Some Problems of a Rigid Elliptical Disk-Inclusion Bonded Inside a Transversely Isotropic Space, Part II: Solutions of the Integral Equations

1999 ◽  
Vol 66 (3) ◽  
pp. 621-630 ◽  
Author(s):  
M. Rahman
Keyword(s):  
Stress Field ◽  
Integral Equations ◽  
General Structure ◽  
Transverse Isotropy ◽  
Elastic Field ◽  
Transversely Isotropic ◽  
Initial Crack ◽  
Closed Form Solutions ◽  
Isotropic Space ◽  
Uniform Stress Field

This is a sequel to the first part of the two-part paper, which addresses the problem of contact of a rigid elliptical disk-inclusion bonded in the interior of a transversely isotropic space under three different types of loading, namely (a) the inclusion is loaded in its plane by a shearing force, whose line of action passes through the center of the inclusion; (b) the inclusion is rotated by a torque whose axis is perpendicular to the plane of the inclusion; (c) the medium is under uniform stress field at infinity in a plane parallel to the plane of the inclusion. In Part I, the problems corresponding to all three cases of loading have been reduced, in a unified manner, to a system of coupled two-dimensional integral equations. Next, based on Dyson’s theorem and Willis’ generalization of Galin’s theorem, the general structure of solution of the coupled integral equations has been established. In this part, closed-form solutions to these equations are derived by using Dyson’s theorem. Full elastic field in the plane of the inclusion is evaluated and it is shown that the stress field near the edge of the inclusion exhibits the familiar square root singularity in linear fracture mechanics. Explicit expressions for the stress intensity factors near the edge of the inclusion are extracted from these solutions. Numerical results are plotted illustrating how these coefficients vary with transverse isotropy and the parametric angle of the ellipse. The results can be used to determine the critical failure load and angle of initial crack propagation for solids containing elliptical inclusions.

Some Problems of a Rigid Elliptical Disk-Inclusion Bonded Inside a Transversely Isotropic Space: Part I

1999 ◽  
Vol 66 (3) ◽  
pp. 612-620 ◽  
Author(s):  
M. Rahman
Keyword(s):  
Fourier Transforms ◽  
Failure Load ◽  
Transverse Isotropy ◽  
Transversely Isotropic ◽  
Two Dimensional ◽  
Closed Form Solutions ◽  
Isotropic Space ◽  
Uniform Stress Field ◽  
Perfect Contact ◽  
Dimensional Integral

The paper addresses the problem of contact of an elliptical inclusion in the form of a thin disk, bonded in the interior of a transversely isotropic space. The inclusion is assumed to be absolutely rigid and in perfect contact with the medium. Three different cases of loading are considered, namely, (a) the inclusion is loaded in its plane by a shearing force, whose line of action passes through the center of the disk; (b) the inclusion is rotated by a torque whose axis is perpendicular to the plane of the inclusion; (c) the medium is under uniform stress field at infinity in a plane parallel to the plane of the inclusion. In the first part of the article, the problems corresponding to all three cases are reduced, in a unified manner, to a system of coupled two-dimensional integral equations by using the theory of two-dimensional Fourier transforms. In the second part, closed-form solutions for these equations are obtained by using Dyson’s theorem and Willis’ generalization of Galin’s theorem. Explicit expressions for the stress intensity factors near the edge of the inclusion are extracted from these solutions. Numerical results are plotted illustrating how these coefficients vary with transverse isotropy and the parametric angle of the ellipse. The results can be used to determine the critical failure load and angle of crack initiation for solids containing elliptical inclusions.

The 〈111〉 Elliptic Inclusion in an Anisotropic Solid of Cubic Symmetry

1982 ◽  
Vol 49 (2) ◽  
pp. 353-360 ◽  
Author(s):  
H. C. Yang ◽  
Y. T. Chou
Keyword(s):  
Stress Field ◽  
Uniform Stress ◽  
Elliptic Inclusion ◽  
Cubic Symmetry ◽  
Elastic Fields ◽  
Closed Form Solutions ◽  
Strain Transformation ◽  
Anisotropic Solid ◽  
Uniform Stress Field ◽  
Free Strain

This paper deals with a generalized plane problem in which a uniform stress-free strain transformation takes place in the region of an elliptic cyclinder (the inclusion) oriented in the 〈111〉 direction in an anisotropic solid of cubic symmetry. Closed-form solutions for the elastic fields and the strain energies are presented. The perturbation of an otherwise uniform stress field due to a 〈111〉 elliptic inhomogeneity is also treated including two extreme cases, elliptic cavities and rigid inhomogeneities.

On the Efficiency of Analyzing 3D Anisotropic, Transversely Isotropic, and Isotropic Bodies in BEM

2010 ◽  
Vol 26 (4) ◽  
pp. 483-491
Author(s):  
Y. C. Shiah ◽  
W. X. Sun
Keyword(s):  
Closed Form ◽  
Computational Efficiency ◽  
Transverse Isotropy ◽  
Three Dimensional ◽  
Transversely Isotropic ◽  
Fundamental Solutions ◽  
Engineering Practice ◽  
Closed Form Solutions ◽  
Anisotropic Bodies ◽  
Isotropic Bodies

ABSTRACTDue to a lack of closed-form solutions for three dimensional anisotropic bodies, the computational burden of evaluating the fundamental solutions in the boundary element method (BEM) has been a research focus over the years. In engineering practice, transversely isotropic material has gained popularity in the use of composites. As a degenerate case of the generally anisotropic material, transverse isotropy still needs to be treated separately to ease the computations. This paper aims to investigate the computational efficiency of the BEM implementations for 3D anisotropic, transversely isotropic, and isotropic bodies. For evaluating the fundamental solutions of 3D anisotropy, the explicit formulations reported in [1,2] are implemented. For treating transversely isotropic materials, numerous closed form solutions have been reported in the literature. For the present study, the formulations presented by Pan and Chou [3] are particularly employed. At the end, a numerical example is presented to compare the computational efficiency of the three cases and to demonstrate how the CPU time varies with the number of meshes.

