2007 Vol. 24, No. 4
2007, 24(4): 1-7.
Abstract:
The polypropylene (PP) pre-foamed granules containing short fibers were fabricated by a combination process of the additives pre-mixing and the secondary extrusion, and then PP foamed composites hybrid-reinforced by short carbon fibers (SCF) and short glass fibers (SGF) were prepared via a post-foaming process in designed dies. The effects of the mass ratio of SCF to SGF under constant fibers loading, the interfacial properties between reinforcement fibers and resin, and the apparent density of foams on the foamed result and mechanical performances of PP foamed composites were investigated. The results indicate that the high temperature melt strength of PP is improved by co-addition of SGF and SCF, which results in the formation of PP foams with fine and closed cell structure. The strength and modulus of the foamed PP composites are improved by the hybrid reinforcing of SGF and SCF and are better than those of monolithic SGF or SCF reinforced foamed PP. When the total fibers mass fraction keeps 15% and the mass ratio of SGF to SCF is 1 ∶ 1, the flexural strength and compressive modulus of foamed PP composites are optimal, and peak values of impact toughness and compressive strength are obtained at the ratio of SGF to SCF as 3 ∶ 1. The apparent density of PP foamed composites influences significantly the impact toughness and compressive strength of PP foamed composites, increasing from 4.29kJ/m2 and 6.57MPa at 0.32g/cm3 to 17.87kJ/m2 and 20.57MPa at 0.45g/cm3, respectively.
The polypropylene (PP) pre-foamed granules containing short fibers were fabricated by a combination process of the additives pre-mixing and the secondary extrusion, and then PP foamed composites hybrid-reinforced by short carbon fibers (SCF) and short glass fibers (SGF) were prepared via a post-foaming process in designed dies. The effects of the mass ratio of SCF to SGF under constant fibers loading, the interfacial properties between reinforcement fibers and resin, and the apparent density of foams on the foamed result and mechanical performances of PP foamed composites were investigated. The results indicate that the high temperature melt strength of PP is improved by co-addition of SGF and SCF, which results in the formation of PP foams with fine and closed cell structure. The strength and modulus of the foamed PP composites are improved by the hybrid reinforcing of SGF and SCF and are better than those of monolithic SGF or SCF reinforced foamed PP. When the total fibers mass fraction keeps 15% and the mass ratio of SGF to SCF is 1 ∶ 1, the flexural strength and compressive modulus of foamed PP composites are optimal, and peak values of impact toughness and compressive strength are obtained at the ratio of SGF to SCF as 3 ∶ 1. The apparent density of PP foamed composites influences significantly the impact toughness and compressive strength of PP foamed composites, increasing from 4.29kJ/m2 and 6.57MPa at 0.32g/cm3 to 17.87kJ/m2 and 20.57MPa at 0.45g/cm3, respectively.
2007, 24(4): 8-12.
Abstract:
Epoxy resin was modified with liquid nitrile-butadiene rubber (LNBR), and unidirectional boron fiber/epoxy resin (Bf/epoxy) composites were fabricated with compression molding. Mechanical properties of the composites without and with 10% LNBR were tested. Failure modes of the unidirectional Bf/epoxy composites without and with 10% LNBR under tensile loads were studied by observing their macro- and micro-fracture surfaces. The results show that 10% LNBR increases the tensile strength, bending strength, interlaminar shear strength and elongation to fracture of the unidirectional Bf/epoxy composite by 18.42%, 13.39%, 28.45% and 43.40% , respectively, while there is a decrease of the tensile modulus and bending modulus. The failure mode is of a mixed fracture mode between cohesion failure and debonding failure on the fracture surface of the unidirectional Bf /epoxy composite with 10% LNBR.
Epoxy resin was modified with liquid nitrile-butadiene rubber (LNBR), and unidirectional boron fiber/epoxy resin (Bf/epoxy) composites were fabricated with compression molding. Mechanical properties of the composites without and with 10% LNBR were tested. Failure modes of the unidirectional Bf/epoxy composites without and with 10% LNBR under tensile loads were studied by observing their macro- and micro-fracture surfaces. The results show that 10% LNBR increases the tensile strength, bending strength, interlaminar shear strength and elongation to fracture of the unidirectional Bf/epoxy composite by 18.42%, 13.39%, 28.45% and 43.40% , respectively, while there is a decrease of the tensile modulus and bending modulus. The failure mode is of a mixed fracture mode between cohesion failure and debonding failure on the fracture surface of the unidirectional Bf /epoxy composite with 10% LNBR.
2007, 24(4): 13-21.
Abstract:
The electro-mechanical properties, relation of current and voltage, and electric resistance pre and post-exposed to an electric field of the epoxy-based composites containing N326, conductive, sprayed and N762 carbon black (CB), respectively, are experimentally studied. The influence of the CB content on the three properties mentioned above is also studied. The test results indicate that electro-mechanical properties, relation of current and voltage and electric resistance variation of the CB filled epoxy-based composites are impacted by the CB diameter and content. The composites containing sprayed CB with a diameter of 123nm in the range of 35%~52.5% by mass fraction have good electro-mechanical properties, linear relation between current and voltage, and no resistance variation post-exposed to an electric field. However, the composites containing conductive CB and N326 CB with the diameters of 33nm and 30nm, respectively, do not have obvious regularity in changing the electro-mechanical properties; the relation of current and voltage is nonlinear, and resistance of the composites post-exposed to an electric field decreases dramatically. The composites containing N762 CB with a diameter of 84nm and sprayed CB with a diameter of 123nm in the amount of 26.25% by mass fraction have regular electro-mechanical properties somewhat; the relation of current and voltage is nonlinear and the resistance of the composites post-exposed to an electric field decreases slightly. Furthermore, a DC circuit model based on the experimental research is proposed. The occurrence of electrical breakdown induces the dramatic decrease of electric resistance of the composites post-exposed to an electric field. Finally, the deformation of the epoxy resin layer between two CB particles is employed to interpret the electro-mechanical properties of the CB filled epoxy-based composites.
