scholarly journals PLASTIC DEFORMATION OF THICK-WALLED SNOW-ICE CYLINDERS UNDER HYDROSTATIC PRESSURE

1962 ◽  
Vol 40 (10) ◽  
pp. 1310-1318 ◽  
Author(s):  
H. H. G. Jellinek
Keyword(s):  
Activation Energy ◽  
Plastic Deformation ◽  
Hydrostatic Pressure ◽  
Strain Rate ◽  
Plastic Flow ◽  
Constant Pressure ◽  
Circumferential Stress ◽  
Sine Function ◽  
Kcal Mole ◽  
Flow Process

The results of experiments on the plastic deformation of hollow snow-ice cylinders, closed at one end, as a function of circumferential stress and temperature are discussed. Data are graphed on deformation as a function of time for a snow-ice cylinder under 7.03 and 14.06 kg/cm2 hydrostatic pressure at −4.5 °C, deformation as a function of hydrostatic pressure from 2.11 to 7.03 kg/cm2, and deformation as a function of temperature at a constant pressure of 10.55 kg/cm2. The natural strain rate of closure at constant circumferential stress and temperature was a constant, which varied with circumferential stress as a sine function and was "exponentially dependent on temperature, with an activation energy of 14.1 kcal/mole at an average circumferential stress of 3.1 kg/cm2. The experiments agree well with an earlier interpretation of the plastic flow process representing flow between grain boundaries.

Derivation of Stress, Strain, Temperature, Strain-Rate Relation for Plastic Deformation

1947 ◽  
Vol 14 (3) ◽  
pp. A229-A230
Author(s):  
J. D. Lubahn
Keyword(s):  
Plastic Deformation ◽  
Plastic Strain ◽  
Strain Rate ◽  
Plastic Flow ◽  
Stress Strain ◽  
Rate Relation ◽  
Temperature Strain

Abstract This paper carries out the derivation and correction of an equation previously presented by J. H. Hollomon and the author, relating to stress for plastic flow (σ), plastic strain (ϵ), strain rate (ϵ.), and temperature (T).

The Yield Condition and Flow Rule for a Metal Subjected to Finite Elastic Volume Change

1971 ◽  
Vol 93 (4) ◽  
pp. 708-712 ◽  
Author(s):  
J. B. Haddow ◽  
T. M. Hrudey
Keyword(s):  
Plastic Deformation ◽  
Hydrostatic Pressure ◽  
Plastic Flow ◽  
Volume Change ◽  
High Hydrostatic Pressure ◽  
Elastic Strain ◽  
Yield Condition ◽  
Flow Rule ◽  
Elastic Plastic ◽  
Plastic Flow Rule

A theory for elastic-plastic deformation with finite elastic strain is outlined. The results of this theory are specialized to consider a metal subjected to high hydrostatic pressure which produces finite elastic volume change. Drucker’s postulate is used to obtain the form of the yield condition and the associated plastic flow rule.

scholarly journals APPLICATION OF CURRENT LINES IN DETERMINING KINEMATIC CHARACTERISTICS IN STATIONARY PROCESSES OF PLASTIC FLOW OF METAL

2021 ◽  
pp. 92-98
Author(s):  
Roman Sivak ◽  
Iryna Нunko ◽  
Roman Zalizniak
Keyword(s):  
Plastic Deformation ◽  
Strain Rate ◽  
Plastic Flow ◽  
Strain State ◽  
Stationary Processes ◽  
Strain Rate Tensor ◽  
Stress Strain ◽  
Stress Strain State ◽  
Kinematic Characteristics ◽  
Current Lines

Methods of theoretical solution of problems in the processing of metals by pressure are insufficiently developed for practical use in the development and implementation of new technologies and improvement of existing ones. To meet the stringent requirements for the accuracy of determining the stress-strain state, it is necessary to have reliable information about the evolution of the development of the plastic deformation process at each point of the metal from the very beginning of the deformation. This will allow to obtain with high accuracy the important characteristics of the technological heredity of the products that they acquire as a result of their plastic processing. The first and important step in the calculations of the stress-strain state is to obtain the kinematic characteristics of the plastic flow of metal in the form of analytical dependences, which will formulate the patterns of deformation in the technological processes of metal forming. The article considers the possibility of applying the method of current functions to determine the components of the strain rate tensor in established stationary processes of plastic deformation. It is assumed that in the case of axisymmetric plastic deformation of a metal in a channel with curvilinear boundaries, the kinematics of the process is similar to a plane flow. In obtaining the equations, the differential equation of current lines taking into account the incompressibility condition was used to determine the components of the strain rate tensor. To explain the physical meaning of the current functions, two infinitely close current lines were considered in the flow plane, and an expression was obtained for the flow through a finite transverse current tube. In the absence of radial velocity components at the boundaries, constraints are obtained that are imposed on derivatives of current functions at these boundaries. The developed method of calculating the kinematic characteristics of plastic deformation for established axisymmetric stationary processes will simplify the mathematical processing of the obtained results and increase the reliability of the determination of the stress-strain state.

