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strain gradient plasticity

Emilio Martínez Pañeda's picture

Gradient plasticity crack tip characterization by means of the extended finite element method (MATLAB code included)

I hope some of you may find this work interesting, the X-FEM non-linear code developed (incorporating linear elasticity, J2 plasticity, and Strain Gradient Plasticity) can be downloaded from www.empaneda.com/codes

Gradient plasticity crack tip characterization by means of the extended finite element method

Emilio Martínez-Pañeda, Sundararajan Natarajan, Stéphane Bordas

Computational Mechanics (2017)

Issues with the implementation of Strain gradient plasticity framework of Niordson and Hutchinson (2003) in ABAQUS UEL

I have implemented the rate-independent strain gradient plasticity framework of Niordson and Hutchinson (2003) in UEL. I was able to validate the results of the shear of infinitely wide thin layer between two rigid surfaces (Niordson and Hutchinson, 2003). However, the UEL subroutine fails to converge for the more complex problem of the shear of finite width slab. I suspect the convergence issues are arising out of internal elastic-plastic boundary conditions and the yield criteria. I have few doubts in this regard.

 

Emilio Martínez Pañeda's picture

Strain gradient plasticity-based modeling of hydrogen environment assisted cracking

I hope some of you may find this work interesting:

Strain gradient plasticity-based modeling of hydrogen environment assisted cracking

Emilio Martínez-Pañeda, Christian F. Niordson, Richard P. Gangloff

Acta Materialia, 117, pp. 321-332

http://www.sciencedirect.com/science/article/pii/S1359645416305183

A pre-print is available at www.empaneda.com

Emilio Martínez Pañeda's picture

On fracture in finite strain gradient plasticity

I hope some of you - particularly those working on strain gradient plasticity or damage and fracture modeling - find this work interesting. 

On fracture in finite strain gradient plasticity

http://www.sciencedirect.com/science/article/pii/S074964191500162X

(A pre-print version is available at www.empaneda.com)

Ph.D. position opened at the University of Brescia, Italy

The group of Mechanics of Solids and Structures at the School of Engineering at the University of Brescia (Italy) has an open PhD position. The appointment will begin on January 1st 2014 for three full years.

The following topics are of interest:

1. small-scale plasticity of metals, with emphasis on modelling the size effect through strain gradient plasticity theories and dislocation mechanics. 2. micromechanics of composite materials, with emphasis on modelling failure.

Strain Gradient Plasticity

Hi all,

I have a strange question that has puzzled me since last almost one year.

There are many SG-plasticity models in the technical literature, sometimes categorized as lower-order or higher-order models.

The problem is :

the constitutive models include the gradient of plastic parameters (e.g. plastic slip).

Tuncay Yalcinkaya's picture

Full scholarships available at European Commission funded workshop on physically based material modeling

European Commission' s JRC (Joint Research Centre) is organizing a workshop on physics based modeling of material properties and experimental observations in collaboration with METU (Middle East Technical University). The workshop will be held in Ankara on 22-23 October 2012.

UEL

Dear Friends,

I have written a UEL for Strain Gradient Plasticity and is working well when i give Boundary condition as Concentrated force, But when i apply displacement boundary condition the it leads to 'system error 144'.

Iknow that system error 144 corresponds to division by zero or infinity, but then why it is coming in on displacement boundary condition is i am worried about.

I will be extremely helpful to anybody for any type of help on above problem.

Thanking you in advance

Soham

UEL

Dear Friends,

I have written an UEL for Strain Gradient Plasticity but it shows following error :

FE SOLVER AND MESH HAVE INCOSISTENT NUMBER OF DOFS

I will be very thankful if someone can throw some light on this error.

Thanking in advance.

Soham

Problem solving Strain Gradient Viscoplasticity based on the framework of Fleck and Hutchinson

I am tyring to solve simple shear problem using a large deformation FE code based on the framework developed by Fleck and Hutchinson for gradient plasticity/viscoplasticity problem (see the attached paper). As the per the formulation, the independent variables are the displacement increments and eqv. plastic strain rate increments. Two sets of equations are solved, one for displacements and the other for plastic strain rates at nodes, following the the above formulation.

dabiao liu's picture

about critical thickness theory

who  can tell me more about the critical thickness theory ?I will be very excited if you   can introduce some reference to me.I know that critical thickness theory is solved rigorously and ursed to validated a useful approximation which is combined with slip distance theory modified for a finite structure size . (physical life review letters :elastic limit and strain hardening of thin wires in torsion)

taimen12345's picture

deal with strain gradient by abaqus

 dear everyone,

I want to ask if anyone deal with strain gradient proposed

by fleck eat. in 1994 and 1997, using subroutine in ABAQUS ?

Mike Ciavarella's picture

Strain gradient plasticity: the flow rule of Fleck and Hutchinson violates thermodynamics ?

A recent paper on JMPS has seriously questioned the foundation of the SGP theory of Fleck and Hutchinson.  The matter is not simple, but is it a good bench test for imechanica to discuss?

doi:10.1016/j.jmps.2008.12.002    

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