1987 Vol. 4, No. 4
1987, 4(4): 1-Ⅱ.
Abstract:
The cure reaction kinetics of tetraglycidyl 4, 4'-diaminodiphenl methane (AG-80)-Diaminodiphenyl sulfone (DDS) epoxy resin system was investigated by isothermal DSC.The DSC data were processed with computer and the DSC curve was simulated by sectional parabola interpolation method.
The cure reaction kinetics of tetraglycidyl 4, 4'-diaminodiphenl methane (AG-80)-Diaminodiphenyl sulfone (DDS) epoxy resin system was investigated by isothermal DSC.The DSC data were processed with computer and the DSC curve was simulated by sectional parabola interpolation method.
1987, 4(4): 8-Ⅳ.
Abstract:
The main purpose of the present paper is to calculate the apecific damping capacity (SDC) of a structure based on the complex moduli and compliances of its material under given harmonic loads and boundary conditions.Firstly,a three-dimensional viscoelastic analysis of complex duli and compliances of orthotropic materials leads to Eds. (23) (24),which express SDC in terms of complex moduli and compliances of the material.
The main purpose of the present paper is to calculate the apecific damping capacity (SDC) of a structure based on the complex moduli and compliances of its material under given harmonic loads and boundary conditions.Firstly,a three-dimensional viscoelastic analysis of complex duli and compliances of orthotropic materials leads to Eds. (23) (24),which express SDC in terms of complex moduli and compliances of the material.
1987, 4(4): 18-Ⅳ.
Abstract:
The fracture behavior and tensile strength of the epoxy composite (Bisphenal-A type epoxide E-51) filled by Al2O3, CaF2 and glass bead were investigated.The relationship between the tensile strength and volume fraction of filler was examined.It was found that the dense boundary layer with a certain thickness onto the surface of the filler would form when the filler was embeded in the epoxy matrix.The strength behavior of such an boundary layer has an important contribution to that of the composite.The tensile strength of three filled composites was measured.
The fracture behavior and tensile strength of the epoxy composite (Bisphenal-A type epoxide E-51) filled by Al2O3, CaF2 and glass bead were investigated.The relationship between the tensile strength and volume fraction of filler was examined.It was found that the dense boundary layer with a certain thickness onto the surface of the filler would form when the filler was embeded in the epoxy matrix.The strength behavior of such an boundary layer has an important contribution to that of the composite.The tensile strength of three filled composites was measured.
1987, 4(4): 24-Ⅵ.
Abstract:
The geometrically nonlinear problem of laminated composite shells have received considerable attention in recent years.However, in the classical geometrically nonlinear theories of shells, the equations of inplane equilibrium have not involved the effect of dofermation.So they are not suitable for the case of relatively large deformation, at least they are not accurate. In this paper, starting from the three dimensional theory of nonlinear elasticity and taking into account of the effect of deformation in all equilibrium equations,we present a new geometrically nonlinear theory of shells which differs from classical theories according to scale-order analysis under the condition of small strains and moderate rotations.The governing equations of nonlinear analysis for orthotropic composite shallow cylindrical shells are derived by the same method in which the effect of transverse shear deformation is considered.The approximate solutions of nonlinear bending for orthotropic laminated composite cylindrical shells with all clamped edges are obtained by the perturbation method.The approximate solutions of nonlinear bending for orthotropic composite shallow cylindrical shells with all edges simply supported are also obtained by the Galerkin procedure, and the effect of transverse shear deformation is taken into account.
The geometrically nonlinear problem of laminated composite shells have received considerable attention in recent years.However, in the classical geometrically nonlinear theories of shells, the equations of inplane equilibrium have not involved the effect of dofermation.So they are not suitable for the case of relatively large deformation, at least they are not accurate. In this paper, starting from the three dimensional theory of nonlinear elasticity and taking into account of the effect of deformation in all equilibrium equations,we present a new geometrically nonlinear theory of shells which differs from classical theories according to scale-order analysis under the condition of small strains and moderate rotations.The governing equations of nonlinear analysis for orthotropic composite shallow cylindrical shells are derived by the same method in which the effect of transverse shear deformation is considered.The approximate solutions of nonlinear bending for orthotropic laminated composite cylindrical shells with all clamped edges are obtained by the perturbation method.The approximate solutions of nonlinear bending for orthotropic composite shallow cylindrical shells with all edges simply supported are also obtained by the Galerkin procedure, and the effect of transverse shear deformation is taken into account.
