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Can someone post an example of UMAT and VUMAT for the same elasto-plastic problem?

I want to understand how the stress update algorithm is modified for the different definitions of stress rate in ABAQUS/Standard and ABAQUS/Explicit formulations. I know the relationships, I just want to see how it's coded in a subroutine.

Also, the Hughes-Winget algorithm is used to update the stress defined by the Green-Naghdi stress rate by using the Jaumann rate. How to implement that in VUMAT? Can someone please post an example to clarify these aspects?

Eral Bele's picture

PhD Studentship in Mechanics of Materials at University College London

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Pai Wang's picture

Fully funded positions at ALL levels - computational research

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ebarbero's picture

How do I count Keyword Blocks in the Abaqus input file?

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The Abaqus documentation, available here:

https://abaqus-docs.mit.edu/2017/English/SIMACAEMODRefMap/simamod-c-inpu...

states the following:

Certain keywords must be used in conjunction with other keywords; forexample, the *ELASTIC and *DENSITY keywords must be used in conjunction with the *MATERIAL keyword. These related keywords must be grouped in a block in the input file; unrelated keywords cannot be specified within this block. 

Rudraprasad Bhattacharyya's picture

Why getting trouble with Abaqus UMAT subroutine when using interaction features like contact or tie?

I am implementing a constitutive relation in UMAT subroutine using the commercial software Abaqus. First, I tested the UMAT subroutine with 'one element model' first. Then I tested with comparatively bigger geometry. It worked fine. Now when I am trying to do a models involving contact, i.e. use of the 'Interaction module'. I am getting error of over-constraint warning for 'Split Tension test of concrete cylinder'. The same input file (except the material definition) is running on Abaqus perfectly with Mohr-Coulomb criteria. I can see a reasonable stress and strain contour.

Modeling Soil around pipeline with stiffeners in abaqus

I never worked with stiffeners in abaqus and now I should use theme. I want to model soil around pipeline with stiffeners. The stiffener behavior has 3 nonlinear components (x,y,z direction).

claudiosaul.lopes's picture

PhD position: multiscale computational mechanics of advanced composites

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Problem with defining corner BC/constraint

Hello all,

I'm trying to model the buckling of a shell structure under thermal load.

The structure is square-shaped.

The left edge must be kept straight. To achieve that, I applied MPC Tie Constraint for its nodes.

The bottom edge must be fixed so that the BC applied at its nodes was U1 = U2 = U3 = 0.

Temperature is applied as a predefined field.

However, when I run the simulation the corner that connects both edges deforms very strangely which makes me question how to model it.

I appreciate any input. Thanks.

About periodic BC for large mesh in ABAQUS

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Hi all,

Leon Mishnaevsky's picture

Abaqus/Python - commands to find nearest node to a given point

Hi,
I need to write a python comman code to find a node (in a given set), nearest to a given point.
The code now looks as follows:
import sys
sys.path.insert(10, 
r'c:/SIMULIA/Abaqus/6.13-3/code/python/lib/abaqus_plugins/findNearestNode')
import nearestNodeModule
nearestNodeModule.hideTextAndArrow()
a = mdb.models['FibreModel'].rootAssembly
n1 = a.instances['Fibre0-1'].nodes

How to find normals stresses in the global x y z direction in ABAQUS?

I am trying to find normal stresses (in the global x-y-z direction) of individual layups (plies) in ABAQUS. While post processing I only find S11 S22 S12. Do I always have to use a transformation matrix to find my Sxx Syy and Sxy? Is there a GUI/ Command way to extract the stresses in each ply in xyz directions?

 

 

how to run a python script after each increment in abaqus.

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hi,

I am doing static stress analysis. in my problem, I have to update my input file after each increment. so for updating the input file, I have to do some calculation depend on the output of the previous increment result. for these calculations, I have to call the odb file after each increment, do some calculations, update the input file and the process will go on. I have written a python script for the calculations from the odb file but don't know how to use this script after each increment.

 

thank you

Mohammed Bouchelarm's picture

Strain values transformed in a rotated x'y'-Cartesian coordinate system with ABAQUS

Dear All,

I'm trying to get strains in some specific points (along a path) from the xy-Cartesian coordinate system to a local x'y'-Cartesian coordinate system rotated through an angle (theta) which means transform the strains (Ex,Ey) to (Ex',Ey') as described in the attached figure, something I usually do manually with Mohr's circle and I wonder if I can do it directly with Abaqus ?

Thank you in advance !

Regards.

Mohammed.

 

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