A comprehensive dynamic model for thermal buckling,elastic vibration and transient response analysis of rotating nanocomposite porous metal-matrix microbeams reinforced with graphene nanoplatelets(GNPs)under a uniform...A comprehensive dynamic model for thermal buckling,elastic vibration and transient response analysis of rotating nanocomposite porous metal-matrix microbeams reinforced with graphene nanoplatelets(GNPs)under a uniform thermal gradient is proposed.Various pore distribution patterns are considered together with different GNPs dispersion rules according to the specific functions.The extended rule of mixture and Halpin-Tsai micromechanics model are employed to evaluate the effective material properties of the nanocomposites.Based on the modified couple stress theory and the improved third-order shear deformation theory,the dynamic equations of the rotating microbeam are established by the Lagrange’s equation.The Chebyshev-based Galerkin method is adopted to discretize these equations,which are then solved by the complex modal analysis and Runge-Kutta-Merson method.Convergence study and comparisons with previous literature are conducted for validation of the present method.A parametric study performed analyzes the effects of angular velocity,thickness-to-length scale parameter ratio,porosity coefficient,weight fraction and geometry of GNPs together with distribution patterns of GNPs and pore on the critical buckling temperature rise,fundamental frequency and time-dependent response of the rotating nanocomposite microbeams.The results reveal significant effects of these parameters on the relevant mechanical behaviors,some of which are even contrary to expectations.Therefore,it is necessary to further study this kind of rotating nanocomposite structures for the optimal design.展开更多
This paper is devoted to investigate the flutter and thermal buckling properties of the functionally graded piezoelectric material(FGPM)plate in supersonic airflow,and the active flutter control is carried out under d...This paper is devoted to investigate the flutter and thermal buckling properties of the functionally graded piezoelectric material(FGPM)plate in supersonic airflow,and the active flutter control is carried out under different temperature fields.The piezoelectric material component of the FGPM plate has gradient changes along the thickness,such as piezoelectricity and dielectric coefficients.The supersonic piston theory is used to evaluate the aerodynamic pressure.Based on the first-order shear deformation theory and Hamilton’s principle with the assumed mode method,the equation of motion of the structural system is deduced.The effect of aerodynamic pressure on the frequency and damping ratio of the FGPM plate is analyzed.Moreover,the flutter and thermal buckling properties of the FGPM and pure metal plates are compared to show the superior aerothermoelastic properties of the FGPM plates.The influences of volume fraction exponent and temperature on the flutter and thermal buckling properties of the FGPM plate are also examined in detail.The LQR controller is adopted to achieve active flutter control.The simulation results show that the present control method can largely improve dynamic stability of the FGPM plate in supersonic airflow and high-temperature environment.展开更多
This paper analyzes the nonlocal thermal buckling and postbuckling behaviors of a multi-layered graphene nanoplatelet(GPL)reinforced piezoelectric micro-plate.The GPLs are supposed to disperse as a gradient pattern in...This paper analyzes the nonlocal thermal buckling and postbuckling behaviors of a multi-layered graphene nanoplatelet(GPL)reinforced piezoelectric micro-plate.The GPLs are supposed to disperse as a gradient pattern in the composite micro-plate along its thickness.The effective material properties are calculated by the Halpin-Tsai parallel model and mixture rule for the functionally graded GPL reinforced piezoelectric(FG-GRP)micro-plate.Governing equations for the nonlocal thermal buckling and postbuckling behaviors of the FG-GRP micro-plate are obtained by the first-order shear deformation theory,the von Kármán nonlinear theory,and the minimum potential energy principle.The differential quadrature(DQ)method and iterative method are introduced to numerically analyze the effects of the external electric voltage,the distribution pattern and characteristic of GPLs,and the nonlocal parameter on the critical buckling behaviors and postbuckling equilibrium path of the FG-GRP micro-plate in thermal environment.展开更多
In this paper, the governing differential equations of elastic stability problems in thermopiezoelectric media are deduced. The solutions of the thermal buckling problems for piezoelectric laminated plates are present...In this paper, the governing differential equations of elastic stability problems in thermopiezoelectric media are deduced. The solutions of the thermal buckling problems for piezoelectric laminated plates are presented in the context of the mathematical theory of elasticity. Owing to the complexity of the eigenvalue problem involved, the critical temperature values of thermal buckling must be solved numerically. The numerical results for piezoelectric/non-piezoelectric laminated plates are presented and the influence of piezoelectricity upon thermal buckling temperature is discussed.展开更多
