2002 Vol. 19, No. 4
2002, 19(4): 1-5.
Abstract:
In this paper, a two-parameter model is proposed to identify the viscosity coefficients of composites. These two parameters are the viscosity coefficient of resin and the viscosity coefficient of carbon fiber in the woof direction respectively. The parameters were identified by using the field measured damping ratio of a cantilever gird, and tested by using the field measured results of other girds. In identifying, the influence of air resistance is taken into account. The result of analysis shows this method is effective, and its error is agreeable.
In this paper, a two-parameter model is proposed to identify the viscosity coefficients of composites. These two parameters are the viscosity coefficient of resin and the viscosity coefficient of carbon fiber in the woof direction respectively. The parameters were identified by using the field measured damping ratio of a cantilever gird, and tested by using the field measured results of other girds. In identifying, the influence of air resistance is taken into account. The result of analysis shows this method is effective, and its error is agreeable.
2002, 19(4): 6-10.
Abstract:
Dielectric properties of 40 percent QR toughening-agent toughened anhydride-cured epoxy resins (EP)and pure anhydride-cured EP were measured. The relationships between the relative permittivity and dielectric loss of cured EP with temperature and frequency were also studied.The interfacial polarization process could be described by the MWS model owing to the phase separation process taking place during the cure.
Dielectric properties of 40 percent QR toughening-agent toughened anhydride-cured epoxy resins (EP)and pure anhydride-cured EP were measured. The relationships between the relative permittivity and dielectric loss of cured EP with temperature and frequency were also studied.The interfacial polarization process could be described by the MWS model owing to the phase separation process taking place during the cure.
2002, 19(4): 11-13.
Abstract:
Nanocomposite was prepared by nanometer TiO2 and epoxy resin. The affects of the content of nanometer TiO2 on the properties of the nanocomposite were studied. The dispersion of TiO2 was observed with TEM. The data of the free volume were studied by the positron annihilation technique. As a result, the tensile strength ,modulus and impact strength of the epoxy resin were increased with the dispersion of nanometer TiO2. The free volume length of the epoxy resin was increased with nanometer.
Nanocomposite was prepared by nanometer TiO2 and epoxy resin. The affects of the content of nanometer TiO2 on the properties of the nanocomposite were studied. The dispersion of TiO2 was observed with TEM. The data of the free volume were studied by the positron annihilation technique. As a result, the tensile strength ,modulus and impact strength of the epoxy resin were increased with the dispersion of nanometer TiO2. The free volume length of the epoxy resin was increased with nanometer.
2002, 19(4): 14-17.
Abstract:
The effect of ultraviolet irradiation at different temperatures of environments in air on the structure and properties of high density polyethylene (HDPE) and the compatibilization effect of HDPE functionalized by ultraviolet irradiation in HDPE/polyvinyl alcohol (PVA)-fiber blend systems are studied through FTIR, surface contact angle measurement with water and mechanical properties test. The results show that —C(C=O)CH3、—CH2C(=O)CH2—、—C(=O)O— oxygen-containing groups are introduced onto HDPE molecular chain during ultraviolet irradiation in air. The rate of HDPE functionalization is increased with the temperature of environments. After ultraviolet irradiating, the Young's modulus and tensile yield strength of HDPE are increased; its elongation at break and notched Izod impact strength are decreased. The proper functionalized HDPE behaves as a compatibilizer in HDPE/PVA-fiber blend; by adding 5 wt% functionalized HDPE (irradiation light intensity is 78 W/m2 and irradiation time is 24 hours) into the HDPE/PVA-fiber (88/12 wt%), the tensile yield strength and notched Izod impact strength of the blend are increased from 28.3 MPa (HDPE/PVA-fiber: 88/12 wt%) to 30.6 MPa and 130 J/m to 163 J/m respectively.
