scholarly journals Identification of the Stress Fields from the Strain Fields in the Isotropic Materials

2012 ◽  
Vol 48 ◽  
pp. 665-672 ◽  
Author(s):  
Michaela Štamborská ◽  
František Šimčák ◽  
Matùš Kalina ◽  
Martin Schrötter
Keyword(s):  
Stress Fields ◽  
Strain Fields ◽  
Isotropic Materials

A Nonlinear Elastic Model for Isotropic Materials With Different Behavior in Tension and Compression

1982 ◽  
Vol 104 (1) ◽  
pp. 26-28 ◽  
Author(s):  
Gianluca Medri
Keyword(s):  
Mechanical Characterization ◽  
Three Dimensional ◽  
Small Deformation ◽  
Stress And Strain ◽  
Elastic Model ◽  
Strain Fields ◽  
Isotropic Materials ◽  
Tension And Compression ◽  
Nonlinear Elastic

This note presents a model suitable for the mechanical characterization of isotropic materials with different behavior in tension and compression. The model has been derived from the nonlinear elastic theory and elaborated to adapt it to the small deformation field; the constitutive relation may reliably correlate stress and strain fields even in three-dimensional elastic problems.

Near-Tip Fields in a Notched Body With Dislocations and Body Forces

1993 ◽  
Vol 60 (4) ◽  
pp. 936-941 ◽  
Author(s):  
Kuang-Chong Wu ◽  
Fong-Tai Chang
Keyword(s):  
Body Force ◽  
Anisotropic Materials ◽  
Anisotropic Elasticity ◽  
Reciprocity Theorem ◽  
Stress Fields ◽  
Isotropic Materials ◽  
Body Forces ◽  
Concentrated Forces

The dominant stress fields due to a dislocation and/or a body force near the tip of an isotropic or anisotropic notched body are derived. The structures of the neartip stress fields for anisotropic materials are constructed by using Stroh ’s formalism for anisotropic elasticity. The intensity coefficients contained in the near-tip fields are determined by Betti’s reciprocity theorem. Special attention is given to orthotropic and isotropic materials. Some explicit results of intensity coefficients due to concentrated forces on the notch faces and dislocations at the wedge bisector are also provided.

A Stress Gradient Theory of Rock Fracture In Drilling

1979 ◽  
Vol 101 (1) ◽  
pp. 46-52 ◽  
Author(s):  
S. R. Swanson
Keyword(s):  
Rock Fracture ◽  
Stress Gradient ◽  
Stress Fields ◽  
Stress And Strain ◽  
Gradient Theory ◽  
Strain Fields ◽  
Fracture Properties ◽  
Spatial Gradients ◽  
Brittle Rocks ◽  
Gradient Effect

It seems likely that improvements in drilling mechanics will result from an understanding of the stress and strain fields in the rock. Along with this an understanding of rock fracture under the appropriate conditions is required. The stress fields in drilling are characterized by high spatial gradients of stress, and the stress gradients are known to interact with rock fracture properties. The present investigation is concerned with quantifying the stress gradient effect on fracture. Laboratory tests were performed on a variety of specimen configurations for three brittle rocks. A very strong effect of stress gradient was found, indicating an apparent elevation of fracture strength with increasing stress gradient. A correlation was shown with a critically stressed distance concept.

Transverse-Isotropic Elastic and Viscoelastic Solids

2004 ◽  
Vol 126 (1) ◽  
pp. 38-44 ◽  
Author(s):  
Alan D. Freed
Keyword(s):  
Finite Strain ◽  
Constitutive Theory ◽  
Simple Shearing ◽  
Viscoelastic Solids ◽  
Strain Fields ◽  
Isotropic Materials ◽  
Transverse Isotropic ◽  
Produce Strain

A set of invariants are presented for transverse-isotropic materials whose gradients produce strain fields, instead of deformation fields as is typically the case. Finite-strain theories for elastic and K-BKZ-type viscoelastic solids are derived. Shear-free and simple shearing deformations are employed to illustrate the constitutive theory.

Oscillations in Interplanar Spacing Vs. sin2ψ a FEM Analysis

1987 ◽  
Vol 31 ◽  
pp. 191-204 ◽  
Author(s):  
I. C. Noyan ◽  
L. T. Nguyen
Keyword(s):  
Strain Field ◽  
Interplanar Spacing ◽  
Fem Analysis ◽  
Polycrystalline Sample ◽  
Stress Fields ◽  
Stress Determination ◽  
Element Analysis ◽  
Strain Fields ◽  
X Ray ◽  
Strain Data

AbstractRecent studies indicate that, if the stress/strain field within the irradiated volume in an x-ray stress determination experiment is inhomogeneous, oscillations occur in the interplanar spacing vs. sin2ψ plots. There is, however, little work on the degree of inhomogeneity required to cause a given oscillation, the uniqueness of the stress fields that can cause a given set of oscillations, or the error caused by applying the traditional methods currently in use to oscillatory data.In this paper, numerical modeling and eiasto-plastic finite element analysis was used to determine the strain fields in the diffracting volume of a polycrystalline sample under load. The elastic strain fields obtained from the analysis were then averaged over the regions that would diffract in an x-ray experiment/and then correlated to x-ray strain data to obtain an idea of the problems described ahove.

