1994 Vol. 11, No. 3
1994, 11(3): 1-6.
Abstract:
Two kinds of wholly aromatic thermotropic liquid crystalline copolyesters (LCP) based on HO- - -OH or HO- -CH2- -OH were prepared, then blended with polysulfone for preparing in-situ composites. The variations on torque of blends in melt process have been studied. And effects of chain structure, molecular weight and content of LCP on rheology of in-situ composites have been investigated. It is obtained from the curves of milting flow that the melts of in-sits composites for polysulfone conform to non-Newton's law of viscosity and showed pseudolasticity. The morphology and compatibility of LCP and polysulfone have been also discussed.
Two kinds of wholly aromatic thermotropic liquid crystalline copolyesters (LCP) based on HO- - -OH or HO- -CH2- -OH were prepared, then blended with polysulfone for preparing in-situ composites. The variations on torque of blends in melt process have been studied. And effects of chain structure, molecular weight and content of LCP on rheology of in-situ composites have been investigated. It is obtained from the curves of milting flow that the melts of in-sits composites for polysulfone conform to non-Newton's law of viscosity and showed pseudolasticity. The morphology and compatibility of LCP and polysulfone have been also discussed.
1994, 11(3): 7-12.
Abstract:
The paper describes the preparation and the performance of wood plastic composites by acrylate monomer impregnation. The factors affecting monomer uptake and conversicm degree were investigated. Experiments showed that polyacrylate-wood plastic composites have higher physico-mechanical performance.
The paper describes the preparation and the performance of wood plastic composites by acrylate monomer impregnation. The factors affecting monomer uptake and conversicm degree were investigated. Experiments showed that polyacrylate-wood plastic composites have higher physico-mechanical performance.
1994, 11(3): 13-18.
Abstract:
It has been studied that the influence of the SEM specimen preparation methods,including chemical etching,element area profile,frozen fracture and frozen polishing,on morphology of toughening and strengthening composites. The results show that the authentic fracture morphology of the composites can be obtained by proper methods of specmen preparation,and it can provide the scientific basis for material research.
It has been studied that the influence of the SEM specimen preparation methods,including chemical etching,element area profile,frozen fracture and frozen polishing,on morphology of toughening and strengthening composites. The results show that the authentic fracture morphology of the composites can be obtained by proper methods of specmen preparation,and it can provide the scientific basis for material research.
1994, 11(3): 19-25.
Abstract:
This research utilizes pressure casting to make Al2O3 fibre grain to form composite with aluminium alloy. This composite material is subjected to a comparison test with ZL108 on wear,elongation. The test results shows that in comparison with ZL108, this coTposite material has more than ten times higher wear resistance both at room and elevated temperatures (400-0),more than twofold higher strength at elevated temperatures, but in wear with fatigue failure,its wear resistance is not noticeably better than that of ZL108,furthermore it accelerates the wear of its pairing material.
This research utilizes pressure casting to make Al2O3 fibre grain to form composite with aluminium alloy. This composite material is subjected to a comparison test with ZL108 on wear,elongation. The test results shows that in comparison with ZL108, this coTposite material has more than ten times higher wear resistance both at room and elevated temperatures (400-0),more than twofold higher strength at elevated temperatures, but in wear with fatigue failure,its wear resistance is not noticeably better than that of ZL108,furthermore it accelerates the wear of its pairing material.
1994, 11(3): 26-32.
Abstract:
SiC matrix composite was fabricated by using polycarbosilane as precursor and continous carbon fibers as reinforcer. The process of the fabrication such as polycarbosilane molecular weight,control of fiber volume fraction,liquid impregnation and pyrolysis of polycarbosilane was investigated. The results show that the process is suitable to fabrication ceramic matrix composite reinfoced with continuous fibers. Properties of the C/SiC composites were studied and the mechanism of fracture is tough fracture.
SiC matrix composite was fabricated by using polycarbosilane as precursor and continous carbon fibers as reinforcer. The process of the fabrication such as polycarbosilane molecular weight,control of fiber volume fraction,liquid impregnation and pyrolysis of polycarbosilane was investigated. The results show that the process is suitable to fabrication ceramic matrix composite reinfoced with continuous fibers. Properties of the C/SiC composites were studied and the mechanism of fracture is tough fracture.
1994, 11(3): 33-37.
Abstract:
SiC coated fibres were obtained by a new method using SiO and CO to form SiC and deposit on to the carbon fibres. Columnar β-SiC grains grew radially out from the carbon fibre surface and formed a SiC coating with corncob-like surface morphology. When the thickness of the SiC coating increases to≥0.2pm, the tensile strength of the SiC coated fibre decreases with the increasing of thickness of SiC coating and this result is coincident with Ochiai' s theoretical model. For the fibres with l}cm SiC coating, their mechanical behavior in tensile is similar to a 1 D brittle fibre-brittle matrix composite with weak fibre-matrix bonding and multiple fracture of SiC coating is shown. The degradation of the carbon fibre core caused by the coating process is discussed.