The effect of ultraviolet irradiation at different temperatures of environments in air on the structure and properties of high density polyethylene (HDPE) and the compatibilization effect of HDPE functionalized by ultraviolet irradiation in HDPE/polyvinyl alcohol (PVA)-fiber blend systems are studied through FTIR, surface contact angle measurement with water and mechanical properties test. The results show that —C(C=O)CH3、—CH2C(=O)CH2—、—C(=O)O— oxygen-containing groups are introduced onto HDPE molecular chain during ultraviolet irradiation in air. The rate of HDPE functionalization is increased with the temperature of environments. After ultraviolet irradiating, the Young's modulus and tensile yield strength of HDPE are increased; its elongation at break and notched Izod impact strength are decreased. The proper functionalized HDPE behaves as a compatibilizer in HDPE/PVA-fiber blend; by adding 5 wt% functionalized HDPE (irradiation light intensity is 78 W/m2 and irradiation time is 24 hours) into the HDPE/PVA-fiber (88/12 wt%), the tensile yield strength and notched Izod impact strength of the blend are increased from 28.3 MPa (HDPE/PVA-fiber: 88/12 wt%) to 30.6 MPa and 130 J/m to 163 J/m respectively.
2002, 19(4): 18-24.
Abstract:
In the RTM process, gate/vent location is one of the most important variables in RTM mold design. The paper proposed an approach to optimize the gate locations. To minimize the maximum distance between gates and vent and treat the trapping volume as penalty, the optimization was conducted. Genetic algorithm (GA) was employed to carry out the optimization procedure to find the optimal gate and vent location. Numerical testing was performed with different shape molds. The case studies showed that the processing performance index is suitable, and the results illustrated that the proposed approach is efficient and effective.
In the RTM process, gate/vent location is one of the most important variables in RTM mold design. The paper proposed an approach to optimize the gate locations. To minimize the maximum distance between gates and vent and treat the trapping volume as penalty, the optimization was conducted. Genetic algorithm (GA) was employed to carry out the optimization procedure to find the optimal gate and vent location. Numerical testing was performed with different shape molds. The case studies showed that the processing performance index is suitable, and the results illustrated that the proposed approach is efficient and effective.
2002, 19(4): 25-28.
Abstract:
The cold plasma technology is used to treat the surface of PET/epoxy. Based on the analysis of the modified surface of fiber by ESCA, the effects of treatment parameters on the properties of PET/epoxy composite are examined in terms of interlaminar shear strength and transverse tensile strength. The results show that cold plasma treatment can make polarity groups such as oxygen and nitrogen increase on the surface of PET/epoxy, which can improve PET/epoxy impregnation with the resin, and therefore the interfacial property of PET/epoxy composite is improved.
The cold plasma technology is used to treat the surface of PET/epoxy. Based on the analysis of the modified surface of fiber by ESCA, the effects of treatment parameters on the properties of PET/epoxy composite are examined in terms of interlaminar shear strength and transverse tensile strength. The results show that cold plasma treatment can make polarity groups such as oxygen and nitrogen increase on the surface of PET/epoxy, which can improve PET/epoxy impregnation with the resin, and therefore the interfacial property of PET/epoxy composite is improved.
2002, 19(4): 29-32.
Abstract:
In this paper, the electric and thermal performances of carbon fibers were described, and the energy transmission from carbon fibers is by means of heat radiation in the high temperature. Using the instant high temperature method, the sizing agent on the surface of carbon fibers was absolutely removed through the analysis and comparison of the untreated and treated carbon fibers under different conditions by XPS and SEM.
In this paper, the electric and thermal performances of carbon fibers were described, and the energy transmission from carbon fibers is by means of heat radiation in the high temperature. Using the instant high temperature method, the sizing agent on the surface of carbon fibers was absolutely removed through the analysis and comparison of the untreated and treated carbon fibers under different conditions by XPS and SEM.
2002, 19(4): 33-37.