Wrinkling of a Fiber-Reinforced Membrane

2008 ◽  
Vol 76 (1) ◽  
Author(s):  
E. Shmoylova ◽  
A. Dorfmann
Keyword(s):  
Boundary Conditions ◽  
Energy Function ◽  
Mechanical Response ◽  
Transverse Isotropy ◽  
Base Material ◽  
Strain Energy Function ◽  
Transversely Isotropic ◽  
Incompressible Material ◽  
Fiber Reinforced ◽  
Relaxed Energy

In this paper we investigate the response of fiber-reinforced cylindrical membranes subject to axisymmetric deformations. The membrane is considered as an incompressible material, and the phenomenon of wrinkling is taken into account by means of the relaxed energy function. Two cases are considered: transversely isotropic membranes, characterized by one family of fibers oriented in one direction, and orthotropic membranes, characterized by two family of fibers oriented in orthogonal directions. The strain-energy function is considered as the sum of two terms: The first term is associated with the isotropic properties of the base material, and the second term is used to introduce transverse isotropy or orthotropy in the mechanical response. We determine the mechanical response of the membrane as a function of fiber orientations for given boundary conditions. The objective is to find possible fiber orientations that make the membrane as stiff as possible for the given boundary conditions. Specifically, it is shown that for transversely isotropic membranes a unique fiber orientation exists, which does not affect the mechanical response, i.e., the overall behavior is identical to a nonreinforced membrane.

Prediction of the Initial Crack Tip Microstructure in a Single Crystal of CuAlNi

1999 ◽  
Author(s):  
Galyna M. Vasko ◽  
Perry H. Leo ◽  
Thomas W. Shield
Keyword(s):  
Stress Field ◽  
Single Crystal ◽  
Crack Opening ◽  
Crack Tip ◽  
Initial Crack ◽  
Single Edge ◽  
Opening Displacement ◽  
Elastic Crack ◽  
Maximum Work ◽  
Anisotropic Elastic

Abstract The austenite to martensite pseudoelastic transformation induced by the anisotropic elastic crack tip stress field in a single crystal of shape memory alloy is considered. It is proposed that the orientation of the initial austenite-martensite interface that forms can be predicted based on knowledge of the stress field, the crystallography of the transformation and one of two selection criteria. These criteria are based on the work of formation of the martensite in stress field and the crack opening displacement the martensite causes at the crack. Predictions of the criteria are compared to experiments on three single edge notched CuAlNi single crystal specimens. Results indicate that the maximum work criterion accurately predicts the orientation of the austenite-martensite interfaces that initially form near a crack.

Transverse isotropy of the upper mantle in the vicinity of Pacific fracture zones

1969 ◽  
Vol 59 (1) ◽  
pp. 59-72
Author(s):  
Robert S. Crosson ◽  
Nikolas I. Christensen
Keyword(s):  
Upper Mantle ◽  
Symmetry Axis ◽  
Transverse Isotropy ◽  
Transversely Isotropic ◽  
Seismic Wave Propagation ◽  
Fracture Zones ◽  
Mantle Material ◽  
Transversely Isotropic Media ◽  
Horizontal Symmetry ◽  
Isotropic Media

Abstract Several recent investigations suggest that portions of the Earth's upper mantle behave anisotropically to seismic wave propagation. Since several types of anisotropy can produce azimuthal variations in Pn velocities, it is of particular geophysical interest to provide a framework for the recognition of the form or forms of anisotropy most likely to be manifest in the upper mantle. In this paper upper mantle material is assumed to possess the elastic properties of transversely isotropic media. Equations are presented which relate azimuthal variations in Pn velocities to the direction and angle of tilt of the symmetry axis of a transversely isotropic upper mantle. It is shown that the velocity data of Raitt and Shor taken near the Mendocino and Molokai fracture zones can be adequately explained by the assumption of transverse isotropy with a nearly horizontal symmetry axis.

Reflection moveout approximations for P-waves in a moderately anisotropic homogeneous tilted transverse isotropy layer

Geophysics ◽  
2017 ◽  
Vol 82 (5) ◽  
pp. C175-C185 ◽  
Author(s):  
Ivan Pšenčík ◽  
Véronique Farra
Keyword(s):  
Transverse Isotropy ◽  
Transversely Isotropic ◽  
P Wave ◽  
Weak Anisotropy ◽  
P Waves ◽  
3D Space ◽  
Axis Of Symmetry ◽  
Relative Errors ◽  
Symmetry Tests ◽  
Ti Media

We have developed approximate nonhyperbolic P-wave moveout formulas applicable to weakly or moderately anisotropic media of arbitrary anisotropy symmetry and orientation. Instead of the commonly used Taylor expansion of the square of the reflection traveltime in terms of the square of the offset, we expand the square of the reflection traveltime in terms of weak-anisotropy (WA) parameters. No acoustic approximation is used. We specify the formulas designed for anisotropy of arbitrary symmetry for the transversely isotropic (TI) media with the axis of symmetry oriented arbitrarily in the 3D space. Resulting formulas depend on three P-wave WA parameters specifying the TI symmetry and two angles specifying the orientation of the axis of symmetry. Tests of the accuracy of the more accurate of the approximate formulas indicate that maximum relative errors do not exceed 0.3% or 2.5% for weak or moderate P-wave anisotropy, respectively.

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