Influence of Electric Fields on the Fracture Behavior of Ferroelectric Ceramics under Combined Electromechanical Loading

2006 ◽  
Vol 306-308 ◽  
pp. 1199-1204 ◽  
Author(s):  
Zhan Wei Liu ◽  
Dai Ning Fang ◽  
Hui Min Xie
Keyword(s):  
Fracture Toughness ◽  
Electric Field ◽  
Electric Fields ◽  
Crack Extension ◽  
Fracture Behavior ◽  
Ferroelectric Ceramics ◽  
Normal Strain ◽  
Electric Field Direction ◽  
Poling Direction ◽  
Electromechanical Loading

In this paper, fracture behavior of ferroelectric ceramics under combined electromechanical loading was investigated using moiré interferometry. It is found that the influence of electric field on fracture toughness is not very larger in the case that the directions of the poling, electric field and crack extension are perpendicular to each other. When the poling direction is parallel to the crack extension direction and both are perpendicular to the electric field direction, the normal strain measured reduced faster than that calculated by FEM with and without electrical loading as the distance away from the crack tip increases. Fracture toughness decreases obviously as the electric-field intensity increases.

Effect of Electromechanical Loadings on Fracture Strength of Piezoelectric Ceramics

2007 ◽  
Vol 353-358 ◽  
pp. 1544-1547
Author(s):  
Byeung Gun Nam ◽  
H.S. Na ◽  
R. Liu ◽  
Katsuhiko Watanabe
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Fracture Strength ◽  
Applied Electric Field ◽  
Crack Extension ◽  
Piezoelectric Ceramics ◽  
Fracture Load ◽  
Open Circuit ◽  
Condition Effect ◽  
Electromechanical Loading

The effect of electromechanical loadings including their sequence, which was motivated by the property of crack energy density for piezoelectric material, was experimentally investigated. Three-point bending fracture test was performed for two piezoelectric ceramics under different electromechanical loading conditions. It was found that the fracture loads under closed circuit condition are greater than those under open circuit condition. Effect of applied electric field on fracture load in the test varied with materials. Applied electric field always enhanced crack extension in C-21 ceramics regardless of their directions, while it produced very little effect on crack extension under negative electric fields in C-2 ceramics. It was also found that electromechanical loading sequence clearly affects fracture strength, although its effect varies also with materials.

Investigations on Multi-axial Domain Switching Criteria for Piezoceramics

2005 ◽  
Vol 881 ◽  
Author(s):  
Bernd Laskewitz ◽  
Dayu Zhou ◽  
Marc Kamlah
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Domain Switching ◽  
Axial Stress ◽  
Initial Domain ◽  
Hollow Cylinders ◽  
Thin Walled ◽  
Electromechanical Loading ◽  
Stress States ◽  
Strain Responses

AbstractInitially unpoled soft PZT was subjected to a proportional, coaxial electromechanical loading. The ratio of compressive stress to electric field was changed between the experiments. From this series of nonlinear polarization and strain responses were obtained. Based on an offset method, initial domain switching states in the two-dimensional stress-electric field space were determined. In continuum mechanics, thin walled tubes are used to investigate multi-axial stress states. In this context, thin walled means a ratio of wall thickness to radius of 1:10 or thinner. However, simple linear dielectric analysis indicates an inhomogeneous electric field distribution in such geometries.Therefore, the suitability of hollow cylinders (in the range from thick to thin walled tubes) for multi-axial electromechanical experiments has to be investigated. Simulations with a finite element tool based on a phenomenological constitutive model for ferroelectric and ferroelastic hysteresis behavior were performed. The results confirm inhomogeneous distributions of electric fields and stresses after poling. A geometry variation is discussed to minimize these effects.