SiC coated fibres were obtained by a new method using SiO and CO to form SiC and deposit on to the carbon fibres. Columnar β-SiC grains grew radially out from the carbon fibre surface and formed a SiC coating with corncob-like surface morphology. When the thickness of the SiC coating increases to≥0.2pm, the tensile strength of the SiC coated fibre decreases with the increasing of thickness of SiC coating and this result is coincident with Ochiai' s theoretical model. For the fibres with l}cm SiC coating, their mechanical behavior in tensile is similar to a 1 D brittle fibre-brittle matrix composite with weak fibre-matrix bonding and multiple fracture of SiC coating is shown. The degradation of the carbon fibre core caused by the coating process is discussed.
1994, 11(3): 38-42.
Abstract:
This paper presents a study of the mechanism for thermal decomposition of SiC fibre reinforced glass-ceramic matrix composite and the relation to crystallization by TG-DTA-MS coupling technique. The thermodynamic and mas spectroscopy analysis for the composite SiC of forming carbon layer on the interphase of the composite SiC fibre/LAS are presented. A comparison between experimental phenomena and theoretical analysis for the thermal decomposition behaviour of both composite SiC fibre/LAS (crystallized and without crystallized) is also made.
This paper presents a study of the mechanism for thermal decomposition of SiC fibre reinforced glass-ceramic matrix composite and the relation to crystallization by TG-DTA-MS coupling technique. The thermodynamic and mas spectroscopy analysis for the composite SiC of forming carbon layer on the interphase of the composite SiC fibre/LAS are presented. A comparison between experimental phenomena and theoretical analysis for the thermal decomposition behaviour of both composite SiC fibre/LAS (crystallized and without crystallized) is also made.
1994, 11(3): 43-49.
Abstract:
Some basic Problems concerning interface fracture of composites,especially of bimaterial combination,and questions resulting from the assumption of different boundary conditions of interface crack models are discussed. Commonly used analytical formulas are unified and different models are summarized and compared by relating well-know pararieters used in the description of an interface. Finaly an availability of using Kc-concept to evaluate the bonding strength of different material combinations is presented.
Some basic Problems concerning interface fracture of composites,especially of bimaterial combination,and questions resulting from the assumption of different boundary conditions of interface crack models are discussed. Commonly used analytical formulas are unified and different models are summarized and compared by relating well-know pararieters used in the description of an interface. Finaly an availability of using Kc-concept to evaluate the bonding strength of different material combinations is presented.
1994, 11(3): 50-55.
Abstract:
This paper develops the numerical approach for the calculation of elastic properries of unidirectional fibre reinforced composite materials based on an effective medium theory.It is then used to calculate the properties of several unidirectional fibre reinforced systems and results show good conformity with experimental data.
This paper develops the numerical approach for the calculation of elastic properries of unidirectional fibre reinforced composite materials based on an effective medium theory.It is then used to calculate the properties of several unidirectional fibre reinforced systems and results show good conformity with experimental data.
1994, 11(3): 56-62.
Abstract:
A composite 4-node quadrilateral degenerated finite element for multilayered shells is presented in this article. The element is derived based on a modified Hu-Washizu variational principle with independently assumed displacement, laminate internal strain fields and stress fields. The element' s performance for static linear problems of composite plates and shells is evaluated. The computed results show that the present element yields accurate solutions for the test problems presented.
A composite 4-node quadrilateral degenerated finite element for multilayered shells is presented in this article. The element is derived based on a modified Hu-Washizu variational principle with independently assumed displacement, laminate internal strain fields and stress fields. The element' s performance for static linear problems of composite plates and shells is evaluated. The computed results show that the present element yields accurate solutions for the test problems presented.
1994, 11(3): 63-69.
Abstract:
A simple method for computing stresses in laminated plates is presented in this paper. Numerical example indicates that the accuracy of the results obtained by using the method is satisfied.
A simple method for computing stresses in laminated plates is presented in this paper. Numerical example indicates that the accuracy of the results obtained by using the method is satisfied.
1994, 11(3): 70-75.
Abstract:
Thin glass/epoxy plates with [O2/902/+452/-452]s were subjected to low velocity impact. To measure the property of damage in composite, we have found Mn (CH3C00)2/CH3COCH3 solution. The new liquild is cheaper and available and th, result is very succeessful. Delay technique has been used to present the pattern of damage area in composites and the relationship between delamination and impact energy. Experimental results have shown that there is a threshold value of impact energy and that a linear relationship holds between delamination area and impact energy. Observing the microsopic pattern of damage area by scanning electron micrography. We have found that the mattix cracks which are parallel to the fiber direction are caused by the tensile stresses and the delamination by the shear stresses.