1987, 4(4): 33-Ⅵ.
Abstract:
Carbon fiber surface properties were systematically studied by means of measuring specific surface, contact angle, wettability surface energy and surface group.Specific surface measured bY dynamic absorption method, increased with the oxidation treatment time, rose from carbon fibers etched bY acid.The most probable pore distribution of carbon fibers tested is in the scope 10-12Å.The changes of surface energy were measured by contact goniometer and increased with oxidation treatment time too.There were the dispersion and polar components of surface energy in which the polar components increased obviously and the dispersion tomponents decreased slightly.The contact angles with respect to epoxy resin or water decreaseed witn the oxidation treated time.The treatment modified the wettabilities of treated fibers toward better ones.Then, changes of wetting velocity of carbon fibers were measured by microbalance.The wetting velocity in water increased about 3 times of ter the oxidattion treament of carbon fibers, which further verified that the wettabilites became better by oxidation treatment.
Carbon fiber surface properties were systematically studied by means of measuring specific surface, contact angle, wettability surface energy and surface group.Specific surface measured bY dynamic absorption method, increased with the oxidation treatment time, rose from carbon fibers etched bY acid.The most probable pore distribution of carbon fibers tested is in the scope 10-12Å.The changes of surface energy were measured by contact goniometer and increased with oxidation treatment time too.There were the dispersion and polar components of surface energy in which the polar components increased obviously and the dispersion tomponents decreased slightly.The contact angles with respect to epoxy resin or water decreaseed witn the oxidation treated time.The treatment modified the wettabilities of treated fibers toward better ones.Then, changes of wetting velocity of carbon fibers were measured by microbalance.The wetting velocity in water increased about 3 times of ter the oxidattion treament of carbon fibers, which further verified that the wettabilites became better by oxidation treatment.
1987, 4(4): 38-Ⅷ.
Abstract:
One of the most important characteristics of symmetric angleply laminates is that there exist two terms, D16 and D26 of bending twisting coupling, that makes it almost impossible to obtain, by using traditional series expansion method, the exact solution.In this present paper, the two-step expansion (TSE) technique, proposed recently by the first author, is employed to give a general solution for bending, buckling and vibration of symmetric angle-ply rectangular laminates.
One of the most important characteristics of symmetric angleply laminates is that there exist two terms, D16 and D26 of bending twisting coupling, that makes it almost impossible to obtain, by using traditional series expansion method, the exact solution.In this present paper, the two-step expansion (TSE) technique, proposed recently by the first author, is employed to give a general solution for bending, buckling and vibration of symmetric angle-ply rectangular laminates.
1987, 4(4): 45-Ⅸ.
Abstract:
In this paper the thermophysical properties of carbon-carbon composites, including the coefficient of thermal conductivity and the coefficient of thermal expansion, were measured and examined from room temperature to 2000℃ by means of laser flash technique, quartz differential dilatometry and laser scanning method.The therural shock resistance properties of 3-D fine woven carbon-carbon composite and 2-D carbon cloth lay-up carbon-carbon composite were analyzed through the thermal shock resistance parameters.The effect of temperatures, densities as well as orientations on the thermat physical properties and thermal shock resistance properties were investigated.It is found that the coefficients of thermal conductivity of carbon-carbon composites decrease with increasing temperature tested.The higher the density the larger the coefficient of thermal conductivity.
In this paper the thermophysical properties of carbon-carbon composites, including the coefficient of thermal conductivity and the coefficient of thermal expansion, were measured and examined from room temperature to 2000℃ by means of laser flash technique, quartz differential dilatometry and laser scanning method.The therural shock resistance properties of 3-D fine woven carbon-carbon composite and 2-D carbon cloth lay-up carbon-carbon composite were analyzed through the thermal shock resistance parameters.The effect of temperatures, densities as well as orientations on the thermat physical properties and thermal shock resistance properties were investigated.It is found that the coefficients of thermal conductivity of carbon-carbon composites decrease with increasing temperature tested.The higher the density the larger the coefficient of thermal conductivity.