The electro-mechanical properties, relation of current and voltage, and electric resistance pre and post-exposed to an electric field of the epoxy-based composites containing N326, conductive, sprayed and N762 carbon black (CB), respectively, are experimentally studied. The influence of the CB content on the three properties mentioned above is also studied. The test results indicate that electro-mechanical properties, relation of current and voltage and electric resistance variation of the CB filled epoxy-based composites are impacted by the CB diameter and content. The composites containing sprayed CB with a diameter of 123nm in the range of 35%~52.5% by mass fraction have good electro-mechanical properties, linear relation between current and voltage, and no resistance variation post-exposed to an electric field. However, the composites containing conductive CB and N326 CB with the diameters of 33nm and 30nm, respectively, do not have obvious regularity in changing the electro-mechanical properties; the relation of current and voltage is nonlinear, and resistance of the composites post-exposed to an electric field decreases dramatically. The composites containing N762 CB with a diameter of 84nm and sprayed CB with a diameter of 123nm in the amount of 26.25% by mass fraction have regular electro-mechanical properties somewhat; the relation of current and voltage is nonlinear and the resistance of the composites post-exposed to an electric field decreases slightly. Furthermore, a DC circuit model based on the experimental research is proposed. The occurrence of electrical breakdown induces the dramatic decrease of electric resistance of the composites post-exposed to an electric field. Finally, the deformation of the epoxy resin layer between two CB particles is employed to interpret the electro-mechanical properties of the CB filled epoxy-based composites.
2007, 24(4): 22-28.
Abstract:
Based on the double well potential theory and Monte Carlo random simulation method, the special dielectric properties, namely the residual polarization and fast relaxation phenomena, of polymeric composites filled with nano-particles are simulated using the dipole system of different constitutions. It is shown that the dipole system can simulate different microscopic constitutions of dielectric materials, and its response to applied stimulus can characterize dielectric properties of materials, and the iteration time needed for the system to stabilize can represent the polarization relaxation velocity of dielectrics under the electrical field. This simulation method is simple and effective for material property research, and it may help developing new materials with special properties.
Based on the double well potential theory and Monte Carlo random simulation method, the special dielectric properties, namely the residual polarization and fast relaxation phenomena, of polymeric composites filled with nano-particles are simulated using the dipole system of different constitutions. It is shown that the dipole system can simulate different microscopic constitutions of dielectric materials, and its response to applied stimulus can characterize dielectric properties of materials, and the iteration time needed for the system to stabilize can represent the polarization relaxation velocity of dielectrics under the electrical field. This simulation method is simple and effective for material property research, and it may help developing new materials with special properties.
2007, 24(4): 29-33.
Abstract:
The magnetoelectric composites have important and potential applications in magnetic-electric energy conversion. It is important to study the magnetoelectric coupling properties at high frequency for their applications. In this paper, magnetoelectric laminate composites were prepared by combining 0-3 type magnetostrictive Terfenol-D (Tb0.30Dy0.70Fe2)/epoxy composite and PZT ceramic. The magnetostriction property of the Terfenol-D/epoxy composite was studied. The dependence of flux density, dielectric property and magnetoelectric effect on frequency and magnetic bias were investigated in detail. It is shown that the laminate composite possesses good dynamic magnetoelectric response with a wide frequency range. The magnetoelectric effect of the laminate composite varies evidently with magnetic bias and there exists an optimized magnetic bias. The magnetoelectric effect of the laminate composite achieves a maximum value of 21.2 V/cmOe at the optimized magnetic bias of 630 Oe and resonant frequency of 69.6kHz . These results were discussed in detail and the magnetoelectric coupling mechanism of the composite laminate was analyzed.
The magnetoelectric composites have important and potential applications in magnetic-electric energy conversion. It is important to study the magnetoelectric coupling properties at high frequency for their applications. In this paper, magnetoelectric laminate composites were prepared by combining 0-3 type magnetostrictive Terfenol-D (Tb0.30Dy0.70Fe2)/epoxy composite and PZT ceramic. The magnetostriction property of the Terfenol-D/epoxy composite was studied. The dependence of flux density, dielectric property and magnetoelectric effect on frequency and magnetic bias were investigated in detail. It is shown that the laminate composite possesses good dynamic magnetoelectric response with a wide frequency range. The magnetoelectric effect of the laminate composite varies evidently with magnetic bias and there exists an optimized magnetic bias. The magnetoelectric effect of the laminate composite achieves a maximum value of 21.2 V/cmOe at the optimized magnetic bias of 630 Oe and resonant frequency of 69.6kHz . These results were discussed in detail and the magnetoelectric coupling mechanism of the composite laminate was analyzed.
2007, 24(4): 34-39.
Abstract:
The 90° L-shape laminates under different conditions were prepared in the vacuum-bag process with the convex tool for unidirectional glass fabric/epoxy resin, and the state of the fiber compaction and defects at different positions were investigated. The experiments were designed to study the effects of the processing conditions on the defects. The results indicate that the redundant resin, void, thickness variation and fiber buckling are the main defect types in the L-shape laminates. In addition, the time of applying pressure, laminate dimension, type of lay-up and edge conditions have significant effects on the fiber compaction and the forming of defects. The mechanisms of the defects forming were analyzed. The thickness variation and the redundant resin are caused by shear flow, the fiber buckling results from axial compression, and entrapped air is the main source of void under the experiment conditions. The results provide important guidances for defects control and processing parameters optimizing in the hot press process.
The 90° L-shape laminates under different conditions were prepared in the vacuum-bag process with the convex tool for unidirectional glass fabric/epoxy resin, and the state of the fiber compaction and defects at different positions were investigated. The experiments were designed to study the effects of the processing conditions on the defects. The results indicate that the redundant resin, void, thickness variation and fiber buckling are the main defect types in the L-shape laminates. In addition, the time of applying pressure, laminate dimension, type of lay-up and edge conditions have significant effects on the fiber compaction and the forming of defects. The mechanisms of the defects forming were analyzed. The thickness variation and the redundant resin are caused by shear flow, the fiber buckling results from axial compression, and entrapped air is the main source of void under the experiment conditions. The results provide important guidances for defects control and processing parameters optimizing in the hot press process.
2007, 24(4): 40-45.
Abstract:
In the storage process, physical or chemical changes might happen for thermosetting resins, which have effects on the rheological characteristics of resin systems and influence the processability. By means of parallel plates the effects of storage time on rheological properties of resin systems were studied for several typical thermosetting resin systems used in the hot press process. The reasons for the change of rheological characteristics were investigated with differential scanning calorimetry, infrared spectrometry and gel permeation chromatography. The influence of storage time on the processing property of resin systems was analyzed using the fluidity. The results show that the storage characteristics of resin systems are determined by the curing reaction of the resin system and the storage characteristic of addition agents in resin system. These results provide some important experimental information to the estimation and optimization of hot press process parameters.
