Magnetomechanical Instabilities in Elastic-Plastic Cylinders, Part II: Plastic Response

1996 ◽  
Vol 63 (3) ◽  
pp. 742-749 ◽  
Author(s):  
D. L. Littlefield
Keyword(s):  
Electric Current ◽  
Plastic Flow ◽  
Plastic Material ◽  
Yield Criterion ◽  
Confining Pressure ◽  
Constitutive Law ◽  
Linear Perturbation ◽  
Uniform Motion ◽  
Elastic Plastic ◽  
Wide Range

The analysis of elastic instabilities in metal cylinders when subjected to electromagnetic fields (Littlefield, 1996a) is extended in this work to include elastic-plastic flow. The cylinder is assumed to be infinitely long and perfectly conducting. The Prandtl-Reuss elastic-plastic material model is the assumed constitutive law, with the von Mises yield criterion employed to limit the effective stress. An axial electric current, assumed to be conducting along the surface of the cylinder, generates a confining pressure, causing plastic flow that is initially assumed to be uniform throughout the cross section. The propagation of small axisymmetric disturbances to this uniform motion is studied by applying linear perturbation theory. Solutions to these equations exhibit a wide range of instability modes, as was the case for the purely elastic results, and the frequency of the oscillating disturbances appears to be suppressed by electromagnetic effects. However, in contrast to the elastic result, no threshold magnetic field exists, and distending instabilities are possible for all levels of electric current. Physical mechanisms resulting in these distinctions are suggested.

Rubber Plastometer with Uniform Rate of Shear—Shearing-Cone Plastometer

1946 ◽  
Vol 19 (3) ◽  
pp. 822-831 ◽  
Author(s):  
G. H. Piper ◽  
J. R. Scott
Keyword(s):  
Plastic Flow ◽  
Mechanical Design ◽  
Plastic Material ◽  
Edge Zone ◽  
Uniform Rate ◽  
Wide Range

Abstract A new shearing-cone plastometer, suitable for investigating the plastic-flow relations of highly viscous materials over a wide range of stress, is described. A mushroom-shaped rotor, having upper and lower surfaces of conical type, is rotated in the plastic material contained in a cylindrical mould. With this type of shearing surface the rate of shear is uniform throughout the material, except for a small edge zone, thus overcoming some disadvantages of previous plastometers. The mechanical design is based on the Mooney shearing-disk plastometer except that provision is made for a wide range of speeds of rotation.

On a Study of the Use of the (T˙) Integral in Fracture Analysis of Solids With Inelastic Rate-Constitutive Laws

1982 ◽  
Vol 104 (4) ◽  
pp. 331-337 ◽  
Author(s):  
M. Nakagaki ◽  
S. N. Atluri
Keyword(s):  
Plastic Material ◽  
Compact Tension ◽  
Compact Tension Specimen ◽  
Constitutive Law ◽  
Fracture Criteria ◽  
Elastic Plastic ◽  
Infinitesimal Deformations ◽  
History Of ◽  
Elastic Plastic Material ◽  
Radial Loading

Here, the following topics are discussed: (i) a new integral (ΔT1) of relevance in the presence of cracks in an elastic-plastic material characterized by a rate-independent incremental constitutive law under the assumption of infinitesimal deformations, (ii) the conditions for path-independency of this integral, (iii) the physical meaning of (ΔT1) whether or not it is path-independent, (iv) its relation to J under conditions of radial loading when deformation theory of plasticity may be valid. The features of this new parameter (ΔT1) are brought out in a numerical solution of a compact tension specimen which is subject to a history of (displacement-controlled) loading/unloading/reloading. The implications of the present results in the context of more rational elastic-plastic fracture criteria are briefly discussed.

Assessment of Elastic–Plastic and Electrical Properties of Printed Silver-Based Interconnects for Flexible Electronics

2018 ◽  
Vol 140 (4) ◽  
Author(s):  
Hsien-Chie Cheng ◽  
Ruei-You Hong ◽  
Wen-Hwa Chen
Keyword(s):  
Electrical Properties ◽  
Dimensional Analysis ◽  
Flexible Electronics ◽  
Plastic Material ◽  
Electrical Performance ◽  
Plastic Properties ◽  
Solvent Content ◽  
Representative Strain ◽  
Elastic Plastic ◽  
Wide Range

In this work, the elastic–plastic properties of the printed interconnects on a glass substrate with Ag-filled polymer-conductor ink are evaluated through a theoretical framework based on finite element (FE) modeling of instrumented sharp indentation, experimental indentation, the concept of the representative strain, and dimensional analysis. Besides, the influences of the ink-solvent content and temperature on the elastic–plastic and electrical properties of the printed Ag-based interconnects are also addressed. First of all, parametric FE indentation analyses are carried out over a wide range of elastic–plastic material parameters. These parametric results together with the concept of the representative strain are used via dimensional analysis to constitute a number of dimensionless functions, and further the forward/reverse algorithms. The forward algorithm is used for describing the indentation load–depth relationship and the reverse for predicting the elastic–plastic parameters of the printed Ag-based interconnects. The proposed algorithms are validated through the correct predictions of the plastic properties of three known metals. At last, their surface morphology, microstructure, and elemental composition are experimentally characterized. Results show that the elastic–plastic properties and electrical sheet resistance of the printed Ag-based interconnects increase with the ink-solvent content, mainly due to the increase of carbon element as a result of the increased ink-solvent residue, whereas their elastic–plastic properties and electrical performance decreases with the temperature.