Truss-core sandwich plates have received much attention in virtue of the high values of strength-to-weight and stiffness-to-weight as well as the great ability of impulseresistance recently. It is necessary to study t...Truss-core sandwich plates have received much attention in virtue of the high values of strength-to-weight and stiffness-to-weight as well as the great ability of impulseresistance recently. It is necessary to study the stability of sandwich panels under the influence of the thermal load. However, the sandwich plates are such complex threedimensional （3D） systems that direct analytical solutions do not exist, and the finite element method （FEM） cannot represent the relationship between structural parameters and mechanical properties well. In this paper, an equivalent homogeneous continuous plate is ideMized by obtaining the effective bending and transverse shear stiffness based on the characteristics of periodically distributed unit cells. The first order shear deformation theory for plates is used to derive the stability equation. The buckling temperature of a simply supported sandwich plate is given and verified by the FEM. The effect of related parameters on mechanical properties is investigated. The geometric parameters of the unit cell are optimized to attain the maximum buckling temperature. It is shown that the optimized sandwich plate can improve the resistance to thermal buckling significantly.展开更多
The nonlinear thermal buckling of symmetrically laminated cylindrically orthotropic shallow spherical shell under temperature field and uniform pressure including transverse shear is studied. Also the analytic formula...The nonlinear thermal buckling of symmetrically laminated cylindrically orthotropic shallow spherical shell under temperature field and uniform pressure including transverse shear is studied. Also the analytic formulas for determining the critical buckling loads under different temperature fields are obtained by using the modified iteration method. The effect of transverse shear deformation and different temperature fields on critical buckling load is discussed.展开更多
In this work,a computational modelling and analysis framework is developed to investigate the thermal buckling behavior of doubly-curved composite shells reinforced with graphene-origami(G-Ori)auxetic metamaterials.A ...In this work,a computational modelling and analysis framework is developed to investigate the thermal buckling behavior of doubly-curved composite shells reinforced with graphene-origami(G-Ori)auxetic metamaterials.A semi-analytical formulation based on the First-Order Shear Deformation Theory(FSDT)and the principle of virtual displacements is established,and closed-form solutions are derived via Navier’s method for simply supported boundary conditions.The G-Ori metamaterial reinforcements are treated as programmable constructs whose effective thermo-mechanical properties are obtained via micromechanical homogenization and incorporated into the shell model.A comprehensive parametric study examines the influence of folding geometry,dispersion arrangement,reinforcement weight fraction,curvature parameters,and elastic foundation support on the critical buckling temperature(CBT).The results reveal that,under optimal folding geometry and reinforcement alignment with principal stress trajectories,the CBT can increase by more than 150%.Furthermore,the combined effect of G-Ori reinforcement and elastic foundation substantially enhances thermal buckling resistance.These findings establish design guidelines for architected composite shells in applications such as aerospace thermal skins,morphing structures,and thermally-responsive systems,and illustrate the potential of auxetic graphene metamaterials for multifunctional,lightweight,and thermally robust structural components.展开更多
This investigation aims to analyze thermal buckling and post-buckling behavior of functionally graded graphene nanoplateletreinforced composite(FG-GPLRC)beams.The beams are classified into two types of ideal and non-i...This investigation aims to analyze thermal buckling and post-buckling behavior of functionally graded graphene nanoplateletreinforced composite(FG-GPLRC)beams.The beams are classified into two types of ideal and non-ideal FG-GPLRC beams in which the ideal beams have smooth profiles of material distributions and another beams have layer-wise distributions of materials.The material profiles of the ideal beams are utilized as the controlling tracks for producing the material distributions of the non-ideal beams via a layer-to-layer integration technique.This technique confirms that the overall weight fraction of the materials is the same for both types of beams.The proposed models can be used to determine the material properties of the beams for further investigation on thermal buckling and post-buckling of the beams.Third-order shear deformation theory is employed to construct the energy equations of the problems,and then they are solved by the implementation of the Jacobi-Ritz method cooperating with the direct iteration procedure and Newton-Raphson technique.From our investigation,it can be disclosed that when non-ideal beams are created using ideal beams parabolic profile,the results differ significantly.However,the differences between the results of ideal and non-ideal beams can be eliminated by adding more layers.展开更多
