1993 Vol. 10, No. 2
1993, 10(2): 1-5.
Abstract:
In this work an im proved deply technique has been adopted to study the characteristics on damage morphclogy of laminates with a surface notch.Two kinds of surface notch:rectangular and circular are profiles have been tested.The results indicated that the improved deply technique can reveal clearly the damage morphology of the laminates,and on some interesting recognitions of the characteristics of damage morphology have been therefore found.
In this work an im proved deply technique has been adopted to study the characteristics on damage morphclogy of laminates with a surface notch.Two kinds of surface notch:rectangular and circular are profiles have been tested.The results indicated that the improved deply technique can reveal clearly the damage morphology of the laminates,and on some interesting recognitions of the characteristics of damage morphology have been therefore found.
1993, 10(2): 7-12.
Abstract:
In this paper,it is studied by mesomechanics to the creep behavior of composite materials under place stresses.The effect of desposition and mechanical properties of fibers and matrix on creep behavior of composite materials is analyzed. Concrete steps to control creep behavor of composite materials are put forward.
In this paper,it is studied by mesomechanics to the creep behavior of composite materials under place stresses.The effect of desposition and mechanical properties of fibers and matrix on creep behavior of composite materials is analyzed. Concrete steps to control creep behavor of composite materials are put forward.
1993, 10(2): 13-16.
Abstract:
The fracture properties such as fracture toughness,K1c,and crack extension force,G1c in a series of short carbon fibre (CF) reinforced polyarylethersulfone with cardo groups (PES-C) composites with different CF content have been measuerd.Meantime,the fractal dimensions Df, of fractured surfaces have been determined by means of slit island method. The results show that Df decreases smoothly with the increasing of lnG1c. An analysis of relationship between Cf and G1c was given on the basis of fracture micromechanism of composite.
The fracture properties such as fracture toughness,K1c,and crack extension force,G1c in a series of short carbon fibre (CF) reinforced polyarylethersulfone with cardo groups (PES-C) composites with different CF content have been measuerd.Meantime,the fractal dimensions Df, of fractured surfaces have been determined by means of slit island method. The results show that Df decreases smoothly with the increasing of lnG1c. An analysis of relationship between Cf and G1c was given on the basis of fracture micromechanism of composite.
1993, 10(2): 17-24.
Abstract:
According to the classical fiber's statistical strength and some hypotheses,the statistical constitutive models of the rate-sensitive fiber and fiber bundle are set up,and the corresponding constitutive equations are deduced.The method to determine the mechanical parameters in the constitutive equations of the rate-sensitive fiber by the tensile impact test of the fiber bundle are proposed from such models.The tensile experiments of the E-glass fiber bundles are performed under the strain race of 10-4-108 l/s in order to examine the validity of the test models and its test method. The test results and its analysis show that the hypotheses of the models are correct an d the test method is practical. Such models explain successfully the mechanical behaviors of fiber under the strain rate of 10-4 1.1×108 l/s.
According to the classical fiber's statistical strength and some hypotheses,the statistical constitutive models of the rate-sensitive fiber and fiber bundle are set up,and the corresponding constitutive equations are deduced.The method to determine the mechanical parameters in the constitutive equations of the rate-sensitive fiber by the tensile impact test of the fiber bundle are proposed from such models.The tensile experiments of the E-glass fiber bundles are performed under the strain race of 10-4-108 l/s in order to examine the validity of the test models and its test method. The test results and its analysis show that the hypotheses of the models are correct an d the test method is practical. Such models explain successfully the mechanical behaviors of fiber under the strain rate of 10-4 1.1×108 l/s.
1993, 10(2): 25-32.