In the storage process, physical or chemical changes might happen for thermosetting resins, which have effects on the rheological characteristics of resin systems and influence the processability. By means of parallel plates the effects of storage time on rheological properties of resin systems were studied for several typical thermosetting resin systems used in the hot press process. The reasons for the change of rheological characteristics were investigated with differential scanning calorimetry, infrared spectrometry and gel permeation chromatography. The influence of storage time on the processing property of resin systems was analyzed using the fluidity. The results show that the storage characteristics of resin systems are determined by the curing reaction of the resin system and the storage characteristic of addition agents in resin system. These results provide some important experimental information to the estimation and optimization of hot press process parameters.
2007, 24(4): 46-50.
Abstract:
The size control equation of the thermal expansion mould was derived from the relative relation between the expansion pressure of the thermal expansion mould and the wall thickness of the composite thrust cylinder and the thickness of the preform used for fabricating the composite thrust cylinder. The thermal expansion mould was fabricated by an integrally casting method. The axial compressive experiment on the integrally fabricated thrust cylinder shows that the thrust cylinder has good mechanical properties and satisfies the design specification. Compared with traditional VARTM, the thermal expansion mould assisted RTM process improves the fiber volume fraction by squeezing the resin out through an inflated thermal expansion mould and improves the compactness of the composites by expansion pressure of the mould; therefore the mechanical properties of the composites were increased.
The size control equation of the thermal expansion mould was derived from the relative relation between the expansion pressure of the thermal expansion mould and the wall thickness of the composite thrust cylinder and the thickness of the preform used for fabricating the composite thrust cylinder. The thermal expansion mould was fabricated by an integrally casting method. The axial compressive experiment on the integrally fabricated thrust cylinder shows that the thrust cylinder has good mechanical properties and satisfies the design specification. Compared with traditional VARTM, the thermal expansion mould assisted RTM process improves the fiber volume fraction by squeezing the resin out through an inflated thermal expansion mould and improves the compactness of the composites by expansion pressure of the mould; therefore the mechanical properties of the composites were increased.
2007, 24(4): 51-57.
Abstract:
The toughness, strength and rigidity of composites can be improved simultaneously by filling plerosphere particles into PP. The effect mechanism for improving the mechanical properties of the polymer filled with plerospheres was studied using the energy dissipation theory. And the method of a in situ observation under the tensile test with SEM was adopted to analyze the dynamic energy dissipation process of the crack generation, propagation and termination in the plerosphere/PP composite. The results show that the particles trigger massive cracks effectively and absorb energy, however, duly terminate the cracks propagation to prevent the deadly crack, which leads to the toughening and strengthening of the polymer. The results of the in situ observation and analysis to the dynamic process supply an effective test evidence for the energy dissipation mechanism in the plerosphere/polymer composite.
The toughness, strength and rigidity of composites can be improved simultaneously by filling plerosphere particles into PP. The effect mechanism for improving the mechanical properties of the polymer filled with plerospheres was studied using the energy dissipation theory. And the method of a in situ observation under the tensile test with SEM was adopted to analyze the dynamic energy dissipation process of the crack generation, propagation and termination in the plerosphere/PP composite. The results show that the particles trigger massive cracks effectively and absorb energy, however, duly terminate the cracks propagation to prevent the deadly crack, which leads to the toughening and strengthening of the polymer. The results of the in situ observation and analysis to the dynamic process supply an effective test evidence for the energy dissipation mechanism in the plerosphere/polymer composite.
2007, 24(4): 58-62.
Abstract:
Under the COMPASS(condensed-phase optimized molecular potentials for atomistic simulation studies) force field, the molecular dynamics(MD) simulation was applied to on 1~3 generation amine-based and butanediamine-based graphite/dendrimers nano-size composite materials. The process of construction and the details of molecular dynamics simulation of the composite system were introduced. The stability and mechanism of six intercalation composites were studied with microcosmic figure and variational energy under the invariable NVT ensemble. The energy variety was analyzed by using the radial distribution function. The results indicate that the bulk of the dendrimer is small, the graphite layer is easy to bend and its systematic total energy is higher. This leads to the instability of the composite system. As a result, the 3G dendrimer is the most stable system.
Under the COMPASS(condensed-phase optimized molecular potentials for atomistic simulation studies) force field, the molecular dynamics(MD) simulation was applied to on 1~3 generation amine-based and butanediamine-based graphite/dendrimers nano-size composite materials. The process of construction and the details of molecular dynamics simulation of the composite system were introduced. The stability and mechanism of six intercalation composites were studied with microcosmic figure and variational energy under the invariable NVT ensemble. The energy variety was analyzed by using the radial distribution function. The results indicate that the bulk of the dendrimer is small, the graphite layer is easy to bend and its systematic total energy is higher. This leads to the instability of the composite system. As a result, the 3G dendrimer is the most stable system.
2007, 24(4): 63-66.
Abstract:
The natural graphite (C)-silver (Ag)/ polyurethane conductive composite films were prepared through in-situ incorporation of silver nanoparticles into the C/PU system by thermal treatment. The morphology of the composite films was characterized by scanning electron microscope (SEM) and transmission electron microscope (TEM). X-ray diffraction (XRD) measurement was performed to trace the silver reduction and aggregation process. The results indicate that the silver ions are reduced to silver atoms and form silver nanoparticles with diameters of about 10nm dispersed in the PU matrix during the thermal treatment process. Furthermore, due to the bridging effect of silver nanoparticles among the natural graphite particles, the introduction of silver nanoparticles matrix has significantly enhanced the conductivity of C/PU composite films.
The natural graphite (C)-silver (Ag)/ polyurethane conductive composite films were prepared through in-situ incorporation of silver nanoparticles into the C/PU system by thermal treatment. The morphology of the composite films was characterized by scanning electron microscope (SEM) and transmission electron microscope (TEM). X-ray diffraction (XRD) measurement was performed to trace the silver reduction and aggregation process. The results indicate that the silver ions are reduced to silver atoms and form silver nanoparticles with diameters of about 10nm dispersed in the PU matrix during the thermal treatment process. Furthermore, due to the bridging effect of silver nanoparticles among the natural graphite particles, the introduction of silver nanoparticles matrix has significantly enhanced the conductivity of C/PU composite films.
2007, 24(4): 67-70.