Abstract:
Carbon fiber reinforced gelatin (C/Gel) biocomposites were prepared by solution and vapor cross-linked modes, respectively. The swelling behavior of the solution cross-linked CL/Gel and CS/Gel composites did not follow the Fick's law; instead, it could be described by a second-order rate equation. Neither the Fick's law nor the second-order rate equation could be used to describe the swelling kinetics of the vapor cross-linked CL/Gel composite that exhibited a lower swelling ratio in comparison to the solution cross-linked counterpart. The maximum swelling ratio (W∞) and swelling rate (K∞) for the solution cross-linked CL/Gel and CS/Gel composites were improved with the increase of fiber volume fraction, the latter showing lower W∞ and K∞ values at an identical fiber level. It is concluded that the fiber architecture and fiber content had an obvious effect on the swelling behavior of the C/Gel composites. The mechanisms governing the phenomena have been discussed in the present paper.
Carbon fiber reinforced gelatin (C/Gel) biocomposites were prepared by solution and vapor cross-linked modes, respectively. The swelling behavior of the solution cross-linked CL/Gel and CS/Gel composites did not follow the Fick's law; instead, it could be described by a second-order rate equation. Neither the Fick's law nor the second-order rate equation could be used to describe the swelling kinetics of the vapor cross-linked CL/Gel composite that exhibited a lower swelling ratio in comparison to the solution cross-linked counterpart. The maximum swelling ratio (W∞) and swelling rate (K∞) for the solution cross-linked CL/Gel and CS/Gel composites were improved with the increase of fiber volume fraction, the latter showing lower W∞ and K∞ values at an identical fiber level. It is concluded that the fiber architecture and fiber content had an obvious effect on the swelling behavior of the C/Gel composites. The mechanisms governing the phenomena have been discussed in the present paper.
2002, 19(4): 38-41.
Abstract:
The types of glass fiber mats and their configuration strongly affect the melt impregnation, void content, mechanical properties of GMT sheets, and the loft ratio of sheets during the preheating process. The configuration of the snitched continuous glass fiber mat is elastic structure, and that is good for melt impregnation and elimination of the air in the sheets. The experimental results show that the snitched continuous glass fiber mat is an ideal reinforcement for GMT sheets, and it has higher permeability over the chopped and complex glass fiber mat. The sheets reinforced by the snitched continuous glass fiber mat have lower void content, and their mechanical properties are balanced.
The types of glass fiber mats and their configuration strongly affect the melt impregnation, void content, mechanical properties of GMT sheets, and the loft ratio of sheets during the preheating process. The configuration of the snitched continuous glass fiber mat is elastic structure, and that is good for melt impregnation and elimination of the air in the sheets. The experimental results show that the snitched continuous glass fiber mat is an ideal reinforcement for GMT sheets, and it has higher permeability over the chopped and complex glass fiber mat. The sheets reinforced by the snitched continuous glass fiber mat have lower void content, and their mechanical properties are balanced.
2002, 19(4): 42-45.
Abstract:
Interface structure and high temperature creep property of the SiC/ZA27 composite have been investigated by means of TEM and HREM. The results show that there are an amorphous layer of 20nm thick and polygonal shaped precipitates on the interface between SiC particles and the ZA27 matrix. SiC particles could enhance the high temperature property of the composite remarkably.
Interface structure and high temperature creep property of the SiC/ZA27 composite have been investigated by means of TEM and HREM. The results show that there are an amorphous layer of 20nm thick and polygonal shaped precipitates on the interface between SiC particles and the ZA27 matrix. SiC particles could enhance the high temperature property of the composite remarkably.
2002, 19(4): 46-50.
Abstract:
The microstructure characteristics of interface in δ-Al2O3 short fiber reinforced Al-5.5Mg alloy composite at different temperatures were observed by TEM. In the meantime, based on the single fiber model of the short fiber reinforced metal matrix composite, the thermal residual stress states of interface were calculated by an elasto-plastic finite element method. The effects of the interfacial thermal residual stress on the mechanical behavior of interface at various temperatures were also discussed. At last, the effects of varied microstructure features and thermal residual stress states of interface on the whole mechanical behavior of the composite were analyzed. It is shown that the microstructure features and thermal residual stress states of interface change with the variation of ambient temperatures, which then results in the different mechanical behavior of the composite.