Abstract:
A general expression for elastic constants of sandwiched composite conical shells is deduced in this paper.An accurate theory to analyze the bending,buckling and vitration of anisotropic sardwiched conical shell swith symmetric orientations is established,based on which a semi-analytical,semi-discrete sectioning algorithm with the characteristics of finite element method is constructed,which can deal with the bending,buckling and vibration of sliells with axially variable thickness,variable orientation,and shells with holes,or arbitrary rotating shells.For engineering purpose,a simple and effective approximate method cectioning equivalent cylinder method is presented.Calculation shows that the method described in this paper is efficient.
A general expression for elastic constants of sandwiched composite conical shells is deduced in this paper.An accurate theory to analyze the bending,buckling and vitration of anisotropic sardwiched conical shell swith symmetric orientations is established,based on which a semi-analytical,semi-discrete sectioning algorithm with the characteristics of finite element method is constructed,which can deal with the bending,buckling and vibration of sliells with axially variable thickness,variable orientation,and shells with holes,or arbitrary rotating shells.For engineering purpose,a simple and effective approximate method cectioning equivalent cylinder method is presented.Calculation shows that the method described in this paper is efficient.
1993, 10(2): 33-38.
Abstract:
In this paper,the non linear stability analysis of laminated composite plate under compression loading is demonstrated by use of Hahn-Tsai nonlinear constitutive relationship. The initial stresses of the plate is the prebuckling state ire obtained by completed plate theory. Numerical results have proved that inplane boundary constraints of the edges could have significant effect on the load capability of the plate,which is quite different from the conclusion given by membrane theory in prebuckling state.
In this paper,the non linear stability analysis of laminated composite plate under compression loading is demonstrated by use of Hahn-Tsai nonlinear constitutive relationship. The initial stresses of the plate is the prebuckling state ire obtained by completed plate theory. Numerical results have proved that inplane boundary constraints of the edges could have significant effect on the load capability of the plate,which is quite different from the conclusion given by membrane theory in prebuckling state.
1993, 10(2): 39-45.
Abstract:
The transverse cracking and delamination damage of the two series (i.e.[±θ/902]S and [0n/902]S) of carbon/epoxy laminates induced by tensile loading were studied experimentally and analysed with finite element method (FEM).In expriments,the damage process of the multi-layer laminates were monitored with acoustic emission (AE) technique and observed by using scanning electron microscope (SEIVI).The relationship of mechanical behaviour,initial damage and damage accumulation with lay-up angle θ were analysed.This study indicatos that the results measured for transverse cracking and delamination are in good agreement with those of predictions by FEM calculations,in which the energy criterion was used. In addition,compression tests were conducted on the testing stage in the SEM and so were the failure processes dynamically observed. Finally, the microscopic failure mechanisms of the laminates having different θ were discussed.
The transverse cracking and delamination damage of the two series (i.e.[±θ/902]S and [0n/902]S) of carbon/epoxy laminates induced by tensile loading were studied experimentally and analysed with finite element method (FEM).In expriments,the damage process of the multi-layer laminates were monitored with acoustic emission (AE) technique and observed by using scanning electron microscope (SEIVI).The relationship of mechanical behaviour,initial damage and damage accumulation with lay-up angle θ were analysed.This study indicatos that the results measured for transverse cracking and delamination are in good agreement with those of predictions by FEM calculations,in which the energy criterion was used. In addition,compression tests were conducted on the testing stage in the SEM and so were the failure processes dynamically observed. Finally, the microscopic failure mechanisms of the laminates having different θ were discussed.
1993, 10(2): 47-52.
Abstract:
This paper deals with the toughening bismaleimide (BMI) resin with thermoplastic (TP) resin,Polysulfone an d Polyether sulfone.The experiment shows that the viscosity of toughened resira is 0.5(Pa·S)at 150℃, the forming pressure of their composites is between 0.3-0.7 (MPa),curing temperature is 180℃,all of the properties mentioned above can meet the technological requirement of autoclave forming. The prepregs impregnated with these resins have quite good tack and drape,the shelf-live is more than one month(at room, temperature).The toughened resins keep quite good heat resistence and can be used permanently at 177℃.The impact strength of their composites increases obviously and, being toughened with PSF,by a factor of 90%.The toughening effect of PSF is better than that of PES.