Crack tip 90° domain switching in tetragonal lanthanum-modified lead zirconate titanate under an electric field

1999 ◽  
Vol 14 (7) ◽  
pp. 2940-2944 ◽  
Author(s):  
Fei Fang ◽  
Wei Yang ◽  
Ting Zhu
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Lead Zirconate Titanate ◽  
Powder Processing ◽  
Domain Switching ◽  
Crack Tip ◽  
Lead Zirconate ◽  
Processing Technique ◽  
Ferroelectric Ceramics ◽  
Zirconate Titanate

Lanthanum-modified lead zirconate titanate ferroelectric ceramics (Pb0.96La0.04)(Zr0.40Ti0.60)0.99O3 were synthesized by the conventional powder processing technique. X-ray diffraction experiments revealed that the samples belong to the tetragonal phase with a = b = 0.4055 nm, c = 0.4109 nm, and c/a = 1.013. After being poled, the samples were indented with a 5-kg Vickers indenter, and lateral electric fields of 0.4 Ec, 0.5 Ec, and 0.6 Ec (Ec = 1100 V/mm) were applied, respectively. Field-emission scanning electron microscopy showed that 90° domain switching appeared near the tip of the indentation crack under a lateral electric field of 0.6 Ec. A mechanism of 90° domain switching near the crack tip under an electric field is discussed.

An Estimation Method of Electric Field Forces on a Single Bubble

2010 ◽  
Author(s):  
Yaozu Song ◽  
Feng Chen ◽  
Yao Peng
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Theoretical Calculations ◽  
Estimation Method ◽  
Electrode System ◽  
Single Bubble ◽  
Theoretical Formula ◽  
Bubble Behavior ◽  
Electrode Structure ◽  
Electric Field Direction

It has been well-known that externally imposed static electric fields have a significant effect on bubble dynamic behavior, especially on bubble departure behavior. With increasing electric field strength, bubble detachment volume decreases and bubble shape elongates along the electric field direction. It is electric field forces that change bubble behavior. The electric field forces can be calculated from theoretical formula for a simple electrode structure. However, for the complex electrode system, it is rather a tough thing to theoretically solve electric field forces. In this work a new method to experimentally estimate electric field forces exerted on a single bubble has been presented. Experimental estimation primarily depends upon decreasing in the buoyancy on the bubble. Furthermore, the calculations coming from theoretical formula have also been completed and the results show that experimental estimations agree well with theoretical calculations.

Development of a Material Constitutive Model and Simulation Technique to Predict Nonlinearities in Piezoelectric Materials under Weak Electric Fields

2017 ◽  
pp. 271-303
Author(s):  
M. K. Samal
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Lead Zirconate Titanate ◽  
Domain Walls ◽  
Piezoelectric Materials ◽  
Experimental Results ◽  
Ferroelectric Ceramics ◽  
Rayleigh Law ◽  
Model And Simulation ◽  
Near Resonance

Piezoceramic materials exhibit different types of nonlinearities depending upon the magnitude of the mechanical and electric field strength in the continuum. Some of the nonlinearities observed under weak electric fields are: presence of superharmonics in the response spectra and jump phenomena etc. especially if the system is excited near resonance. It has also been observed by many researchers that, at weak alternating stress fields, the relationship between the piezoelectrically induced charge and applied stress in ferroelectric ceramics, has the same form as the Rayleigh law (for magnetization versus magnetic field) in ferromagnetic materials. Applicability of the Rayleigh law to the piezoelectric effect has been demonstrated for Lead Zirconate Titanate ceramics by many researchers and their experimental results indicate that the dominant mechanism responsible for piezoelectric hysteresis and the dependence of the piezoelectric coefficient on the applied alternating stress is the pinning of non-180° domain walls. In this chapter, the Rayleigh law for ferromagnetic hysteresis has been modified and incorporated in a nonlinear electric enthalpy function and then applied in the analysis of hysteresis behavior of piezoelectric continua. Analytical solutions have been derived for a cantilever beam actuated by two piezo-patches attached to the top and bottom of the beam and excited by opposite electric fields. Analysis has been carried out at different electric field excitations of varying amplitude and frequencies and the results have been compared with the available experimental results from literature.

