Wyniki wyszukiwania - BazTech

1

On the problem of vibration protection of rotor systems with elastic adaptive elements of quasi-zero stiffness

Klitnoi Volodymyr, Gaydamaka Anatoliy

Diagnostyka

|

2020

|

Vol. 21, No. 2

69--75

EN

The analysis of scientific publications for rotor systems on the elastic supports made it possible to develop a basic version of the design scheme of active elastic support with controlled quasi-zero stiffness based on adaptive piezoceramic elements. The main components of the mathematical model of the functioning of active elastic supports with controlled quasi-zero stiffness based on adaptive piezoceramic elements are substantiated, which will help create the foundations of a theory for solving the problem of effective vibration protection. Numerical results show the possibility of effective applying of the proposed solution to the problem of rotor vibration damping.

2

Penny-shaped crack in a piezoceramic cylinder under Mode I loading

Narita F., Lin S., Shindo Y.

Archives of Mechanics

|

2003

|

Vol. 55, nr 3

275-304

EN

The electroelastic response of a penny-shaped crack in a piezoelectric cylinder of finite radius is investigated in this study. Fourier and Hankel transforms are used to reduce the problem to the solution of a pair of dual integral equations. They are then reduced to a Fredholm integral equation of the second kind. Numerical values of the stress intensity factor, energy release rate and energy density factor for piezoelectric ceramics are obtained to show the influence of applied electrical loads.

3

Transverse Actuation of Laminated Plates via Active Layers with Piezoceramic Fibers

Pietrzakowski M.

Zeszyty Naukowe Politechniki Rzeszowskiej. Mechanika

|

2002

|

z. 60 [197]

497-505

EN

In the paper the problem of orthotropic actuation of transverse structural vibrations using the Interdigitated Electrode Piezoelectric Fiber Composites (IDEPFCs) is analysed. The system considered is a thin symmetrically laminated rectangular plate with the embedded active IDEPFC layers or patches glued to the plate surfaces. The uniform fields approach is applied to derive the electromechanical constitutive relations and to model the piezoelectric device effective properties. The governing equation of the plate motion induced by the actuators supplied with an external voltage is formulated and solved for the steady-state case and simply supported boundary conditions. The influence of the piezoceramic material fraction and the active composite architecture including an orientation of the principal material axes on the dynamic response of the system is numerically examined and discussed.

4

Zależność temperaturowej stabilności częstotliwości rezonansowej od stopnia kowalentności wiązań B-O w piezoceramice typu PZT

Surowiak Z., Gavrilyachenko S. V., Kupriyanov M.F., Bochenek D.

Archiwum Nauki o Materiałach

|

2000

|

T. 21, nr 3-4

177-188

PL

Wykazano, że podstawową metodą polepszenia temperaturowej stabilności rezonansowej przetworników piezoceramicznych na bazie PZT jest dobór odpowiedniego składu chemicznego. Dotyczy to szczególnie pierwiastków podstawianych w pozycje B opisywanego układu. Ze wzrostem elektroujemności (EN) pierwiastków B wzrasta stopień kowalentności wiązań, a tym samym spontaniczna deformacja (delta) regularnej komórki elementarnej perowskitu. Piezoceramika staje się ferroelektrycznie twardsza, a jej struktura domenowa stabilniejsza, tzn. słabiej podatna na oddziaływania zewnętrzne, w tym na zmianę temperatury. W konsekwencji maleje delta fr/fr.

EN

It is shown that the choice of proper chemical composition is the basic method of improving thermal resonance stability of the piezoceramic transducers on the PZT basis. It mainly concerns elements substituted in positions B of the described system. With the increase of electronegativity of the B elements, the degree of bond covalence increases and, so does the simultaneous spontaneous deformation of the regular elementary cell of perovskite. Piezoceramics becomes ferroelectrically harder and its domain structure more stable, i.e. less voulnerable to exterior influences e.g. temperature change. As a consequence delta fr/fr decreases.