This paper deals with the toughening bismaleimide (BMI) resin with thermoplastic (TP) resin,Polysulfone an d Polyether sulfone.The experiment shows that the viscosity of toughened resira is 0.5(Pa·S)at 150℃, the forming pressure of their composites is between 0.3-0.7 (MPa),curing temperature is 180℃,all of the properties mentioned above can meet the technological requirement of autoclave forming. The prepregs impregnated with these resins have quite good tack and drape,the shelf-live is more than one month(at room, temperature).The toughened resins keep quite good heat resistence and can be used permanently at 177℃.The impact strength of their composites increases obviously and, being toughened with PSF,by a factor of 90%.The toughening effect of PSF is better than that of PES.
1993, 10(2): 53-60.
Abstract:
The component and processing of the carbon-carbon (C/C) composite with diffusion type coating have been studied,and the results of the oxidation resistant performance and dynamic environment tests are given.It has been shown by analyzing the microstructure,that SiC coating formed by the reaction on C/C composite surface is the combination of chemical convetting coating and C/C composite,which is gradient interface of which components are continuously changing where it constructs the functionally gradient material,makes SiC coating have excellent performances.
The component and processing of the carbon-carbon (C/C) composite with diffusion type coating have been studied,and the results of the oxidation resistant performance and dynamic environment tests are given.It has been shown by analyzing the microstructure,that SiC coating formed by the reaction on C/C composite surface is the combination of chemical convetting coating and C/C composite,which is gradient interface of which components are continuously changing where it constructs the functionally gradient material,makes SiC coating have excellent performances.
1993, 10(2): 61-67.
Abstract:
This paper mainly studies the influence of content and orientation of fibers upon the electrical properties of unidirctional glass fiber reinforced epoxy resin composites.The results indicate that the change of fiber orientation and the direction of applied electric field results in the change of breakdown strength,and the bigger the angle between fiber orienration and direction of electric field is,the higher the breakdown strength. The electrical properties of unidirectional fiber laminted plate decrease with the increase of fiber content.This paper establishes a submicroscopical dielec1ric model of unidirectional fiber composite,and on the basis of this model,the relationship between the breakdown intensity or electrical constant with the fiber content and orientation was theoretically predicated,the results between experiment and theory show a good agreement.
This paper mainly studies the influence of content and orientation of fibers upon the electrical properties of unidirctional glass fiber reinforced epoxy resin composites.The results indicate that the change of fiber orientation and the direction of applied electric field results in the change of breakdown strength,and the bigger the angle between fiber orienration and direction of electric field is,the higher the breakdown strength. The electrical properties of unidirectional fiber laminted plate decrease with the increase of fiber content.This paper establishes a submicroscopical dielec1ric model of unidirectional fiber composite,and on the basis of this model,the relationship between the breakdown intensity or electrical constant with the fiber content and orientation was theoretically predicated,the results between experiment and theory show a good agreement.
1993, 10(2): 69-75.
Abstract:
A study is carried out to investigate the melting and crystallization behaviour of PPS/PES blend and its composite reinforced by carbon fiber.The experimzntal results show that PES and carbon fiber have remarkable influence on the melting and crystallization behaviour of PPS.
A study is carried out to investigate the melting and crystallization behaviour of PPS/PES blend and its composite reinforced by carbon fiber.The experimzntal results show that PES and carbon fiber have remarkable influence on the melting and crystallization behaviour of PPS.
1993, 10(2): 77-83.
