The finite element equations considering the geometrical nonlinearity of piezoelectric smart structures are derived based on the total Lagrange method under the assumption of weak coupling between electricity and mech...The finite element equations considering the geometrical nonlinearity of piezoelectric smart structures are derived based on the total Lagrange method under the assumption of weak coupling between electricity and mechanics. Buckling and post-buckling of piezoelectric-plate with various boundary conditions are investigated. The calculated results show that piezoelectric effects and external voltage can hardly affect the buckling and post-bucking characteristics of piezoelectric-plate under uniaxial pressure while the buckling caused by displacement in-plane has much to do with the electric field.展开更多
The equations of motion governing the vibration of a cantilever beam with partially treated self-sensing active constrained layer damping treatment(SACLD) are derived by application of the extended Hamilton principle....The equations of motion governing the vibration of a cantilever beam with partially treated self-sensing active constrained layer damping treatment(SACLD) are derived by application of the extended Hamilton principle. The assumed-modes method and closed loop velocity feedback control law are used to analyze and control the flexural vibration of the beam nle influences of the bonding layer and piezoelectric layer thickness, material properties, placements of the Diezoelectric patch and feedback control parameters on the actuation ability of the vibration suppression are investigated. Some design considerations for pure passive, pure active control, and self-sensing active constrained layer damping are discussed.展开更多
Besides the creep strength, creep ductility has also been recognized as an important material parameter, since low ductility is often associated with notch sensitivity and concomitant premature failure, especially bri...Besides the creep strength, creep ductility has also been recognized as an important material parameter, since low ductility is often associated with notch sensitivity and concomitant premature failure, especially brittle fracture. Creep rupture data of 9Cr-1Mo-V-Nb-N show that the creep ductility decreases with decreasing stress at constant temperature or with decreasing temperature at constant stresses. SEM and TEM were used to investigate the mechanism of rupture ductility after long term creep was related to the decrease of mobile dislocation density, the coarsening and coalescence of carbides and the decrease of shear lip size. (Edited author abstract) 8 Refs.展开更多
A basic solution in series form for the three-phase composite cylindrical model in antiplane piezoelectricity subjected to the action of a singularity in the intermediate matrix region is presented. The solution is ob...A basic solution in series form for the three-phase composite cylindrical model in antiplane piezoelectricity subjected to the action of a singularity in the intermediate matrix region is presented. The solution is obtained through the complex potential approach in conjunction with the techniques of analytical continuation, singularity analysis, Laurent series expansion in an annular region and Cauchy integral formulae, etc. Based on the complex potentials obtained, explicit expressions for the distribution of stress and electric displacement in the three regions are also derived.展开更多
Based on the general solution of three-dimensional problems inpiezoelectric medium, with the method of Green's functins~[2],axisymmetric boundary-value problems are discussed. The purpose ofthis research is for an...Based on the general solution of three-dimensional problems inpiezoelectric medium, with the method of Green's functins~[2],axisymmetric boundary-value problems are discussed. The purpose ofthis research is for analyzing the effective on mechanics andelectricity of the piezoelectric ceramics caused by voids andinclusions. The displacement, traction and electric Green's functionscorresponding to circular ring loads acting in the interior of apiezoelectric ceramic are obtained. A cylindrical coordinate systemis employed and Hankel transform are applied with respect to radialcoor- dinates. Explicit solutions for Green's functions are presentedin terms of infinite integrals of Lipshitz- Hankel type. By solving atraction boundary-value problem, the solution scheme is illustrate.展开更多
In this paper, a simple but inberent relation between theL-integral and the Buekner work conjugate integral is proved forcrack problems in isotropic, anisotropic, and dissimilar materi- als,respectively. It is found t...In this paper, a simple but inberent relation between theL-integral and the Buekner work conjugate integral is proved forcrack problems in isotropic, anisotropic, and dissimilar materi- als,respectively. It is found that, in the above-mentioned three cases,the L-integral, from the math- ematical point of view as well as inprinciple, arises from Betti's reciprocal theorem. This means thatthe Bueckner work conjugate integral is a more generalpath-independent integral than the others since any otherpath-independent integrals could be derived by using the Buecknerintegral while choosing a different subsidiary stress-displacementfield.展开更多
