共查询到20条相似文献,搜索用时 31 毫秒
1.
The coupled problem of the forced axisymmetric vibrations and self-heating of electrothermoviscoelastic cylindrical shells
with piezoceramic actuators under monoharmonic electromechanical loading is solved. The temperature dependence of the complex
characteristics of the passive and piezoactive materials is taken into account. The coupled nonlinear problem of electrothermoelasticity
is solved by using a time-marching method with discrete orthogonalization at each time step (to integrate the equations of
elasticity) and an explicit finite-difference method (to solve the heat-conduction equations). An analysis is made of the
effect of the boundary conditions at the shell ends, the dimensions of the piezoactuator, and the self-heating temperature
on the actuator voltage and the effectiveness of active damping of the forced vibrations of the shell under uniform transverse
monoharmonic pressure 相似文献
2.
Piezoelectric wafer type actuator/sensor is widely used to generate and sense Lamb waves for Structural Health Monitoring (SHM). However, multiple Lamb waves modes are generally excited with this type of transducer. As a result, there is some difficulty in using Lamb waves for damage detection. To selectively generate a single A0/S0 Lamb mode, the tuned excitation of Lamb waves has been studied by some researchers. This paper investigates the design of the PZT actuator/sensor bonded to beam-like structure for generating single A0/S0 Lamb mode. In the study it is found that some factors, including the bonding layer, the unknown material properties and dynamical characteristics of the beam, will influence the design of PZT actuator/sensor. Piezoelectric impedance technique is introduced to facilitate the design of PZT actuator/sensor. Crack detection in beam using the tuned A0/S0 Lamb waves is performed. 相似文献
3.
V. L. Karlash 《International Applied Mechanics》2007,43(5):547-553
An attempt is made to systematize experimental data for a rectangular piezoceramic plate and to compare them with those on
planar vibrations of a thin piezoceramic half-disk. Experimental data on planar vibrations of a half-disk are discussed for
the first time. Neighboring vibration modes of a rectangular plate with solid electrodes demonstrate strong superposition
and coupling
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Translated from Prikladnaya Mekhanika, Vol. 43, No. 5, pp. 89–96, May 2007. 相似文献
4.
V. L. Karlash 《International Applied Mechanics》2007,43(7):786-793
The evolution of the planar vibrations of a rectangular piezoceramic plate as its aspect ratio is changed starting with 1
is studied. Experimental data are obtained using an integrated technique based on Meson’s circuit, Onoe’s circuit, and a piezotransformer
transducer. As the aspect ratio increases (square plate becomes rectangular), the intensity of electromagnetic vibrations
rapidly increases at the first longitudinal resonance and gradually decreases in the first radial mode. When the aspect ratio
is changed so that the length of one of the plate sides remains constant, the resonant frequencies of all vibration modes
change too
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Translated from Prikladnaya Mekhanika, Vol. 43, No. 7, pp. 98–106, July 2007. 相似文献
5.
Katica Hedrih 《Acta Mechanica Sinica》2006,22(5):487-501
This paper presents an analytical and numerical analysis of free and forced transversal vibrations of an elastically connected double-plate system. Analytical solutions of a system of coupled partial differential equations, which describe corresponding dynamical free and forced processes, are obtained using Bernoulli’s particular integral and Lagrange’s method of variation constants. It is shown that one-mode vibrations correspond to two-frequency regime for free vibrations induced by initial conditions and to three-frequency regime for forced vibrations induced by one-frequency external excitation and corresponding initial conditions. The analytical solutions show that the elastic connection between plates leads to the appearance of two-frequency regime of time function, which corresponds to one eigenamplitude function of one mode, and also that the time functions of different vibration modes are uncoupled, for each shape of vibrations. It has been proven that for both elastically connected plates, for every pair of m and n, two possibilities for appearance of the resonance dynamical states, as well as for appearance of the dynamical absorption, are present. Using the MathCad program, the corresponding visualizations of the characteristic forms of the plate middle surfaces through time are presented.The English text was polished by Keren Wang. 相似文献
6.