1987, 4(4): 51-Ⅸ.
Abstract:
The laminated composite cone-cylindrical connected shell under internal pressure is analysed by the use of finite element displacement method based on laminated anisotropic shell theory. The numerical calculations are performed by using a computer program DDJTTQ-3, which was developed from the general purpose program DDJ-W for composed structure analysis[1]. The conecylidrical connected shell is modeled by using triangular laminated composite shell elements on the base of discrete Kirchhoff's hypothesis and taking coupling effect into consideration.The expression of foregoing element stiffness matrix is given in the rapar.Two numerical examples are presented for both isotropic and laminated composite cone-cylindrical shell junction.The numerical results show that the computational results in this paper agree well with those from 3-D and axisymmetric curve finite element methods, which proves that the triangular laminated composite shell element is quite accurate.The displacement variation along the shell is strongly dependent on the elastic behaviour and ply numbers of composite materials.
The laminated composite cone-cylindrical connected shell under internal pressure is analysed by the use of finite element displacement method based on laminated anisotropic shell theory. The numerical calculations are performed by using a computer program DDJTTQ-3, which was developed from the general purpose program DDJ-W for composed structure analysis[1]. The conecylidrical connected shell is modeled by using triangular laminated composite shell elements on the base of discrete Kirchhoff's hypothesis and taking coupling effect into consideration.The expression of foregoing element stiffness matrix is given in the rapar.Two numerical examples are presented for both isotropic and laminated composite cone-cylindrical shell junction.The numerical results show that the computational results in this paper agree well with those from 3-D and axisymmetric curve finite element methods, which proves that the triangular laminated composite shell element is quite accurate.The displacement variation along the shell is strongly dependent on the elastic behaviour and ply numbers of composite materials.
1987, 4(4): 56-Ⅹ.
Abstract:
In order to obtain quality carbon fiber, it is necessary to get theinformation about the fiber processing.The paper here discribes the analysis of different processed carbon fibers on cross sections by the use of Scanning Auger Microprobe (SAM).The sample of carbon fiber is displayed on the scanning electron microscope(SEM) with the magnification of 104 times and then tests are done within a single f fiber.The Auger line scanning and the point analysis for carbon fibers,with the tensile strength of 3.43 GPa, 3.13 GPa and 2.45 GPa, respectively,are taken.The difference of carbonization state between the skin and the core of a carbon fiber in the chemical reactions of different preoxidation and carbonization can be observed in both the intensity of the carbon signal and the shape of the Auger peaks.
In order to obtain quality carbon fiber, it is necessary to get theinformation about the fiber processing.The paper here discribes the analysis of different processed carbon fibers on cross sections by the use of Scanning Auger Microprobe (SAM).The sample of carbon fiber is displayed on the scanning electron microscope(SEM) with the magnification of 104 times and then tests are done within a single f fiber.The Auger line scanning and the point analysis for carbon fibers,with the tensile strength of 3.43 GPa, 3.13 GPa and 2.45 GPa, respectively,are taken.The difference of carbonization state between the skin and the core of a carbon fiber in the chemical reactions of different preoxidation and carbonization can be observed in both the intensity of the carbon signal and the shape of the Auger peaks.
1987, 4(4): 61-Ⅺ.
Abstract:
Damage accumulation in composite laminates under fatigue has been investigated by many authors.To monitor the compliance change of the specimen is one of the approaches.In this paper Moire method was used to measure the compliance change of GRP specimen after certain fatigue cycles.Since Moire fringes provide whole field of displacement and strain and also concentrate at the crack tip, this method can monitor the compliance change and the propagation of the crack and damage zone.Two kinds of CARP laurinates were investegated and different characteristics of damage propagation were revealed.
Damage accumulation in composite laminates under fatigue has been investigated by many authors.To monitor the compliance change of the specimen is one of the approaches.In this paper Moire method was used to measure the compliance change of GRP specimen after certain fatigue cycles.Since Moire fringes provide whole field of displacement and strain and also concentrate at the crack tip, this method can monitor the compliance change and the propagation of the crack and damage zone.Two kinds of CARP laurinates were investegated and different characteristics of damage propagation were revealed.
1987, 4(4): 66-Ⅻ.
