Domain switch toughening in polycrystalline ferroelectrics

2006 ◽  
Vol 21 (1) ◽  
pp. 13-20 ◽  
Author(s):  
Jianxin Wang ◽  
Chad M. Landis
Keyword(s):  
Fracture Toughness ◽  
Crack Growth ◽  
Domain Switching ◽  
Ferroelectric Ceramic ◽  
Material Behavior ◽  
Constitutive Law ◽  
Ferroelectric Ceramics ◽  
The Finite Element Method ◽  
Switching Models ◽  
Domain Switch

Mode I steady crack growth was analyzed to determine the toughening due to domain switching in ferroelectric ceramics. A multi-axial, electromechanically coupled, incremental constitutive theory is applied to model the material behavior of the ferroelectric ceramic. The constitutive law is then implemented within the finite element method to study steady crack growth. The effects of mechanical and electrical poling on the fracture toughness are investigated. Results for the predicted fracture toughness, remanent strain distributions, and domain switching zone shapes and sizes are presented. Finally, the model predictions are discussed in comparison discrete switching models and to experimental observations.

Domain Switch Toughening in Polycrystalline Ferroelectrics

2005 ◽  
Vol 881 ◽  
Author(s):  
Chad M. Landis ◽  
Jianxin Wang
Keyword(s):  
Fracture Toughness ◽  
Crack Growth ◽  
Domain Switching ◽  
Ferroelectric Ceramic ◽  
Material Behavior ◽  
Constitutive Law ◽  
Ferroelectric Ceramics ◽  
The Finite Element Method ◽  
Model Predictions ◽  
Domain Switch

AbstractMode I steady crack growth is analyzed to determine the toughening due to domain switching in poled ferroelectric ceramics. A multi-axial, electromechanically coupled, incremental constitutive theory is applied to model the material behavior of the ferroelectric ceramic. The constitutive law is then implemented within the finite element method to study steady crack growth. The effects of mechanical and electrical poling on the fracture toughness are investigated. Results for the predicted fracture toughness, remanent strain and remanent polarization distributions, and domain switching zone shapes and sizes are presented. Finally, the model predictions are discussed in comparison to experimental observations.

A Phenomenological Constitutive Model of Ferroelectrics with Gradual Domain Switching

2007 ◽  
Vol 345-346 ◽  
pp. 813-816
Author(s):  
L. Yu ◽  
Shou Wen Yu ◽  
Xi Qiao Feng
Keyword(s):  
Constitutive Model ◽  
Domain Switching ◽  
Volume Fraction ◽  
Internal Variable ◽  
Ferroelectric Materials ◽  
Constitutive Law ◽  
Ferroelectric Ceramics ◽  
External Loading ◽  
Nonlinear Hysteresis ◽  
Gradual Domain Switching

In this paper, a phenomenological, nonlinear constitutive relation of ferroelectric ceramics is established by considering the fact that domain switching happens gradually with the external loading. A simplified gradual switching model is suggested and implemented into the constitutive law of ferroelectric materials. The volume fraction of domain switching is used as the internal variable in the model, and its evolution equation with mechanical/electrical loading is given. Comparison with experimental results shows that this simple constitutive model can predict the nonlinear hysteresis responses of ferroelectric materials.

Domain Switching and Crack Tip Opening Stress Variation in Ferroelectric Ceramics

2005 ◽  
Vol 297-300 ◽  
pp. 2557-2566
Author(s):  
Sang Joo Kim ◽  
Yun Jae Kim
Keyword(s):  
Electric Fields ◽  
Domain Switching ◽  
Crack Tip ◽  
Ferroelectric Ceramic ◽  
External Stress ◽  
Ferroelectric Ceramics ◽  
Crack Plane ◽  
Ceramic Specimen ◽  
Stress Variation ◽  
Crack Tip Opening

Evolution of switching zone near a crack tip in ferroelectric ceramics is calculated using the constitutive equations proposed in [1], with an assumption that switching-induced internal fields are minimized by fine domain microstructures and moving charges. A two-dimensional ferroelectric ceramic specimen that has an edge crack and that is poled perpendicular to the crack plane are subjected to external stress and electric fields. Diverse crack tip microstructures are obtained depending on both the history and the ratio of electric and stress loads. It is shown that opposite crack tip opening stresses under the same electric fields are due to opposite distributions of piezoelectric coefficients in the specimens with different crack tip microstructures.

Electric Dipole Model and Computer Simulation of the Fracture Behavior of a Conductive Crack in a Dielectric Material

2004 ◽  
Vol 855 ◽  
Author(s):  
Tianhong Wang ◽  
Xiaosheng Gao
Keyword(s):  
Fracture Toughness ◽  
Lead Zirconate Titanate ◽  
Electric Dipole ◽  
Fracture Behavior ◽  
Domain Switching ◽  
Dielectric Material ◽  
Dipole Model ◽  
Ferroelectric Ceramics ◽  
Mechanical Fracture ◽  
Microstructural Modeling

ABSTRACTFracture tests on poled and depoled lead zirconate titanate (PZT) ceramics indicate that purely electric fields are able to propagate the conductive cracks (notches) and fracture the samples. To understand the fracture behavior of conducting cracks in ferroelectric ceramics, an electric dipole model is proposed, in which a discrete electric dipole is used to represent the local spontaneous polarization and the force couples are used to represent the local strains. The electric dipole model provides basic solutions for microstructural modeling. The microstructural modeling is based on a domain switching mechanism. The domain structure is simulated with a grid of points where polarizations and strains vary with the applied loads. As a first step study, the microstructural modeling is conducted for a dielectric material with a conductive crack. The simulation result explains why the electric fracture toughness is much higher than the mechanical fracture toughness.

