grow in the reaction bonded silicon nitride. In-situ β-SiC whiskers grow on the Si3N4 matrix and in the pores,after the porous compacts of Si3N4 are infiltrated with phenolic resin and tetraetyl silicate,La203 as catalyst. There is a droplet on the top of each β-SiC whisker,which suggests that it grows by the Vapour-Liquid-Solid mechanism. When two and more such whiskers with different directions occur,the whisker network is formed. The microstructure of in-situ whisker depends on the experimental conditions. With the time and temperature increased,the in-situ whiskers become wider and longer. The experimental results show that in-situ whiskers can increase not only the fracture strength but also fracture toughness.
Two new methods to prepare in-situ whiskers reinforced Silicon Nitride matrix composites are proposed. When Si powders containing CaFz as catalyst are nitrided,in-situ β-Si3N4 whiskers grow in the reaction bonded silicon nitride. In-situ β-SiC whiskers grow on the Si3N4 matrix and in the pores,after the porous compacts of Si3N4 are infiltrated with phenolic resin and tetraetyl silicate,La203 as catalyst. There is a droplet on the top of each β-SiC whisker,which suggests that it grows by the Vapour-Liquid-Solid mechanism. When two and more such whiskers with different directions occur,the whisker network is formed. The microstructure of in-situ whisker depends on the experimental conditions. With the time and temperature increased,the in-situ whiskers become wider and longer. The experimental results show that in-situ whiskers can increase not only the fracture strength but also fracture toughness.
1995, 12(1): 50-55.
Abstract:
Self-propagating High-temperature Synthesis (SHS) is becoming an important process to prepare materials, but the synthesized products are usually multi-porous and cracking-like due to a violent gas evolution sharp temperature variation during the process.For the preparation of densified materials,a densification process is absolutely necessary. In this paper,a few densification processes of coordination of SHS are introduced,and some mechanical properties of multi-phase materials prepared by means of them are reviewed.
Self-propagating High-temperature Synthesis (SHS) is becoming an important process to prepare materials, but the synthesized products are usually multi-porous and cracking-like due to a violent gas evolution sharp temperature variation during the process.For the preparation of densified materials,a densification process is absolutely necessary. In this paper,a few densification processes of coordination of SHS are introduced,and some mechanical properties of multi-phase materials prepared by means of them are reviewed.
1995, 12(1): 56-59.
Abstract:
1995, 12(1): 60-67.
Abstract:
The new non-linear geometrical differential equations for arbitrary composites shells are derived on the basis of 3-dimensional non-linear theory in curveilinear coordinates. The Washizu equation in modified and a more accurate stability equation is expected to be established based upon it.
The new non-linear geometrical differential equations for arbitrary composites shells are derived on the basis of 3-dimensional non-linear theory in curveilinear coordinates. The Washizu equation in modified and a more accurate stability equation is expected to be established based upon it.
1995, 12(1): 68-74.
Abstract:
According to the basic thermodynamic principle and the previous models,a computer program is developed to analyse the interfacial reaction of intermetallics matrix composites. Five intermetallics matrices,Ti3Al,TiAl,FeAl,NiAl and NbAl3,and ten ceramocs reinforcements,B4C,SiC,TiC;TiB,TiB2,AlB12;TiN,AlN;SiO2,Al203 are investigated. Thus,for a given intermetallics matrix,the potential suitable reinforcement materials are identified.
According to the basic thermodynamic principle and the previous models,a computer program is developed to analyse the interfacial reaction of intermetallics matrix composites. Five intermetallics matrices,Ti3Al,TiAl,FeAl,NiAl and NbAl3,and ten ceramocs reinforcements,B4C,SiC,TiC;TiB,TiB2,AlB12;TiN,AlN;SiO2,Al203 are investigated. Thus,for a given intermetallics matrix,the potential suitable reinforcement materials are identified.
1995, 12(1): 75-80.
Abstract:
A quasi-3D finite element method is used to investigate the residual stresses due to curing in symmetric composite laminates reinforced by hybrid fibers. This paper presents the results of computation for residual stresses in Kevlar/Epoxy-Aluminium laminate in free state or prestressed state under various levels of service temperature. The residual stresses in Aluminium-Glass/Epoxy-Kevlar/Epoxy laminate caused by curing without pretension are also presented here. A very satisfactory degree of accuracy is obtained from the numerical results compared with the experimental evidence by means of method of embedded strain gages. It is shown that the quasi-3D finite element method is a valuable approach for investigating residual stresses in designing and manufacturing the laminates to obtain optimal mechanical performance.
A quasi-3D finite element method is used to investigate the residual stresses due to curing in symmetric composite laminates reinforced by hybrid fibers. This paper presents the results of computation for residual stresses in Kevlar/Epoxy-Aluminium laminate in free state or prestressed state under various levels of service temperature. The residual stresses in Aluminium-Glass/Epoxy-Kevlar/Epoxy laminate caused by curing without pretension are also presented here. A very satisfactory degree of accuracy is obtained from the numerical results compared with the experimental evidence by means of method of embedded strain gages. It is shown that the quasi-3D finite element method is a valuable approach for investigating residual stresses in designing and manufacturing the laminates to obtain optimal mechanical performance.
1995, 12(1): 81-91.