Abstract:
The core-shell Ag-Ga/polymethyl methacrylate nanoparticles were prepared by the emulsion polymerization method under ultrasonic irradiation in-situ without any initiators or metal reducer. HREM, EDS and XRD experiments were performed to characterize the nanoparticles. The results indicate that the nanocomposite particles possess a core-shell structure with diameters of 80~200nm, as well as excellent monodispersity. The phenomenon that the polymer forms the shell via layer-by-layer self-assembly is found. XRD proves the existence of Ag0.72Ga0.28 and the probability of new Ag-Ga alloy because of two unknown diffraction peaks.
The core-shell Ag-Ga/polymethyl methacrylate nanoparticles were prepared by the emulsion polymerization method under ultrasonic irradiation in-situ without any initiators or metal reducer. HREM, EDS and XRD experiments were performed to characterize the nanoparticles. The results indicate that the nanocomposite particles possess a core-shell structure with diameters of 80~200nm, as well as excellent monodispersity. The phenomenon that the polymer forms the shell via layer-by-layer self-assembly is found. XRD proves the existence of Ag0.72Ga0.28 and the probability of new Ag-Ga alloy because of two unknown diffraction peaks.
2007, 24(4): 71-75.
Abstract:
The Cu-Ag composite nanoparticles were prepared by a both gas and liquid phases stabilizing method. The structure and morphology and surface layer as well as oxidation resistance of the particles were studied using X-ray diffraction(XRD), high-resolution transmission electron microscopy(HRTEM), infrared spectrum analysis, chemical analysis, gas analysis, and differential thermal and thermogravimetry analysis. The results show that the particle size ranges from 20nm to 150nm. The surface of particles consists of a bi-layer including a terpineol(C10H18O) molecules layer and an oxide one; the bi-layer prevents the particles from further oxidation in air. The terpineol molecules are oxidized at about 220℃ in air. The Cu-Ag composite nanoparticles are violently oxidized at about 340℃ because the terpineol molecules of the surface of the particles are oxidized. At the temperature below 220℃, the oxidation resistance of the Cu-Ag composite nanoparticles prepared by the both gas and liquid phases stabilizing method is better than that by the gas phase stabilizing method.
The Cu-Ag composite nanoparticles were prepared by a both gas and liquid phases stabilizing method. The structure and morphology and surface layer as well as oxidation resistance of the particles were studied using X-ray diffraction(XRD), high-resolution transmission electron microscopy(HRTEM), infrared spectrum analysis, chemical analysis, gas analysis, and differential thermal and thermogravimetry analysis. The results show that the particle size ranges from 20nm to 150nm. The surface of particles consists of a bi-layer including a terpineol(C10H18O) molecules layer and an oxide one; the bi-layer prevents the particles from further oxidation in air. The terpineol molecules are oxidized at about 220℃ in air. The Cu-Ag composite nanoparticles are violently oxidized at about 340℃ because the terpineol molecules of the surface of the particles are oxidized. At the temperature below 220℃, the oxidation resistance of the Cu-Ag composite nanoparticles prepared by the both gas and liquid phases stabilizing method is better than that by the gas phase stabilizing method.
2007, 24(4): 76-81.
Abstract:
The composite powders, in which the nano-Al2O3 particles are dispersed on the micrometer copper particles, were prepared by the mechanical alloying(MA). The shapes and size distributions of the composite powders were improved by the spherical process. The nanometer Al2O3/Cu composites were individually fabricated by the hot pressing (HP) and spark plasma sintering (SPS). The properties of the sintered composites with Al2O3 mass fractions of 0%, 0.5%, 1.0% and 1.5% were investigated, including density, electric conductivity and bending strength. The microstructures of the composite powders and fractures of the sintered samples were analyzed by SEM and the element analysis of micro-area. The results show that the bending strength of the composites increases and then decreases while the electric conductivity varies randomly with the increase of Al2O3 mass fraction. The SPS is superior to the HP, comparing the density, bending strength and electric conductivity of the composites with the same Al2O3 mass fraction. The ductile fracture occurs under bending loading.
The composite powders, in which the nano-Al2O3 particles are dispersed on the micrometer copper particles, were prepared by the mechanical alloying(MA). The shapes and size distributions of the composite powders were improved by the spherical process. The nanometer Al2O3/Cu composites were individually fabricated by the hot pressing (HP) and spark plasma sintering (SPS). The properties of the sintered composites with Al2O3 mass fractions of 0%, 0.5%, 1.0% and 1.5% were investigated, including density, electric conductivity and bending strength. The microstructures of the composite powders and fractures of the sintered samples were analyzed by SEM and the element analysis of micro-area. The results show that the bending strength of the composites increases and then decreases while the electric conductivity varies randomly with the increase of Al2O3 mass fraction. The SPS is superior to the HP, comparing the density, bending strength and electric conductivity of the composites with the same Al2O3 mass fraction. The ductile fracture occurs under bending loading.
2007, 24(4): 82-87.
Abstract:
The monotonic tensile and uniaxial ratcheting behaviors of T6-treated SiCP/6061Al alloy composites were numerically simulated at 300℃ by using ABAQUS and employing a single-particulate cell model of the composites and 2-D axi-symmetrical 6-node element. In the simulation, a new unified visco-plastic constitutive model, which simulated the ratcheting of the material reasonably, was proposed to describe the time-dependent cyclic deformation behavior of the matrix. It is shown from the simulations that the finite element model proposed in this work simulates the uniaxial ratcheting of the composites and its time-dependence, and the simulations agree with the corresponding experiments well. It is also shown that the cyclic deformation of the composites is heterogeneous and complicated in meso-scale.
The monotonic tensile and uniaxial ratcheting behaviors of T6-treated SiCP/6061Al alloy composites were numerically simulated at 300℃ by using ABAQUS and employing a single-particulate cell model of the composites and 2-D axi-symmetrical 6-node element. In the simulation, a new unified visco-plastic constitutive model, which simulated the ratcheting of the material reasonably, was proposed to describe the time-dependent cyclic deformation behavior of the matrix. It is shown from the simulations that the finite element model proposed in this work simulates the uniaxial ratcheting of the composites and its time-dependence, and the simulations agree with the corresponding experiments well. It is also shown that the cyclic deformation of the composites is heterogeneous and complicated in meso-scale.
2007, 24(4): 88-94.