In this paper,the thermal buckling behavior of composite laminated plates under a uniform temperature distribution is studied.A finite element of four nodes and 32 degrees of freedom(DOF),the bending and mechanical pr...In this paper,the thermal buckling behavior of composite laminated plates under a uniform temperature distribution is studied.A finite element of four nodes and 32 degrees of freedom(DOF),the bending and mechanical previously developed for buckling of laminated composite plates,is extended to investigate the thermal buckling behavior of laminated composite plates.Based upon the classical plate theory,the present finite element is a combination of a linear isoparametric membrane element and a high precision rectangular Hermitian element.The numerical implementation of the present finite element allowed the comparison of the numerical obtained results with results obtained from the literature:1)with element of the same order,2)the first order shear defo^ation theory,3)the high order shear deformation theory and 4)the three-dimensional solution.It was found that the obtained results were very close to the reference results and the proposed element offers a good convergence speed.Furthermore,a parametrical study was also conducted to investigate the effect of the anisotropy of composite materials on the critical buckling temperature of laminated plates.The study showed that:1)the critical buckling temperature generally decreases with the increasing of the modulus ratio EL/ET and thermal expansion ratio aT/aL,and 2)the boundary conditions and the orientation angles signifi-cantly affect the critical buckling temperature of laminated plates.展开更多
In this study,the thermodynamic behaviors of the intrinsic frequency and buckling temperature of rectangular plates of functionally graded materials(FGMs)are explored based on the modified couple stress theory(MCST)an...In this study,the thermodynamic behaviors of the intrinsic frequency and buckling temperature of rectangular plates of functionally graded materials(FGMs)are explored based on the modified couple stress theory(MCST)and the novel dual powerlaw scale distribution theory.The effects of linear,homogeneous,and non-homogeneous temperature fields on the frequency and buckling temperature of FGM microplates are evaluated in detail.The results show that the porosity greatly affects the mechanical properties of FGM plates,reducing their frequency and flexural temperature compared with non-porous plates.Different temperature profiles alter plate frequencies and buckling temperatures.The presence and pattern of scale effect parameters are also shown to be crucial for the mechanical response of FGM plates.The present research aims to provide precise guidelines for the micro-electro-mechanical system(MEMS)fabrication by elucidating the complex interplay between thermal,material,and structural factors that affect the performance of FGM plates in advanced applications.展开更多
This paper elucidates the interactive buckling behaviors of an inflated envelope under coupled mechanical and thermal loads, especially the longitudinal wrinkling bifurcation and hoop ovalization buckling. The longitu...This paper elucidates the interactive buckling behaviors of an inflated envelope under coupled mechanical and thermal loads, especially the longitudinal wrinkling bifurcation and hoop ovalization buckling. The longitudinal bending buckling process of the inflated envelope can be divided into three continuous stages, which are global buckling, interactive global-local buckling, and kink. A variety of hoop ovalization buckling modes are observed under coupled mechanical-thermal load. Unlike the mechanical case, thermal load leads to a hoop negative ovalization buckling. In addition, it can accelerate the longitudinal coupled bifurcation and resist the hoop coupled ovalization buckling. Moreover, the bending resistance of the inflated envelope will be improved when the length of the structure is increased, resulting in the difficulty of it to become wrinkled. These results provide a new insight into the buckling behaviors of an inflated envelope under coupled external loads, and give a reference for the design of the inflated envelope.展开更多
Analysis of thermal post-buckling of FGM （Functionally Graded Material） Timoshenko beams subjected to transversely non-uniform temperature rise is presented. By accurately considering the axial extension and transve...Analysis of thermal post-buckling of FGM （Functionally Graded Material） Timoshenko beams subjected to transversely non-uniform temperature rise is presented. By accurately considering the axial extension and transverse shear deformation in the sense of theory of Timoshenko beam, geometrical nonlinear governing equations including seven basic unknown functions for functionally graded beams subjected to mechanical and thermal loads were formulated. In the analysis, it was assumed that the material properties of the beam vary continuously as a power function of the thickness coordinate. By using a shooting method, the obtained nonlinear boundary value problem was numerically solved and thermal buckling and post-buckling response of transversely nonuniformly heated FGM Timoshenko beams with fixed-fixed edges were obtained. Characteristic curves of the buckling deformation of the beam varying with thermal load and the power law index are plotted. The effects of material gradient property on the buckling deformation and critical temperature of beam were discussed in details. The results show that there exists the tension-bend coupling deformation in the uniformly heated beam because of the transversely non-uniform characteristic of materials.展开更多
Sandwich piezoelectric semiconductor(PS)structures have significant applications in multi-functional semiconductor devices.The analysis of multi-field coupling behaviors of PS structures is of fundamental importance i...Sandwich piezoelectric semiconductor(PS)structures have significant applications in multi-functional semiconductor devices.The analysis of multi-field coupling behaviors of PS structures is of fundamental importance in developing novel PS devices.In this paper,we develop a general temperature-deformation-polarization-carrier(TDPC)coupling model for sandwich-type PS beams involving pyroelectricity under thermal loadings,based on three-dimensional(3D)basic equations of the thermo-piezoelectric semiconductor(TPS).We derive analytical solutions for extensional,bending,and buckling deformations of simply-supported sandwich n-type PS beams subjected to open-circuit and electrically isolated boundary conditions.The accuracy of the proposed model in this paper is verified through finite element simulations implemented in the COMSOL software.Numerical results show that the initial electron concentration and the thickness ratio of the PS layer to the beam's total thickness have a significant effect on thermally induced extensional and bending responses,as well as critical buckling mechanical and thermal loadings.This study provides a theoretical framework and guidance for designing semiconductor devices based on sandwich PS beam structures.展开更多
