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LAMINATED PIEZOELECTRIC PLATE FOR ACTIVE UNDERWATER ACOUSTIC CONTROL

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Acta Mechanica Solida Sinica 2001年第4期14卷 306-311页

作者： Zhao Hanzhong (department of mechanics,huazhong university of science and technology,wuhan 430074,China) department of mechanics Huazhong Univ. of Sci. and Technol. Wuhan 430074 China

The pressure reflected from a bi-laminated piezoelectric plate hasbeen determined using the Thomson-Haskell matrix method. The plate iscomposed of a piezoelectric layer with grounded vacuum and An elasticlayer in contact with the fluid. An incident plane wave in the fluidmedium strikes the plate at dif- Ferent angles. The required electricpotential across the piezoelectric layer to cancel the reflectionfrom the Fluid/elastic boundary has been determined for thepiezoelectric material PZT-5 at various thickness parame- Ters andincident frequencies.

关键词： underwater acoustic control laminated piezoelectric plate acousticscattering acoustic radiation

ACOUSTIC REFLECTION FROM A BAFFLED ELASTIC/PIEZOELECTRIC PLATE

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Acta Mechanica Solida Sinica 2002年第2期15卷 156-162页

作者： Zhao Hanzhong (department of mechanics,huazhong university of science and technology,wuhan 430074,China) department of mechanics Huazhong Univ. of Sci. and Technol. Wuhan 430074 China

A finite difference/boundary integral procedure to determine theacoustic reflected pressure from a fluid-loaded bi-laminated plate isdescribed. The bi-laminate is composed of a piezoelectric layer andan elastic layer in contact with the fluid, and is held by anacoustically hard baffle. In the numerical model, the fluid pressureat fluid/solid interface is replaced by a continuum of point sourcesweighted by the normal acceleration of the elastic plate, and thegoverning equation system is solved in the solid domain.

关键词： acoustic reflection baffled palte finite difference boundary integral

LAMINATED VISCOELASTIC PLATE WITH INCLUSIONS FOR PASSIVE UNDER-WATER ACOUSTIC CONTROL

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Acta Mechanica Solida Sinica 2002年第1期15卷 23-29页

作者： Zhao Hanzhong (department of mechanics,huazhong university of science and technology,wuhan 430074,China) department of mechanics Huazhong Univ. of Sci. and Technol. Wuhan 430074 China

The effectiveness of a fluid-loaded sandwiched viscoelastic layerin suppressing acoustic scat- tering and radiation has been estimatedusing the Thomson-Haskell matrix method. The GU (Gaunaurd andUberall) resonance theory has been adopted to handle three types ofviscoelastic substrates with air -filled in- Clusions. The effects ofthe varying thickness of the substrates, the volume fractions of theinclusions and fre- Quencies of incident waves have been studied todetermine the optimal strategies of signal reduction. In theInvestigation, the monopole resonance phenomena of the inclusionshave been taken into account.

关键词： underwater acoustic control laminated viscoelastic plate air-filledinclusion

ACOUSTIC REFLECTION FROM A PERIODIC ELASTIC/PIEZOELECTRIC PLATE

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Acta Mechanica Solida Sinica 2003年第4期16卷 321-326页

作者： Zhao Hanzhong (department of mechanics,huazhong university of science and technology,wuhan 430074,China) department of mechanics Huazhong Univ. of Sci./Technology Wuhan 430074 China

The acoustic reflected pressure from a periodic elastic/piezoelectric laminated plate is studied for the purpose of acoustic reflection control.A finite difference/boundary integral procedure to determine the reflected pressure from the fluid-loaded plate is *** the numerical model,a Green's function in the form of infinite sum is employed and a boundary integral is performed to replace the fluid pressure at fluid/solid interface by a continuum of point sources weighted by the normal acceleration of the elastic *** equation system is then solved only in the solid *** is demonstrated that an appropriate applied voltage potential across the piezoelectric layer has the effect of cancelling the fundamental propagating mode,and there,is no reflection for frequencies up to the cut-off frequency of the next propagating mode if the fundamental mode has been eliminated.

关键词： acoustic reflection periodic plate finite difference boundary integral

GREEN'S FUNCTIONS FOR 2D PROBLEMS OF ANISOTROPIC PIEZOELECTRIC MATERIAL WITH A STRIP REGION

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Acta Mechanica Solida Sinica 2000年第2期13卷 149-154页

作者： Hu Yiantai Huang Yuying Chen Chuanyao zhong weifang (Dept.of mechanics,huazhong university of science and technology,wuhan 430074,China) Dept. of mechanics Huazhong Univ. of Sci. and Technol. Wuhan 430074 China

By using Stroh's formalism and the conformal mapping technique,we derive the simple ex- plicit elastic fields of a generalized line dislocation and a generalized line force in a general anisotropic piezo- electric strip with fixed surfaces,which are two fixed conductor *** solutions obtained are usually considered as Green's functions which play important roles in the boundary element *** Coulomb forces of the distributed charges along the region boundaries on the line charge q at z^0 are analysed in detail. The results are valid not only for plane and antiplane problems but also for the coupled problems between in- plane and outplane deformations.