Fatigue Investigation of Elastomeric Structures

2010 ◽  
Vol 38 (3) ◽  
pp. 194-212 ◽  
Author(s):  
Bastian Näser ◽  
Michael Kaliske ◽  
Will V. Mars
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Material Behavior ◽  
Period Effect ◽  
Numerical Representation ◽  
Material Force ◽  
Strain Behavior ◽  
Dissipative Effects ◽  
Elastomeric Materials

Abstract Fatigue crack growth can occur in elastomeric structures whenever cyclic loading is applied. In order to design robust products, sensitivity to fatigue crack growth must be investigated and minimized. The task has two basic components: (1) to define the material behavior through measurements showing how the crack growth rate depends on conditions that drive the crack, and (2) to compute the conditions experienced by the crack. Important features relevant to the analysis of structures include time-dependent aspects of rubber’s stress-strain behavior (as recently demonstrated via the dwell period effect observed by Harbour et al.), and strain induced crystallization. For the numerical representation, classical fracture mechanical concepts are reviewed and the novel material force approach is introduced. With the material force approach at hand, even dissipative effects of elastomeric materials can be investigated. These complex properties of fatigue crack behavior are illustrated in the context of tire durability simulations as an important field of application.

Direct measurement of the domain switching contribution to the dynamic piezoelectric response in ferroelectric ceramics

2006 ◽  
Vol 89 (9) ◽  
pp. 092901 ◽  
Author(s):  
Jacob L. Jones ◽  
Mark Hoffman ◽  
John E. Daniels ◽  
Andrew J. Studer
Keyword(s):  
Direct Measurement ◽  
Domain Switching ◽  
Ferroelectric Ceramics ◽  
Piezoelectric Response

The Fracture Toughness of Hardened Tool Steels

1987 ◽  
Vol 109 (4) ◽  
pp. 314-318 ◽  
Author(s):  
D. F. Watt ◽  
Pamela Nadin ◽  
S. B. Biner
Keyword(s):  
Fracture Toughness ◽  
Crack Growth ◽  
Slow Crack Growth ◽  
Crack Opening ◽  
Compact Tension ◽  
Testing Procedure ◽  
Tool Steels ◽  
Opening Displacement ◽  
Tempering Temperature ◽  
Toughness Testing

This report details the development of a three-stage fracture toughness testing procedure used to study the effect of tempering temperature on toughness in 01 tool steel. Modified compact tension specimens were used in which the fatigue precracking stage in the ASTM E-399 Procedure was replaced by stable precracking, followed by a slow crack growth. The specimen geometry has been designed to provide a region where slow crack growth can be achieved in brittle materials. Three parameters, load, crack opening displacement, and time have been monitored during the testing procedure and a combination of heat tinting and a compliance equation have been used to identify the position of the crack front. Significant KIC results have been obtained using a modified ASTM fracture toughness equation. An inverse relationship between KIC and hardness has been measured.

Semi-inverse method for predicting stress–strain relationship from cone indentations

2003 ◽  
Vol 18 (9) ◽  
pp. 2068-2078 ◽  
Author(s):  
A. DiCarlo ◽  
H. T. Y. Yang ◽  
S. Chandrasekar
Keyword(s):  
A Priori ◽  
Model Material ◽  
Material Behavior ◽  
The Finite Element Method ◽  
Stress Strain ◽  
Indentation Tests ◽  
Strain Relationship ◽  
Initial Force ◽  
Relationship Of ◽  
Force Displacement

A method for determining the stress–strain relationship of a material from hardness values H obtained from cone indentation tests with various apical angles is presented. The materials studied were assumed to exhibit power-law hardening. As a result, the properties of importance are the Young's modulus E, yield strength Y, and the work-hardening exponent n. Previous work [W.C. Oliver and G.M. Pharr, J. Mater. Res. 7, 1564 (1992)] showed that E can be determined from initial force–displacement data collected while unloading the indenter from the material. Consequently, the properties that need to be determined are Y and n. Dimensional analysis was used to generalize H/E so that it was a function of Y/E and n [Y-T. Cheng and C-M. Cheng, J. Appl. Phys. 84, 1284 (1999); Philos. Mag. Lett. 77, 39 (1998)]. A parametric study of Y/E and n was conducted using the finite element method to model material behavior. Regression analysis was used to correlate the H/E findings from the simulations to Y/E and n. With the a priori knowledge of E, this correlation was used to estimate Y and n.

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