Free vibration of statically thermal postbuckled functionally graded material （FGM） beams with surface-bonded piezoelectric layers subject to both temperature rise and voltage is studied. By accurately considering t...Free vibration of statically thermal postbuckled functionally graded material （FGM） beams with surface-bonded piezoelectric layers subject to both temperature rise and voltage is studied. By accurately considering the axial extension and based on the Euler-Bernoulli beam theory, geometrically nonlinear dynamic governing equations for FGM beams with surface-bonded piezoelectric layers subject to thermo-electro- mechanical loadings are formulated. It is assumed that the material properties of the middle FGM layer vary continuously as a power law function of the thickness coordinate, and the piezoelectric layers are isotropic and homogenous. By assuming that the amplitude of the beam vibration is small and its response is harmonic, the above mentioned non-linear partial differential equations are reduced to two sets of coupled ordinary differential equations. One is for the postbuckling, and the other is for the linear vibration of the beam superimposed upon the postbuckled configuration. Using a shooting method to solve the two sets of ordinary differential equations with fixed-fixed boundary conditions numerically, the response of postbuckling and free vibration in the vicinity of the postbuckled configuration of the beam with fixed-fixed ends and subject to transversely nonuniform heating and uniform electric field is obtained. Thermo-electric postbuckling equilibrium paths and characteristic curves of the first three natural frequencies versus the temperature, the electricity, and the material gradient parameters are plotted. It is found that the three lowest frequencies of the prebuckled beam decrease with the increase of the temperature, but those of a buckled beam increase monotonically with the temperature rise. The results also show that the tensional force produced in the piezoelectric layers by the voltage can efficiently increase the critical buckling temperature and the natural frequency.展开更多
In the present work,thermo-electro-mechanical buckling behavior of functionally graded piezoelectric(FGP)nanobeams is investi-gated based on higher-order shear deformation beam theory.The FGP nanobeam is subjected to ...In the present work,thermo-electro-mechanical buckling behavior of functionally graded piezoelectric(FGP)nanobeams is investi-gated based on higher-order shear deformation beam theory.The FGP nanobeam is subjected to four types of thermal loading including uniform,linear,and sinusoidal temperature rise as well as heat conduction through the beam thickness.Thermo-electro-mechanical properties of FGP nanobeam are supposed to change continuously in the thickness direction based on power-law model.To consider the influences of small-scale sizes,Eringen’s nonlocal elasticity theory is adopted.Applying Hamilton’s princi-ple,the nonlocal governing equations of an FGP nanobeam in thermal environments are obtained and are solved using Navier-type analytical solution.The significance of various parameters,such as thermal loadings,external electric voltage,power-law index,nonlocal parameter,and slenderness ratio on thermal buck-ling response of size-dependent FGP nanobeams is investigated.展开更多
This work presents a theoretical study for thermo-mechanical buckling of size-dependent magneto-electro-thermo-elastic func-tionally graded(METE-FG)nanoplates in thermal environments based on a refined trigonometric p...This work presents a theoretical study for thermo-mechanical buckling of size-dependent magneto-electro-thermo-elastic func-tionally graded(METE-FG)nanoplates in thermal environments based on a refined trigonometric plate theory.Temperature field has uniform,linear,and nonlinear distributions across the thick-ness.Nonlinear thermal loadings are considered as heat conduc-tion(HC)and sinusoidal temperature rise(STR).A power law function is applied to govern the gradation of material properties through the nanoplate thickness.Considering coupling impacts between magneto,electro,thermo-mechanical loadings,the equa-tions of motion,and distribution of magneto-electrical field across the thickness direction of the METE-FG nanoplate are derived.The exact solutions for critical buckling temperatures of METE-FG nanoplates are introduced implementing Navier’s method.Moreover,the accuracy of the present formulation is examined by comparing the obtained results with published ones.Furthermore,the effects played by the magneto-electrical field,various temperature rises,nonlocality,power law index,side-to-thickness ratio,and aspect ratio on the critical buckling tempera-ture response are all investigated and reported.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.12232012,11872031)the Postgraduate Research&Practice Innovation Program of Jiangsu Province(Grant No.SJCX24_1292)the Outstanding Scientific and Technological Innovation Team in Colleges and Universities of Jiangsu Province.