The microstructure characteristics of interface in δ-Al2O3 short fiber reinforced Al-5.5Mg alloy composite at different temperatures were observed by TEM. In the meantime, based on the single fiber model of the short fiber reinforced metal matrix composite, the thermal residual stress states of interface were calculated by an elasto-plastic finite element method. The effects of the interfacial thermal residual stress on the mechanical behavior of interface at various temperatures were also discussed. At last, the effects of varied microstructure features and thermal residual stress states of interface on the whole mechanical behavior of the composite were analyzed. It is shown that the microstructure features and thermal residual stress states of interface change with the variation of ambient temperatures, which then results in the different mechanical behavior of the composite.
2002, 19(4): 51-55.
Abstract:
The effects of the reinforcing particle size and strain rate on deformation localization behavior of SiCP/6151Al composites are investigated by making use of Split Hopkinson Bar and MTS-810 Materials Testing System with specially-designed hat-shaped specimens, which can produce a shear loading in the specimen. The experimental results demonstrate that the strengthening effect for the small-size particle-reinforced composite is higher than that for the large-size particle-reinforced composite. However, the small-size particle-reinforced composite is more prone to deformation localization than the large-particle composite under impact loading. The mechanisms leading to deformation localization in particle reinforced metal matrix composites are discussed in this paper as well.
The effects of the reinforcing particle size and strain rate on deformation localization behavior of SiCP/6151Al composites are investigated by making use of Split Hopkinson Bar and MTS-810 Materials Testing System with specially-designed hat-shaped specimens, which can produce a shear loading in the specimen. The experimental results demonstrate that the strengthening effect for the small-size particle-reinforced composite is higher than that for the large-size particle-reinforced composite. However, the small-size particle-reinforced composite is more prone to deformation localization than the large-particle composite under impact loading. The mechanisms leading to deformation localization in particle reinforced metal matrix composites are discussed in this paper as well.
2002, 19(4): 56-60.
Abstract:
The effects of B/TiO2 mole rates on XD(Exothermic Dispersion) reaction and mechanical properties of Al-TiO2-B system were studied in this paper. The test results show that with the increase of B/TiO2 mole rate from 0 to 2, the distribution of Al2O3 particles was improved and the amount of Al3Ti phase decreased and finally disappeared, the ultimate strength of the composites increased from 224.5MPa to 354.5MPa and its elongation from 3.2% to 5.8%; the actual combustion temperature and combustion velocity decreased, however, the density of combustion products increased.
The effects of B/TiO2 mole rates on XD(Exothermic Dispersion) reaction and mechanical properties of Al-TiO2-B system were studied in this paper. The test results show that with the increase of B/TiO2 mole rate from 0 to 2, the distribution of Al2O3 particles was improved and the amount of Al3Ti phase decreased and finally disappeared, the ultimate strength of the composites increased from 224.5MPa to 354.5MPa and its elongation from 3.2% to 5.8%; the actual combustion temperature and combustion velocity decreased, however, the density of combustion products increased.
2002, 19(4): 61-68.
Abstract:
Based on the most updated and authorized thermodynamic data, the reactions between SiC and Al2O3 have be studied using the equilibrium theory of chemical reactions. The partial pressure of each gaseous product of the reactions is quantitatively analyzed by taking into accounts the carbon activity in SiC and unit and reduced activities of solid reaction products. The chemical stability of SiC-Al2O3 interface under an inert ambient of 1 atmosphere has been judged. The criterion used in the judgement is that the total pressure of all gaseous products is over 1 atmosphere. The quantitative results are provided as reliable references for materials research.
Based on the most updated and authorized thermodynamic data, the reactions between SiC and Al2O3 have be studied using the equilibrium theory of chemical reactions. The partial pressure of each gaseous product of the reactions is quantitatively analyzed by taking into accounts the carbon activity in SiC and unit and reduced activities of solid reaction products. The chemical stability of SiC-Al2O3 interface under an inert ambient of 1 atmosphere has been judged. The criterion used in the judgement is that the total pressure of all gaseous products is over 1 atmosphere. The quantitative results are provided as reliable references for materials research.
