scholarly journals Plastic yield criterion and hardening of porous single crystals

2018 ◽  
Vol 132-133 ◽  
pp. 80-95 ◽  
Author(s):  
J. Paux ◽  
R. Brenner ◽  
D. Kondo
Keyword(s):  
Single Crystals ◽  
Yield Criterion ◽  
Plastic Yield

scholarly journals The critical shear stress of mercury single crystals

1937 ◽  
Vol 163 (912) ◽  
pp. 34-53 ◽  
Keyword(s):  
Plastic Deformation ◽  
Shear Stress ◽  
Melting Point ◽  
Single Crystal ◽  
Single Crystals ◽  
Critical Shear Stress ◽  
Impurity Content ◽  
Thermal Agitation ◽  
Plastic Yield ◽  
Metal Single Crystals

The influence of very small quantities of impurity on the critical shear stress of metal single crystals has an important bearing on the mechanism of their plastic deformation. For investigations in this field, mercury is a very suitable metal: its impurity content can easily be reduced to an extremely low level (Hulett 1911) and it contains no dissolved gases (Hulett 1911). Also, as first pointed out by Andrade (1914), single crystal wires of this metal can be prepared without difficulty. The low melting point of mercury (-38∙8° C.) is far from being a disadvantage. The crystals can be maintained at -60° C., and at a temperature so near the melting point the thermal agitation may be expected to accentuate phenomena not observable at lower temperatures, if such agitation plays the important part in the mechanism of glide ascribed to it (Taylor 1934; Polanyi 1934; Orowan 1934). As a possible instance of this, the experiments to be described have revealed the existence of a preliminary “set” preceding the true plastic yield. Widely differing forms of slip band have also been observed, and are described elsewhere (Greenland 1937). It is hoped that these results will throw further light on the mechanism of glide.

scholarly journals MAPPROXIMATING STRESSES IN THE VICINITY OF A CAVITY EXPANDING AT A CONSTANT VELOCITY IN A MEDIUM WITH THE MOHR - COULOMB PLASTICITY CONDITION

2019 ◽  
Vol 81 (2) ◽  
pp. 177-190 ◽  
Author(s):  
V. L. Kotov
Keyword(s):  
Constant Velocity ◽  
Yield Criterion ◽  
Plastic Region ◽  
Plasticity Condition ◽  
Practical Applications ◽  
Plastic Yield ◽  
Runge Kutta Method ◽  
Wide Range ◽  
Self Similar Solution ◽  
Internal Friction Coefficient

A one-dimensional problem of a spherical cavity expanding at a constant velocity from a point in an infinite elastoplastic medium is considered. The problem has a first-kind self-similar solution. Elastoplastic deformation of the soil is described based on Hooke's law and the Mohr-Coulomb yield criterion. An analytical solution of the problem in the elastic region contacting with the plastic yield region has been obtained. To determine stress and velocity fields in the plastic region, a known algorithm, based on the shooting method, of analyzing a boundary-value problem for a system of two first-order ordinary differential equations, including the fourth-order Runge - Kutta method, has been realized. An effective algorithm of numerically analyzing an expanding cavity problem, earlier proposed in the works by М. Forrestal et al., makes it possible to solve the problem accurately enough for practical applications. A formula for determining the critical pressure - the minimal pressure required for the nucleation, accounting for internal pressure of a cavity in the framework of the Mohr - Coulomb yield criterion, has been derived, which is a generalization of the earlier published solution for an elastic ideally plastic medium with Tresca's criterion. The obtained critical value was compared with a numerical solution in a full formulation at the cavity expansion velocities close to zero in a wide range of variation of the parameters of the Mohr - Coulomb yield criterion. It is shown that the inaccuracy of the approximation of the proposed formula does not exceed 6% for the variation of the internal friction coefficient all over the admissible range, and for the initial value of the yield strength increasing by three orders of magnitude.

scholarly journals Influence of the Non-Schmid Effects on the Ductility Limit of Polycrystalline Sheet Metals

Materials ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 1386 ◽  
Author(s):  
Mohamed Ben Bettaieb ◽  
Farid Abed-Meraim
Keyword(s):  
Single Crystal ◽  
Mechanical Behavior ◽  
Single Crystals ◽  
Plastic Flow ◽  
Yield Criterion ◽  
Experimental Studies ◽  
Crystallographic Structure ◽  
Sheet Metals ◽  
Localized Necking ◽  
The Impact