The pyroelectric effect of phase transition induced with temperature in Nb-modified Pb(Zr,Sn,Ti)O3 antiferroelectric-ferroelectric ceramics is studied. Experimental results reveal that the phase transitions are accomp...The pyroelectric effect of phase transition induced with temperature in Nb-modified Pb(Zr,Sn,Ti)O3 antiferroelectric-ferroelectric ceramics is studied. Experimental results reveal that the phase transitions are accompanied with marked pyroelectric peaks, there exists the close relation between the type of phase transition and the shape of pyroelectric peak. Because of the variations of phase transition, various pyroelectric spectra result. The pyroelectric spectrum can display the polarization effect and some inferior phase transitions with temperature variations, such as antiferroelectric AFEA-AFEB or ferroelectric FEL-FEH transition, which are not detected by the conventional dielectric measurement.展开更多
In this paper, first, we present the comparison theorem and the (generalized) Stein-Rosenberg theorem for the GMPOR method, which improves some recent results([9,11,13]). Second, we also give the convergent theorem of...In this paper, first, we present the comparison theorem and the (generalized) Stein-Rosenberg theorem for the GMPOR method, which improves some recent results([9,11,13]). Second, we also give the convergent theorem of the GMPOR method, which generalizes the corresponding result of [9]. Finally, we provide the real interval such that the generalized extrapolated Jacobi iterative method and the generalized SOR methods simultaneously converge, one of the main results in [1] is extended.展开更多
The multiple field-induced phase transition in 4 at.% La modified Pb(Zr,Sn,Ti)O 3 family with temperature from -40℃ to 45℃ in reported. Two electric field-induced transitions from a metastable antiferroelectric phas...The multiple field-induced phase transition in 4 at.% La modified Pb(Zr,Sn,Ti)O 3 family with temperature from -40℃ to 45℃ in reported. Two electric field-induced transitions from a metastable antiferroelectric phase to two ferroelectric phases are observed is polarization at the applied field of 4 MV/m. The critical field of phase transition between two ferroelectric phases is not larger than 2.5 MV/m, about ten to twenty percent of that ever found in PZT based ceramics. Lattice structure is shown to be orthorhombic by X-ray diffraction. Dielectric investigation reveals a relaxor-like ferroelectric behavior. Temperature-electric field phase diagram is also presented. An appreciate kind of materials is provided to investigate multiple field-induced phase transition with PZT-based ceramics.展开更多
An equation used to calculate electromagnetic pressure for confining and shaping a plate-form melt with small or medium thickness is brought forward. The equation gives a precise relationship between electromagnetic p...An equation used to calculate electromagnetic pressure for confining and shaping a plate-form melt with small or medium thickness is brought forward. The equation gives a precise relationship between electromagnetic pressure factor p and current frequency f, melt thickness a and electromagnetic parameter MX ?The main results can be summarized as follows: ( i )展开更多
基金the National Natural Science Foundation of China(No.59635140)
文摘The finite element equations considering the geometrical nonlinearity of piezoelectric smart structures are derived based on the total Lagrange method under the assumption of weak coupling between electricity and mechanics. Buckling and post-buckling of piezoelectric-plate with various boundary conditions are investigated. The calculated results show that piezoelectric effects and external voltage can hardly affect the buckling and post-bucking characteristics of piezoelectric-plate under uniaxial pressure while the buckling caused by displacement in-plane has much to do with the electric field.
基金the National Natural Science Foundation of China(No.59635140)
文摘The equations of motion governing the vibration of a cantilever beam with partially treated self-sensing active constrained layer damping treatment(SACLD) are derived by application of the extended Hamilton principle. The assumed-modes method and closed loop velocity feedback control law are used to analyze and control the flexural vibration of the beam nle influences of the bonding layer and piezoelectric layer thickness, material properties, placements of the Diezoelectric patch and feedback control parameters on the actuation ability of the vibration suppression are investigated. Some design considerations for pure passive, pure active control, and self-sensing active constrained layer damping are discussed.