2002, 19(4): 69-75.
Abstract:
The structure of the two step rectangle 3D braided composites with five-direction and three-demension is truly described and analyzed. Three kinds of unit cells have been divided. According to the braiding movement rule, the axial yarns keep static in the axial direction and the braiding yarns run across along the diagonal direction at an angel of 45° with the preform surface to and fro in a proper order to bind up the axial yarns. Through surveying the cross section and the section cut longitudinally at a 45° angle with the preform surface of the composites, the true cross sections and the shapes of axial and braiding yarns are described clearly. Thereby, the volume of the deformations of axial yarns being flattened by the braiding yarns and the fiber volume fraction in the axial yarn are determined.
The structure of the two step rectangle 3D braided composites with five-direction and three-demension is truly described and analyzed. Three kinds of unit cells have been divided. According to the braiding movement rule, the axial yarns keep static in the axial direction and the braiding yarns run across along the diagonal direction at an angel of 45° with the preform surface to and fro in a proper order to bind up the axial yarns. Through surveying the cross section and the section cut longitudinally at a 45° angle with the preform surface of the composites, the true cross sections and the shapes of axial and braiding yarns are described clearly. Thereby, the volume of the deformations of axial yarns being flattened by the braiding yarns and the fiber volume fraction in the axial yarn are determined.
2002, 19(4): 76-80.
Abstract:
In this paper, the variation equation of the composite rectangular laminate plates subjected to uniformly distributed follower forces is deduced based on the variation principle of the quasi-natural frequency of the non-conservative system self-excited vibration. The basic equations of the finite element and the characteristic equations used to solve the critical loading and natural frequency are obtained. The critical loads are computed for composite rectangular plates bearing follower forces with various boundary conditions and different aspect ratios. It is concluded from the analysis that boundary conditions affect the dynamic stability and the buckling pattern of plates. The angle-ply directions of composite laminate plates have an influence on the buckling load.
In this paper, the variation equation of the composite rectangular laminate plates subjected to uniformly distributed follower forces is deduced based on the variation principle of the quasi-natural frequency of the non-conservative system self-excited vibration. The basic equations of the finite element and the characteristic equations used to solve the critical loading and natural frequency are obtained. The critical loads are computed for composite rectangular plates bearing follower forces with various boundary conditions and different aspect ratios. It is concluded from the analysis that boundary conditions affect the dynamic stability and the buckling pattern of plates. The angle-ply directions of composite laminate plates have an influence on the buckling load.
2002, 19(4): 81-85.
Abstract:
Based on the finite element analysis, the methods of design optimization and sensitivity analysis for the composite laminated plate structures with structural buckling stability as constraint or objective are studied. A dependence of critical buckling load sensitivity on the stress field and external loads is discussed in detail, and its different computational methods in the problems of the size, shape and stacking sequence optimizations are proposed. A design model for buckling stability optimization of the composite laminated plates is built, and the sequential linear programming (SLP) and sequential quadratic programming (SQP) are adopted to solve the optimization problem. The design model and solution methods proposed are available for complex structures with composite laminated plates and can also be combined with static, frequency and dynamic response optimization. The methods have been implemented in the software JIFEX for the finite element analysis and design optimization of general purpose structures. The numerical examples demonstrate the validation of the algorithm and program of the paper.
Based on the finite element analysis, the methods of design optimization and sensitivity analysis for the composite laminated plate structures with structural buckling stability as constraint or objective are studied. A dependence of critical buckling load sensitivity on the stress field and external loads is discussed in detail, and its different computational methods in the problems of the size, shape and stacking sequence optimizations are proposed. A design model for buckling stability optimization of the composite laminated plates is built, and the sequential linear programming (SLP) and sequential quadratic programming (SQP) are adopted to solve the optimization problem. The design model and solution methods proposed are available for complex structures with composite laminated plates and can also be combined with static, frequency and dynamic response optimization. The methods have been implemented in the software JIFEX for the finite element analysis and design optimization of general purpose structures. The numerical examples demonstrate the validation of the algorithm and program of the paper.
