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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 7470-7473 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In piezoelectric or ferroelectric crystals, which are often employed in ultrasonics applications, the acoustic field of small amplitude is governed by the equations of elasticity of infinitesimal displacement gradients and the electromagnetic (EM) field is governed by Maxwell's equations. The interactions between the mechanical and electromagnetic fields are mainly due to the couplings in the constitutive equations. The governing equations consisting of field equations and constitutive equations are called the equations of piezoelectromagnetism. In a dielectric crystal of volume V bounded by a surface S which separates V from an outer vacuum V', the kinetic-energy density and electric enthalpy density are defined. By introducing these density functions in a variational principle and by requiring the independent variations of the mechanical displacement, the scalar and vector potentials of the EM field, it is shown that the equations of piezoelectromagnetism and the appropriate jump conditions are obtained. The present variational principle reduces to those for Maxwell's equations, the equations of elasticity, and the equations of piezoelectricity, respectively.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 7083-7092 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Two-dimensional equations for guided electromagnetic waves propagating in a dielectric plate surrounded by free space were recently derived from the three-dimensional Maxwell's equations. These equations are employed for the study of vibrations of circular disk dielectric resonators embedded in free space. Closed form solutions are obtained for which the continuity conditions of the tangential E and H fields at the end faces and the lateral cylindrical surface are accommodated. It is found that the solutions represent two types of modes: (1) the modes in which the electric field is transverse to the axis of the disk [transverse electric (TE) modes] and (2) the modes in which the magnetic field is transverse to the axis of the resonator [transverse magnetic (TM) modes]. Frequency equations are solved and resonance frequencies are computed as functions of the diameter-to-thickness ratio a/b for TE and TM modes. It is found that the computational results presented as Ωˆ [≡ω/(π/2b)c] vs a/b curves are independent of the refractive index nˆ. Hence, these curves can be conveniently applied to the dielectric disks of any nˆ. Predicted results are compared with the experimental data by Cohn [IEEE Trans. Microwave Theory Tech. MTT-16, 218 (1968)], Chow [IEEE Trans. Microwave Theory Tech. MTT-14, 439 (1966)], and Yee [IEEE Trans. Microwave Theory Tech. MTT-13, 256 (1965)], and with the computational results by Chow [IEEE Trans. Microwave Theory Tech. MTT-14, 439 (1966)] and Yee [IEEE Trans. Microwave Theory Tech. MTT-13, 256 (1965)]. It may be seen that present predictions agree overall with different sets of experimental data and for modes of various types and order.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 7152-7161 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Plane-wave propagation in an infinite plate is analyzed by the linear three-dimensional theory of piezoelectricity. The general dispersion relation, valid for any degree of anisotropy and for the commonly applicable electrical boundary conditions, is formulated. The general equation yielding the surface wave velocities is also derived. A numerical algorithm, potentially applicable to piezoelectric plates of any material symmetry, is developed. Results are obtained for particular crystal cuts of practical interest and waves propagating in the coordinate directions. Comparison with corresponding predictions by the purely elastic theory allows assessment of the effect of electromechanical coupling as well as of the accuracy of the computed dispersion relationships.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 7069-7082 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Two-dimensional governing equations of successively higher-order approximations for guided electromagnetic (EM) waves in an isotropic dielectric plate surrounded by free space are deduced from the three-dimensional Maxwell's equations by expanding the EM vector potential in a series of trigonometric functions of a thickness coordinate in the plate and in exponentially decaying functions of a thickness coordinate in the upper and lower halves of free space. By further satisfying the continuity conditions of the EM field at the interfaces between the plate and free space, a single system of two-dimensional governing equations is obtained. Solutions and dispersion relations are obtained from the two-dimensional approximate equations. Dispersion curves are computed and compared with the corresponding ones obtained from the solutions of the three-dimensional Maxwell's equations for the transverse electric (TE) and transverse magnetic (TM) waves of the first four modes and for values of the refractive index nˆ=1.5, 5, 15. It is shown that the agreement between the approximate and exact dispersion curves is very close for various order of TE and TM waves and for a broad range of the values of nˆ. For bounded plates with edges in contact with free space, a uniqueness theorem for the solutions of the system of two-dimensional equations is derived from which the specification of continuity conditions on the components of the two-dimensional H and E fields at the edges are established.