Abstract:
The carbon nanotube (CNT)/zinc composite film was prepared by the composite electrodeposition. It is remarkable that the zinc deposit on the surface of CNTs is very smooth and continuous, and no apparent interfacial defect is observed. In contrast to the currently known CNT/metal composites, such distinguished interfacial feature is rare. The SEM observation illustrates that, while the films deform, the optimum interface coupling permits debonding and sliding of the CNTs within the matrix. CNTs are pulled out of the matrix in the wake and stretched between crack faces. Although the debonding and sliding of CNTs in the matrix would weaken the interfacial cohesion, the residual sliding friction at the interface still contributes to the load transfer. When the crack grew wider, CNTs begin to deform and fracture completely. Moreover, the bridging nanotubes tend to align perpendicular to the crack direction, and these high strength tubes shear the matrix while they shift inside the composite. All these behaviors consume energy and contribute to the reinforcement. The average Vickers hardness of the CNT/zinc coating increased progressively from HV178.3 to HV493.5.
The carbon nanotube (CNT)/zinc composite film was prepared by the composite electrodeposition. It is remarkable that the zinc deposit on the surface of CNTs is very smooth and continuous, and no apparent interfacial defect is observed. In contrast to the currently known CNT/metal composites, such distinguished interfacial feature is rare. The SEM observation illustrates that, while the films deform, the optimum interface coupling permits debonding and sliding of the CNTs within the matrix. CNTs are pulled out of the matrix in the wake and stretched between crack faces. Although the debonding and sliding of CNTs in the matrix would weaken the interfacial cohesion, the residual sliding friction at the interface still contributes to the load transfer. When the crack grew wider, CNTs begin to deform and fracture completely. Moreover, the bridging nanotubes tend to align perpendicular to the crack direction, and these high strength tubes shear the matrix while they shift inside the composite. All these behaviors consume energy and contribute to the reinforcement. The average Vickers hardness of the CNT/zinc coating increased progressively from HV178.3 to HV493.5.
2007, 24(4): 95-100.
Abstract:
The reliability of 2D C/SiC composite was investigated by the methods of probability together with statistics, including the analysis of flexural strength, the comparison of calculated failure probabilities with experimental data and the prediction of reliabilities, hazard function and reliable strength. The linear regression analysis and the test of goodness of fit for 2D C/SiC composite indicate that the normal, logarithm normal and 3-parameter Weibull models can well characterize the flexural strength. The parameters in the mathematical models of failure probability function, reliability function, hazard rate function and reliable strength function of this composite were developed, so that the failure probability, reliability and hazard rate can be calculated in the case of a given flexural strength, and also the reliable strength can be calculated in the case of a given allowed reliability. The maximum relative error of median strength between models prediction and experiment is 0.07%, and the calculations of failure probability compare satisfactorily to experimental results.
The reliability of 2D C/SiC composite was investigated by the methods of probability together with statistics, including the analysis of flexural strength, the comparison of calculated failure probabilities with experimental data and the prediction of reliabilities, hazard function and reliable strength. The linear regression analysis and the test of goodness of fit for 2D C/SiC composite indicate that the normal, logarithm normal and 3-parameter Weibull models can well characterize the flexural strength. The parameters in the mathematical models of failure probability function, reliability function, hazard rate function and reliable strength function of this composite were developed, so that the failure probability, reliability and hazard rate can be calculated in the case of a given flexural strength, and also the reliable strength can be calculated in the case of a given allowed reliability. The maximum relative error of median strength between models prediction and experiment is 0.07%, and the calculations of failure probability compare satisfactorily to experimental results.
2007, 24(4): 101-105.
Abstract:
3D-braided carbon fiber reinforced silicon carbide ceramic matrix composites (3D C/SiC) were investigated on the environmental properties in various oxidizing atmosphere. The mass variation and the residual strength as a function of the temperature were determined. Based on the architecture and microstructure, the contributions of the constituents in 3D C/SiC to properties and its evolving were analyzed. The results show that the mass variation with temperature correlates well with the residual strength change with temperature. Therefore, the mass variation is more fundamental and reliable for material characterization in simulating environments than the residual strength.
3D-braided carbon fiber reinforced silicon carbide ceramic matrix composites (3D C/SiC) were investigated on the environmental properties in various oxidizing atmosphere. The mass variation and the residual strength as a function of the temperature were determined. Based on the architecture and microstructure, the contributions of the constituents in 3D C/SiC to properties and its evolving were analyzed. The results show that the mass variation with temperature correlates well with the residual strength change with temperature. Therefore, the mass variation is more fundamental and reliable for material characterization in simulating environments than the residual strength.
2007, 24(4): 106-111.
Abstract:
Measuring the components of carbon/carbon (C/C) composites is an effective way of performance analysis and processing optimization. In this study, a new self-adaptive algorithm of multi-object image segmentation was proposed based on the characteristic of the polarized light microscopic images of C/C composites with pure pyrocarbon fabricated by the chemistry vapor infiltration and the principle of pattern recognition. The optimal thresholds between pores, fibers and pyrocarbons were automatically computed using the improved Otsus method according to the rule of the maximal variance between-class. The experimental results show that the method is effective to separate C/C composites, no matter whether the proportion or the distribution of the components is high or low, massive or scattered. The segmentation quality is fit for the further measurement of C/C composites components.
Measuring the components of carbon/carbon (C/C) composites is an effective way of performance analysis and processing optimization. In this study, a new self-adaptive algorithm of multi-object image segmentation was proposed based on the characteristic of the polarized light microscopic images of C/C composites with pure pyrocarbon fabricated by the chemistry vapor infiltration and the principle of pattern recognition. The optimal thresholds between pores, fibers and pyrocarbons were automatically computed using the improved Otsus method according to the rule of the maximal variance between-class. The experimental results show that the method is effective to separate C/C composites, no matter whether the proportion or the distribution of the components is high or low, massive or scattered. The segmentation quality is fit for the further measurement of C/C composites components.
2007, 24(4): 112-117.
Abstract:
The friction and wear properties of carbon/carbon (C/C) composites with a rough laminar (RL) matrix carbon at various braking velocities were tested by using the MM-1000 laboratory scale dynamometer. The microstructures and morphologies of the worn surfaces were investigated by using micro-Raman spectroscopy and SEM respectively. The results are as follows. The C/C composite with an RL matrix carbon possesses excellent friction-velocity characteristics. The effects of braking velocity on the friction coefficient can be attributed to that on the temperature elevation of the worn surface as well as the thickness and continuity of the friction film. At 5 m/s braking velocity, the friction coefficient is low due to the absorption of hydrosphere and no continuous friction film formed; the friction coefficient reaches the peak at 10 m/s due to the desorption of hydrosphere and multi-layer thick friction film formed. With the increase of braking velocity, the thickness of the friction film decreased, resulting in the drop of friction coefficient wear rate values. When the braking velocity is above 25m/s, the temperature elevation of the worn surfaces results in the increase of mass loss by oxidation and linear wear losses, and the friction coefficient also slightly declines (0.3).