文摘A comprehensive dynamic model for thermal buckling,elastic vibration and transient response analysis of rotating nanocomposite porous metal-matrix microbeams reinforced with graphene nanoplatelets(GNPs)under a uniform thermal gradient is proposed.Various pore distribution patterns are considered together with different GNPs dispersion rules according to the specific functions.The extended rule of mixture and Halpin-Tsai micromechanics model are employed to evaluate the effective material properties of the nanocomposites.Based on the modified couple stress theory and the improved third-order shear deformation theory,the dynamic equations of the rotating microbeam are established by the Lagrange’s equation.The Chebyshev-based Galerkin method is adopted to discretize these equations,which are then solved by the complex modal analysis and Runge-Kutta-Merson method.Convergence study and comparisons with previous literature are conducted for validation of the present method.A parametric study performed analyzes the effects of angular velocity,thickness-to-length scale parameter ratio,porosity coefficient,weight fraction and geometry of GNPs together with distribution patterns of GNPs and pore on the critical buckling temperature rise,fundamental frequency and time-dependent response of the rotating nanocomposite microbeams.The results reveal significant effects of these parameters on the relevant mechanical behaviors,some of which are even contrary to expectations.Therefore,it is necessary to further study this kind of rotating nanocomposite structures for the optimal design.
基金supported by the National Natural Science Foundation of China(Nos.11502159 and 11761131006)the Fundamental Research Funds for the Central Universities.
文摘This paper is devoted to investigate the flutter and thermal buckling properties of the functionally graded piezoelectric material(FGPM)plate in supersonic airflow,and the active flutter control is carried out under different temperature fields.The piezoelectric material component of the FGPM plate has gradient changes along the thickness,such as piezoelectricity and dielectric coefficients.The supersonic piston theory is used to evaluate the aerodynamic pressure.Based on the first-order shear deformation theory and Hamilton’s principle with the assumed mode method,the equation of motion of the structural system is deduced.The effect of aerodynamic pressure on the frequency and damping ratio of the FGPM plate is analyzed.Moreover,the flutter and thermal buckling properties of the FGPM and pure metal plates are compared to show the superior aerothermoelastic properties of the FGPM plates.The influences of volume fraction exponent and temperature on the flutter and thermal buckling properties of the FGPM plate are also examined in detail.The LQR controller is adopted to achieve active flutter control.The simulation results show that the present control method can largely improve dynamic stability of the FGPM plate in supersonic airflow and high-temperature environment.
基金Project supported by the National Natural Science Foundation of China(Nos.11802005,12172012,11832002,and 11427801)the General Program of Science and Technology Development Project of Beijing Municipal Education Commission of China(No.KM201910005035)
文摘This paper analyzes the nonlocal thermal buckling and postbuckling behaviors of a multi-layered graphene nanoplatelet(GPL)reinforced piezoelectric micro-plate.The GPLs are supposed to disperse as a gradient pattern in the composite micro-plate along its thickness.The effective material properties are calculated by the Halpin-Tsai parallel model and mixture rule for the functionally graded GPL reinforced piezoelectric(FG-GRP)micro-plate.Governing equations for the nonlocal thermal buckling and postbuckling behaviors of the FG-GRP micro-plate are obtained by the first-order shear deformation theory,the von Kármán nonlinear theory,and the minimum potential energy principle.The differential quadrature(DQ)method and iterative method are introduced to numerically analyze the effects of the external electric voltage,the distribution pattern and characteristic of GPLs,and the nonlocal parameter on the critical buckling behaviors and postbuckling equilibrium path of the FG-GRP micro-plate in thermal environment.