Active vibration control for a kind of two-hinged plate is developed in this paper. A finite element model for the hinged plate integrated with distributed piezoelectric sensors and actuators is derived, including bending and torsional modes of vibration. In this model, the hinges are simplified as regular plate elements to facilitate operation. The state space representations for bending and torsional vibrations are obtained. Based on two low-order models of the bending and torsional motion, two H ∞ robust controllers are designed for suppressing the vibrations of the bending and torsional modes, respectively. The simulation results indicate the effectiveness and feasibility of the designed H ∞ controllers. The vibration magnitudes of the low-order modes can be reduced without affecting the high frequency modes. 相似文献
7.
V. L. Karlash 《International Applied Mechanics》2008,44(4):361-387
Scientific results from studies on the resonant electromechanical vibrations of piezoceramic thin-walled shells of revolution,
their fragments, and segmented cylinders are analyzed, systematized, and generalized. Considerable attention is focused on
experimental studies of resonant vibrations. It is shown that the modes in which deformation occurs inphase throughout the
volume are of the highest intensity in all piezoceramic shell structures
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Translated from Prikladnaya Mekhanika, Vol. 44, No. 4, pp. 3–34, April 2008. 相似文献
8.
Free nonaxisymmetric vibrations of radially polarized hollow piezoceramic cylinders of finite length
The three-dimensional problem of free nonaxisymmetric vibrations of hollow piezoceramic cylinders with axial polarization
is considered. An efficient numerical analytic method to solve boundary-value problems is proposed. The original three-dimensional
problem of electroelasticity is reduced to a two-dimensional problem by representing the displacement components as standing
circumferential waves. Spline collocation with respect to the axial coordinate is used to reduce this two-dimensional problem
to an eigenvalue boundary-value problem with respect to the radial coordinate. This problem is solved by the stable discrete-orthogonalization
and incremental-search methods. Numerical results are presented and the natural frequencies of the cylinders are analyzed
in a wide range of their geometric characteristics 相似文献
9.
In the framework of the nonlinear theory of flexible shallow shells, we study free bending vibrations of a thin-walled circular cylindrical shell hinged at the end faces. The finite-dimensional shell model assumes that the excitation of large-amplitude bending vibrations inevitably results in the appearance of radial vibrations of the shell. The modal equations are obtained by the Bubnov-Galerkin method. The periodic solutions are found by the Krylov-Bogolyubov method. We show that if the tangential boundary conditions are satisfied “in the mean,” then, for a shell of finite length, significant errors arise in determining its nonlinear dynamic characteristics. We prove that small initial irregularities split the bending frequency spectrum, the basic frequency being smaller than in the case of an ideal shell. 相似文献
10.
Using a piezo rotary and axial vibrator (PRAV) the viscoelastic properties of a fresh Al2O3 coating that is deposited on a well-chosen plate can be measured simultaneously during drying. There are three types of vibrations
available to be excited and detected in their resonance modes, by measuring resonance frequencies f
k and half-widths h
k, before and after coating as a function of time: axial vibration, bending vibration to get the evolving Young’s modulus and
rotary vibration to follow the viscosity increase during drying of the thin coating. This information is contained in the
complex frequency shifts Ωk = 2Δf
k /f
k + iΔh
k /f
k of the three vibration modes caused by the coating on the plate. A derivation of the relationships, their validation on Newtonian
liquids and experimental applications carried out using the PRAV are given in the paper. 相似文献
11.