Crack Initiation From Homogeneous and Bimaterial Corners

1997 ◽  
Vol 64 (4) ◽  
pp. 811-818 ◽  
Author(s):  
J. L. Grenestedt ◽  
S. Hallstrom
Keyword(s):  
Crack Initiation ◽  
Crack Propagation ◽  
Small Crack ◽  
Stress Fields ◽  
Isotropic Materials

Fracture initiated at a corner between two different isotropic materials is considered. A “small” crack, well within the region dominated by the asymptotic stress fields of the noncracked corner, is modeled and the stress intensities associated with the tip of the small crack are determined. Different criteria for the direction of crack propagation are studied.

scholarly journals Process of Identifying Stress Fields from Strain Fields in the Specimen with a Hole

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Michaela Štamborská ◽  
Miroslav Kvíčala ◽  
Vratislav Mareš
Keyword(s):  
Tensile Tests ◽  
Image Correlation ◽  
Stress Fields ◽  
Uniaxial Tensile ◽  
Main Attention ◽  
Identification Procedure ◽  
Complex State ◽  
Strain Fields ◽  
State Of Stress ◽  
Correlation System

The paper is focused on the process of identifying stress fields from strain fields in the specimen with a hole. The experiment was realized on the specimen with a hole made from anisotropic material. The main attention is paid to the analysis of deformation in the areas of stress (near the hole). That geometry generates a heterogeneous strain field which has been measured during the test using a digital image correlation system. The advantage of using heterogeneous strain fields in the identification procedure is that a complex state of stress-strain can be analyzed at the same time. On the other hand the stress field cannot be directly computed from the test and a suitable identification procedure has to be developed. Here, the virtual fields method (VFM) adapted for plastic strain has been used to identify the hardening behaviour and the anisotropy of the material. The values obtained by the VFM have been compared with the results coming from a standard identification made with uniaxial tensile tests.

Investigate on Flexible Thixo-Extrusion of Complex Part

2012 ◽  
Vol 192-193 ◽  
pp. 299-304 ◽  
Author(s):  
Xiao Lei Lv ◽  
Kai Kun Wang ◽  
Lu Zhou
Keyword(s):  
Mechanical Properties ◽  
Velocity Field ◽  
Effective Strain ◽  
Front Surface ◽  
Stress Fields ◽  
Flow Front ◽  
Strain Fields ◽  
Complex Part ◽  
Different Dimensions ◽  
Extrusion Technology

An inventive method of flexible thixo-extrusion technology was put forward, in which the stress status on flow front surface was controlled during thixo-forming. A complex part with different dimensions in three axis directions was designed. The velocity of sliding die was controlled by spring. This kind of die construction could make sure that the flow front of the slurry was always in compressive stress status. The velocity field, effective strain fields, effective stress fields were simulated and analyzed. The results showed that the thixo-extruded complex part was produced under compressive forming state, which forecast good mechanical properties in the practical experiment.

Analysis of Fine Stress Fields in Metal Matrix Composites Using HOLZ Patterns

2007 ◽  
Vol 539-543 ◽  
pp. 848-853
Author(s):  
M. Shibata ◽  
Yoshito Takemoto ◽  
Ichiro Shimizu
Keyword(s):  
Metal Matrix ◽  
Small Area ◽  
Squeeze Casting ◽  
Stress Fields ◽  
Stress And Strain ◽  
Matrix Composites ◽  
Strain Fields ◽  
Transmission Electron ◽  
Reinforcement Material ◽  
The Matrix

Aluminium alloy composites reinforced with aluminium borate whiskers (ABw), developed recently by SHIKOKU KASEI KOUGYOU Co. Ltd., Japan, were fabricated using squeeze casting. The large mismatch in the coefficients of thermal expansion (CTE) between the reinforcement material and the matrix can generate significant stress and strain in composites during thermal cycling or during fabrication of the composites when using squeeze casting. When a transmission electron microscope is used to irradiate a very small area of a thin film of the material with a convergent electron beam of several nm in diameter, High Order Laue Zone patterns (HOLZ patterns) are obtained. These HOLZ patterns can reveal fine strain fields in the reinforcement materials that are used in composites fabricated using squeeze casting. Each (001) plane in the ABw was rotated towards the [020] direction by up to 0.5 ﾟ. With a unit of nearly 400 nm × 400 nm, each (100) plane was rotated towards the [020] direction in a corkscrew pattern. In addition the strain and the stress generated during the fabrication of the composites were estimated by using the finite element methods taking into account the anisotropies in both the CTE and the elastic modulus of the reinforcement material.

Characteristic Geometry and Diffraction Contrast of Dispersed ThO2 Crystals

1969 ◽  
Vol 27 ◽  
pp. 168-169
Author(s):  
R. J. Horylev ◽  
L. E. Murr
Keyword(s):  
Dark Field ◽  
Particle Orientation ◽  
Contrast Effects ◽  
Strain Fields ◽  
Diffraction Contrast ◽  
Dispersed Particles ◽  
Field Electron Microscopy ◽  
Dark Field Electron ◽  
Particle Images ◽  
Diffraction Effects

Smith has shown by dark-field electron microscopy of extracted ThO2 particles from TD-nickel (2% ThO2) that they possess single crystal characteristics. It is generally assumed that these particle dispersions are incoherent. However, some diffraction effects associated with the particle images appeared to be similar to coherency strain fields. The present work will demonstrate conclusively that ThO2 dispersed particles in TD-nickel (2% ThO2) and TD-NiCr (2% ThO2, 20% Cr, Ni) are single crystals. Moreover, the diffraction contrast effects are extinction fringes. That is, these effects arise because of the particle orientation with respect to the electron beam and the extinction conditions for various operating reflections The particles are in fact incoherent.

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