An account of plasticity in the hole-drilling method of residual stress measurement

1995 ◽  
Vol 30 (3) ◽  
pp. 227-233 ◽  
Author(s):  
M Beghini ◽  
L Bertini ◽  
P Raffaelli
Keyword(s):  
Residual Stress ◽  
Stress Measurement ◽  
Plastic Material ◽  
Yield Criterion ◽  
Residual Stress Measurement ◽  
Hole Drilling ◽  
Plane Stress Condition ◽  
Elastic Plastic ◽  
Hole Drilling Method ◽  
Drilling Method

The elastic-plastic stress-strain field produced in a thin plate under equibiaxial loading during the operation of drilling a through-thickness hole was analysed. The plane stress condition and Tresca yield criterion were assumed for an elastic-perfectly plastic material. These hypotheses allowed the problem to be formulated by means of ordinary differential equations which were analytically solved. Within these particular conditions, the results gave indications of the effect produced by plasticity on the widely used hole-drilling method for residual stress measurement. In particular, the equality of final results with those obtained for a plate with a pre-existing hole loaded in an elastic-plastic regime gives useful indications for the experimental analysis of the effect of plasticity on residual stress measurement.

The Study of Elastic-Plastic Fatigue Behavior of Nigerian-Rolled NST 37-2 Steel

2010 ◽  
Vol 3 ◽  
pp. 28-41
Author(s):  
B.O. Malomo ◽  
S.A. Ibitoye ◽  
L.O. Adekoya
Keyword(s):  
Numerical Study ◽  
Plastic Material ◽  
Yield Criterion ◽  
Kinematic Hardening ◽  
Fatigue Behavior ◽  
Numerical Results ◽  
Test Material ◽  
Flow Rule ◽  
Static Fatigue ◽  
Elastic Plastic

The NST 37-2 steel represents about 75% volume of Nigerian-produced steel which is yet to be fully characterized for its fatigue behavior. Thus, its suitability for many applications is questionable. This paper presents a framework based on the theory of elasto-plasticity in order to make appropriate recommendations in this regard. Experimentally, tensile tests were carried out on test specimens to establish the baseline material properties of the steel in annealed, as-rolled, normalized and hardened/tempered conditions. Fatigue tests were then conducted at 60% Su; 70% Su and 80% Su of the test material and fractographic examinations on the test specimens were subsequently carried out. The frequency harmonic fatigue analysis was implemented in the ANSYS software environment for the numerical study. The elastic-plastic material property was described by the von Mises yield criterion, the flow rule of Prandtl-Reuss, and the kinematic hardening rule of Prager. The numerical results indicate with respect to rate-dependence fatigue behavior that the annealed test specimen is most resilient under cyclic deformation as compared with the normalized, hardened/tempered and as-rolled specimens respectively. The experimental and numerical results were found to be in close agreement and based on the general performance, the steel material is recommended for use in low cycle, quasi-static fatigue applications.

An Asperity Microcontact Model Incorporating the Transition From Elastic Deformation to Fully Plastic Flow

1999 ◽  
Vol 122 (1) ◽  
pp. 86-93 ◽  
Author(s):  
Yongwu Zhao ◽  
David M. Maietta ◽  
L. Chang
Keyword(s):  
Plastic Flow ◽  
Elastic Deformation ◽  
Rough Surfaces ◽  
Plasticity Index ◽  
Contact Load ◽  
Elastic Plastic ◽  
Surface Separation ◽  
Surface Plasticity ◽  
Wide Range ◽  
The Mean

This paper presents an elastic-plastic asperity microcontact model for contact between two nominally flat surfaces. The transition from elastic deformation to fully plastic flow of the contacting asperity is modeled based on contact-mechanics theories in conjunction with the continuity and smoothness of variables across different modes of deformation. The relations of the mean contact pressure and contact area of the asperity to its contact interference in the elastoplastic regime of deformation are respectively modeled by logarithmic and fourth-order polynomial functions. These asperity-scale equations are then used to develop the elastic-plastic contact model between two rough surfaces, allowing the mean surface separation and the real area of contact to be calculated as functions of the contact load and surface plasticity index. Results are presented for a wide range of contact load and plasticity index, showing the importance of accurately modeling the deformation in the elastoplastic transitional regime of the asperity contacts. The results are also compared with those calculated by the GW and CEB models, showing that the present model is more complete in describing the contact of rough surfaces. [S0742-4787(00)01201-7]