Abstract:
The choice of materials used in making retaining rings for generator plays very important role in studying large central power statior. generators.The unility of advanced composites which have a high stiffnes-to-weight ratio, high strength-to-weight can offer significant advantages to electrical industry.The composite retaining ring is a laminated shell of uniform-thickness orthotropic layers.The forces acting upon the ring are the centrifugal f once (ω=3000 rpm),thermal stresses due to the difference of the temperature between the inner and outer surfaces of the ring and the unsymmetrical pressures of the coils exerted on the inner surface.In this paper a generalized laminated shell finite element formula including transverse shear strains is presented and a tomputer programme is written for this problem.
The choice of materials used in making retaining rings for generator plays very important role in studying large central power statior. generators.The unility of advanced composites which have a high stiffnes-to-weight ratio, high strength-to-weight can offer significant advantages to electrical industry.The composite retaining ring is a laminated shell of uniform-thickness orthotropic layers.The forces acting upon the ring are the centrifugal f once (ω=3000 rpm),thermal stresses due to the difference of the temperature between the inner and outer surfaces of the ring and the unsymmetrical pressures of the coils exerted on the inner surface.In this paper a generalized laminated shell finite element formula including transverse shear strains is presented and a tomputer programme is written for this problem.
1987, 4(4): 72-Ⅷ.
Abstract:
Because of nonuniform distribution and irregular arrangement of fibres in the composite lamina,the foundamental difference betwean fibres(or matrix) in the lamina and separate bundles of fibre (pure matrix),the difficulty of determining elastic properties of a separate bundle of fibre by experiments, the problem of determining the elastic constants, E2,G12,G23,v23,etc.,by micromechanical method has not been solved very well,althouth it has been discuseed for many years.All of the available mixture laws have some faults.Under some conditions the results given by these laws are relatively near to experimental results, but under other conditions they are not.To get valuable and relatively simple semi-emprical formulas, it is necessary to tempera and analyse various formulas based on different models.
Because of nonuniform distribution and irregular arrangement of fibres in the composite lamina,the foundamental difference betwean fibres(or matrix) in the lamina and separate bundles of fibre (pure matrix),the difficulty of determining elastic properties of a separate bundle of fibre by experiments, the problem of determining the elastic constants, E2,G12,G23,v23,etc.,by micromechanical method has not been solved very well,althouth it has been discuseed for many years.All of the available mixture laws have some faults.Under some conditions the results given by these laws are relatively near to experimental results, but under other conditions they are not.To get valuable and relatively simple semi-emprical formulas, it is necessary to tempera and analyse various formulas based on different models.
1987, 4(4): 79-ⅩⅣ.
Abstract:
The microstructure of bamboo was investigated and correlated with the mechanical properties of this material under tensile and flexural stresses. The netural structure of bamboo was found to contain characteristics similar to fibre-reinforced composites; thick-walled fibrous cells of the filamentous}unidirectionally aligned vascular bundles were embedded within a matrix of soft and thin-walled parenchymatous cells.The fibre content was non-uniformly distributed within the wall thickness and found to accentuate from the interior to the exterior surface. Test bamboo strips were prepared from internodal sections by cutting into sectors and further splitting circumferentially into specimens of about 1 mm thick, the fibre contents of which were determined by inspection under a microscope.Under tensile stress, Young's modulus was linearly related to fibre content as well as tensile strength.When bending stress was applied, a linear relationship was again found between the bending modulus and fibre density.
The microstructure of bamboo was investigated and correlated with the mechanical properties of this material under tensile and flexural stresses. The netural structure of bamboo was found to contain characteristics similar to fibre-reinforced composites; thick-walled fibrous cells of the filamentous}unidirectionally aligned vascular bundles were embedded within a matrix of soft and thin-walled parenchymatous cells.The fibre content was non-uniformly distributed within the wall thickness and found to accentuate from the interior to the exterior surface. Test bamboo strips were prepared from internodal sections by cutting into sectors and further splitting circumferentially into specimens of about 1 mm thick, the fibre contents of which were determined by inspection under a microscope.Under tensile stress, Young's modulus was linearly related to fibre content as well as tensile strength.When bending stress was applied, a linear relationship was again found between the bending modulus and fibre density.
