Deformation Bounds for Bodies Which Creep in the Plastic Range

1970 ◽  
Vol 37 (2) ◽  
pp. 426-430 ◽  
Author(s):  
F. A. Leckie ◽  
A. R. S. Ponter
Keyword(s):  
Energy Dissipation ◽  
Yield Condition ◽  
Stress Fields ◽  
Plastic Range ◽  
Plastic Deformations

Previous results on bounding the energy dissipation of bodies which creep have been extended to include plastic deformations. The theorems, which are derived, show that previous results can be used, provided the stress fields which are selected nowhere exceed the value of the ratio n/n + 1 of the yield condition for stress.

Strain Hardening in the Yielded Compound Cylinder

1962 ◽  
Vol 84 (2) ◽  
pp. 220-224
Author(s):  
S. J. Becker ◽  
H. Kraus
Keyword(s):  
Plastic Deformation ◽  
Strain Hardening ◽  
Plane Strain ◽  
Yield Condition ◽  
Plastic Range ◽  
Linear Strain ◽  
Compound Cylinder ◽  
Small Strains ◽  
Tresca Yield Condition ◽  
Generalized Plane Strain

The theory of a previous paper which was designed for nonhardening plastic deformation of simple and compound cylinders in axisymmetric generalized plane strain is extended to include linear strain hardening in the plastic range. The method, which is limited to small strains, uses a modified Tresca yield condition and assumes incompressibility for both the plastic and the elastic ranges.

Limit Loads of Circular Plates Under Combined Loading

1973 ◽  
Vol 40 (3) ◽  
pp. 799-802 ◽  
Author(s):  
H. M. Haydl ◽  
A. N. Sherbourne
Keyword(s):  
Yield Criterion ◽  
Yield Condition ◽  
Combined Loading ◽  
Stress Fields ◽  
Collapse Load ◽  
Circular Plates ◽  
Limit Loads ◽  
Title Problem ◽  
Interaction Curves ◽  
Von Mises

Limit loads of circular plates under combined transverse and in-plane loading are given for the von Mises yield condition. Ivanov’s approximation to the Ilyushin yield surface is used. Collapse load interaction curves and stress fields are given for simply supported and clamped plates. The results are compared with existing solutions for the title problem based on the Tresca yield criterion.

Thermal Stresses in an Elastic, Work-Hardening Sphere

1960 ◽  
Vol 27 (4) ◽  
pp. 629-634 ◽  
Author(s):  
Chintsun Hwang
Keyword(s):  
Work Hardening ◽  
Thermal Stresses ◽  
Yield Condition ◽  
Numerical Data ◽  
Spherical Body ◽  
Thermal And Mechanical Properties ◽  
Plastic Range ◽  
Cooling Process ◽  
Von Mises ◽  
Transient Thermal

In this paper, a method is presented for obtaining the transient thermal-stress distribution and the residual stresses in a spherical body where the time-dependent temperature distribution is symmetrical with respect to the center of the sphere. The material is assumed to be elastoplastic, while in the plastic range it work-hardens isotropically. The von Mises yield condition is used. The thermal and mechanical properties of the material are assumed to be temperature independent. The problem is reduced to a single nonlinear differential equation which is solved numerically on the NCR 304 digital computer. Several sets of numerical data representing various degrees of work-hardening in the spherical bodies during a cooling process are presented.

Coulomb–Mohr Granular Materials: Quasi-static Flows and the Highly Frictional Limit

2008 ◽  
Vol 61 (6) ◽  
Author(s):  
Grant M. Cox ◽  
Ngamta Thamwattana ◽  
Scott W. McCue ◽  
James M. Hill
Keyword(s):  
Granular Materials ◽  
Soil Mechanics ◽  
Yield Condition ◽  
Stress Fields ◽  
Flow Rule ◽  
Axially Symmetric ◽  
Governing Equations ◽  
Frictional Materials ◽  
Good Agreement ◽  
Strong Agreement

One approach to modeling fully developed shear flow of frictional granular materials is to use a yield condition and a flow rule, in an analogous way to that commonly employed in the fields of metal plasticity and soil mechanics. Typically, the yield condition of choice for granular materials is the Coulomb–Mohr criterion, as this constraint is relatively simple to apply but at the same time is also known to predict stresses that are in good agreement with experimental observations. On the other hand, there is no strong agreement within the engineering and applied mechanics community as to which flow rule is most appropriate, and this subject is still very much open to debate. This paper provides a review of the governing equations used to describe the flow of granular materials subject to the Coulomb–Mohr yield condition, concentrating on the coaxial and double-shearing flow rules in both plane strain and axially symmetric geometries. Emphasis is given to highly frictional materials, which are defined as those granular materials that possess angles of internal friction whose trigonometric sine is close in value to unity. Furthermore, a discussion is provided on the practical problems of determining the stress and velocity distributions in a gravity flow hopper, as well as the stress fields beneath a standing stockpile and within a stable rat-hole.

scholarly journals Динамическая модель упруго-пластического нормального столкновения сферической частицы с полупространством с учетом адгезионного взаимодействия в зоне контакта