2002, 19(4): 86-91.
Abstract:
In this paper, an improved LCW-type refined higher-order, thick-laminated-shell theory is presented to analyze vibration of thick cylindrical shells. The new displacement model is developed, which is in the form of a cubic function of the thickness coordinate and is in the form of a quadric function. Using the boundary conditions, transverse shear forces of the upper and nether surfaces are zero, the above- mentioned displacement field is predigested and unknown quantities are reduced to seven. A finite element expression based on the above theory is suggested. The accuracy of the present theory is examined by applying it to a typical free vibration problem. The results are compared with analytic solutions of higher-order shear deformation theory by Soldatos and Lam. The present theory shows the deflections more accurately than those obtained from the previous works. In this paper, the variation of fundamental frequency parameter for a thick shell with the L/R ratio shows that, owing to including effects of normal stress and normal strain, the present theory is more adaptive to structures with small length-to-radius L/R ratios.
In this paper, an improved LCW-type refined higher-order, thick-laminated-shell theory is presented to analyze vibration of thick cylindrical shells. The new displacement model is developed, which is in the form of a cubic function of the thickness coordinate and is in the form of a quadric function. Using the boundary conditions, transverse shear forces of the upper and nether surfaces are zero, the above- mentioned displacement field is predigested and unknown quantities are reduced to seven. A finite element expression based on the above theory is suggested. The accuracy of the present theory is examined by applying it to a typical free vibration problem. The results are compared with analytic solutions of higher-order shear deformation theory by Soldatos and Lam. The present theory shows the deflections more accurately than those obtained from the previous works. In this paper, the variation of fundamental frequency parameter for a thick shell with the L/R ratio shows that, owing to including effects of normal stress and normal strain, the present theory is more adaptive to structures with small length-to-radius L/R ratios.
2002, 19(4): 92-95.
Abstract:
A critical external pressure calculation method of 3D 4-step braided composite shell is presented in this paper. Two test results of critical external pressure for this kind of cylindrical shell are given. Calculation results are well consistent with test results. The calculation method presented in this paper has been proved and can be used in the design of this kind of composite shell.
A critical external pressure calculation method of 3D 4-step braided composite shell is presented in this paper. Two test results of critical external pressure for this kind of cylindrical shell are given. Calculation results are well consistent with test results. The calculation method presented in this paper has been proved and can be used in the design of this kind of composite shell.
2002, 19(4): 96-100.
Abstract:
This paper studied the effect of silane coupling agents on the flexural properties and water resistance of HAC/PVA based macro defect free (MDF) composites. The chemical interaction between γ-methacryloxypropyl trimethoxy silane (A-174TM) and monocalcium aluminate (CaAl2O4) was also studied using x-ray photoelectron spectroscopy (XPS). The SiOH group in A-174TM reacted with M-OH group in the surface of CaAl2O4 to form M-O-Si- bond (M=Ca,Al) in a condensation reaction. A new Ca(2p3/2) signature at 347.65ev or Ca(2p1/2) signature at 350.85ev and a new Al(2p) signature at 73.90ev were associated with the formation of the new bond. Accordingly, the authors proposed the chemical reaction model of the silane cross-coupling agent at HAC/PVA interface and the mechanism of the silane cross coupling agent in increasing the strength and improving the water resistance of HAC/PVA based MDF composites.
This paper studied the effect of silane coupling agents on the flexural properties and water resistance of HAC/PVA based macro defect free (MDF) composites. The chemical interaction between γ-methacryloxypropyl trimethoxy silane (A-174TM) and monocalcium aluminate (CaAl2O4) was also studied using x-ray photoelectron spectroscopy (XPS). The SiOH group in A-174TM reacted with M-OH group in the surface of CaAl2O4 to form M-O-Si- bond (M=Ca,Al) in a condensation reaction. A new Ca(2p3/2) signature at 347.65ev or Ca(2p1/2) signature at 350.85ev and a new Al(2p) signature at 73.90ev were associated with the formation of the new bond. Accordingly, the authors proposed the chemical reaction model of the silane cross-coupling agent at HAC/PVA interface and the mechanism of the silane cross coupling agent in increasing the strength and improving the water resistance of HAC/PVA based MDF composites.