A Rate-Dependent Inelastic Constitutive Model—Part I: Elastic-Plastic Flow

1991 ◽  
Vol 113 (3) ◽  
pp. 314-323 ◽  
Author(s):  
F. Ellyin ◽  
Z. Xia
Keyword(s):  
Constitutive Model ◽  
Plastic Flow ◽  
Inelastic Deformation ◽  
Experimental Results ◽  
Elastic Plastic ◽  
Rate Dependent ◽  
Wide Range ◽  
Strain Stress ◽  
Standard Tests ◽  
Inelastic Processes

In this part a rate-dependent elastic-plastic constitutive model is presented which is an extension of our earlier rate-indpendent model. The effect of prior creep on the subsequent inelastic deformation is also included. The model can be used to predict inelastic processes with variable strain (stress) rates. It is shown, through comparison with the experimental results, that most of the rate-effect features of the material response can be simulated by the model. Despite the wide range of application, the model is relatively simple and incorporated a few material constants which could be easily determined from standard tests.

scholarly journals A Simple Model for Elastic-Plastic Contact of Granular Geomaterials

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Jian Wang ◽  
Qimin Li ◽  
Changwei Yang ◽  
Yidan Huang ◽  
Caizhi Zhou
Keyword(s):  
Material Properties ◽  
Yield Criterion ◽  
Contact Process ◽  
Confining Pressure ◽  
Elastic Plastic ◽  
Nonlinear Fitting ◽  
Von Mises ◽  
Stress And Strain Rate ◽  
The Given ◽  
Element Method

We propose a simple elastic-plastic contact model by considering the interaction of two spheres in the normal direction, for use in discrete element method (DEM) simulations of geomaterials. This model has been developed by using the finite element method (FEM) and nonlinear fitting methods, in the form of power-law relation of the dimensionless normal force and displacement. Only four parameters are needed for each loading-unloading contact process between two spheres, which are relevant to material properties evaluated by FEM simulations. Within the given range of material properties, those four parameters can be quickly accessed by interpolating the data appended or by regression functions supplied. Instead of the Von Mises (V-M) yield criterion, the Drucker–Prager (D-P) criterion is used to describe the yield behavior of contacting spheres in this model. The D-P criterion takes the effects of confining pressure, the intermediate principal stress, and strain rate into consideration; thus, this model can be used for DEM simulation of geomaterials as well as other granular materials with pressure sensitivity.

Scale Effects on Contact Deformation of Elastic-Plastic Solids

2005 ◽  
Author(s):  
K. Komvopoulos
Keyword(s):  
Scale Effects ◽  
Plastic Material ◽  
Discrete Models ◽  
Contact Deformation ◽  
Roughness Effects ◽  
Length Scales ◽  
Elastic Plastic ◽  
Wide Range ◽  
Asperity Contacts ◽  
Interacting Surfaces

Surface roughness effects result in asperity contacts spanning a wide range of length scales. In view of the multi-scale roughness of real surfaces, contact deformation of solid bodies exhibits strong scale dependence. Therefore, it is essential that contact mechanics analyses account for the evolution of deformation over a range of length scales, similar to that of the wavelengths comprising the topographies of the interacting surfaces. Results from finite element method (FEM) and molecular dynamics (MD) analyses based on continuum and discrete models of the interacting solids, respectively, reveal important effects of topography, length parameters (e.g., indenter tip radius, coating thickness, and penetration depth), surface traction, and elastic-plastic material properties on the deformation behavior at different length scales.

Fatigue Analysis of Notched Shafts under Multiaxial Synchronous Cyclic Loading

2007 ◽  
Vol 348-349 ◽  
pp. 233-236
Author(s):  
N. Pitatzis ◽  
G. Savaidis ◽  
A. Savaidis ◽  
Chuan Zeng Zhang
Keyword(s):  
Plastic Material ◽  
Yield Criterion ◽  
Notch Root ◽  
Strain Curve ◽  
Local Stress ◽  
Fatigue Loading ◽  
Material Behavior ◽  
Stress Strain ◽  
Elastic Plastic ◽  
Von Mises

Parametrical elastic-plastic finite element analyses of a circumferentially notched shaft subjected to multiaxial synchronous fatigue loading are performed considering two load combinations: (1) constant tension with cyclic torsion and (2) constant torsion with cyclic tensioncompression. The load amplitudes and the mean loads are varied to investigate their influences on the local stress-strain responses. The Multilayer Plasticity Model of Besseling in conjunction with the von Mises yield criterion is applied to describe the elastic-plastic material behavior. Coarse and fine meshes as well as three different types of multilinear approximations (twenty-, five- and threesegments) of the material stress-strain curve are used. Numerical results are presented to reveal the mutual interactions between the applied normal and torsional loads and the stress-strain response at the notch-root.

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