Electric Current Dependent Fracture in GaN Piezoelectric Semiconductor Ceramics

In this paper, the fracture behavior of GaN piezoelectric semiconductor ceramics was investigated under combined mechanical and electric loading by using three-point bending tests and numerical analysis. The experimental results demonstrate that, in contrast to traditional insulating piezoelectric ceramics, electric current is a key factor in affecting the fracture characteristics of GaN ceramics. The stress, electric displacement, and electric current intensity factors were numerically calculated and then a set of empirical formulae was obtained. By fitting the experimental data, a fracture criterion under combined mechanical and electrical loading was obtained in the form of an ellipsoid function of intensity factors. Such a fracture criterion can be extended to predict the failure behavior of other piezoelectric semiconductors or devices with a crack, which are useful in their reliability design and applications.

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Analysis of Flexural Vibrations of a Piezoelectric Semiconductor Nanoplate Driven by a Time-Harmonic Force

Materials ◽

10.3390/ma14143926 ◽

2021 ◽

Vol 14 (14) ◽

pp. 3926

Author(s):

Mengen Li ◽

Qiaoyun Zhang ◽

Bingbing Wang ◽

Minghao Zhao

Keyword(s):

Electron Concentration ◽

Smart Devices ◽

Harmonic Force ◽

Plate Structures ◽

Piezoelectric Semiconductor ◽

Initial Electron ◽

Time Harmonic ◽

Semiconductor Plate ◽

Flexural Vibrations ◽

Piezoelectric Semiconductors

The performance of devices fabricated from piezoelectric semiconductors, such as sensors and actuators in microelectromechanical systems, is superior; furthermore, plate structures are the core components of these smart devices. It is thus important to analyze the electromechanical coupling properties of piezoelectric semiconductor nanoplates. We established a nanoplate model for the piezoelectric semiconductor plate structure by extending the first-order shear deformation theory. The flexural vibrations of nanoplates subjected to a transversely time-harmonic force were investigated. The vibrational modes and natural frequencies were obtained by using the matrix eigenvalue solver in COMSOL Multiphysics 5.3a, and the convergence analysis was carried out to guarantee accurate results. In numerical cases, the tuning effect of the initial electron concentration on mechanics and electric properties is deeply discussed. The numerical results show that the initial electron concentration greatly affects the natural frequency and electromechanical fields of piezoelectric semiconductors, and a high initial electron concentration can reduce the electromechanical fields and the stiffness of piezoelectric semiconductors due to the electron screening effect. We analyzed the flexural vibration of typical piezoelectric semiconductor plate structures, which provide theoretical guidance for the development of new piezotronic devices.

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Comparison of the fracture and failure behavior of injection-molded ?- and ?-polypropylene in high-speed three-point bending tests

Journal of Applied Polymer Science ◽

10.1002/(sici)1097-4628(19970613)64:11<2057::aid-app1>3.0.co;2-i ◽

1997 ◽

Vol 64 (11) ◽

pp. 2057-2066 ◽

Cited By ~ 144

Author(s):

J. Karger-Kocsis ◽

J. Varga ◽

G. W. Ehrenstein

Keyword(s):

High Speed ◽

Failure Behavior ◽

Bending Tests ◽

Three Point Bending ◽

Injection Molded

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The Higher Order Crack Tip Fields for Interfacial Crack between Linear Functionally Graded and Homogeneous Piezoelectric Materials

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1015.97 ◽

2014 ◽

Vol 1015 ◽

pp. 97-100

Author(s):

Yao Dai ◽

Xiao Chong ◽

Ying Chen

Keyword(s):

Piezoelectric Materials ◽

Electric Displacement ◽

Interfacial Crack ◽

Crack Tip ◽

Higher Order ◽

Functionally Graded ◽

Linear Functions ◽

Intensity Factors ◽

Crack Tip Fields ◽

Functionally Graded Piezoelectric Materials

The higher order crack-tip fields for an anti-plane crack situated in the interface between functionally graded piezoelectric materials (FGPMs) and homogeneous piezoelectric materials (HPMs) are presented. The mechanical and electrical properties of the FGPMs are assumed to be linear functions of y perpendicular to the crack. The crack surfaces are supposed to be insulated electrically. By using the method of eigen-expansion, the higher order stress and electric displacement crack tip fields for FGPMs and HPMs are obtained. The analytic expressions of the stress intensity factors and the electric displacement intensity factors are derived.