Abstract:
A bending analysis,with consideration of transverse shear deformation,is presented for antisymmetric angle-ply composite laminates. A closed form solution is obtained by use of Simplified Discrete-Layer Theory (SDLT).The governing equations are derived on the basis of the general equations obtained by the principle of minimum potential energy through introduction of additional assumptions suitable for the laminate layout. Numerical computations are carried out for a few example laminates by SDLT,Classical Plate Theory (CPT) and First-order Shear Deformation Theory (FSDT) ,All the results obtained are compared with the three dimensional solutions from the literature. It is shown that the bending problems of antisymmetric angle-ply laminates are solved effectively by SDLT.
A bending analysis,with consideration of transverse shear deformation,is presented for antisymmetric angle-ply composite laminates. A closed form solution is obtained by use of Simplified Discrete-Layer Theory (SDLT).The governing equations are derived on the basis of the general equations obtained by the principle of minimum potential energy through introduction of additional assumptions suitable for the laminate layout. Numerical computations are carried out for a few example laminates by SDLT,Classical Plate Theory (CPT) and First-order Shear Deformation Theory (FSDT) ,All the results obtained are compared with the three dimensional solutions from the literature. It is shown that the bending problems of antisymmetric angle-ply laminates are solved effectively by SDLT.
1995, 12(1): 92-99.
Abstract:
An experimental study on damage and failure of T300 carbon fibre reinforced QY8911 bismaleimide resin laminated composite subjected to low-velocity impact is presented. Three kinds of cross-ply lay-up construction of the laminate were considered. Three-point bending beam specimens were tested with an instrumented drop weight impact tester. The impact load history curve was recorded. By changing impact velocity,the impact energy threshold was determined. The damage mode was examined with SEM and found to be interlaminar shear delamination coupling with matrix cracking in 90°layers. For the sake of comparison,static 3-point bending test was also conducted. The bending load versus deflection curves and failure strength of the two cases have no significant difference. The one dimensional harmonic vibration model of the hammer-beam system was proposed to model the impact dynamic behaviour for the case of below threshold impact. The explanation of ignorance of stress wave propagation effect was given.
An experimental study on damage and failure of T300 carbon fibre reinforced QY8911 bismaleimide resin laminated composite subjected to low-velocity impact is presented. Three kinds of cross-ply lay-up construction of the laminate were considered. Three-point bending beam specimens were tested with an instrumented drop weight impact tester. The impact load history curve was recorded. By changing impact velocity,the impact energy threshold was determined. The damage mode was examined with SEM and found to be interlaminar shear delamination coupling with matrix cracking in 90°layers. For the sake of comparison,static 3-point bending test was also conducted. The bending load versus deflection curves and failure strength of the two cases have no significant difference. The one dimensional harmonic vibration model of the hammer-beam system was proposed to model the impact dynamic behaviour for the case of below threshold impact. The explanation of ignorance of stress wave propagation effect was given.
1995, 12(1): 100-105.
Abstract:
In this paper a nine-mode rectangle element of composite sandwich plate is developed and applied to the large deflection analysis of symmetric composite sandwich plates. The effects of boundary conditions,shear moduli of core and the thickness ratio between the core and the faceplates on solution of large deflection are discussed. Some meaningful results are obtained.
In this paper a nine-mode rectangle element of composite sandwich plate is developed and applied to the large deflection analysis of symmetric composite sandwich plates. The effects of boundary conditions,shear moduli of core and the thickness ratio between the core and the faceplates on solution of large deflection are discussed. Some meaningful results are obtained.
1995, 12(1): 106-110.
Abstract:
Based on a previous paper the theoretical formula with the weighted factor and oriented angles of different kinds of fibers as optimum parameters,for hybrid or thotropic cylindrical shells is given. The usable conditions are discussed. A discriminant,which enablas one to identify whether the optimun parameters are extreme points,is proposed for the hybrid fiber cylindrical shells under the external pressure. The examples in this paper show that the formula can be used not only to determine the optimum paremeters for hybrid fiber cylindrical shell,but also to find out the optimum fiber content and the ply orintations of fiber for fiber reinforced homogenous cylindrical shells.
Based on a previous paper the theoretical formula with the weighted factor and oriented angles of different kinds of fibers as optimum parameters,for hybrid or thotropic cylindrical shells is given. The usable conditions are discussed. A discriminant,which enablas one to identify whether the optimun parameters are extreme points,is proposed for the hybrid fiber cylindrical shells under the external pressure. The examples in this paper show that the formula can be used not only to determine the optimum paremeters for hybrid fiber cylindrical shell,but also to find out the optimum fiber content and the ply orintations of fiber for fiber reinforced homogenous cylindrical shells.
1995, 12(1): 111-117.
Abstract:
An equivalent analysis method for sandwich shells made of composite materials is studied. The formulae of the interval forces and displacements of the sandwich shell are deduced from the shell theory.and by comparing the formulae with those of a single-deck anisotropic,hell the equivalent conditions are given for both shells. Therefore.the mechanic analysis of the sandwich shell can be converted to the analysis of a single-deck equivalent anisotropic,hell that is easy to solve by finite element method. At last an engineering example is computed. The results confirm the validity of this method.
An equivalent analysis method for sandwich shells made of composite materials is studied. The formulae of the interval forces and displacements of the sandwich shell are deduced from the shell theory.and by comparing the formulae with those of a single-deck anisotropic,hell the equivalent conditions are given for both shells. Therefore.the mechanic analysis of the sandwich shell can be converted to the analysis of a single-deck equivalent anisotropic,hell that is easy to solve by finite element method. At last an engineering example is computed. The results confirm the validity of this method.