2002, 19(4): 101-105.
Abstract:
A novel bioabsorbable composite was prepared from chitin fiber reinforced PCL matrix, and the ARES was used to study the dynamic rheological behaviors of the composite melts. The increase of Cf obviously enhanced the complex modulus and complex viscosity. And when Cf was increased from 45% to 55%, the G* curve showed the obvious'yielding behavior' like the mechanical properties, that was to say, the G* had no variation with the change of frequency in a wide range. Moreover, the elasticity (G') was over that of viscidity, which might be contributed to the formation of the 'network of fiber particle', and might result in a disadvantage for processing. For the G '~G″ plots and η″~η',the reinforcement of fiber increased the elasticity, prolonged the mail relaxation time, and widened the relaxation spectrum of the melts.
A novel bioabsorbable composite was prepared from chitin fiber reinforced PCL matrix, and the ARES was used to study the dynamic rheological behaviors of the composite melts. The increase of Cf obviously enhanced the complex modulus and complex viscosity. And when Cf was increased from 45% to 55%, the G* curve showed the obvious'yielding behavior' like the mechanical properties, that was to say, the G* had no variation with the change of frequency in a wide range. Moreover, the elasticity (G') was over that of viscidity, which might be contributed to the formation of the 'network of fiber particle', and might result in a disadvantage for processing. For the G '~G″ plots and η″~η',the reinforcement of fiber increased the elasticity, prolonged the mail relaxation time, and widened the relaxation spectrum of the melts.
2002, 19(4): 106-113.
Abstract:
A piezoelectric cantilever subjected to a uniform loading or a voltage on the upper surface of the beam is studied. The density of the beam is considered to be of functionally gradient properties. By use of the inverse method or semi-inverse method, the stress functions and induction functions in the form of polynomials for the problem are found. Based on these functions the analytical solutions of the FGM cantilever are obtained. The uniform loading is applied axially and laterally on the upper surface or is a voltage. Finally, as particular cases, the solutions of a piezoelectric cantilever with constant body force as well as without body force are obtained.
A piezoelectric cantilever subjected to a uniform loading or a voltage on the upper surface of the beam is studied. The density of the beam is considered to be of functionally gradient properties. By use of the inverse method or semi-inverse method, the stress functions and induction functions in the form of polynomials for the problem are found. Based on these functions the analytical solutions of the FGM cantilever are obtained. The uniform loading is applied axially and laterally on the upper surface or is a voltage. Finally, as particular cases, the solutions of a piezoelectric cantilever with constant body force as well as without body force are obtained.
2002, 19(4): 114-117.
Abstract:
The microstructurebonding strengthwear resistance and hardness values of the WC/CuMnNi coating prepared on the surface of 45 steel by brazing have been investigated in this work with the aid of microscope SEM HRB-hardness determiningEPMA and X-ray diffraction.The experimental results show that the microstructure of the composite coating is homogeneous,and an intermetallic compound exists at the interface between the substrate and the coating,leading to a higher bonding strength;the wear resistance of the composite coating is superior to that of the 45 steel quenched from 840 ℃ and tempered at 180 ℃.
The microstructurebonding strengthwear resistance and hardness values of the WC/CuMnNi coating prepared on the surface of 45 steel by brazing have been investigated in this work with the aid of microscope SEM HRB-hardness determiningEPMA and X-ray diffraction.The experimental results show that the microstructure of the composite coating is homogeneous,and an intermetallic compound exists at the interface between the substrate and the coating,leading to a higher bonding strength;the wear resistance of the composite coating is superior to that of the 45 steel quenched from 840 ℃ and tempered at 180 ℃.