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Nonuniformly Loaded Stack of Antiplane Shear Cracks in One-Dimensional Piezoelectric Quasicrystals

Advances in Materials Science and Engineering ◽

10.1155/2018/4847837 ◽

2018 ◽

Vol 2018 ◽

pp. 1-11

Author(s):

G. E. Tupholme

Keyword(s):

Electric Displacement ◽

Polar Angle ◽

Antiplane Shear ◽

Shear Cracks ◽

Intensity Factors ◽

One Dimensional ◽

Isotropic Solid ◽

Special Cases ◽

Field Intensity Factors ◽

Explicit Representations

Representations in a closed form are derived, using an extension to the method of dislocation layers, for the phonon and phason stress and electric displacement components in the deformation of one-dimensional piezoelectric quasicrystals by a nonuniformly loaded stack of parallel antiplane shear cracks. Their dependence upon the polar angle in the region close to the tip of a crack is deduced, and the field intensity factors then follow. These exhibit that the phenomenon of crack shielding is dependent upon the relative spacing of the cracks. The analogous analyses, that have not been given previously, involving non-piezoelectric or non-quasicrystalline or simply elastic materials can be straightforwardly considered as special cases. Even when the loading is uniform and the crack is embedded in a purely elastic isotropic solid, no explicit representations have been available before for the components of the field at points other than directly ahead of a crack. Typical numerical results are graphically displayed.

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A Piezoelectric Screw Dislocation Interacting with a Dielectric Crack in a Hexagonal Piezoelectric Material

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.9.183 ◽

2005 ◽

Vol 9 ◽

pp. 183-190

Author(s):

Jin Xi Liu ◽

X.L. Liu

Keyword(s):

Electric Field ◽

Screw Dislocation ◽

Electric Displacement ◽

Image Force ◽

Mapping Method ◽

Piezoelectric Medium ◽

Intensity Factors ◽

Potential Jump ◽

Piezoelectric Screw Dislocation ◽

Dielectric Crack

This paper is concerned with the interaction of a piezoelectric screw dislocation with a semi-infinite dielectric crack in a piezoelectric medium with hexagonal symmetry. The solution of the considered problem is obtained from the dislocation solution of a piezoelectric half-plane adjoining a gas medium of dielectric constant ε0 by using the conformal mapping method. The intensity factors of stress, electric displacement and electric field and the image force on the dislocation are given explicitly. The effect of electric boundary conditions on the dislocation-crack interaction is analyzed and discussed in detail. The results show that ε0 only influences the electric displacement and electric field intensity factors and the image force produced by the electric potential jump.

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Interaction of a Screw Dislocation with Interface and Wedge-Shaped Cracks in One-Dimensional Hexagonal Piezoelectric Quasicrystals Bimaterial

Mathematical Problems in Engineering ◽

10.1155/2019/1037297 ◽

2019 ◽

Vol 2019 ◽

pp. 1-7

Author(s):

Lian he Li ◽

Yue Zhao

Keyword(s):

Screw Dislocation ◽

Electric Fields ◽

Electric Displacement ◽

Image Force ◽

Coupling Constants ◽

Geometrical Parameters ◽

Intensity Factors ◽

One Dimensional ◽

Special Cases ◽

Analytical Expressions

Interaction of a screw dislocation with wedge-shaped cracks in one-dimensional hexagonal piezoelectric quasicrystals bimaterial is considered. The general solutions of the elastic and electric fields are derived by complex variable method. Then the analytical expressions for the phonon stresses, phason stresses, and electric displacements are given. The stresses and electric displacement intensity factors of the cracks are also calculated, as well as the force on dislocation. The effects of the coupling constants, the geometrical parameters of cracks, and the dislocation location on stresses intensity factors and image force are shown graphically. The distribution characteristics with regard to the phonon stresses, phason stresses, and electric displacements are discussed in detail. The solutions of several special cases are obtained as the results of the present conclusion.

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Deformation and Failure Behavior of Wooden Sandwich Composites with Taiji Honeycomb Core under a Three-Point Bending Test

Materials ◽

10.3390/ma11112325 ◽

2018 ◽

Vol 11 (11) ◽

pp. 2325 ◽

Cited By ~ 6

Author(s):

Jingxin Hao ◽

Xinfeng Wu ◽

Gloria Oporto ◽

Jingxin Wang ◽

Gregory Dahle ◽

...