文摘In this paper, the governing differential equations of elastic stability problems in thermopiezoelectric media are deduced. The solutions of the thermal buckling problems for piezoelectric laminated plates are presented in the context of the mathematical theory of elasticity. Owing to the complexity of the eigenvalue problem involved, the critical temperature values of thermal buckling must be solved numerically. The numerical results for piezoelectric/non-piezoelectric laminated plates are presented and the influence of piezoelectricity upon thermal buckling temperature is discussed.
基金Project supported by the National Natural Science Foundation of China(No.91116008)
文摘Truss-core sandwich plates have received much attention in virtue of the high values of strength-to-weight and stiffness-to-weight as well as the great ability of impulseresistance recently. It is necessary to study the stability of sandwich panels under the influence of the thermal load. However, the sandwich plates are such complex threedimensional （3D） systems that direct analytical solutions do not exist, and the finite element method （FEM） cannot represent the relationship between structural parameters and mechanical properties well. In this paper, an equivalent homogeneous continuous plate is ideMized by obtaining the effective bending and transverse shear stiffness based on the characteristics of periodically distributed unit cells. The first order shear deformation theory for plates is used to derive the stability equation. The buckling temperature of a simply supported sandwich plate is given and verified by the FEM. The effect of related parameters on mechanical properties is investigated. The geometric parameters of the unit cell are optimized to attain the maximum buckling temperature. It is shown that the optimized sandwich plate can improve the resistance to thermal buckling significantly.
基金the National Natural Science Foundation of China(No.10572054)
文摘The nonlinear thermal buckling of symmetrically laminated cylindrically orthotropic shallow spherical shell under temperature field and uniform pressure including transverse shear is studied. Also the analytic formulas for determining the critical buckling loads under different temperature fields are obtained by using the modified iteration method. The effect of transverse shear deformation and different temperature fields on critical buckling load is discussed.
文摘In this work,a computational modelling and analysis framework is developed to investigate the thermal buckling behavior of doubly-curved composite shells reinforced with graphene-origami(G-Ori)auxetic metamaterials.A semi-analytical formulation based on the First-Order Shear Deformation Theory(FSDT)and the principle of virtual displacements is established,and closed-form solutions are derived via Navier’s method for simply supported boundary conditions.The G-Ori metamaterial reinforcements are treated as programmable constructs whose effective thermo-mechanical properties are obtained via micromechanical homogenization and incorporated into the shell model.A comprehensive parametric study examines the influence of folding geometry,dispersion arrangement,reinforcement weight fraction,curvature parameters,and elastic foundation support on the critical buckling temperature(CBT).The results reveal that,under optimal folding geometry and reinforcement alignment with principal stress trajectories,the CBT can increase by more than 150%.Furthermore,the combined effect of G-Ori reinforcement and elastic foundation substantially enhances thermal buckling resistance.These findings establish design guidelines for architected composite shells in applications such as aerospace thermal skins,morphing structures,and thermally-responsive systems,and illustrate the potential of auxetic graphene metamaterials for multifunctional,lightweight,and thermally robust structural components.
基金supported by the Thailand Science Research and Innovation Fund(Grant No.FRB660041/0227).
文摘This investigation aims to analyze thermal buckling and post-buckling behavior of functionally graded graphene nanoplateletreinforced composite(FG-GPLRC)beams.The beams are classified into two types of ideal and non-ideal FG-GPLRC beams in which the ideal beams have smooth profiles of material distributions and another beams have layer-wise distributions of materials.The material profiles of the ideal beams are utilized as the controlling tracks for producing the material distributions of the non-ideal beams via a layer-to-layer integration technique.This technique confirms that the overall weight fraction of the materials is the same for both types of beams.The proposed models can be used to determine the material properties of the beams for further investigation on thermal buckling and post-buckling of the beams.Third-order shear deformation theory is employed to construct the energy equations of the problems,and then they are solved by the implementation of the Jacobi-Ritz method cooperating with the direct iteration procedure and Newton-Raphson technique.From our investigation,it can be disclosed that when non-ideal beams are created using ideal beams parabolic profile,the results differ significantly.However,the differences between the results of ideal and non-ideal beams can be eliminated by adding more layers.