Utz von Wagner 《International Journal of Non》2004,39(4):673-688
Characteristic non-linear effects can be observed, when piezoceramics are excited using weak electric fields. In experiments with longitudinal vibrations of piezoceramic rods, the behavior of a softening Duffing-oscillator including jump phenomena and multiple stable amplitude responses at the same excitation frequency and voltage is observed. Another phenomenon is the decrease of normalized amplitude responses with increasing excitation voltages. For such small stresses and weak electric fields as applied in the experiments, piezoceramics are usually described by linear constitutive equations around an operating point in the butterfly hysteresis curve. The non-linear effects under consideration were, e.g. observed and described by Beige and Schmidt [1,2], who investigated longitudinal plate vibrations using the piezoelectric 31-effect. They modeled these non-linearities using higher order quadratic and cubic elastic and electric terms. Typical non-linear effects, e.g. dependence of the resonance frequency on the amplitude, superharmonics in spectra and a non-linear relation between excitation voltage and vibration amplitude were also observed e.g. by von Wagner et al. [3] in piezo-beam systems. In the present paper, the work is extended to longitudinal vibrations of non-slender piezoceramic rods using the piezoelectric 33-effect. The non-linearities are modeled using an extended electric enthalpy density including non-linear quadratic and cubic elastic terms, coupling terms and electric terms. The equations of motion for the system under consideration are derived via the Ritz method using Hamilton's principle. An extended kinetic energy taking into consideration the transverse velocity is used to model the non-slender rods. The equations of motion are solved using perturbation techniques. In a second step, additional dissipative linear and non-linear terms are used in the model. The non-linear effects described in this paper may have strong influence on the relation between excitation voltage and response amplitude whenever piezoceramic actuators and structures are excited at resonance. 相似文献
12.
The radial nonstationary vibrations of a piezoceramic cylinder polarized across the thickness and subjected to mechanical
dynamic loading are studied. To solve the initial–boundary-value problem, mesh approximations and difference schemes are used.
The electromechanical state of the cylinder under an instantaneously applied constant force is analyzed in detail 相似文献
13.
The present investigation is aimed at studying the effect of rotation on propagation of Rayleigh—Lamb waves in a homogeneous
isotropic thermoelastic diffusive plate of finite width in the framework of different theories of thermoelasticity, including
the Coriolis and centrifugal forces. The medium is subjected to stress-free, thermally insulated, isothermal, and chemical
potential boundary conditions and is rotating about an axis perpendicular to its plane. Secular equations corresponding to
the symmetric and skew-symmetric modes of the plate are derived. Phase velocities and attenuation coefficients of various
possible modes of wave propagation are computed from the secular equations. Amplitudes of displacements, temperature, and
concentration for symmetric and skew-symmetric modes of plate vibrations are computed numerically. The computed results are
presented graphically. 相似文献
14.
A Kirchhoff-Love type applied theory is used to study the specific characteristics of harmonic waves and vibrations of a helically
anisotropic shell. Special attention is paid to axisymmetric and bending vibrations. In both cases, the dispersion equations
are constructed and a qualitative and numerical analysis of their roots and the corresponding elementary solutions is performed.
It is shown that the skew anisotropy in the axisymmetric case generates a relation between the longitudinal and torsional
vibrations which is mathematically described by the amplitude coefficients of homogeneous waves. In the case of a shell with
rigidly fixed end surfaces, the dependence of the first two natural frequencies on the shell length and the helical line slope
α, i.e., the geometric parameter of helical anisotropy, is studied. A boundary value problem in which longitudinal vibrations
are generated on one of the end surfaces and the other end is free of forces and moments is considered to analyze the degree
of transformation of longitudinal vibrations into longitudinally torsional vibrations. In the case of bending vibrations,
two problems for a half-infinite shell are studied as well. In the first problem, the waves are excited kinematically by generating
harmonic vibrations of the shell end surface in the plane of the axial cross-section, and it is shown that the axis generally
moves in some closed trajectories far from the end surface. In the second problem, the reflection of a homogeneous wave incident
on the shell end is examined. It is shown that the “boundary resonance” phenomenon can arise in some cases. 相似文献
15.
Katica? Hedrih 《Archive of Applied Mechanics (Ingenieur Archiv)》2008,78(9):725-735
Based on the author’s previously published results for transversal free vibrations of axially moving sandwich belts described
by coupled partial differential equations, which are derived and analytically solved, this paper contains new analytical results,
for forced vibrations of the same system excited by transversal external excitation. The transversal forced vibrations of
the axially moving sandwich belts are described by the coupled partial nonhomogeneous differential equations. The partial
differential equations are analytically solved. Bernoulli’s method of particular integrals and Lagrange’s method of the variations
of the constants are used. 相似文献
16.