Keyword(s):

Shear Failure ◽

Dominant Role ◽

Honeycomb Structure ◽

Structure Design ◽

Bending Test ◽

Failure Behavior ◽

Sandwich Composites ◽

Honeycomb Core ◽

Deformation And Failure ◽

Three Point Bending

A new type of Taiji honeycomb structure bonded outside with wood-based laminates was characterized from a mechanical standpoint. Both theoretical and experimental methods were employed to analyze comprehensively the deformation behavior and failure mechanism under a three-point bending test. The analytical analysis reveals that a Taiji honeycomb has 3.5 times higher strength in compression and 3.44 times higher strength in shear compared with a traditional hexagonal honeycomb. Considering the strength-weight issue, the novel structure also displays an increase in compression strength of 1.75 times and shear strength of 1.72 times. Under a three-point bending test, indentation and core shear failure played the dominant role for the total failure of a wooden sandwich with Taiji honeycomb core. Typical face yield was not observed due to limited thickness-span ratio of specimens. Large spans weaken the loading level due to the contribution of global bending stress in the compressive skin to indentation failure. A set of analytical equations between mechanical properties and key structure parameters were developed to accurately predict the threshold stresses corresponding to the onset of those deformation events, which offer critical new knowledge for the rational structure design of wooden sandwich composites.

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Closed-form solution for piezoelectric layer with two collinear cracks parallel to the boundaries

Mathematical Problems in Engineering ◽

10.1155/mpe/2006/91846 ◽

2006 ◽

Vol 2006 ◽

pp. 1-16 ◽

Cited By ~ 3

Author(s):

B. M. Singh ◽

J. Rokne ◽

R. S. Dhaliwal

Keyword(s):

Closed Form ◽

Integral Equations ◽

Piezoelectric Layer ◽

Electric Displacement ◽

Closed Form Solution ◽

Finite Width ◽

Intensity Factors ◽

Collinear Cracks ◽

Triple Integral Equations ◽

Electromechanical Loading

We consider the problem of determining the stress distribution in an infinitely long piezoelectric layer of finite width, with two collinear cracks of equal length and parallel to the layer boundaries. Within the framework of reigning piezoelectric theory under mode III, the cracked piezoelectric layer subjected to combined electromechanical loading is analyzed. The faces of the layers are subjected to electromechanical loading. The collinear cracks are located at the middle plane of the layer parallel to its face. By the use of Fourier transforms we reduce the problem to solving a set of triple integral equations with cosine kernel and a weight function. The triple integral equations are solved exactly. Closed form analytical expressions for stress intensity factors, electric displacement intensity factors, and shape of crack and energy release rate are derived. As the limiting case, the solution of the problem with one crack in the layer is derived. Some numerical results for the physical quantities are obtained and displayed graphically.

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Stresses at the Surface of a Flat Three-Dimensional Ellipsoidal Cavity

Journal of Engineering Materials and Technology ◽

10.1115/1.3443360 ◽

1976 ◽

Vol 98 (2) ◽

pp. 164-172 ◽

Cited By ~ 6

Author(s):

L. Mirandy ◽

B. Paul

Keyword(s):

Stress Intensity ◽

Applied Stress ◽

Surface Stress ◽

Fracture Criterion ◽

Three Dimensional ◽

Two Dimensional ◽

Intensity Factors ◽

Ellipsoidal Cavity ◽

Isotropic Elastic Medium ◽

Analytical Expressions

The stress field associated with a thin ellipsoidal cavity in an isotropic elastic medium with arbitrary tractions at distant boundaries is needed to generalize Griffith’s two-dimensional fracture criterion. Such a solution is given here. It is first formulated for a general ellipsoidal cavity having principal semiaxes a, b, and c, and then it is reduced to the specific case of a “flat” ellipsoid for which a and b are very much greater than c. An explicit solution of the general problem is possible but the results are somewhat unwieldy. The dominant terms of an asymptotic solution for small c/b, however, are shown to provide remarkably simple expressions for the stresses everywhere on the surface of the cavity. The applied normal stress parallel to the c axis and the shears lying in a plane perpendicular to it were found to produce surface stresses proportional to (b/c) × applied stress, with the amplification of other components of applied stress being negligible in comparison. Analytical expressions for the location and magnitude of the maximum surface stress are developed along with stress intensity factors for the elliptical crack (c = 0). Three dimensional effects due to ellipsoidal planform aspect ratio (b/a) and Poisson’s ratio are reported.

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