The yield criterion in rate-independent single crystal plasticity is most often defined by the classical Schmid law. However, various experimental studies have shown that the plastic flow of several single crystals (especially with Body Centered Cubic crystallographic structure) often exhibits some non-Schmid effects. The main objective of the current contribution is to study the impact of these non-Schmid effects on the ductility limit of polycrystalline sheet metals. To this end, the Taylor multiscale scheme is used to determine the mechanical behavior of a volume element that is assumed to be representative of the sheet metal. The mechanical behavior of the single crystals is described by a finite strain rate-independent constitutive theory, where some non-Schmid effects are accounted for in the modeling of the plastic flow. The bifurcation theory is coupled with the Taylor multiscale scheme to predict the onset of localized necking in the polycrystalline aggregate. The impact of the considered non-Schmid effects on both the single crystal behavior and the polycrystal behavior is carefully analyzed. It is shown, in particular, that non-Schmid effects tend to precipitate the occurrence of localized necking in polycrystalline aggregates and they slightly influence the orientation of the localization band.

Unified plastic yield criterion for ductile solids.

AIAA Journal ◽  
1973 ◽  
Vol 11 (10) ◽  
pp. 1428-1429 ◽  
Author(s):  
MANOJ MAITRA ◽  
KAMALESH MAJUMDAR ◽  
ANIRUDDHA DAS
Keyword(s):  
Yield Criterion ◽  
Plastic Yield

Large-Deflection Bending of Clamped Metal Foam-Filled Rectangular Tubes

2017 ◽  
Vol 09 (03) ◽  
pp. 1750043 ◽  
Author(s):  
Jianxun Zhang ◽  
Qinghua Qin ◽  
Yan Yang ◽  
Xuehui Yu ◽  
Shangjun Chen ◽  
...  
Keyword(s):  
Analytical Model ◽  
Large Deflection ◽  
Metal Foam ◽  
Yield Criterion ◽  
Structural Response ◽  
Flat Punch ◽  
Plastic Yield ◽  
Rectangular Tube ◽  
Foam Filled ◽  
Rectangular Tubes

Large-deflection bending of fully clamped slender metal foam-filled rectangular tubes is investigated theoretically, experimentally and numerically. A plastic yield criterion for the foam-filled rectangular tube is proposed. Considering the filled foam strength effect and the interaction of bending and stretching, an analytical solution is proposed to predict the structural response of the foam-filled rectangular tubes transversely loaded by a flat punch. Clamped bending tests of aluminium alloy foam-filled rectangular tubes are conducted. The analytical model captures experimental results reasonably. Numerical calculations are carried out to predict the large-deflection behavior of the foam-filled tubes, and good agreement is achieved between the analytical solutions and numerical results. The effects of wall thickness of tube, punch size and filled foam strength are discussed in detail. It is demonstrated that the present analytical model can reasonably predict the post-yield behavior of the foam-filled rectangular tube.

Atomic-Scale Study of Plastic-Yield Criterion in Nanocrystalline Cu at High Strain Rates

2009 ◽  
Vol 41 (2) ◽  
pp. 523-531 ◽  
Author(s):  
A.M. Dongare ◽  
A.M. Rajendran ◽  
B. Lamattina ◽  
D.W. Brenner ◽  
M.A. Zikry
Keyword(s):  
High Strain ◽  
Yield Criterion ◽  
Atomic Scale ◽  
Strain Rates ◽  
High Strain Rates ◽  
Plastic Yield

A Yield Criterion Based on Mean Shear Stress

2014 ◽  
Vol 611-612 ◽  
pp. 3-10
Author(s):  
Wilko C. Emmens ◽  
A.H. van den Boogaard
Keyword(s):  
Shear Stress ◽  
Plane Strain ◽  
Yield Criterion ◽  
Maximum Shear Stress ◽  
Crystallographic Direction ◽  
Yield Criteria ◽  
General Finding ◽  
Plastic Yield ◽  
Yield Loci ◽  
Actual Orientation

This work investigates the relation between shear stress and plastic yield considering that a crystal can only deform in a limited set of directions. The shear stress in arbitrary directions is mapped for some cases showing relevant differences. Yield loci based on mean shear stress are constructed. The Tresca yield criterion can be improved by averaging the shear stress over directions near the direction of maximum shear stress. Yield criteria based on averaging over crystallographic direction show a clear influence of the actual orientation of these direction, notably in case of few crystallographic directions. The general finding is that the higher the isotropy of a material, the lower the plane strain factor. The shape of the yield loci is comparable to those derived by the Hershey criterion with exponents lower than 3.

Sign in / Sign up

Export Citation Format

Share Document