The friction and wear properties of carbon/carbon (C/C) composites with a rough laminar (RL) matrix carbon at various braking velocities were tested by using the MM-1000 laboratory scale dynamometer. The microstructures and morphologies of the worn surfaces were investigated by using micro-Raman spectroscopy and SEM respectively. The results are as follows. The C/C composite with an RL matrix carbon possesses excellent friction-velocity characteristics. The effects of braking velocity on the friction coefficient can be attributed to that on the temperature elevation of the worn surface as well as the thickness and continuity of the friction film. At 5 m/s braking velocity, the friction coefficient is low due to the absorption of hydrosphere and no continuous friction film formed; the friction coefficient reaches the peak at 10 m/s due to the desorption of hydrosphere and multi-layer thick friction film formed. With the increase of braking velocity, the thickness of the friction film decreased, resulting in the drop of friction coefficient wear rate values. When the braking velocity is above 25m/s, the temperature elevation of the worn surfaces results in the increase of mass loss by oxidation and linear wear losses, and the friction coefficient also slightly declines (0.3).
2007, 24(4): 118-122.
Abstract:
Based on the carbon fiber reinforced paper type friction material prepared by our laboratory, the influences of curing pressure on the friction materials, including porosity, dynamic friction coefficient, static/dynamic friction coefficient ratio and friction torque, were studied. The results show that the porosities of samples decrease with the increasing curing pressure; dynamic friction coefficients of samples decrease at different curing pressures with increasing the braking pressure, while the influence on the static/dynamic coefficient ratios is somewhat complex: with increasing the braking pressure, the static/dynamic coefficient ratios of the samples cured at relatively lower pressures tend to rise slightly, as the static/dynamic coefficient ratios of the samples cured at higher pressures tend to decline; there arises a slight cock at the end of the friction torques gradually. 3.4MPa is the proper curing pressure for the carbon fiber reinforced paper based friction material with fixed component, taking all of the influences shown above into account.
Based on the carbon fiber reinforced paper type friction material prepared by our laboratory, the influences of curing pressure on the friction materials, including porosity, dynamic friction coefficient, static/dynamic friction coefficient ratio and friction torque, were studied. The results show that the porosities of samples decrease with the increasing curing pressure; dynamic friction coefficients of samples decrease at different curing pressures with increasing the braking pressure, while the influence on the static/dynamic coefficient ratios is somewhat complex: with increasing the braking pressure, the static/dynamic coefficient ratios of the samples cured at relatively lower pressures tend to rise slightly, as the static/dynamic coefficient ratios of the samples cured at higher pressures tend to decline; there arises a slight cock at the end of the friction torques gradually. 3.4MPa is the proper curing pressure for the carbon fiber reinforced paper based friction material with fixed component, taking all of the influences shown above into account.
2007, 24(4): 123-127.
Abstract:
The suppositions of the cross-section shape of yarns, especially weft yarns, in composite materials are different when predicting mechanical properties of three dimensional woven reinforced composite materials. The roundness, raceway, convex and rectangle shapes were assumed as the cross-section of weft yarns while the rectangle shape was assumed as the cross-section of warp yarns. In this paper, the elastic modulus was predicted for four different angle-interlock structural composite materials using the stiffness averaging method and the iso-strain mechanical model. Contrasting with digital photos of the composite materials and with experimental results of the elastic modulus, the result shows that the roundness assumption of weft yarn cross-sections is far inaccurate and the predicting result of elastic modulus under the condition of the roundness assumption is much smaller. There is little difference in the predicting results of elastic modulus between raceway, convex and rectangle cross-sections of the weft yarn assumptions and the predicting results are in better agreement with the experiment results of the elastic modulus.
The suppositions of the cross-section shape of yarns, especially weft yarns, in composite materials are different when predicting mechanical properties of three dimensional woven reinforced composite materials. The roundness, raceway, convex and rectangle shapes were assumed as the cross-section of weft yarns while the rectangle shape was assumed as the cross-section of warp yarns. In this paper, the elastic modulus was predicted for four different angle-interlock structural composite materials using the stiffness averaging method and the iso-strain mechanical model. Contrasting with digital photos of the composite materials and with experimental results of the elastic modulus, the result shows that the roundness assumption of weft yarn cross-sections is far inaccurate and the predicting result of elastic modulus under the condition of the roundness assumption is much smaller. There is little difference in the predicting results of elastic modulus between raceway, convex and rectangle cross-sections of the weft yarn assumptions and the predicting results are in better agreement with the experiment results of the elastic modulus.
Experimental analysis on the yarns section of three-dimensional five-directional braided composites
2007, 24(4): 128-132.
Abstract:
A series of cross-section images of three-dimensional (3D) five-directional braided composites were captured by the charge-coupled device (CCD) microscope, and then the yarns arrangements and their section patterns were discussed. The experimental results show that the yarns arrangements are different in the different cross-sections of 3D five-directional braided composites, and they are changing periodically. The braiding yarns section looks like a flat convex lens approximately. The axial yarns are almost straightened, but their sections are changing from fanlike shape to triangle shape alternately along their axes. The surface yarns arrangements are related to the interior yarns pattern, and their sections are near to the elliptical shape.
A series of cross-section images of three-dimensional (3D) five-directional braided composites were captured by the charge-coupled device (CCD) microscope, and then the yarns arrangements and their section patterns were discussed. The experimental results show that the yarns arrangements are different in the different cross-sections of 3D five-directional braided composites, and they are changing periodically. The braiding yarns section looks like a flat convex lens approximately. The axial yarns are almost straightened, but their sections are changing from fanlike shape to triangle shape alternately along their axes. The surface yarns arrangements are related to the interior yarns pattern, and their sections are near to the elliptical shape.
2007, 24(4): 133-139.
Abstract:
The mechanical properties of three-dimensional and four-directional braided composites were investigated by macroscopic compressive experiments. The experimental results show that the mechanical properties and compressive failure mechanism of the composites change with the increase of the braided angles. When the braided angle is small, the material behaves as the brittle characteristics. But if the braided angle is larger than a critical angle, the stress-stain curve of the specimen approaches nonlinear, behaving mostly as the characteristics of plastic failure. The acoustic emission data can reveal the damage evolution during the compressive testing.