Statistical aspects of microplasticity: experiments, discrete dislocation simulations and stochastic continuum models

2013 ◽  
Vol 22 (3-4) ◽  
pp. 89-100 ◽  
Author(s):  
Michael Zaiser
Keyword(s):  
Plastic Deformation ◽  
Plastic Flow ◽  
Deformation Behaviour ◽  
Computational Modelling ◽  
Constitutive Models ◽  
Constitutive Modelling ◽  
Flow Process ◽  
Discrete Dislocation ◽  
Deformation Properties ◽  
Deformation Processes

AbstractThe plastic deformation properties of microscale and nanoscale specimens differ from those of their macroscopic counterparts as the discrete nature of the elementary processes governing plastic flow becomes directly visible. In such specimens, details of the initial defect microstructure may exert a strong influence on the recorded deformation behaviour, which accordingly exhibits significant scatter even amongst specimens that share an identical preparation history. The plasticity of microsamples appears as a sequence of spatially and temporally localised events and not as the smooth and continuous flow process envisaged by classical continuum elastoplasticity. These observations pose a significant challenge to constitutive modelling. In this feature article, we discuss the statistics of fluctuations in microscale and nanoscale plasticity and discuss the implications for computational modelling of plastic deformation processes on microscale and nanoscales. We propose a new type of constitutive models that combine a classical continuum description of the elastic problem with a stochastic description of the dynamics of plastic flow.

MANUFACTURE INVESTIGATION OF CARTRIDGE WITH BOTTOM-MOST PART FLANGE BY DIRECT EXTRUSION WITH COUNTERPUNCH. REPORT 13. DETERMINATION OF DEFORMED STATE UNDER STRAITENED EXTRUSION IN FOURTH CENTRAL AREA OF PLASTIC DEFORMATION

2020 ◽  
Vol 0 (4) ◽  
pp. 43-51
Author(s):  
A. L. Vorontsov ◽  
◽  
I. A. Nikiforov ◽  
Keyword(s):  
Plastic Deformation ◽  
Plastic Flow ◽  
Central Area ◽  
Direct Extrusion ◽  
Deformed State ◽  
Cumulative Deformation ◽  
The Given ◽  
General Method

Formulae have been obtained that are necessary to calculate cumulative deformation in the process of straitened extrusion in the central area closed to the working end of the counterpunch. The general method of plastic flow proposed by A. L. Vorontsov was used. The obtained formulae allow one to determine the deformed state of a billet in any point of the given area. The formulae should be used to take into account the strengthening of the extruded material.

Formability of Explosive Welded Mg/Al Bimetallic Bar

2016 ◽  
Vol 716 ◽  
pp. 114-120 ◽  
Author(s):  
Sebastian Mróz ◽  
Piotr Szota ◽  
Teresa Bajor ◽  
Andrzej Stefanik
Keyword(s):  
Plastic Deformation ◽  
Strain Rate ◽  
Process Parameters ◽  
Metal Forming ◽  
Explosive Welding ◽  
Physical Modelling ◽  
Main Process ◽  
Compression Tests ◽  
Welding Method

The paper presents the results of physical modelling of the plastic deformation of the Mg/Al bimetallic specimens using the Gleeble 3800 simulator. The plastic deformation of Mg/Al bimetal specimens characterized by the diameter to thickness ratio equal to 1 was tested in compression tests. The aim of this work was determination of the range of parameters as temperature and strain rate that mainly influence on the plastic deformation of Mg/Al bars during metal forming processes. The tests were carried out for temperature range from 300 to 400°C for different strain rate values. The stock was round 22.5 mm-diameter with an Al layer share of 28% Mg/Al bars that had been produced using the explosive welding method. Based on the analysis of the obtained testing results it has been found that one of the main process parameters influencing the plastic deformation the bimetal components is the initial stock temperature and strain rate values.

Vulcanization of Elastomers. 23. The Chemical Kinetics of Vulcanization Reactions and The Physical Properties of The Vulcanizates. I

1960 ◽  
Vol 33 (2) ◽  
pp. 335-341
Author(s):  
Walter Scheele ◽  
Karl-Heinz Hillmer
Keyword(s):  
Activation Energy ◽  
Physical Properties ◽  
Chemical Kinetics ◽  
Kcal Mole ◽  
First Order ◽  
Equilibrium Swelling ◽  
Kinetics Of ◽  
Kinetics Of Vulcanization ◽  
Limiting Value ◽  
Good Agreement

Abstract As a complement to earlier investigations, and in order to examine more closely the connection between the chemical kinetics and the changes with vulcanization time of the physical properties in the case of vulcanization reactions, we used thiuram vulcanizations as an example, and concerned ourselves with the dependence of stress values (moduli) at different degrees of elongation and different vulcanization temperatures. We found: 1. Stress values attain a limiting value, dependent on the degree of elongation, but independent of the vulcanization temperature at constant elongation. 2. The rise in stress values with the vulcanization time is characterized by an initial delay, which, however, is practically nonexistent at higher temperatures. 3. The kinetics of the increase in stress values with vulcanization time are both qualitatively and quantitatively in accord with the dependence of the reciprocal equilibrium swelling on the vulcanization time; both processes, after a retardation, go according to the first order law and at the same rate. 4. From the temperature dependence of the rate constants of reciprocal equilibrium swelling, as well as of the increase in stress, an activation energy of 22 kcal/mole can be calculated, in good agreement with the activation energy of dithiocarbamate formation in thiuram vulcanizations.

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