文摘In this paper,the thermal buckling behavior of composite laminated plates under a uniform temperature distribution is studied.A finite element of four nodes and 32 degrees of freedom(DOF),the bending and mechanical previously developed for buckling of laminated composite plates,is extended to investigate the thermal buckling behavior of laminated composite plates.Based upon the classical plate theory,the present finite element is a combination of a linear isoparametric membrane element and a high precision rectangular Hermitian element.The numerical implementation of the present finite element allowed the comparison of the numerical obtained results with results obtained from the literature:1)with element of the same order,2)the first order shear defo^ation theory,3)the high order shear deformation theory and 4)the three-dimensional solution.It was found that the obtained results were very close to the reference results and the proposed element offers a good convergence speed.Furthermore,a parametrical study was also conducted to investigate the effect of the anisotropy of composite materials on the critical buckling temperature of laminated plates.The study showed that:1)the critical buckling temperature generally decreases with the increasing of the modulus ratio EL/ET and thermal expansion ratio aT/aL,and 2)the boundary conditions and the orientation angles signifi-cantly affect the critical buckling temperature of laminated plates.
基金Project supported by the National Key Research and Development Program of China(No.2022YFB3207100)Hubei Provincial Strategic Scientist Training Plan(No.2022EJD009)the Fundamental Research Funds for the Central Universities of China(No.2042023kf1041)。
文摘In this study,the thermodynamic behaviors of the intrinsic frequency and buckling temperature of rectangular plates of functionally graded materials(FGMs)are explored based on the modified couple stress theory(MCST)and the novel dual powerlaw scale distribution theory.The effects of linear,homogeneous,and non-homogeneous temperature fields on the frequency and buckling temperature of FGM microplates are evaluated in detail.The results show that the porosity greatly affects the mechanical properties of FGM plates,reducing their frequency and flexural temperature compared with non-porous plates.Different temperature profiles alter plate frequencies and buckling temperatures.The presence and pattern of scale effect parameters are also shown to be crucial for the mechanical response of FGM plates.The present research aims to provide precise guidelines for the micro-electro-mechanical system(MEMS)fabrication by elucidating the complex interplay between thermal,material,and structural factors that affect the performance of FGM plates in advanced applications.
基金supported by the National Natural Science Foundation of China (Grants 11172079, 11572099)the Program for New Century Excellent Talents in Harbin Institute of Technology (Grant NCET-11-0807)+1 种基金the Natural Science Foundation of Heilongjiang Province of China (A2015002)the Fundamental Research Funds for the Central Universities (Grant HIT.BRETⅢ.201209)
文摘This paper elucidates the interactive buckling behaviors of an inflated envelope under coupled mechanical and thermal loads, especially the longitudinal wrinkling bifurcation and hoop ovalization buckling. The longitudinal bending buckling process of the inflated envelope can be divided into three continuous stages, which are global buckling, interactive global-local buckling, and kink. A variety of hoop ovalization buckling modes are observed under coupled mechanical-thermal load. Unlike the mechanical case, thermal load leads to a hoop negative ovalization buckling. In addition, it can accelerate the longitudinal coupled bifurcation and resist the hoop coupled ovalization buckling. Moreover, the bending resistance of the inflated envelope will be improved when the length of the structure is increased, resulting in the difficulty of it to become wrinkled. These results provide a new insight into the buckling behaviors of an inflated envelope under coupled external loads, and give a reference for the design of the inflated envelope.
基金Project supported by the National Natural Science Foundation of China (No.10472039)
文摘Analysis of thermal post-buckling of FGM （Functionally Graded Material） Timoshenko beams subjected to transversely non-uniform temperature rise is presented. By accurately considering the axial extension and transverse shear deformation in the sense of theory of Timoshenko beam, geometrical nonlinear governing equations including seven basic unknown functions for functionally graded beams subjected to mechanical and thermal loads were formulated. In the analysis, it was assumed that the material properties of the beam vary continuously as a power function of the thickness coordinate. By using a shooting method, the obtained nonlinear boundary value problem was numerically solved and thermal buckling and post-buckling response of transversely nonuniformly heated FGM Timoshenko beams with fixed-fixed edges were obtained. Characteristic curves of the buckling deformation of the beam varying with thermal load and the power law index are plotted. The effects of material gradient property on the buckling deformation and critical temperature of beam were discussed in details. The results show that there exists the tension-bend coupling deformation in the uniformly heated beam because of the transversely non-uniform characteristic of materials.