The mechanical properties of three-dimensional and four-directional braided composites were investigated by macroscopic compressive experiments. The experimental results show that the mechanical properties and compressive failure mechanism of the composites change with the increase of the braided angles. When the braided angle is small, the material behaves as the brittle characteristics. But if the braided angle is larger than a critical angle, the stress-stain curve of the specimen approaches nonlinear, behaving mostly as the characteristics of plastic failure. The acoustic emission data can reveal the damage evolution during the compressive testing.
2007, 24(4): 140-144.
Abstract:
An expression was derived for the pyroelectric coefficient of ferroelectric ceramic-ferroelectric polymer 0-3/1-3 composites; the influence of ceramic volume fraction v2 and the ratio of ceramic grain size to film thickness(G/t) on the pyroelectric coefficient(pc) and pc/ε c of ferroelectric composites is discussed. The results show that when G/t≥0.5, at different ceramic volume fractions v2, the pyroelectric coefficient tends to become constant. This means that the influence of G/t on the pyroelectric coefficient is neglectable. When ceramic volume fraction v2=0.1 and G/t increases, pc/εc will reach its maximum. When G/t=0.9, pc/εc of ferroelectric composites is 8 times larger than that of pure PZT ceramics. v2=0.1 and G/t=0.9 were the best technological condition. Additionally, theoretical curves and experimental data fit each other at low ceramic volume fractions and low G/t.
An expression was derived for the pyroelectric coefficient of ferroelectric ceramic-ferroelectric polymer 0-3/1-3 composites; the influence of ceramic volume fraction v2 and the ratio of ceramic grain size to film thickness(G/t) on the pyroelectric coefficient(pc) and pc/ε c of ferroelectric composites is discussed. The results show that when G/t≥0.5, at different ceramic volume fractions v2, the pyroelectric coefficient tends to become constant. This means that the influence of G/t on the pyroelectric coefficient is neglectable. When ceramic volume fraction v2=0.1 and G/t increases, pc/εc will reach its maximum. When G/t=0.9, pc/εc of ferroelectric composites is 8 times larger than that of pure PZT ceramics. v2=0.1 and G/t=0.9 were the best technological condition. Additionally, theoretical curves and experimental data fit each other at low ceramic volume fractions and low G/t.
2007, 24(4): 145-153.
Abstract:
The Voronoi cell finite element method (VCFEM) was adopted to replace the classical displacement based finite element method in numerical simulation of the equivalent mechanical property of heterogeneous materials. The parametric variational principle and quadratic programming method were coupled with the VCFEM for the analysis of the two-dimensional heterogeneous problem. Finite element formulations were derived and a standard quadratic programming model was deduced from the problem. The influence of the microscopic inclusion on the overall mechanical response of heterogeneous materials was studied. The mechanical properties of heterogeneous materials depend mostly on the size, shape and distribution of the material phases of the microstructure. Some numerical examples were presented and compared with ANSYS, and the results demonstrate the validity and effectiveness of the method developed.
The Voronoi cell finite element method (VCFEM) was adopted to replace the classical displacement based finite element method in numerical simulation of the equivalent mechanical property of heterogeneous materials. The parametric variational principle and quadratic programming method were coupled with the VCFEM for the analysis of the two-dimensional heterogeneous problem. Finite element formulations were derived and a standard quadratic programming model was deduced from the problem. The influence of the microscopic inclusion on the overall mechanical response of heterogeneous materials was studied. The mechanical properties of heterogeneous materials depend mostly on the size, shape and distribution of the material phases of the microstructure. Some numerical examples were presented and compared with ANSYS, and the results demonstrate the validity and effectiveness of the method developed.
2007, 24(4): 154-160.
Abstract:
Advanced composite grids structures (AGS) have found many applications in the aerospace structure engineering. A load reconstruction method was investigated to estimate low velocity impact load on an AGS plate by the authors. In the part, an approximate method was presented to calculate transverse low velocity impact responses on an AGS plate. Considering the rib section eccentricity e and stretch blending coupling effect, an AGS plate equivalent stiffness model was improved. Based on the improved model and the unsymmetrical Mindlin plate theory, an AGS forward response approximate model was built with state-space equations. Fourier series expansion was utilized to solve the dynamic equations. The practicability of the presented method in this part was examined by numerical experiments and good results were obtained. The study would provide a theoretical basis for the load reconstruction on AGS plate Ⅱ : Inverse solver.
Advanced composite grids structures (AGS) have found many applications in the aerospace structure engineering. A load reconstruction method was investigated to estimate low velocity impact load on an AGS plate by the authors. In the part, an approximate method was presented to calculate transverse low velocity impact responses on an AGS plate. Considering the rib section eccentricity e and stretch blending coupling effect, an AGS plate equivalent stiffness model was improved. Based on the improved model and the unsymmetrical Mindlin plate theory, an AGS forward response approximate model was built with state-space equations. Fourier series expansion was utilized to solve the dynamic equations. The practicability of the presented method in this part was examined by numerical experiments and good results were obtained. The study would provide a theoretical basis for the load reconstruction on AGS plate Ⅱ : Inverse solver.
2007, 24(4): 161-165.
Abstract:
Based on the first-order shear deformation theory of the composite laminated plate, an FEA model and the method of free vibration analysis for the composite laminates with multiple through-width delaminations were developed, and a linearity contact model was established to simulate the interaction between upper and lower sub-laminates along the delaminated region during the vibration process. The effects of the location and numbers of delamination, and boundary condition of the laminates on the vibration characteristic were discussed. From some typical examples, the results show that, with the variation of delamination location along the length direction, the influence of inner delaminations on frequencies is greater than that of the surface delaminations, but both variation trends are approximate. With the delaminations nearer to the middle plane along the thickness direction, the influence is more severe. When the delaminations are near to the surface and the edges constraints of the laminates are weak, the vibration analysis for the multiple delaminations case can be simplified into that for the one delamination case.
Based on the first-order shear deformation theory of the composite laminated plate, an FEA model and the method of free vibration analysis for the composite laminates with multiple through-width delaminations were developed, and a linearity contact model was established to simulate the interaction between upper and lower sub-laminates along the delaminated region during the vibration process. The effects of the location and numbers of delamination, and boundary condition of the laminates on the vibration characteristic were discussed. From some typical examples, the results show that, with the variation of delamination location along the length direction, the influence of inner delaminations on frequencies is greater than that of the surface delaminations, but both variation trends are approximate. With the delaminations nearer to the middle plane along the thickness direction, the influence is more severe. When the delaminations are near to the surface and the edges constraints of the laminates are weak, the vibration analysis for the multiple delaminations case can be simplified into that for the one delamination case.