Thin glass/epoxy plates with [O2/902/+452/-452]s were subjected to low velocity impact. To measure the property of damage in composite, we have found Mn (CH3C00)2/CH3COCH3 solution. The new liquild is cheaper and available and th, result is very succeessful. Delay technique has been used to present the pattern of damage area in composites and the relationship between delamination and impact energy. Experimental results have shown that there is a threshold value of impact energy and that a linear relationship holds between delamination area and impact energy. Observing the microsopic pattern of damage area by scanning electron micrography. We have found that the mattix cracks which are parallel to the fiber direction are caused by the tensile stresses and the delamination by the shear stresses.
1994, 11(3): 76-81.
Abstract:
Two-dimensional finite element analysis of the double-cantilever beam specimen was performed using 8-node isoparametric,quadrilateral elements to evaluate compliance and strain-energy-release rate GI. The GI values were computed using J-integral method. The effects of the carck length,the thickness of specimen and the modular in thickness direction on the evaluation of GI according to simple-beam-theory were investigated.
Two-dimensional finite element analysis of the double-cantilever beam specimen was performed using 8-node isoparametric,quadrilateral elements to evaluate compliance and strain-energy-release rate GI. The GI values were computed using J-integral method. The effects of the carck length,the thickness of specimen and the modular in thickness direction on the evaluation of GI according to simple-beam-theory were investigated.
1994, 11(3): 82-90.
Abstract:
On this paper,a stress version of the hybrid finite strip method is established and applied to orthotropic and isotropic rectangular plates. This work is based on the modified complementary energy principle. On the formulation of hybrid finite strip,the streess in the strips and the displacements at the boundaries between the strips are assumed. Numerical examples demonstrate that the proposed method is reasonable and convergent rapidly to the exact solution.
On this paper,a stress version of the hybrid finite strip method is established and applied to orthotropic and isotropic rectangular plates. This work is based on the modified complementary energy principle. On the formulation of hybrid finite strip,the streess in the strips and the displacements at the boundaries between the strips are assumed. Numerical examples demonstrate that the proposed method is reasonable and convergent rapidly to the exact solution.
1994, 11(3): 91-96.
Abstract:
Using Rayleigh-Ritz Method and Finite-layers Method the free vibrations of angle-ply thick laminates Qf bimodulus composite materrials with simple supported boundary conditions are inverstigated. The effects of various parameters of laminates on fundamental frequencies are discussed.
Using Rayleigh-Ritz Method and Finite-layers Method the free vibrations of angle-ply thick laminates Qf bimodulus composite materrials with simple supported boundary conditions are inverstigated. The effects of various parameters of laminates on fundamental frequencies are discussed.
1994, 11(3): 97-104.
Abstract:
The Hamilton canonical equation and a semi-analytical solution for orthotropic thick plates are presented in this paper. The approach gives up any assumption of displacements and stresses. The exact solution is derived by the state space control method. Furthermore,appling the transfer matrix method,the continuity of interlaminar stresses and displacements are satisfied,and the number of voviables are reduced greatly.
The Hamilton canonical equation and a semi-analytical solution for orthotropic thick plates are presented in this paper. The approach gives up any assumption of displacements and stresses. The exact solution is derived by the state space control method. Furthermore,appling the transfer matrix method,the continuity of interlaminar stresses and displacements are satisfied,and the number of voviables are reduced greatly.
1994, 11(3): 105-111.
Abstract:
The end notched flexure (ENF) test was employed in an investigation of interlaminar fracture behavior in Mode II static and, fatigue loading for carbon/epoxy composites T300/M10 and HTA/6376. Under static loading,both of the materials exhibited bittle unstable and brittle stable behavior of crack growth. Stable Mode II crack growth was observed during fatigue loading with R=0.1 in a larger range of cyclic strain energy release rate. A consistent relation of crack growth rate to the cyclic strain energy release rate was obtained for the composites. Within the range of moderate crack growth rate,the data of Mode II fatigue crack growth obeyed a power law. The trend of reduction in crack growth rate data with degredation in cyclic strain energy release rate suggests the presence of a threshold strain energy release rate. Compared with T300/914C,HTA/6376 and T300/M10 have higher crack growth resistance.
The end notched flexure (ENF) test was employed in an investigation of interlaminar fracture behavior in Mode II static and, fatigue loading for carbon/epoxy composites T300/M10 and HTA/6376. Under static loading,both of the materials exhibited bittle unstable and brittle stable behavior of crack growth. Stable Mode II crack growth was observed during fatigue loading with R=0.1 in a larger range of cyclic strain energy release rate. A consistent relation of crack growth rate to the cyclic strain energy release rate was obtained for the composites. Within the range of moderate crack growth rate,the data of Mode II fatigue crack growth obeyed a power law. The trend of reduction in crack growth rate data with degredation in cyclic strain energy release rate suggests the presence of a threshold strain energy release rate. Compared with T300/914C,HTA/6376 and T300/M10 have higher crack growth resistance.
