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1
Content available Axial vibration of bars using fractional viscoelastic material models
Łabędzki P., Pawlikowski R., Radowicz A.
Vibrations in Physical Systems
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2018
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Vol. 29
art. no. 2018009
EN
This paper presents dynamic analysis of a bar with one end fixed and other free, loaded with force at its free end. The viscoelastic material of the bar is described by fractional models (Scot-Blair, Voigt, Maxwell and Zener models). Rayleigh-Ritz and Laplace transform methods were applied to obtain closed-form solution of the considered problem.
2
Content available remote Analiza teoretyczno-symulacyjna transformatora piezoelektrycznego
Łabędzki P., Pawlikowski R., Radowicz A.
Mechanik
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2016
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R. 89, nr 12
1836--1839
PL
Przedstawiono analizę teoretyczno-symulacyjną transformatora piezoelektrycznego o dowolnej konfiguracji. Poszukiwano optymalnych parametrów geometrycznych ze względu na uzyskiwane wzmocnienie napięcia. Dokonano analizy pracy transformatora przy różnych postaciach drgań własnych dla dwóch różnych materiałów.
EN
Theoretical and simulation analysis for the description of a piezoelectric transformer with respect to unrestricted configuration is developed. The working conditions of the transformer dependent on various eigen vibrations for two different kinds of material are considered and the influence of the gauge optimal parameters on a voltage amplification have been studied.
3
Content available Conversion excitation of intense sound fields in crystals
Alshits V., Bessonova D., Lyubimov V., Radowicz A.
Vibrations in Physical Systems
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2014
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Vol. 26
13--20
EN
The resonant excitation of an intense elastic wave in a crystal is described through a special nonspecular reflection close to a conversion when almost all the energy from the incident pump wave falls into the near-surface narrow high-intensity reflected beam. The resonance arises when the excited reflected wave is close to the bulk eigenmode satisfying the condition of free boundary. It is shown that the choice of the crystal surface parallel to a symmetry plane allows simultaneous optimization of reflection geometry when the intensity maximum for the excited wave is accompanied by the intensity minimum for the other (parasite) reflected wave. And the conversion criterion of vanishing of the above minimum is determined by one definite condition on elastic moduli. On this basis the series of real monoclinic, orthorhombic and hexagonal crystals were chosen where the resonant reflection in non-symmetric sagittal planes proves to be very close to conversion.
4
Content available remote Topological wave features near degeneracies in acoustics and optics of absorptive crystals
Alshits V., Lyubimov V., Radowicz A.
Vibrations in Physical Systems
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2012
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Vol. 25
33--40
EN
The unified formalism for description of acoustic and optic properties is developed for directions close to degeneracies in absorbing crystals. The absorption splits a conical degeneracy which causes topological transformations in polarization and geometrical features of degenerate branches. Polarization ellipses distributions gain singularities at the degeneracy points characterized by the Poincaré indices n = ±1/4. The slowness surfaces acquire lines of self-intersection connecting the split degeneracy points where the wedge of intersection has infinitely sharp tips. Geometrical and polarization singularities due to absorption create non-trivial features in conical refraction. For any direction of propagation in the vicinity of the split axes the ray velocity precesses along the universal cone of refraction. Kinematics of this precession appreciably depends on the propagation direction. Conditions for experimental observation of the predicted effects are discussed.
5
Electric componentes of acoustic fields in piezoelectrics and some their topological features
Alshits V. I., Lyubimov V. N., Radowicz A.
Zeszyty Naukowe Politechniki Świętokrzyskiej. Mechanika
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2004
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Z. 81
45-69
EN
The existence conditions of zero electric fields E and zero electric displacements D are studied for bulk acoustic waves in piezoelectric crystals. General equations are derived for lines of zero electric fields, E(m) = O, and for specific points mo of vanishing electric displacements, D(mo) = O, on the unit sphere of propagation directions m2 = 1. It is proved that the both types of specific directions must exist in any (even triclinic) crystals.The obtained equations are solved for a series of examples of particular crystal symmetry. It is shown that the vectors D(m) being generally orthogonal to the wave normal m are characterized bydefinite orientational singularities in the vicinity of mo and can be described by the poincare indices n+O, +- 1 or +-2. The algebraic expressions for indices n are found both for unrestricted anisotropy and for a series of particular cases.
6
Green's function for an infinite piezoelectric strip with a general line defect
Nowacki J. P., Alshits V. L., Radowicz A.
Journal of Technical Physics
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2002
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Vol. 43, no 2
133-153
EN
The 2D electro-elastic fields are found in the piezoelectric strip with the straight general line defect parallel to the surfaces and consisting of the four coinciding sources: the line of forces, the charged line, the dislocation line and its electrostatic analogue. Electrically, the strip is supposed to be placed between two isotropic dielectric media. Mechanically, three boundary conditions are considered: (i) both the surfaces are free; (ii) both the surfaces are clamped; and (iii) one surface is free and the other is clamped. The solutions obtained for a general case of unrestricted anisotropy are presented in the form of convergent Fourier integrals, in terms of the eigenvectors and eigenvalues of the generalized Stroh problem. Determination of these eigenvalues and eigenvectors requires additional computing. Specific features of the derived solutions at infinity are analyzed.
7
The peculiarities of the resonant excitations of surface elastic waves in dissipative anisotropic media
Alshits V. I., Lyubimov V. N., Radowicz A.
Zeszyty Naukowe Politechniki Świętokrzyskiej. Mechanika
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1998
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Z. 66
45-53
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