Ulrich Werner 《Archive of Applied Mechanics (Ingenieur Archiv)》2010,80(12):1333-1352
This paper shows that dynamic air gap torques in converter-fed induction motors may not only cause torsional vibrations in
the drive train, but may also cause lateral vibrations of the motor itself—including bending vibrations of the rotor shaft—,
if the motor is mounted on a soft foundation. Based on a simplified analytical model, the mathematical correlation between
rotor-stator interaction, oil film characteristics of sleeve bearings, the influence of a soft foundation—coupling angular
and lateral displacement of the stator—and excitation from dynamic air gap torques is shown. In addition to the absolute orbits
of the rotor, stator, shaft journals and bearing housings, also the relative orbits between rotor and stator and between shaft
journals and bearing housings are mathematically described. Further, the paper shows the influence of the oil film coefficients
of the sleeve bearings on the elliptical shape of the orbits. Therefore, the paper presents a possibility to optimize the
whole system—converter, motor and foundation—concerning lateral vibrations, caused by dynamic air gap torques. 相似文献
17.
On the free vibrations of a piezoceramic hollow sphere 总被引:1,自引:0,他引:1
The aim of the paper is to analyze the free vibrations of a piezoceramic hollow sphere with radial polarization. Using the cnoidal method and a genetic algorithm solves the equations of a radially inhomogeneous spherically isotropic piezoelastic medium. The Reddy and the cosine laws represent the functionally graded property of material. It is seen that for a piezoceramic hollow sphere, the piezoelectric effect consists in increasing the values for the natural frequencies in the specified classes of vibrations. 相似文献
18.
V. L. Karlash 《International Applied Mechanics》2005,41(7):709-747
The scientific results on the resonant electromechanical vibrations of piezoceramic plates in the form of disks, rings, and
polygons obtained over the last 30 years are analyzed, systematized, and generalized. Emphasis is on experimental methods.
It is shown that all piezoceramic plates have vibration modes at which deformations are in-phase over the entire volume of
the body
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Translated from Prikladnaya Mekhanika, Vol. 41, No. 7, pp. 3–46, July 2005. 相似文献
19.
The basic equations for thin-walled thermoviscoelastic plates with distributed piezoelectric actuators under monoharmonic
mechanical and electric loads are derived. The thermomechanical behavior of materials is described using the concept of complex
characteristics. Variational methods of solving nonlinear problems of active damping of the bending vibrations of plates are
considered. The effect of dissipative heating on the damping of the axisymmetric bending vibrations of a circular plate is
examined as an example
Translated from Prikladnaya Mekhanika, Vol. 45, No. 2, pp. 107–123, February 2009. 相似文献
20.
《International Journal of Solids and Structures》2007,44(7-8):2209-2224
A non-linear control strategy is applied to a simply supported uniform elastic beam subjected to an axial end force at the principal-parametric resonance frequency of the first skew-symmetric mode. The control input consists of the bending couples applied by two pairs of piezoceramic actuators attached onto both sides of the beam surfaces and symmetrically with respect to the midspan, driven by the same voltage, thus resulting into symmetric control forces. This control architecture has zero control authority, in a linear sense, onto skew-symmetric vibrations. The non-linear transfer of energy from symmetric motions to skew-symmetric modes, due to non-linear inertia and curvature effects, provides the key physical mechanism for channelling suitable control power from the actuators into the linearly uncontrollable mode. The reduced dynamics of the system, constructed with the method of multiple scales directly applied to the governing PDE’s and boundary conditions, suggest effective forms of the control law as a two-frequency input in sub-combination resonance with the parametrically driven mode. The performances of different control laws are investigated. The relative phase and frequency relationships are designed so as to render the control action the most effective. The control schemes generate non-linear controller forces which increase the threshold for the activation of the parametric resonance thus resulting into its annihilation. The theoretical predictions are compared with experimentally obtained results. 相似文献