2019 ◽  
Vol 61 (2) ◽  
pp. 302
Author(s):  
Я.А. Ляшенко
Keyword(s):  
Experimental Data ◽  
Plastic Deformation ◽  
Energy Dissipation ◽  
Initial Velocity ◽  
Mechanical Energy ◽  
Normal Velocity ◽  
Plastic Deformations ◽  
Homogeneous Particle ◽  
Mechanical Energy Dissipation ◽  
Simulation Results

AbstractThe problem of a collision of a spherical homogeneous particle with a half-space is solved numerically. The coefficient of the normal velocity restitution is calculated as a function of the initial velocity in the presence of the mechanical energy dissipation due to plastic deformations and adhesion interaction between the surfaces of contacting bodies. The strain hardening effect is taken into account using the criterion of nonlocal plasticity introduced before. The study is carried out in dimensionless parameters, which makes it universal. The analytical expression is found for the critical initial velocity above which a plastic deformation starts. The simulation results agree well with the available experimental data.

scholarly journals Progressive Post-Yield Behavior of Human Cortical Bone in Shear

2011 ◽  
Author(s):  
Xuanliang Neil Dong ◽  
Qing Luo ◽  
Bijay Giri ◽  
Xiaodu Wang
Keyword(s):  
Energy Dissipation ◽  
Cortical Bone ◽  
Bone Fragility ◽  
Stress Fields ◽  
Yield Behavior ◽  
Test Region ◽  
Loading Modes ◽  
Iosipescu Test ◽  
Progressive Loading ◽  
Loading Scheme

Post-yield behavior is important for bone fragility since it accounts for the major part of energy dissipation of bone. Therefore, it is essential to study the post-yield behavior of bone to understand the different pathways for energy dissipation [1]. The post-yield behavior of bone may depend on the different loading modes. Previous studies have utilized a novel progressive loading scheme to study the post-yield behavior of cortical bone at tension [2] and compression [3]. However, few studies have reported post-yield behaviors of cortical bone in shear [4]. One of major challenges in shear tests of cortical bone is to achieve a uniform stress field over a test region. For example, the notches of the Iosipescu test may cause non-constant stress fields and locally high stresses when small amounts of bending are present [5]. The objective of this study was to develop the progressive loading scheme of shear in bone using an inclined double notch shear test, in which homogeneous shear stress fields were produced [5].

Brittle Coatings for Quantitative Strain Measurements

1942 ◽  
Vol 9 (4) ◽  
pp. A184-A188 ◽  
Author(s):  
A. V. de Forest ◽  
Greer Ellis ◽  
F. B. Stern
Keyword(s):  
High Speed ◽  
Test Procedure ◽  
Plastic Range ◽  
Sewing Machine ◽  
Plastic Deformations ◽  
Strain Measurements ◽  
Elastic And Plastic Deformations ◽  
Quantitative Analyses ◽  
The Impact ◽  
Fatigue Failures

Abstract The use of brittle coatings in stress analysis is discussed in this paper. Particular reference is made to the “Stresscoat” materials and method which can effect quantitative analyses within the elastic range by use of brittle coatings alone. In the plastic range, the flaking off of the coating is shown to be caused by a compression component of strain of about 1 per cent. Graphs and illustrations show the effect of such variables as coat thickness, time of dry, temperature and humidity, creep, and bubbles in the coating. Test procedure is outlined. Application of the method to a part from a high-speed sewing machine shows stress values and correlation of results with fatigue failures. Another application illustrated is a plate, penetrated by a bullet, showing elastic and plastic deformations during the impact loading.

Masonry: the brittle or plastic material?

2019 ◽  
pp. 22-28
Keyword(s):  
Plastic Material ◽  
Experimental Studies ◽  
Point Of View ◽  
Plastic Properties ◽  
Plastic Deformations ◽  
Base Materials ◽  
Stress States ◽  
Creep Deformations ◽  
Structural Point

The results of experimental studies of masonry on the action of dynamic and static (short-term and long-term) loads are presented. The possibility of plastic deformations in the masonry is analyzed for different types of force effects. The falsity of the proposed approach to the estimation of the coefficient of plasticity of masonry, taking into account the ratio of elastic and total deformations of the masonry is noted. The study of the works of Soviet scientists revealed that the masonry under the action of seismic loads refers to brittle materials in the complete absence of plastic properties in it in the process of instantaneous application of forces. For the cases of uniaxial and plane stress states of the masonry, data on the coefficient of plasticity obtained from the experiment are presented. On the basis of experimental studies the influence of the strength of the so-called base materials (brick, mortar) on the bearing capacity of the masonry, regardless of the nature of the application of forces and the type of its stress state, is noted. The analysis of works of prof. S. V. Polyakov makes it possible to draw a conclusion that at the long application of the load, characteristic for the masonry are not plastic deformations, but creep deformations. It is shown that the proposals of some authors on the need to reduce the level of adhesion of the mortar to the brick for the masonry erected in earthquake-prone regions in order to improve its plastic properties are erroneous both from the structural point of view and from the point of view of ensuring the seismic resistance of structures. It is noted that the proposal to assess the plasticity of the masonry of ceramic brick walls and large-format ceramic stone with a voidness of more than 20% is incorrect, and does not meet the work of the masonry of hollow material. On the basis of the analysis of a large number of research works it is concluded about the fragile work of masonry.

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