Abstract:
The dynamic mechanical properties of CPVC/GF composites were investigated by using Viscoelastic Analyzer.The corrosion resistance behavior of the composites in water and dilute acid,alkali,salt solution was studied by referring to the pertinent experimental standards.The surface microstructure of the samples corroded was detected by SEM.The results show that the CPVC/GF composite is a kind of excellent materials with corrosion resistance below 70℃ and the mechanism of corrosion may be the coordinated action of physical permeation and chemical reaction.As a result,it will be favorable for compounding, processing and utilizing of this CPVC composite.
The dynamic mechanical properties of CPVC/GF composites were investigated by using Viscoelastic Analyzer.The corrosion resistance behavior of the composites in water and dilute acid,alkali,salt solution was studied by referring to the pertinent experimental standards.The surface microstructure of the samples corroded was detected by SEM.The results show that the CPVC/GF composite is a kind of excellent materials with corrosion resistance below 70℃ and the mechanism of corrosion may be the coordinated action of physical permeation and chemical reaction.As a result,it will be favorable for compounding, processing and utilizing of this CPVC composite.
1993, 10(2): 85-89.
Abstract:
Using Differential Scanning Calorimeteter according to Ellerstein's method,the thermal curing reaction of the Epoxy Resin 618#/DDS/Accelerator AB system is studied. With the help of computer,the key parameters and the apparent kinetics equation of the curing reaction characteristic and the pot life of the resin are predicted.
Using Differential Scanning Calorimeteter according to Ellerstein's method,the thermal curing reaction of the Epoxy Resin 618#/DDS/Accelerator AB system is studied. With the help of computer,the key parameters and the apparent kinetics equation of the curing reaction characteristic and the pot life of the resin are predicted.
1993, 10(2): 91-98.
Abstract:
In this paper,the microhardness and continuous heating specific heat of AZ91 magnesium alloy and SiCw/AZ91 Mg composite were, determined by micro-hardometer and adiabatic specific heat measurer,respectively,and the aged microstructures were observed by SEM. The effects of aging temperature and time on the precipitation structure were analyzed. The results show that the microhardnesses of both the composite and the AZ91 magnesium alloy increased after aging processes.The specific heat curves of the AZ91 magnesium alloy are similar to that of the SiCw/AZ91 Mg composite.Only when the aging temperatures are between 200℃ and 225℃,the aging microstructures of the SiCw/AZ91 Mg composite apear, and its morphology is similar to the continuous precipitation structure.
In this paper,the microhardness and continuous heating specific heat of AZ91 magnesium alloy and SiCw/AZ91 Mg composite were, determined by micro-hardometer and adiabatic specific heat measurer,respectively,and the aged microstructures were observed by SEM. The effects of aging temperature and time on the precipitation structure were analyzed. The results show that the microhardnesses of both the composite and the AZ91 magnesium alloy increased after aging processes.The specific heat curves of the AZ91 magnesium alloy are similar to that of the SiCw/AZ91 Mg composite.Only when the aging temperatures are between 200℃ and 225℃,the aging microstructures of the SiCw/AZ91 Mg composite apear, and its morphology is similar to the continuous precipitation structure.
1993, 10(2): 99-105.
Abstract:
The behaviour of high temperature plastic flow wear of WC-steel composite material by using tha methods of high temperature plastic flow friction and wear test,has been investgated in this paper.The strutcture,feature of worn surface and subsurface structure after test have been observed by means of SEM.The results show that the high temperature plastic flow wear resistance of WC-steel composite material is nine times more than that of 5CrNiMo die steel.The behaviour of high temperature plastic flow wear of WC-steel composite material behaves mainly the separation of WC particles and abrasive grain wear.
The behaviour of high temperature plastic flow wear of WC-steel composite material by using tha methods of high temperature plastic flow friction and wear test,has been investgated in this paper.The strutcture,feature of worn surface and subsurface structure after test have been observed by means of SEM.The results show that the high temperature plastic flow wear resistance of WC-steel composite material is nine times more than that of 5CrNiMo die steel.The behaviour of high temperature plastic flow wear of WC-steel composite material behaves mainly the separation of WC particles and abrasive grain wear.