Electro-optic phenomena

2004 ◽  
Author(s):  
Robert E. Newnham
Keyword(s):  
Light Intensity ◽  
Electric Field ◽  
Electric Fields ◽  
Communication Systems ◽  
Ferroelectric Ceramics ◽  
Refractive Indices ◽  
Lead Lanthanum Zirconate Titanate ◽  
Lanthanum Zirconate ◽  
The Third ◽  
Electro Optic

Optical beams can be controlled by manipulating the refractive indices and absorption coefficients with applied electric fields. In communication systems electro-optic effects are used in phase and amplitude modulation, in beam deflectors, and in tunable filters. Three such effects are illustrated in Fig. 28.1. Lead lanthanum zirconate titanate (PLZT) is a transparent electroceramic that can be prepared in several different ferroelectric forms with large electro-optic coefficients. When prepared in a normal ferroelectric form it can be used in two different ways. A light-tunable shutter is constructed by coating a multidomain ceramic of PLZT with a photoconducting layer and transparent electrodes. A bias voltage on the electrodes is transferred to the ceramic when the photoconductor is illuminated. The electric field alters the domain structure and the degree of light scattering, controlling the intensity of light. Fully poled ferroelectric ceramics exhibit the linear electro-optic effect Using planar electrodes the PLZT is poled perpendicular to the optical beam. Polarizer and analyzer are positioned in the ±45◦ positions, and light intensity is controlled by altering the birefringence with an electric field. The third experiment utilizes a pseudo-cubic PLZT composition with a large quadratic electro-optic effect. No poling is required in this case. With polarizer and analyzer again in the ±45◦ positions, the transmitted light intensity is proportional to E2 rather than E. Linear and quadratic electro-optic coefficients are defined in terms of the fieldinduced changes in the optical indicatrix: . . . Bij(E) − Bij(0) = Δ

scholarly journals Deformation of Emulsion Droplet with Clean and Particle-Covered Interface under an Electric Field

Materials ◽  
2020 ◽  
Vol 13 (13) ◽  
pp. 2984
Author(s):  
Muhammad Salman Abbasi ◽  
Haroon Farooq ◽  
Hassan Ali ◽  
Ali Hussain Kazim ◽  
Rabia Nazir ◽  
...  
Keyword(s):  
Electric Field ◽  
Simulation Model ◽  
Electric Fields ◽  
Applied Electric Field ◽  
Small Deformation ◽  
Spherical Shape ◽  
Emulsion Droplet ◽  
Navier Stokes Equation ◽  
New Findings ◽  
Electric Field Direction

The electrohydrodynamic deformation of an emulsion droplet with a clean and particle-covered interface was explored. Here, the electrohydrodynamic deformation was numerically and experimentally demonstrated under the stimuli of moderate and strong electric fields. The numerical method involves the coupling of the Navier–Stokes equation with the level set equation of interface tracking and the governing equations of so-called leaky dielectric theory. The simulation model developed for a clean interface droplet was then extended to a capsule model for densely particle-covered droplets. The experiments were conducted using various combinations of immiscible oils and particle suspensions while the electric field strength ~105 V/m was generated using a high voltage supply. The experimental images obtained by the camera were post-processed using an in-house image processing code developed on the plat-form of MATLAB software. The results show that particle-free droplets can undergo prolate (deformation in the applied electric field direction) or oblate deformation (deformation that is perpendicular to the direction of the applied electric field) of the droplet interface, whereas the low-conductivity particles can be manipulated at the emulsion interface to form a ‘belt’, ‘helmet’ or ‘cup’ morphologies. A densely particle-covered droplet may not restore to its initial spherical shape due to ‘particle jamming’ at the interface, resulting in the formation of unique droplet shapes. Densely particle-covered droplets behave like droplets covered with a thin particle sheet, a capsule. The deformation of such droplets is explored using a simulation model under a range of electric capillary numbers (i.e., the ratio of the electric stresses to the capillary stresses acting at the droplet interface). The results obtained are then compared with the theory and experimental findings. It was shown that the proposed simulation model can serve as a tool to predict the deformation/distortion of both the particle-free and the densely particle-covered droplets within the small deformation limit. We believe that this study could provide new findings for the fabrication of complex-shaped species and colloidosomes.

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