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Showing papers by "Wuhan University of Technology published in 1993"



Journal ArticleDOI
TL;DR: A general theoretical framework for predicting the effective properties of piezoelectric composites in terms of multiple-scattering theory is developed and the first-order approximation of the theory is given and a numerical study of the effective piezOElectric coefficients are presented.
Abstract: We develop a general theoretical framework for predicting the effective properties of piezoelectric composites in terms of multiple-scattering theory. For transversely isotropic piezoelectric composites of aligned cylindrical fibers exhibiting transversely isotropic piezoelectricity embedded in an isotropic matrix, we give the first-order approximation of the theory and present a numerical study of the effective piezoelectric coefficients. It predicts the enhanced hydrostatic and voltage piezoelectric coefficients for the two-phase fiber-reinforced piezoelectric composites. The theoretical predictions also compare reasonably well with the experimental results.

58 citations


Journal ArticleDOI
TL;DR: In this article, an interpretation of Biot's poroviscoelasticity theory based on micromechanics is presented, where the coupling effects between pore pressure diffusion and rock matrix deformation give rise to similar but different time dependent phenomena.

28 citations


Journal ArticleDOI
TL;DR: A kind of evaluation model in which both y and @b are variable and with linear convex constraint and an iterative computation method that makes use of alternating projection between two convex sets is proposed.

24 citations


Journal ArticleDOI
TL;DR: A general theoretical framework is developed for the determination of the overall nonlinear behavior of a two-phase composite, with randomly oriented elastic and ellipsoidal particles embedded in a ductile medium, in terms of the multiple-scattering theory.
Abstract: This paper is concerned with the description of the nonlinear mechanical properties of composite media. We develop a general theoretical framework for the determination of the overall nonlinear behavior of a two-phase composite, with randomly oriented elastic and ellipsoidal particles embedded in a ductile medium, in terms of the multiple-scattering theory. This theory is versatile enough to provide results under any proportionally increasing combined stress. Two solutions, namely, non-self-consistent and self-consistent solutions, for the nonlinear behavior are discussed. The theoretical predictions also compare reasonably with the experimental results

20 citations


Journal ArticleDOI
TL;DR: In this article, the effects of particle size of the commercial TiC on the mechanical properties of the Ni3Al-matrix composites were studied and the results showed that the mechanical property of the composites decrease with increasing particle size.
Abstract: In this paper, the possibilities of preparing TiC-reinforced Ni3Al-matrix composites by SM (self-propagating high temperature synthesis and melting process) were examined. Two kinds of composites, namely, commercial TiC-reinforcement and synthesized TiC-reinforcement Ni3Al-matrix composites, were fabricated. The effects of particle size of the commercial TiC on the mechanical properties of the Ni3Al-matrix composites were studied. The results show that the mechanical properties of the composites decrease with increasing particle size of the commercial TiC. The microstructures of 35 wt. % TiC + 65 wt. % Ni3Al composites produced by SM technology from the four elements Ti, C, Ni, and Al were examined. The results show that in these composites, the particle size of TiC synthesized in situ is fine and that the materials have considerable high-temperature bending strength and fracture toughness.

20 citations


Journal ArticleDOI
TL;DR: The physical properties of the compound with and without Fe 2 O 3 were measured and these were combined with the analysis of the hydration process and products by using XRD, DTA and calorimeter equipment to determine the heat of hydration etc as discussed by the authors.

19 citations


Journal ArticleDOI
TL;DR: In this paper, a general formula to define the onset wind velocity for 2-D coupled galloping oscillations of tower buildings with square section is presented, and several important conclusions are obtained, such as: if the two fundamental natural frequencies of a tower building in two mutually orthogonal horizontal principal axes are the same, galloping may take place in the two axial directions at the same time.

15 citations


Journal ArticleDOI
TL;DR: In this paper, the authors explicitly corrects an error in equations (8) and (9) of Schulgasser's paper, and give the first-order approximate results for the effective properties of transversely isotropic piezoelectric composites.
Abstract: This short paper explicitly corrects an error in equations (8) and (9) of Schulgasser's paper [Schulgasser (1992) J. Mech. Phys. Solids 40, 473–479]. summarizes the exact general results derived from multiple-scattering scheme, and finally gives the first-order approximate results for the effective properties of transversely isotropic piezoelectric composites.

11 citations


Journal ArticleDOI
Qiang Li1, Y.L. Zhang1, R.Z. Yuan1, X.H. Huang1, D.J. Jin1 
TL;DR: In this paper, the authors have grown large-size Tb 0.27 DY 0.73 Fe 2 (Terfenol) single crystals completely without contamination using a magnetic levitation cold crucible CZ (Czochralski) technique.

10 citations


Journal ArticleDOI
TL;DR: In this paper, a model simulating a coupled-juid-structure impact buckling phenomenon is constructed, where a small imperfection elastoplastic column is attached by its upper end to a large mass and by its lower end to an aflatplate; it then perpendicularly impacts a viscous water free surface from a certain drop height or in a certain falling velocity.

