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Amit Pandey's picture

Stress Relaxation


I would like to seek comments on : Room temperature stress relaxation and governing mechanisms that contribute to the plasticity that occurs during this process. As, most of the available work on relaxation is done at elevated temperatures.

Please check more on this thread by hari@


 I have also attach papers by Prof Hart and Prof Krempl that did throw some light on this particular subject.

stress relaxation- doubt

Attached herewith a classical paper by Hart on introducing a concept of constant hardness curves refuting that absolute strain should not be considered as a state variable.


The interesting part is he uses a stress relaxation test to prove the same. Stress relaxation test, here refers to a tensile test, where the test is stopped after say certain amount of plastic deformation. The stress drops a little, but the total strain is constant. However, it is argued that there is a small inelastic deformation, which is the cause of this load or stress drop.



The objective of the workshop, co-organized by Joint Research Centre of the European Commission and Middle East Technical University, is to discuss the present status of physics based constitutive modelling of metallic materials and associated experimental methods.

The Workshop is funded by the European Commission's Integration and Enlargment Programme.  There is no cost for attending the Workshop. A limited number of scholarships is available for participants from the target countries (see attached flyer).

how to model user defined creep in ANSYS?

Is there a place I can find explained examples or tutorials on how to model user defined creep in ANSYS?


I need to follow the creep law __>      effective creep strain (e at time t) = S. T. e^(-H)


S=(a0)^t.(sigma)^(a1) ;     T = t^(a2)+(a3).t^(a4)+(a5)t^(a6)   ; H = (a7)/[(theta)+273.16]

a0 to a7 are material constants.

I have the experimental data and tried to fit the curve in Ansys to obtain the material constants. 

I tried to follow the ansys help file steps. But facing erros messages.

German French Summer School 2012 - Hardening and Damage of Materials under Finite Deformations

Dear all,

We are pleased to announce the forthcoming Summer
School on “Hardening and Damage of Materials under Finite Deformations:
Constitutive Modeling and Numerical Implementation
”, which will take place in
Dortmund, Germany from September 3rd to 7th, 2012 and is organized by Prof.
Dr.-Ing. A. Erman Tekkaya of TU Dortmund and Dr. Tudor Balan of LEM3,

German French Summer School 2012 - Hardening and Damage of Materials under Finite Deformations

Dear all,

We are pleased to announce the forthcoming Summer
School on “Hardening and Damage of Materials under Finite Deformations:
Constitutive Modeling and Numerical Implementation
”, which will take place in
Dortmund, Germany from September 3rd to 7th, 2012 and is organized by Prof.
Dr.-Ing. A. Erman Tekkaya of TU Dortmund and Dr. Tudor Balan of LEM3,

Panagiotis KOTRONIS's picture

Post Doc Position: Risk-based Selection of Constitutive Models for Geotechnical Analysis, EC Nantes (France)

Post Doc description:

Soil, as a typical natural material, has very complex behaviour which is very difficult to be accurately modelled. In geotechnical engineering, about half of the accidents are caused by insufficient designs. The soil’s constitutive model is the fundamental issue for modelling and analyzing soil-related engineering systems.

Notched tensile specimens and force-displacement response.

 Dear forum members,

I'm trying to simulate a tensile test (of ductile material) using smooth and notched specimens. I've started with a simple model without damage (isotropic von Mises plasticity implemented in ABAQUS) to compare the force vs. displacement response between simulations and experiments.

cdeng's picture

MSc position in computational materials science at the University of Manitoba

Two Masters' positions are now available for the winter semester (starting in January), 2013 on computational materials sciene in the Department of Mechanical and Manufacturing Engineering at the Unviersity of Manitoba. The potential student(s) will work on the thermostability and mechanical properties in nanocrystalline materials and crystalline/amorphous composites. Students with strong interests in atomistic simulations (MD, ab inito, monte carlo, etc.) and good programming skills (C, Fortran, etc.) are encouraged to apply. Intrested students please send a CV and inquires to Prof.

saberelarem's picture

Deformation rates and localization of an active fault system

The Corinth Rift in Greece is one of the most active extensional regions in the Mediterranean area (Fig. 1). The Corinth Rift Laboratory project (CRL, is based on the cooperation of various european institutions that merge their efforts to study fault mechanics and related hazards in this natural laboratory where numerous continuous observations are made. The present rift is asymmetric and deformation is very localized.

shahram's picture

ABAQUS 6.11.1 and suitable version of FORTRAN for writing a VUMAT subroutine?