基金Project supported by the National Natural Science Foundation of China(No.11672265)。
文摘Sandwich piezoelectric semiconductor(PS)structures have significant applications in multi-functional semiconductor devices.The analysis of multi-field coupling behaviors of PS structures is of fundamental importance in developing novel PS devices.In this paper,we develop a general temperature-deformation-polarization-carrier(TDPC)coupling model for sandwich-type PS beams involving pyroelectricity under thermal loadings,based on three-dimensional(3D)basic equations of the thermo-piezoelectric semiconductor(TPS).We derive analytical solutions for extensional,bending,and buckling deformations of simply-supported sandwich n-type PS beams subjected to open-circuit and electrically isolated boundary conditions.The accuracy of the proposed model in this paper is verified through finite element simulations implemented in the COMSOL software.Numerical results show that the initial electron concentration and the thickness ratio of the PS layer to the beam's total thickness have a significant effect on thermally induced extensional and bending responses,as well as critical buckling mechanical and thermal loadings.This study provides a theoretical framework and guidance for designing semiconductor devices based on sandwich PS beam structures.
基金supported by the National Natural Science Foundation of China (Nos. 10872083 and10602021)the Doctoral Foundation of Ministry of Education of China (No. 200807310002)
文摘Free vibration of statically thermal postbuckled functionally graded material （FGM） beams with surface-bonded piezoelectric layers subject to both temperature rise and voltage is studied. By accurately considering the axial extension and based on the Euler-Bernoulli beam theory, geometrically nonlinear dynamic governing equations for FGM beams with surface-bonded piezoelectric layers subject to thermo-electro- mechanical loadings are formulated. It is assumed that the material properties of the middle FGM layer vary continuously as a power law function of the thickness coordinate, and the piezoelectric layers are isotropic and homogenous. By assuming that the amplitude of the beam vibration is small and its response is harmonic, the above mentioned non-linear partial differential equations are reduced to two sets of coupled ordinary differential equations. One is for the postbuckling, and the other is for the linear vibration of the beam superimposed upon the postbuckled configuration. Using a shooting method to solve the two sets of ordinary differential equations with fixed-fixed boundary conditions numerically, the response of postbuckling and free vibration in the vicinity of the postbuckled configuration of the beam with fixed-fixed ends and subject to transversely nonuniform heating and uniform electric field is obtained. Thermo-electric postbuckling equilibrium paths and characteristic curves of the first three natural frequencies versus the temperature, the electricity, and the material gradient parameters are plotted. It is found that the three lowest frequencies of the prebuckled beam decrease with the increase of the temperature, but those of a buckled beam increase monotonically with the temperature rise. The results also show that the tensional force produced in the piezoelectric layers by the voltage can efficiently increase the critical buckling temperature and the natural frequency.
文摘In the present work,thermo-electro-mechanical buckling behavior of functionally graded piezoelectric(FGP)nanobeams is investi-gated based on higher-order shear deformation beam theory.The FGP nanobeam is subjected to four types of thermal loading including uniform,linear,and sinusoidal temperature rise as well as heat conduction through the beam thickness.Thermo-electro-mechanical properties of FGP nanobeam are supposed to change continuously in the thickness direction based on power-law model.To consider the influences of small-scale sizes,Eringen’s nonlocal elasticity theory is adopted.Applying Hamilton’s princi-ple,the nonlocal governing equations of an FGP nanobeam in thermal environments are obtained and are solved using Navier-type analytical solution.The significance of various parameters,such as thermal loadings,external electric voltage,power-law index,nonlocal parameter,and slenderness ratio on thermal buck-ling response of size-dependent FGP nanobeams is investigated.
文摘This work presents a theoretical study for thermo-mechanical buckling of size-dependent magneto-electro-thermo-elastic func-tionally graded(METE-FG)nanoplates in thermal environments based on a refined trigonometric plate theory.Temperature field has uniform,linear,and nonlinear distributions across the thick-ness.Nonlinear thermal loadings are considered as heat conduc-tion(HC)and sinusoidal temperature rise(STR).A power law function is applied to govern the gradation of material properties through the nanoplate thickness.Considering coupling impacts between magneto,electro,thermo-mechanical loadings,the equa-tions of motion,and distribution of magneto-electrical field across the thickness direction of the METE-FG nanoplate are derived.The exact solutions for critical buckling temperatures of METE-FG nanoplates are introduced implementing Navier’s method.Moreover,the accuracy of the present formulation is examined by comparing the obtained results with published ones.Furthermore,the effects played by the magneto-electrical field,various temperature rises,nonlocality,power law index,side-to-thickness ratio,and aspect ratio on the critical buckling tempera-ture response are all investigated and reported.
