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How to study a inverse problem? Know the orbit, solve the constraint condition.

Dear all,

Now I face a noval problem, and I do not know how to deal with it, even cannot begin the first step.

As we know, the formulation of a classical mechanical question  is given the initial condition and the constraint condition, and solve the unknown orbit. Now I face a inverse problem. I know the initial condition and the orbit, and would like to solve the unknown constraint condition.

Is there anyone could give some seggestion, I don't know how to do it. Thanks.


Selection of element bsed on the location in abaqus using python script.

I'm facing problem while writing a script for a parametric study.
After changing the each parameter the model changes and and the loaction of the interested element changes based on those parameters.
Also the element number changes.
Is there any command in python script to choose the elements based on the location ? 

Thank you in advance

Rajesh Kumar

Arash_Yavari's picture

The Geometry of Discombinations and its Applications to Semi-Inverse Problems in Anelasticity

The geometric formulation of continuum mechanics provides a powerful approach to understand and solve problems in anelasticity where an elastic deformation is combined with a non-elastic component arising from defects, thermal stresses, growth effects, or other effects leading to residual stresses. The central idea is to assume that the material manifold, prescribing the reference configuration for a body, has an intrinsic, non-Euclidean, geometric structure. Residual stresses then naturally arise when this configuration is mapped into Euclidean space.

Masters/Ph.D position available

 On behalf

 A fully funded Masters or Ph.D student position is available @ Monash University, Malaysia Campus. The project will be supervised by Dr.Ean Hin OOI ( ). Kindly email your enquiries to

Implementing XFEM in ABAQUS using dynamic implicit step

Is there anybody who has implemented XFEM in ABAQUS using dynamic implicit step? My model runs fine when I use 'static, general' step but when I change it to 'dynamic, implicit' I get following error message"The following XFEM cracks are failing to correctly generate and says crack domain contains invalid element shape." Please let me know what do I need to change in the model to fix this error. 

Thanks so much for your help,


Vinod Kushvaha 

Fan Xu's picture

Bridging techniques in a multi-scale modeling of pattern formation

Bridging techniques in a multi-scale modeling of pattern formation

F. Xu, H. Hu, M. Potier-Ferry, S. Belouettar

International Journal of Solids and Structures (2014), doi:



How the pressure in ANSYS is implemented?

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There are several possibilities for the realization of the presure load.
example, when I apply a pressure to an area (lets say, thin rectangular
plate) the area of the plate grows during the deformation process. One
possibility is to keep the pressure per unit area constant (in this case
the total force acting on a plate grows during the deformation) and the
second is to keep constant the total force acting on the plate (in this
case the force per unit area decreases with the deformation). I looked

generat initial stresses ?

Hi everybody

I am a geotech engineer, I use a program Abaqus, I want to know 
when I use tow layers of soil, each layer with their properties, when i use the contact between these layers

my question is; How i generat initial stresses without discontinuity between the two layers ?


Davide Bigoni's picture

Stress concentration near stiff inclusions

Do singular stress fields exist close to rigid corners?

See the photoelastic investigation at

Acta Mechanica Sinica, Vol.30, Issue 3, 2014 is online now!

Dear everyone!

The third issue in 2014 (Volume 30, Issue 3) of Acta Mechanica Sinica (AMS) is now online.

Welcome to this SCI-indexed journal for rapid publication of your exciting results.


Phase-field modeling and simulation of fracture in brittle materials with strongly anisotropic surface energy

Crack propagation in brittle materials with anisotropic surface energy is important in applications involving
single crystals, extruded polymers, or geological and organic materials. Furthermore, when this anisotropy
is strong, the phenomenology of crack propagation becomes very rich, with forbidden crack propagation
directions or complex sawtooth crack patterns. This problem interrogates fundamental issues in fracture
mechanics, including the principles behind the selection of crack direction. Here, we propose a variational

Problem in steel connection model using abaqus

Hello Everyone,

I'm trying to model an extended shear tab connection using ABAQUS 6.13-2, I've tried to model 4 connections and I compared the results I've got with the experimental work, and I noticed that the FEA is way stiffer that the experimental work, I have only one warning and it says "If significant clearance/overclosure exists between surface pair (assembly__pickedsurf579,assembly__pickedsurf580) and the master surface does not have rotational degrees of freedom, adjustment is recommended for correct enforcement of the tie constraint"

Compression buckling of polymeric beam/column


I have a problem with a stacked colum of elastomeric membranes (natural rubber or silicone).

I am looking for a compression buckling criterion that applies for hyperelastic materials in presence of large deformations (up to 400%).

I've read about Haringx formula, that should apply for these materials, but I suspect that it is valid for small strains only.

My question is:

- is there a suitable buckling criterion for this case?

Nonlinear stiffness for cohesive behaviour

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Hi all,

 Does anyone know how to define nonliner (or exponential) stiffness for cohesive behaviour (for ascending branch before damage)? In CAE it's only allowed to enter one value



Deformation gradient change in Abaqus

Help needed!! in Abaqus

I have UMAT written to update stress and material tangent components for a user defined material model. I need stretch ratio as an input for my material model. For this I am using deformation gradient from UMAT. Problem is, when there is constant strain (strain rate = 0), for example when material stretched to 100% strain (rubber) and then held at that strain for certain time to see stress relaxation, the deformation gradient should give the same value of 100% strain, but to my surprise this is changing. Can any one help me with this.   


Drawing a 2D sketch on XZ plane in ABAQUS!

Hello All,

I am trying to make a 2D shell layer on XZ plane. To capture buckling of shell layer with 3-point bending load, I am required to model a 2D sketch on XZ plane. Modeling this way I can use shell elements' bending degrees of freedom. But ABAQUS always pick defauly XY plane to start with. 

Does anyone know how to draw a sketch on XZ plane?


Jay Patel 

Modeling a curved graphene sheet

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I'm trying to simlate the buckling behavior of a grpahene sheet using ANSYS APDL 14.5

In my analysis I need to have a graphene sheet that is curved with a variable radius for different cases. I was wondering if there is a faster way to model the graphene sheet assuming that the carbon-carbon bonds are modelled as elastic beam elements( beam 188) and the nodes are represnted by the carbon atoms.


 --Naveen R--

2014 Melosh Medalist

Phani Motamarri, from the University of Michigan, is the 2014 Melosh Medalist for his paper "A Spectral Finite-Element Based Method For Large-Scale Quantum Mechanical Calculations Using Kohn-Sham Density Functional Theory".  Please join me in congratulating Phani!

malfano's picture

Post Doctoral Openings at COHMAS/KAUST - Mechanical integrity of bio-inspired composites

The Division of Physical Sciences and Engineering at King Abdullah University of Science and Technology (KAUST) invites applications for a Postdoctoral fellow in Mechanical Engineering at the Composite and Heterogeneous Material Analysis and Simulation Laboratory (COHMAS,

Field of study


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