I need to write a Vumat subroutine in ABAQUS 6.11.1, and I dont know where should I begin from exactly? can anybody help me with the suitable version of Fortran for this version of ABAQUS and the steps I need to take for writing a SUBROUTINE in ABAQUS?

 Thank you guys 

Shailendra's picture

Minisymposium on "Plasticity: Bridging the Scales from Micro to Macro" at IWCMM XXII, Baltimore, MD, USA (Sept. 24-26, 2012)

Dear friends and colleagues,

This is to inform you of the minisymposium

Plasticity: Bridging the Scales from Micro to Macro

to be organized at the 22nd International Workshop on Computational Mechanics of Materials (IWCMM XXII) and request you to consider submitting an abstract. The workshop will be held in Baltimore, MD, USA during September 24-26, 2012.

ansys problem

Free Tags: 

i am working on autofrettage process in a cylinder with end caps . and i have problems with it. which material model is better to be used , what is the proper element to model it .  what is the best  number of substeps ? and there are errors when i am trying to apply pressure load.

FEAP - user element subroutines

Choose a channel featured in the header of iMechanica: 

Hi all,

my question is about the history data storage in FEAP.

I am writing element subroutine (elmt01) in FEAP 8.3  for a history dependent problem (crystal plasticity).

Jonathan Zimmerman's picture

Submit an abstract for IMECE-2012 sympoisum "Multiscale Perspectives on Plasticity in Metals"

My co-organizers and I invite you to submit an abstract to the upcoming symposium “Multiscale Perspectives on Plasticity in Metals” at the ASME 2012 International Mechanical Engineering Congress & Exposition (IMECE), to be held November 9-15, 2012 in Houston, Texas. This symposium will explore the unique challenges to understanding plastic deformation in metals and formulating material models that can accurately predict thermo-mechanical deformation.

Postdoctoral positions in statistical modeling of fracture and plasticity

We anticipate the opening of four postdoctoral positions in 2012 to work on statistical aspects of fracture and plasticity,  and in particular on size effects in the fracture of  disordered media and in microplasticity.  The positions will be funded by the ERC Advanced Grant 2011, SIZEFFECTS.

Notes on thermoplasticity

I've recently had the opportunity to take another look at plasticity in the large deformation context.  I've avoided going into geometric and other issues involved with multiplicative deformations (points stressed in earlier blog posts by Giovanni (node/11545), Arash (node/11623)  and Xiabo (node/11599).  Attached are some old notes that I'd prepared some years ago to help me with the details.  I hope they're of use to other students of mechanics.

-- Biswajit

Siamak60's picture

Linking error for Abaqus and Fortran




Oden Warren's picture

EXTENDED ABSTRACT SUBMISSION: Nanobrücken II: A Nanomechanical Testing Workshop, March 22-23, 2012, INM Saarbrücken, Germany

Dear Colleague:

You are cordially invited to attend Nanobrücken II:  A Nanomechanical Testing Workshop, jointly presented by INM - Leibniz Institute for New Materials and Hysitron, Inc., with co-sponsorship from the JEOL company. This is the second workshop in the Nanobrücken series. The workshop's scope has been broadened, and the abstract submission deadline is now February 19, 2012.

Postdoctoral postion in Computational Crystal Plasticity at RPI

There is an immediate opening for a postdoctoral research position in the Advanced Computational Research Lab at RPI, Troy NY to work on Crystal Plasticity Finite Element Methods. Currently we are working on interesting advances in the areas of radiation damage and high strain rate loading conditions. Encouraged to apply are creative, self-motivated individuals with a sound baclkground in computational mechanics, CPFEM and materials science. RPI is home to the CCNI, one of the most powerful university-based supercomputational research facilities in the world.



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