The transient response of two coplanar cracks in a piezoelectric ceramic under antiplane mechanical and inplane electric impacting loads is investigated in the present paper. Laplace and Fourier transforms are used to...The transient response of two coplanar cracks in a piezoelectric ceramic under antiplane mechanical and inplane electric impacting loads is investigated in the present paper. Laplace and Fourier transforms are used to reduce the mixed boundary value problems to Cauchy-type singular integral equations in Laplace transform domain, which are solved numerically. The dynamic stress and electric displacement factors are obtained as the functions of time and geometry parameters. The present study shows that the presence of the dynamic electric field will impede or enhance the propagation of the crack in piezoelectric ceramics at different stages of the dynamic electromechanical load. Moreover, the electromechanical response is greatly affected by the ratio of the space of the cracks and the crack length.展开更多
The piezoelectric ceramic transformer has been more and more widely applied in elec tronic devices of high voltage and small current due to its novel features in the high voltage field: very high voltage step-up ratio...The piezoelectric ceramic transformer has been more and more widely applied in elec tronic devices of high voltage and small current due to its novel features in the high voltage field: very high voltage step-up ratio, small in size, light in weight and non-metal material in use; it cannot be burnt while the load circuit is shorted, and broken down in high voltage field;展开更多
Main aim of the presented paper is the theoretical analysis and experimental verification of the transformation parameters for the new type of nonhomogeneously poled ring transformer.The input part is poled in the thi...Main aim of the presented paper is the theoretical analysis and experimental verification of the transformation parameters for the new type of nonhomogeneously poled ring transformer.The input part is poled in the thickness direction and output part in the radial direction.Two transformer geometries are studied—the input part is at inner ring segment,or it is at the outer ring segment.The optimum electrode size aspect ratios have been found experimentally as d_(1)=D≈0:60-0:65 for the ring with aspect ratio d=D¼0:2.The fundamental as well as higher overtone resonances were studied for the transformation ratio,the optimum resistive load,efficiency and no-load transformation ratio.Higher overtones have better transformation parameters compared to the fun-damental resonance.The new type ring transformer exhibits very high transformation ratios up to 200 under no-load and up to 13.4 under a high efficiency of 97%at the optimum load conditions of 10kΩ.Strong electric field gradient at the output circuit is applicable for the electrical discharge generation.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
文摘The transient response of two coplanar cracks in a piezoelectric ceramic under antiplane mechanical and inplane electric impacting loads is investigated in the present paper. Laplace and Fourier transforms are used to reduce the mixed boundary value problems to Cauchy-type singular integral equations in Laplace transform domain, which are solved numerically. The dynamic stress and electric displacement factors are obtained as the functions of time and geometry parameters. The present study shows that the presence of the dynamic electric field will impede or enhance the propagation of the crack in piezoelectric ceramics at different stages of the dynamic electromechanical load. Moreover, the electromechanical response is greatly affected by the ratio of the space of the cracks and the crack length.
文摘The piezoelectric ceramic transformer has been more and more widely applied in elec tronic devices of high voltage and small current due to its novel features in the high voltage field: very high voltage step-up ratio, small in size, light in weight and non-metal material in use; it cannot be burnt while the load circuit is shorted, and broken down in high voltage field;
基金This work was supported by the Czech Ministry of Education under the project LO1213.
文摘Main aim of the presented paper is the theoretical analysis and experimental verification of the transformation parameters for the new type of nonhomogeneously poled ring transformer.The input part is poled in the thickness direction and output part in the radial direction.Two transformer geometries are studied—the input part is at inner ring segment,or it is at the outer ring segment.The optimum electrode size aspect ratios have been found experimentally as d_(1)=D≈0:60-0:65 for the ring with aspect ratio d=D¼0:2.The fundamental as well as higher overtone resonances were studied for the transformation ratio,the optimum resistive load,efficiency and no-load transformation ratio.Higher overtones have better transformation parameters compared to the fun-damental resonance.The new type ring transformer exhibits very high transformation ratios up to 200 under no-load and up to 13.4 under a high efficiency of 97%at the optimum load conditions of 10kΩ.Strong electric field gradient at the output circuit is applicable for the electrical discharge generation.
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.
