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Hidroxid's blog

XFEM crack under compression.

Submitted by Hidroxid on

Hi all,

 

I am doing crack modelling (XFEM) under moving compression and traction loading in Abaqus but I get warning regarding the crack under compression load as follows:

"THE LOADING CONDITION MIGHT MAKE MAIN CRACK UNDER COMPRESSION AT  NSET "X" THE CRACK PROPAGATION DIRECTION CANNOT BE PREDICTED. A VALUE OF ZERO IS PROVIDED FOR IT."

Anyone facing the same issue?

Kind regards,

Omid

Applying a moving pressure and traction in Abaqus

Submitted by Hidroxid on

Hello all,

I have applied a moving ellyptical hertzian pressure load on a surface using a DLOAD which works, but I also need the traction load which is the multiplication of this pressure with a friction coeffcient.

Does anybody have any clue how to do it? Directly through abaqus or inside the same DLOAD?

 

Kind regards,

Omid

Huang's Crystal Plasticity UMAT taking into account Bauschinger effect for cyclic loading (kinematic hardening)

Submitted by Hidroxid on

Hello,  

In the Crystal Plascticity UMAT model for Abaqus (by prof. Hunag) the Bauschinger effect which is important for cyclic loading, is not considered.  

Is there any edited version of this UMAT considering this effect for cyclic loading (by also considering kinematic hardening)?

 

Kind regards,

Omid 

Crystal Plasticity User Material for Abaqus incorporating twinning

Submitted by Hidroxid on

Hello,

The most famous user material (UMAT) for Abaqus is the UMAT from prof. Hunag. But the twinning is not implemented in it.

Does anyone know if theere is any other UMATs which the twinning effect (plastic deformation due to twinning) is implemented?

 

Kind regards,

Omid

Pressure load on element-based surface? or converting element-based surface to geometric surface to apply pressure in abaqus?

Submitted by Hidroxid on

I would like to use pressure load on a element based surface, in Abaqus. This surface is a combination of small surface elements (in an orphan mesh). But to apply pressure load you need to have a geometic surface.

How can I do this? Is it possible to make a geometric surface using this element-based surface?

 

Regards,

Omid

 

Assigning crystal plasticity material constants for one crystal with more than one element (default of Dr Huangs model)

Submitted by Hidroxid on

Hi!

 

I am just a beginner in Abaqus UMAT and I have started working with Dr Huang's crystal plasticity UMAT in Abaqus.

When I am assigning one material constants for one element crystal it works but when I try to assign it to more than one element for one crystal (for example group of elements with same grain orientation) it give me error code 144.

Can anybody explain me the reason?

 

 

Thanks in advance,

Kind regards,

Omid

 

Linking Abaqus 6.14-1 with Microsoft Visual Studio 12.0 (2013) and Composer XE 2013 SP1 (Update 1)

Submitted by Hidroxid on

I am tryring to link Abaqus 6.14-1 with Microsoft Visual Studio 12.0 (2013) and Composer XE 2013 SP1 (Update 1) (complier version 14) based on some instrcutions mentioned in following links:

http://www.researchgate.net/post/how_can_i_link_the_abaqus64-bit_and_fortran

http://imechanica.org/node/15894

problem with reduced quadratic elements (C3D20R) while used in a node to surface contact discretization

Submitted by Hidroxid on

Hello,

Can anyone explain to me what is the problem with reduced quadratic elements (C3D20R) while used in a node to surface contact discretization?

I am using a traction-seperation formulation cohesive surface and for that I can only define node to surface contact. In this case element types of C3D8I and C3D20 work but C3D20R does not work! (I am using Abaqus)

Thanks a lot,

Reading abaqus field output data using python scripts in an especial coordinate (x,y,z location) and not node/element set

Submitted by Hidroxid on

Hello everyone,

I am using python scripts to extract the field output (displacements) in a nodeset (which was defined in the model) and it does not seem that difficult but I have a question regarding reading output data for a especial coordinate (x,y,z location) and not the node label since when you change the discretization you lose the previous node labels. Does anyone have any idea how to do so?