Influence of small cyclic and DC electrical loads on the fracture toughness of ferroelectric ceramics

Although piezoelectric ceramics are widely used, the structural reliability of these materials in long‐term service is still a concern. In this study, a nondestructive method for assessing material strength reliability using partial discharge (PD) tests is proposed. The PD inception electric field and the flexure strength are both controlled by the defects in the ceramics which suggests that the PD test can be an alternative nondestructive method for evaluating the structural reliability of piezoelectric ceramics. PD and four‐point flexure tests were carried out on piezoelectric ceramics. The influence of the PD test on samples was investigated by comparing the microstructure and electrical properties before and after the PD test. Samples which were not PD tested were also fractured and compared. It was found that no strength degradation was caused by the PD test. Weibull analysis revealed a correlation between the distribution in values for PD inception electric field and flexure strength.

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“…). These observations are in good agreement with previous reports . Obvious defects including pores are clearly seen.…”

Section: Resultssupporting

confidence: 93%

“…These observations are in good agreement with previous reports. 32,33 Obvious defects including pores are clearly seen. No distinct difference was observed between the fracture surfaces for specimens with and without the PD test.…”

Section: (A) (B)mentioning

confidence: 98%

Investigation of Partial Discharge and Fracture Strength in Piezoelectric Ceramics

et al. 2014

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“…J An air filled EC crack under the constraint of electrical breakdown behaves similar to a permeable crack, which is in agreement with experimental observations (Schneider et al, 2003;Engert et al, 2011). 3.…”

Section: Discussionsupporting

confidence: 87%

“…By decreasing the value of dielectric strength to E d ¼1 MV/m, of the order of the experimentally measured value for air (Tipler, 1987), the crack behavior approaches that of a permeable crack. Interestingly, experiments also confirm that the effective permittivity inside the air filled crack is much higher than that of air and the effect of applied electric fields in retarding crack growth decreases significantly with increasing the permittivity of the crack interior (Schneider et al, 2003;Engert et al, 2011).…”

Section: Propagating Cracks In Piezoelectricsmentioning

confidence: 71%

Phase-field modeling of crack propagation in piezoelectric and ferroelectric materials with different electromechanical crack conditions

Abdollahi

Arias

2012

Journal of the Mechanics and Physics of Solids

140

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a b s t r a c tWe present a family of phase field models for fracture in piezoelectric and ferroelectric materials. These models couple a variational formulation of brittle fracture with, respectively, (1) the linear theory of piezoelectricity, and (2) a Ginzburg Landau model of the ferroelectric microstructure to address the full complexity of the fracture phenomenon in these materials. In these models, both the cracks and the ferroelectric domain walls are represented in a diffuse way by phase fields. The main challenge addressed here is encoding various electromechanical crack models (introduced as crack face boundary conditions in sharp models) into the phase field framework. The proposed models are verified through comparisons with the corresponding sharp crack models. We also perform two dimensional finite element simulations to demonstrate the effect of the different crack face conditions, the electromechanical loading and the media filling the crack gap on the crack propagation and the microstructure evolution. Salient features of the results are compared with experiments.

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“…For the type of fracture mechanics model considered here, even the grain structure of the material is neglected and straight cracks are assumed. However, it is observed in fracture experiments with PZT that the fracture surfaces have typically a roughness on the order of the grain size [31,32]. Hence, the characteristic dimensions being associated with crack bridging and, possibly, microcracking effects are probably determined by the grain size as well.…”

Section: Characteristic Size Of the Fpzmentioning

confidence: 99%

On the Prediction of R-Curves for Ferroelectroelastic Ceramics

Stark

Neumeister

Balke

2013

Journal of Applied Mechanics

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In ferroeiectroeiastic ceramics, the process of fracture is accompanied by significant inelastic deformation due to domain switching. This leads to an apparent toughening of the material, which is known as R-curve behavior. A promising approach to predict Rcwves is based on one parameter fracture criteria. The scope of this paper is the examination of the physical validity of these criteria for realistic material behavior. Besides a general discussion of the problem, fracture of the lead zirconate titanate ceramic PIC151 is examined. Thereby, restriction is made to purely mechanical material behavior. The results indicate that the usage of one parameter fracture criteria is questionable. This is due to a confiict between the length scale of the zone wherein the asymptotic crack tip singularity dominates in the field solution of the continuum model and the length scale associated with the fi-acture process zone. It is concluded that an incorporation of the fracture process into the used fracture mechanics model is necessary to capture transient fracture of ferroeiectroeiastic ceramics properly.

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Influence of small cyclic and DC electrical loads on the fracture toughness of ferroelectric ceramics

Cited by 14 publications

References 36 publications

Investigation of Partial Discharge and Fracture Strength in Piezoelectric Ceramics

Investigation of Partial Discharge and Fracture Strength in Piezoelectric Ceramics

Phase-field modeling of crack propagation in piezoelectric and ferroelectric materials with different electromechanical crack conditions

On the Prediction of R-Curves for Ferroelectroelastic Ceramics

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