2007, 24(4): 166-171.
Abstract:
The non-woven ultrathin fibers film with a thickness about 0.1mm was made by use of electrospinning. This film was incorporated into the middle interface of a composite laminate, which was cured and cut into double cantilever beam (DCB) specimens. Blank DCB specimens were prepared in the same way. The mode Ⅰ interlaminar fracture toughness was measured according to ASTM D5528 standard. The experimental results show that the mode Ⅰ critical strain energy release rate is improved about 35% by using the non-woven film compared to the blank specimens. The propagation of cracks for those two kinds of specimens is analyzed by use of the FE method. It shows that the numerical results are well in agreement with the experimental results and a better understanding of the fracture mechanics is obtained by the numerical analysis.
The non-woven ultrathin fibers film with a thickness about 0.1mm was made by use of electrospinning. This film was incorporated into the middle interface of a composite laminate, which was cured and cut into double cantilever beam (DCB) specimens. Blank DCB specimens were prepared in the same way. The mode Ⅰ interlaminar fracture toughness was measured according to ASTM D5528 standard. The experimental results show that the mode Ⅰ critical strain energy release rate is improved about 35% by using the non-woven film compared to the blank specimens. The propagation of cracks for those two kinds of specimens is analyzed by use of the FE method. It shows that the numerical results are well in agreement with the experimental results and a better understanding of the fracture mechanics is obtained by the numerical analysis.
2007, 24(4): 172-177.
Abstract:
On the basis of the first order shear deformation theory, a nonlinear finite element analysis method has been developed to study the thermal buckling behavior of delaminated advanced composite grid plates. The temperature dependent thermal and mechanical properties of the composite were considered and a constrained model was established to ensure deformation compatibility between sub-laminates in the front of the delamination. Comparing the thermal critical temperature and buckling modes of the bare and single direction stiffened laminates with those of advanced grid stiffened laminates (AGS), the result shows that the advanced grid composite laminates possess stronger thermal bucking resistance; however thermal critical temperature values are reduced and the corresponding buckling modes are also changed with increasing the delamination area. The methods and conclusions provided have the reference value for composite structure designers in load capacity prediction and damage tolerance design of AGS.
On the basis of the first order shear deformation theory, a nonlinear finite element analysis method has been developed to study the thermal buckling behavior of delaminated advanced composite grid plates. The temperature dependent thermal and mechanical properties of the composite were considered and a constrained model was established to ensure deformation compatibility between sub-laminates in the front of the delamination. Comparing the thermal critical temperature and buckling modes of the bare and single direction stiffened laminates with those of advanced grid stiffened laminates (AGS), the result shows that the advanced grid composite laminates possess stronger thermal bucking resistance; however thermal critical temperature values are reduced and the corresponding buckling modes are also changed with increasing the delamination area. The methods and conclusions provided have the reference value for composite structure designers in load capacity prediction and damage tolerance design of AGS.
2007, 24(4): 178-184.
Abstract:
The strain concentration tensor for the inclusions in a two-phase composite is derived from the strain field integral equation based on the concept of the so called strain Green tensor. In contrast with the traditional Mori- Tanaka (MT) strain concentration tensor derived with the dilute method, such a strain concentration tensor includes a term related to the volume fraction and distribution of inclusions, whereby a modified Mori-Tanaka method considering the doubly periodic microstructural characteristics is developed. The traditional MT method has proven to be quite accurate in predicting the effective moduli of fiber reinforced composites with the hexagonal array of cylindrical fibers; however, it can not represent square symmetric effective properties of composites with a square array of fibers. The present method gets rid of such a drawback, and provides compact expressions for the effective stiffness and compliance tensors with the same self-consistency as the traditional MT method. A comparison with finite element calculations demonstrates the efficiency and accuracy of the present method.
The strain concentration tensor for the inclusions in a two-phase composite is derived from the strain field integral equation based on the concept of the so called strain Green tensor. In contrast with the traditional Mori- Tanaka (MT) strain concentration tensor derived with the dilute method, such a strain concentration tensor includes a term related to the volume fraction and distribution of inclusions, whereby a modified Mori-Tanaka method considering the doubly periodic microstructural characteristics is developed. The traditional MT method has proven to be quite accurate in predicting the effective moduli of fiber reinforced composites with the hexagonal array of cylindrical fibers; however, it can not represent square symmetric effective properties of composites with a square array of fibers. The present method gets rid of such a drawback, and provides compact expressions for the effective stiffness and compliance tensors with the same self-consistency as the traditional MT method. A comparison with finite element calculations demonstrates the efficiency and accuracy of the present method.
2007, 24(4): 185-192.
Abstract:
The free and forced vibration of the large deformation composite plate embedded with shape memory alloy (SMA) fibers was investigated. Based on the thermo-mechanical constitutive equation of SMA proposed by Brinson, the constitutive relationships for evaluation of the properties of a hybrid SMA composite ply were obtained following the rule of mixtures. And based on the nonlinear theory of symmetrically laminated anisotropic plates, the governing equations of flexural vibration in terms of displacement and stress functions were derived. The Galerkin method was used to reduce the original partial differential equation into a nonlinear ordinary differential equation, which was then solved by the harmonic balance method. The numerical results show that the relationship between nonlinear natural frequency ratio and temperature for the composite plate has similar characteristics to those of the linear one, and the effects of temperature on forced response behavior during phase transformation from martensite to austenite are significant. The effects of the volume fraction of the SMA fiber, aspect ratio and free vibration amplitude on the dynamical behavior of the plate were also discussed.
The free and forced vibration of the large deformation composite plate embedded with shape memory alloy (SMA) fibers was investigated. Based on the thermo-mechanical constitutive equation of SMA proposed by Brinson, the constitutive relationships for evaluation of the properties of a hybrid SMA composite ply were obtained following the rule of mixtures. And based on the nonlinear theory of symmetrically laminated anisotropic plates, the governing equations of flexural vibration in terms of displacement and stress functions were derived. The Galerkin method was used to reduce the original partial differential equation into a nonlinear ordinary differential equation, which was then solved by the harmonic balance method. The numerical results show that the relationship between nonlinear natural frequency ratio and temperature for the composite plate has similar characteristics to those of the linear one, and the effects of temperature on forced response behavior during phase transformation from martensite to austenite are significant. The effects of the volume fraction of the SMA fiber, aspect ratio and free vibration amplitude on the dynamical behavior of the plate were also discussed.
