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Material Modelling

Hi all,

      I doing modelling on soft clay behaviour which exhibit softening behaviour during constant strain loading. Here i followed a non-associated flow rule for better prediction of dilation . For the case of non-associated flow rule yield function and plastic potential function should not same i clear in that , my doubt is that we can use two different surface for yield and plastic potential function (eg: linear surface as yield surface and elliptical surface as plastic potential )? 

Analytical elastic-plastic solutions for the torsion of a round bar with a heterogeneous cross section


I am trying to derive/find an analytical expression
for the torsion of a round bar made of an heterogeneous material. But I just do
not seem to find any solution available in the literature other than for a
homogeneous material, which can be find in any theory of plasticity book (e.g.
Theory of Plasticity, 3rd Ed., J. Chakarabarty, pp. 132-136).

Orthotropic plasticity model

Dear all,

Is there any one of you know a material model which can reflect the orthotropic , hysteresis, and load ratio dependence behaviors? 

Every helps would be highly appreciated.


Kindest regards,


kourousis's picture

Mini-symposium 'Cyclic Plasticity Models for Sheet Metal Forming' - NUMISHEET 2014

Dear Colleagues,

I would like to invite to you to submit an abstract to the mini-symposium on 'Cyclic Plasticity Models for Sheet Metal Forming' at the 9th International Conference on Numerical Simulation of 3D Sheet Metal Forming Processes (NUMISHEET) to be held at Melbourne - Australia January 6-10, 2014 ( 

Jaafar El-Awady's picture

Pre-straining effects on the power-law scaling of size-dependent strengthening in Ni single crystals

Pre-straining effects on the power-law scaling of size-dependent strengthening in Ni single crystals

Jaafar A. El-Awady, Michael D. Uchic, Paul A. Shade, Sang-Lan Kim, Satish I. Rao, Dennis M. Dimiduk, Christopher Woodward


Volume 68, Issues 3–4, February 2013, Pages 207–210


Piriform yield surface

Taxonomy upgrade extras: 
Dan Gianola's picture

Variable Plasticity in Metallic Glass Nanowires

Tunable Tensile Ductility in Metallic Glasses

D.J. Magagnosc, R. Ehrbar, G. Kumar, M.R. He, J. Schroers, D.S. Gianola

Scientific Reports 3 (2013) 1096 

Nonlinear Dynamics - 2013. Registration deadline extended till January 28th

Dear Colleagues,

The new deadline for abstract (plain text, 400 word limit) submission is now January 28, 2013.


The 4th conference "Nonlinear Dynamics -2013" will be held from 19 until 22 June, 2013 in Sevastopol (Ukraine).

Conference web-site:


The conference is organised by:

Amit Acharya's picture

An observation on the experimental measurement of dislocation density

Amit Acharya and Robin J. Knops

(to appear in Journal of Elasticity)

The common practice of ignoring the elastic strain gradient in measurements of geometrically necessary dislocation (GND) density is critically examined. It is concluded that the practice may result in substantial errors. Our analysis points to the importance of spatial variations of the elastic strain field in relation to its magnitude in inferring estimates of dislocation density from measurements.

Kamyar M Davoudi's picture

Dislocation Climb in Two-Dimensional Discrete Dislocation Dynamics

In this paper, dislocation climb is incorporated in a two-dimensional discrete dislocation dynamics model. Calculations are carried out for polycrystalline thin films, passivated on one or both surfaces. Climb allows dislocations to escape from dislocation pile-ups and reduces the strain-hardening rate, especially for fully passivated films. Within the framework of this model, climb modifies the dislocation structures that develop during plastic deformation and results in the formation of pile-ups on slip planes that do not contain any dislocation sources.

Tuncay Yalcinkaya's picture

Full scholarships available at European Commission funded workshop on fracture and damage mechanics in Antalya / Turkey

European Commission' s JRC (Joint Research Centre) is organizing the 2nd workshop on physics based modeling of material properties and experimental observations in collaboration with TOBB University of Economics and Technology. The workshop will be held in Antalya/Turkey on 15-17 May 2013, and the special focus will be fracture and damage mechanics.

4th International Conference "Nonlinear Dynamics - 2013" , Sevastopol, Ukraine, 19-22 June, 2013

Dear Colleagues,

The Organizing Committee of the 4th conference ND-2013 is pleased to invite you to participate at the Nonlinear Dynamics Conference to be held from 19 until 22 June, 2013 in Sevastopol (UKRAINE).

Conference web-site:


The conference is organised by:

what's detwinning

Now I am doing some work about nanotwinned copper, and don't understand what's the nature of "detwinning". 

Could any disappearance of the original nanotwin structure and the formation of a single grain or a new twin structure with TBs in a different orientation and/or with different TB spacing be called detwinning?

Advanced Finite Plasticity Textbooks

While reading the article

"An alternative approach to finite plasticity based on material isomorphisms " (1999) by Prof. Bertram, the first thing that attracted my attention was the quote [by Prof. Naghdi (late)]:

LSDYNA UMAT- history variable choice


I'm presently working on implementing anisotropic yield criteria in LSDYNA as UMAT.

I understand from the LSDYNA documents that effective plastic strain is a default history variable.  So when we code, can we omit the update of effective plastic strain as a history variable? If so, where is it stored and how is it retrieved during post-processing ?

Laurence Brassart's picture

Reactive flow in solids

By Laurence Brassart and Zhigang Suo


Post-doc position opening in POSTECH, South Korea

A postdoctoral researcher position is available in the area of sheet metal forming, plasticity theory, computational modeling of forming of advanced high strength steels, light-weight alloys  at POSTECH (Pohang University of Science and Technology) working under the supervision of Prof. Myoung-Gyu Lee. He/She will also work with Prof. Frederic Barlat who is a world famous scholar in the field of plasticity. Candidates with a strong background in plasticity theory, computational mechanics of sheet metals, failure analysis are highly encouraged to apply.

Amit Acharya's picture

Jump condition for GND evolution

Acharya, A., Jump conditions for GND evolution as a constraint on slip transmission at grain boundaries, Philosophical Magazine, 87(8-9), 1349-1359, 2007 (see attachment)

Solid/Fluid Mechacnics

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In my research i am trying to develop a new model for plastic deformation, and i suspect there is a strong similarity between

plasticity and turbulent flow !.

My question is: if there is workd done trying to apply Reynolds decomposition (Reynolds Stress) to the governing equations and solved plasticity problem in Solids?


Yaron B.S.


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