Stress field intensity factors for propagating brittle cracks

1967 ◽  
Vol 3 (2) ◽  
Author(s):  
T.A.C. Stock
Keyword(s):  
Stress Field ◽  
Field Intensity ◽  
Intensity Factors ◽  
Field Intensity Factors

Three-Dimensional Electroelastic Analysis of a Piezoelectric Material With a Penny-Shaped Dielectric Crack

2004 ◽  
Vol 71 (6) ◽  
pp. 866-878 ◽  
Author(s):  
Xian-Fang Li ◽  
Kang Yong Lee
Keyword(s):  
Boundary Conditions ◽  
Piezoelectric Material ◽  
Field Intensity ◽  
Three Dimensional ◽  
Intensity Factors ◽  
Elementary Functions ◽  
Dual Integral Equations ◽  
Electroelastic Field ◽  
Field Intensity Factors ◽  
Dielectric Crack

Previous studies assumed that a crack is either impermeable or permeable, which are actually two limiting cases of a dielectric crack. This paper considers the electroelastic problem of a three-dimensional transversely isotropic piezoelectric material with a penny-shaped dielectric crack perpendicular to the poling axis. Using electric boundary conditions controlled by the boundaries of an opening crack, the electric displacements at the crack surfaces are determined. The Hankel transform technique is employed to reduce the considered problem to dual integral equations. By solving resulting equations, the results are presented for the case of remote uniform loading, and explicit expressions for the electroelastic field at any point in the entire piezoelectric body are given in terms of elementary functions. Moreover, the distribution of asymptotic field around the crack front and field intensity factors are determined. Numerical results for a cracked PZT-5H ceramic are evaluated to examine the influence of the dielectric permittivity of the crack interior on the field intensity factors, indicating that the electric boundary conditions at the crack surfaces play an important role in determining electroelastic field induced by a crack, and that the results are overestimated for an impermeable crack, and underestimated for a permeable crack.

scholarly journals Exact Solutions for Interaction of Parallel Screw Dislocations with a Wedge Crack in One-Dimensional Hexagonal Quasicrystal with Piezoelectric Effects

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Xin Lv ◽  
Guan-Ting Liu
Keyword(s):  
Crack Propagation ◽  
Field Line ◽  
Field Intensity ◽  
Wedge Angle ◽  
Image Force ◽  
Intensity Factors ◽  
One Dimensional ◽  
Line Force ◽  
Shaped Crack ◽  
Field Intensity Factors

The purpose of this paper is to consider the interaction between many parallel dislocations and a wedge-shaped crack and their collective response to the external applied generalized stress in one-dimensional hexagonal piezoelectric quasicrystal, employing the complex variable function theory and the conformal transformation method; the problem for the crack is reduced to the solution of singular integral equations, which can be further reduced to solving Riemann–Hilbert boundary value problems. The analytical solutions of the generalized stress field are obtained. The dislocations are subjected to the phonon field line force, phason field line force, and line charge at the core. The positions of the dislocations are arbitrary, but the dislocation distribution is additive. The dislocation is not only subjected to the external stress and the internal stress generated by the crack, but also to the force exerted on it by other dislocations. The closed-form solutions are obtained for field intensity factors and the image force on a screw dislocation in the presence of a wedge-shaped crack and a collection of other dislocations. Numerical examples are provided to show the effects of wedge angle, dislocation position, dislocation distribution containing symmetric configurations and dislocation quantities on the field intensity factors, energy release rate, and image force acting on the dislocation. The principal new physical results obtained here are (1) the phonon stress, phason stress, and electric displacement singularity occur at the crack tip and dislocations cores, (2) the increasing number of dislocations always accelerates the crack propagation, (3) the effect of wedge angle on crack propagation is related to the distribution of dislocations, and (4) the results of the image force on the dislocation indicate that the dislocations can either be attracted or rejected and reach stable positions eventually.

Analysis of multiple moving mode-III cracks in a functionally graded magnetoelectroelastic half-plane

2017 ◽  
Vol 28 (19) ◽  
pp. 2823-2834 ◽  
Author(s):  
Mojtaba Ayatollahi ◽  
Mojtaba Mahmoudi Monfared ◽  
Mahsa Nourazar
Keyword(s):  
Integral Equations ◽  
Half Plane ◽  
Field Intensity ◽  
Electric Displacement ◽  
Singular Integral Equations ◽  
Functionally Graded ◽  
Intensity Factors ◽  
Mode Iii ◽  
Singular Stress ◽  
Field Intensity Factors

This study deals with the interaction of multiple moving mode-III cracks in a functionally graded magnetoelectroelastic half-plane. The cracks are assumed to be either magneto-electrically impermeable or permeable. First, the singular stress, electric displacement, and magnetic induction fields in a half-plane with dislocations are obtained in closed form by the means of complex Fourier transform and then the problem is reduced to a system of singular integral equations in a set of unknown functions representing dislocation densities. These integral equations are Cauchy singular and are solved numerically to determine field intensity factors for multiple moving cracks. The results show that the crack velocity has great effect on the field intensity factors.

Comparison of several BEM-based approaches in evaluating crack-tip field intensity factors in piezoelectric materials

2014 ◽  
Vol 189 (1) ◽  
pp. 111-120 ◽  
Author(s):  
Jun Lei ◽  
Hongyan Wang ◽  
Chuanzeng Zhang ◽  
Tinh Quoc Bui ◽  
Felipe Garcia-Sanchez
Keyword(s):  
Field Intensity ◽  
Piezoelectric Materials ◽  
Crack Tip ◽  
Intensity Factors ◽  
Crack Tip Field ◽  
Field Intensity Factors

scholarly journals Surface effects on a mode-III reinforced nano-elliptical hole embedded in one-dimensional hexagonal piezoelectric quasicrystals

2021 ◽  
Vol 42 (5) ◽  
pp. 625-640
Author(s):  
Zhina Zhao ◽  
Junhong Guo
Keyword(s):  
Surface Layer ◽  
Boundary Conditions ◽  
Field Intensity ◽  
Surface Effect ◽  
Crack Tip ◽  
Elliptical Hole ◽  
Engineering Practice ◽  
Intensity Factors ◽  
One Dimensional ◽  
Field Intensity Factors

AbstractTo effectively reduce the field concentration around a hole or crack, an anti-plane shear problem of a nano-elliptical hole or a nano-crack pasting a reinforcement layer in a one-dimensional (1D) hexagonal piezoelectric quasicrystal (PQC) is investigated subject to remotely mechanical and electrical loadings. The surface effect and dielectric characteristics inside the hole are considered for actuality. By utilizing the technique of conformal mapping and the complex variable method, the phonon stresses, phason stresses, and electric displacements in the matrix and reinforcement layer are exactly derived under both electrically permeable and impermeable boundary conditions. Three size-dependent field intensity factors near the nano-crack tip are further obtained when the nano-elliptical hole is reduced to the nano-crack. Numerical examples are illustrated to show the effects of material properties of the surface layer and reinforced layer, the aspect ratio of the hole, and the thickness of the reinforcing layer on the field concentration of the nano-elliptical hole and the field intensity factors near the nano-crack tip. The results indicate that the properties of the surface layer and reinforcement layer and the electrical boundary conditions have great effects on the field concentration of the nano-hole and nano-crack, which are useful for optimizing and designing the microdevices by PQC nanocomposites in engineering practice.

Sign in / Sign up

Export Citation Format

Share Document