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 3411-3422 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In a previous article a set of first-order equations of motion is obtained for contoured crystal plates and for frequencies up to and including those of the fundamental thickness-shear modes. In the present article the governing equations of contoured plates are extended to include the electric potential which is coupled to the mechanical fields by the piezoelectric effect. These equations are, then, employed for the study of piezoelectrically forced thickness-shear and flexural vibrations of beveled AT-cut quartz plate, i.e., the plate with a portion of uniform thickness between the two wings of the double wedge. Analytical solutions are obtained by Frobenius method. Displacements, stresses, and electric potential are derivable from six independent functions which are in the form of infinite power series. In addition to the calculations of resonance frequencies and mode shapes, the effects of the contouring on the forced mechanical displacements, electric potential, surface charge, and capacitance ratio are examined. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 3403-3410 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A system of two-dimensional equations of motion of successively higher-order approximations for contoured crystal plates are deduced from the three-dimensional equations of elasticity by expansion of displacements in a series of trigonometrical functions of the thickness coordinate of the plates. By removing the first-order thickness-stretch mode and the first-order x2x3 (or fast) thickness-shear mode and all the higher ones, a set of first-order equations of motion is obtained for contoured crystal plates and for frequencies up to and including those of the fundamental x1x2 (or slow) thickness-shear mode. The coupled thickness-shear and flexural vibrations are studied for contoured quartz strip resonators having the shape of (a) a double wedge and (b) a plate with beveled edges. Exact solutions in terms of infinite power series are obtained by Frobenius method for the plates with linearly varying thickness in the x1 direction. Frequency spectra and mode shapes are computed for both types of resonators. The effects of the contour on the frequencies and modes are examined. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 63-72 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Two-dimensional governing equations for guided electromagnetic waves in isotropic or cubic crystal dielectric plates are extended to include the piezo-optic effect in the constitutive equations. These equations are then employed to study the frequency shifts of transverse electric modes caused by stresses in circular disk dielectric resonators under three cases of loading conditions: (1) a pair of diametral forces, (2) steady vertical acceleration, and (3) steady horizontal acceleration. In the latter two cases, the bottom face of the disk is bounded to a rigid supporting base.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 80 (1996), S. 3457-3465 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The two-dimensional first-order equations of incremental vibrations superposed on the steady and homogeneous thermal deformations of crystal plates by Lee and Yong are reduced to a set of four coupled equations for frequencies up to and including those of the fundamental x1x2 (or slow) thickness-shear mode. These equations are employed to study the frequency–temperature relations of the thickness-shear and flexural vibrations of beveled plates of AT cut of quartz. Closed form solutions for the uniform portion and analytical solutions in terms of infinite power series for the contoured portions are obtained. By requiring these solutions to satisfy the continuity conditions and traction-free edge conditions, the frequency equation is obtained. Effects of the contouring and the orientation angle of the plate are examined systematically by computing the frequency changes as a function of temperature increment for various values of geometric parameters and the orientation angle of the plate. Similar results for the uniform and finite plates are also computed and presented for comparison. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 1224-1232 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A formula for predicting the stress effect on the electromagnetic resonances of dielectric resonators is obtained by applying a perturbation method to the three-dimensional Maxwell's equations in which the dielectric permittivity tensor is perturbed by the applied stress (or strain) field through the piezo-optic effect. The dielectric resonator, which is surrounded by infinite free space, can be isotropic or anisotropic and of arbitrary shape. By using previously obtained two-dimensional closed-form solutions as the approximate unperturbed solutions, stress effect on the electromagnetic resonances in a dielectric circular disk is studied. Frequency changes of both the transverse electric and transverse magnetic modes are computed for disks of gallium arsenide and under three cases of loading: (1) a pair of diametral forces, (2) steady vertical acceleration, and (3) steady horizontal acceleration. In the latter two cases, the bottom face of the disk is supported by a rigid base. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 7681-7695 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A system of one-dimensional equations of motion for AT-cut quartz strip resonators with narrow width and for frequencies up to and including the fundamental thickness shear is deduced from the two-dimensional, first-order equations for piezoelectric crystal plates by Lee, Syngellakis, and Hou [J. Appl. Phys. 61, 1249 (1987)] by expanding the mechanical displacements and electric potentials in a series of trigonometric functions of the width coordinate. By neglecting the piezoelectric coupling and the weak mechanical coupling through c56, four groups of coupled equations of motion are obtained. For the equations of each group, closed form solutions are obtained and the traction-free conditions at four edges are accommodated. Dispersion curves and frequency spectrum are computed for quartz strips. The predicted frequency as a function of the length-to-thickness ratio and as a function of the width-to-thickness ratio of the quartz strips is compared with experimental data with good agreement.
    Type of Medium: Electronic Resource
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