关键词： Stroh's formalism conformal mapping technique piezoelectricity anisotropie elasticity Green's functions Coulomb forces

GREEN'S FUNCTIONS FOR A 2D ANISOTROPIC MEDIUM WITH A HYPERBOLIC BOUNDARY

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Acta Mechanica Solida Sinica 2000年第1期13卷 17-24页

作者： Hu Yiantai Huang Yuying Chen Chuanyao (department of mechanics,huazhong university of science and technology,wuhan 430074,China) department of mechanics Huazhong Univ. of Sci. and Technol. Wuhan 430074 China

By using Stroh's formalism and the conformal mapping technique,this paper derives simple exphcit Green's functions of a piezoelectric anisotropic body with a free or fixed hyperbolic *** corresponding elastic fields in the medium are obtained,*** particular,degenerated solutions of an ex- ternal crack from those of a hyperbolic problem are analysed in *** the singular stress fields and the fracture mechanics parameters are *** solutions obtained are valid not only for plane and antiplane problems but also for the coupled ones between inplane and outplane deformations.

关键词： Stroh's formalism conformal mapping Green's functions external crack stress intensity factors

HOPF BIFURCATION OF A NONLINEAR RESTRAINED CURVED PIPE CONVEYING FLUID BY DIFFERENTIAL QUADRATURE METHOD

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Acta Mechanica Solida Sinica 2003年第4期16卷 345-352页

作者： Wang Lin Ni Qiao Huang Yuying (department of mechanics,huazhong university of science and technology,wuhan 430074,China) department of mechanics Huazhong Univ. of Sci./Technology Wuhan 430074 China

This paper proposes a new method for investigating the Hopf bifurcation of a curved pipe conveying fluid with nonlinear spring *** nonlinear equation of motion is derived by forces equilibrium on microelement of the system under *** spatial coordinate of the system is discretized by the differential quadrature method and then the dynamic equation is solved by the Newton-Raphson *** numerical solutions show that the inner fluid velocity of the Hopf bifurcation point of the curved pipe varies with different values of the parameter, nonlinear spring *** on this,the cycle and divergent motions are both found to exist at specific fluid flow velocities with a given value of the nonlinear spring *** results are useful for further study of the nonlinear dynamic mechanism of the curved fluid conveying pipe.

关键词： curved fluid conveying pipe Hopf bifurcation nonlinear vibration DQM

DYNAMIC SIMULATION OF ROTATING SHELLS COUPLED WITH LIQUID

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Acta Mechanica Solida Sinica 2001年第2期14卷 169-175页

作者： Wei Fayuan Li Shiqi Huang Yuying~1 zhong Yifang (College of Mechanical science and Engineering, huazhong university of science and technology, wuhan 430074, China) (1 department of mechanics, huazhong university of science and technology, wuhan 430074,China) Coll. of Mech. Sci. and Engineering Huazhong Univ. of Sci. and Technol. Wuhan 430074 China department of mechanics Huazhong Univ. of Sci. and Technol. Wuhan 430074 China

The dynamic behaviors of rotating shells coupled with liquid areshown. The shell under con- sideration has arbitrary boundaryconditions and a complex shape. A modified boundary element methodand finite strip technique are used to improve the computingefficiency and to guarantee the continuity conditions on theliquid-shell interaction plane. The effects of various parameterssuch as shell's thickness and liquid depth are investigated. Dynamicsimulations are applied to several typical shell-liquid systems, andthe natu- ral frequencies, mode shapes and response of vibration arecalculated numerically.

关键词： rotting shells dynamic simulation fluid-solid interaction

A SEMI-ANALYTICAL AND SEMI-NUMERICAL METHOD FOR SOLVING 2-D SOUND-STRUCTURE INTERACTION PROBLEMS

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Acta Mechanica Solida Sinica 2003年第2期16卷 116-126页

作者： Xiang Yu Huang Yuying (College of Civil Engineering and mechanics,huazhong university of science and technology,wuhan 430074,China) Coll. of Civ. Eng. and mechanics Huazhong Univ. of Sci./Technology Wuhan 430074 China

Based on the transfer matrix method and the virtual source simulation technique, this paper proposes a novel semi-analytical and semi-numerical method for solving 2-D sound- structure interaction problems under a harmonic *** any integration segment, as long as its length is small enough,along the circumferential curvilinear coordinate,the non- homogeneous matrix differential equation of an elastic ring of complex geometrical shape can be rewritten in terms of the homogeneous one by the method of extended homogeneous capacity proposed in this *** the exterior fluid domain,the multi-circular virtual source simulation technique is *** source density distributed on each virtual circular curve may be ex- panded as the Fourier's *** with the inverse fast Fourier transformation,a higher accuracy and efficiency method for solving 2-D exterior Helmholtz's problems is presented in this *** the aspect of solution to the coupling equations,the state vectors of elastic ring induced by the given harmonic excitation and generalized forces of coefficients of the Fourier series can be obtained respectively by using a high precision integration scheme combined with the method of extended homogeneous capacity put forward in this *** to the superposition princi- ple and compatibility conditions at the interface between the elastic ring and fluid,the algebraic equation of system can be directly constructed by using the least square *** of acoustic radiation from two typical fluid-loaded elastic rings under a harmonic concentrated force are *** results show that the method proposed is more efficient than the mixed FE-BE method in common use.

关键词： sound-structure interaction acoustic radiatlon multi-circular virtual source simulation technique transfer matrix method inverse fast Fourier transformation semi-analytical and semi-numerical method