文摘Besides the creep strength, creep ductility has also been recognized as an important material parameter, since low ductility is often associated with notch sensitivity and concomitant premature failure, especially brittle fracture. Creep rupture data of 9Cr-1Mo-V-Nb-N show that the creep ductility decreases with decreasing stress at constant temperature or with decreasing temperature at constant stresses. SEM and TEM were used to investigate the mechanism of rupture ductility after long term creep was related to the decrease of mobile dislocation density, the coarsening and coalescence of carbides and the decrease of shear lip size. (Edited author abstract) 8 Refs.
文摘A basic solution in series form for the three-phase composite cylindrical model in antiplane piezoelectricity subjected to the action of a singularity in the intermediate matrix region is presented. The solution is obtained through the complex potential approach in conjunction with the techniques of analytical continuation, singularity analysis, Laurent series expansion in an annular region and Cauchy integral formulae, etc. Based on the complex potentials obtained, explicit expressions for the distribution of stress and electric displacement in the three regions are also derived.
基金the National Natural Science Foundation of Chinathe Foundation of the Open Laboratory of Solid Mechanics
文摘Based on the general solution of three-dimensional problems inpiezoelectric medium, with the method of Green's functins~[2],axisymmetric boundary-value problems are discussed. The purpose ofthis research is for analyzing the effective on mechanics andelectricity of the piezoelectric ceramics caused by voids andinclusions. The displacement, traction and electric Green's functionscorresponding to circular ring loads acting in the interior of apiezoelectric ceramic are obtained. A cylindrical coordinate systemis employed and Hankel transform are applied with respect to radialcoor- dinates. Explicit solutions for Green's functions are presentedin terms of infinite integrals of Lipshitz- Hankel type. By solving atraction boundary-value problem, the solution scheme is illustrate.
文摘In this paper, a simple but inberent relation between theL-integral and the Buekner work conjugate integral is proved forcrack problems in isotropic, anisotropic, and dissimilar materi- als,respectively. It is found that, in the above-mentioned three cases,the L-integral, from the math- ematical point of view as well as inprinciple, arises from Betti's reciprocal theorem. This means thatthe Bueckner work conjugate integral is a more generalpath-independent integral than the others since any otherpath-independent integrals could be derived by using the Buecknerintegral while choosing a different subsidiary stress-displacementfield.
文摘The pyroelectric effect of phase transition induced with temperature in Nb-modified Pb(Zr,Sn,Ti)O3 antiferroelectric-ferroelectric ceramics is studied. Experimental results reveal that the phase transitions are accompanied with marked pyroelectric peaks, there exists the close relation between the type of phase transition and the shape of pyroelectric peak. Because of the variations of phase transition, various pyroelectric spectra result. The pyroelectric spectrum can display the polarization effect and some inferior phase transitions with temperature variations, such as antiferroelectric AFEA-AFEB or ferroelectric FEL-FEH transition, which are not detected by the conventional dielectric measurement.
文摘In this paper, first, we present the comparison theorem and the (generalized) Stein-Rosenberg theorem for the GMPOR method, which improves some recent results([9,11,13]). Second, we also give the convergent theorem of the GMPOR method, which generalizes the corresponding result of [9]. Finally, we provide the real interval such that the generalized extrapolated Jacobi iterative method and the generalized SOR methods simultaneously converge, one of the main results in [1] is extended.
文摘The multiple field-induced phase transition in 4 at.% La modified Pb(Zr,Sn,Ti)O 3 family with temperature from -40℃ to 45℃ in reported. Two electric field-induced transitions from a metastable antiferroelectric phase to two ferroelectric phases are observed is polarization at the applied field of 4 MV/m. The critical field of phase transition between two ferroelectric phases is not larger than 2.5 MV/m, about ten to twenty percent of that ever found in PZT based ceramics. Lattice structure is shown to be orthorhombic by X-ray diffraction. Dielectric investigation reveals a relaxor-like ferroelectric behavior. Temperature-electric field phase diagram is also presented. An appreciate kind of materials is provided to investigate multiple field-induced phase transition with PZT-based ceramics.
文摘An equation used to calculate electromagnetic pressure for confining and shaping a plate-form melt with small or medium thickness is brought forward. The equation gives a precise relationship between electromagnetic pressure factor p and current frequency f, melt thickness a and electromagnetic parameter MX ?The main results can be summarized as follows: ( i )