Journal ArticleDOI
TL;DR: The finite element method determining dynamic response of random structures subjected to random dynamic load is studied and formulas for dynamic response and reliability based on random resistibility are proposed.
Abstract: The finite element method determining dynamic response of random structures subjected to random dynamic load is studied, the formulas for dynamic response of random structures and reliability based on random resistibility are proposed in this paper.

Journal ArticleDOI
TL;DR: In this article, a method is formulated for calculating the sensitivities of natural frequencies and mode shapes directly with respect to structural parameters, valid for discrete systems and also suitable for distributed structures when combined with the finite element method.


Journal ArticleDOI
TL;DR: In this article, the effects of heat treatment on the mechanical properties of AIN-SiC whisker composites with Y 2 O 3 and SiO 2 additives has been studied and the phase composition, microstructure and grain boundary phase structure have been characterized by combining XRD, SEM, TEM/EDXA and HREM techniques.
Abstract: The effects of heat – treatment on the mechanical properties of AIN – SiC whisker composites with Y 2 O 3 and SiO 2 additives has been studied. When the sample containing 10 wt% Y 2 O 3 +SiO 2 (Y 2 O 3 /SiO 2 = 1/0. 66) was treated at 1300°C in air for 140 hours the strength of compositqs was raised from 481 MPa to 784 MPa. The phase composition, microstructure and grain boundary phase structure have been characterized by combining XRD, SEM, TEM/EDXA and HREM techniques. The reinforcement mechanism of the composites results from crystallization of the glass phase in the grain boundary at the high temperature oxidizing atmosphere to form the crossing structure of 2Hδ Sialon fibrous phase and SiC whisker.

Journal ArticleDOI
TL;DR: In this paper, the effects of Fe-implanted zirconia and post-implantation thermal annealing on electrical properties and structure of an implanted layer were studies by electric measurement, X-ray photoelectron spectroscopy (XPS) and Xray diffraction (XRD), which showed that the implanted Fe ion was mainly in a charge state of Fe 2+ and the sections of Fe2+ were incorporated into the ZrO2 lattice, forming a FeZrO3 compound.
Abstract: Fe ions were implanted into yttria stabilized zirconia with doses of 5×1015 -2×1017 ions/cm2 at an energy of 140 KeV. The effects of Fe-implanted zirconia and post-implantation thermal annealing on electrical properties and structure of an implanted layer were studies by electric measurement, X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). It was found that the resistivity for the as-implanted sample decreased greatly with increasing ion dose, and at high dose the resistivity decreasing gradually. After annealing at 1200°C in N2 environment, the resistivity relative to that for the as-implanted sample had clearly marked decreases. Results of the XRD and XPS measurements showed that the implanted Fe ion was mainly in a charge state of Fe2+ and the sections of Fe2+ were incorporated into the ZrO2 lattice, forming a FeZrO3 compound. Finally, the conductivity mechanisms were discussed briefly.

Journal ArticleDOI
TL;DR: The single-server general queuing model G1/G/1 is studied for a modified Erlangian input that covers a wide range of bursty and nonbursty input processes.
Abstract: The single-server general queuing model G1/G/1 is studied for a modified Erlangian input that covers a wide range of bursty and nonbursty input processes. The E/sub k//G/1 model is analyzed using spectral factorization, and explicit form performance is evaluated in terms of the mean and variance of the waiting time. >


Journal ArticleDOI
TL;DR: In this article, the authors considered the initial value problem of semilinear stochastic evolution equation in Hilbert Space and obtained two conclusions of uniqueness of the mild solution of (1) which include the corresponding results in [4].


Journal ArticleDOI
TL;DR: In this paper, the thermoelectric polycrystalline ceramic materials were prepared by a new ceramic technology, which is simpler than the Bridgman and powder metallurgy processes.
Abstract: Thermoelectric polycrystalline ceramic materials were prepared by a new ceramic technology. Samples of p-type 72% Sb2Te3 + 25% Bi2Te3 + 3% Sb2Se3 doped with tellurium and 90% Bi2Te3 + 5% Sb2Te3 + 5% Sb2Se3 doped with Sbl3 or Agl were studied. The new ceramic cooling materials have an inhomogeneous structure, but higher mechanical strength and thermoelectric properties. The method is simpler than the Bridgman and powder metallurgy processes. Measurements of properties show that sintering temperature and time effect the thermoelectric properties of the samples. Scanning electron microscopy shows that the polycrystalline ceramic materials have an obvious layered structure. The doping of the materials was studied, including doping variety and doping concentration. The figure of merit for n-type doped with Sbl3 is 2.9 × 10−3 K−1, while that for p-type doped with tellurium is 3.1 × 10−1 K−1.