1993, 10(2): 107-112.
Abstract:
In order to arrive at a high interface bond strength of diamond-copper alloy composite materials,interface structure and properties between Ti-clad diamond and copper alloy are investigated by x-ray diffration analysis,SEM observation and griding test.Test results show that interface reaction between Ti clading and diamond occurs between 600-1200°.The epitaxial islands of TiC are formed acid grow on the diamond surface.The metallurgical bond of inter face between diamond and copper alloy is obtained. Bond strength between clad diamond and copper alloy remains at the level of 8×107Pa.The grinding ratio of samples made from Ti-clad diamond is 30% higher than that without clad diamond.
In order to arrive at a high interface bond strength of diamond-copper alloy composite materials,interface structure and properties between Ti-clad diamond and copper alloy are investigated by x-ray diffration analysis,SEM observation and griding test.Test results show that interface reaction between Ti clading and diamond occurs between 600-1200°.The epitaxial islands of TiC are formed acid grow on the diamond surface.The metallurgical bond of inter face between diamond and copper alloy is obtained. Bond strength between clad diamond and copper alloy remains at the level of 8×107Pa.The grinding ratio of samples made from Ti-clad diamond is 30% higher than that without clad diamond.
1993, 10(2): 113-120.
Abstract:
Carbon fiber was covered with metals,such as Cu,Ni,Cr,Sn etc, by means of continue-electrodeposit.The composite materials were made by vacuum-hot-press diffusion method. The effects of several kinds of alloy elements on interface characteristic,structures and properties of C/Cu composites,and the quantitative interface strength of the compositce were studied in the paper.
Carbon fiber was covered with metals,such as Cu,Ni,Cr,Sn etc, by means of continue-electrodeposit.The composite materials were made by vacuum-hot-press diffusion method. The effects of several kinds of alloy elements on interface characteristic,structures and properties of C/Cu composites,and the quantitative interface strength of the compositce were studied in the paper.
1993, 10(2): 121-126.
Abstract:
A method of measuring the interface bonding strength of C/Al camposite precursor wires and the effect on the Tensile strength had been studied in this paper.We also provided a small scale shear testing machine made by ourselve to measure the langitudinal shear strength of cumposite wires.The interface bonding strength was expressed by converting the longitudinal shear strength of camposite wire through calculation.Generally, interface shear strength is equal to the longitudinal shear strength multiplied by a coefficient.It is found in the experiment that for a certain interface shear strength range the tensile strength of composite wire is inverse proportional to the interface shear strength.
A method of measuring the interface bonding strength of C/Al camposite precursor wires and the effect on the Tensile strength had been studied in this paper.We also provided a small scale shear testing machine made by ourselve to measure the langitudinal shear strength of cumposite wires.The interface bonding strength was expressed by converting the longitudinal shear strength of camposite wire through calculation.Generally, interface shear strength is equal to the longitudinal shear strength multiplied by a coefficient.It is found in the experiment that for a certain interface shear strength range the tensile strength of composite wire is inverse proportional to the interface shear strength.
1993, 10(2): 127-130.
Abstract:
The interfacial reaction between granular SiC and nickel in Ni/SiC composite plating at high temperature was studied.The results show that obvious interfacial reactions took place in the plating an annealing it at 600℃,800℃ and 1000℃ for 1 hour. The corresponin g products are Ni3Si, Ni5Si2 and Ni2Si, respectively.The resistance to wear of the platings relate to the products of the interfacial reactions indirectly.
The interfacial reaction between granular SiC and nickel in Ni/SiC composite plating at high temperature was studied.The results show that obvious interfacial reactions took place in the plating an annealing it at 600℃,800℃ and 1000℃ for 1 hour. The corresponin g products are Ni3Si, Ni5Si2 and Ni2Si, respectively.The resistance to wear of the platings relate to the products of the interfacial reactions indirectly.
