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shreeram111's picture

UMAT Non linear Viscoelasticity - Algorithm verification?

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Hello everybody,

           My task is to write a UMAT for Non-linear Viscoelasicity based on Schapery's model in ABAQUS. I have coded the routine, but I am still not able to predict correct response. I tried to debug it as much as I can. I understand that it would be difficult for anybody to understand my code. So, I have attached a flowchart (pdf) of the whole algorithm that I follow. It would be nice if you could check that and correct me if I am wrong.

Thanks in advance for your time and consideration

Regards

Shree

Dario Schiano Moriello's picture

Formulation of Continuum Shell Elements - ABAQUS

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Hello,
I am looking for an explanation about the formulation used for CONTINUMM SHELL elements in ABAQUS.

Modelling cyclic behaviour of soil using UMAT

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I have been trying to model the cyclic behaviour of soil. I got a UMAT. But when I'm using UMAT, it is creating lot many errors (like numerical singularity and excessive distortion). I have constrained it properly. I tried running my model with an inbuilt material (clay plasticity) and I'm getting results. Here I'm not even able to move from the initial geostatic step. Can anyone please help

renganathan sekar's picture

Is it possible to import a FE Assembly to SIMPACK?

In ABAQUS, I have modelled a assembly containing two parts with lot of constraints and other engineering features which are very crucial to my FE analysis. The job ran successfully and I have got satisfactory results. As a next step, I would like to import this model into the Multi Body Software SIMPACK as a flexible body. This would require the introduction of substructuring concepts and I referred to SIMPACK tutorials for exact way of doing it. My question is, can we import an assembly into SIMPACK. Because the tutorials explain only a part being impoted into SIMPACK.

Write out local material orientation

I have a vibration problem where I have assigned the local material orientation by assigning points a and b. By assigning points a and b, I define one material direction in my local coordinate system - direction 3. From Abaqus documentation, I understand that the other two directions are assigned to be orthogonal to the 3rd direction but are set somewhat arbitrarily. I want to write out the directions so that I know the three vectors defining all three directions of the local material orientation.

I found that I can write out the local orientation averaged at each node by using: 

Write out local material orientation

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I have set up a vibration problem. I assign a local material orientation by assigning coordinates a and b to define the 3rd material direction. From documentation, I understand that the other two directions are assigned to be orthotropic to the 3rd direction. Beyond that, I think that they are set somewhat arbitrarily. I want to output each component of the local material orientation.

How to link gfortran with Abaqus6.14 ?

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Dear Abaqus Experts:

 

I am new Subroutine user and I want to analyze plastic deformation behavior of micro component.

So, I have to link Abaqus,gfortran,and Microsoft Visual Studio.

I tried several methods by reference to the following link,but I have not yet been successful in them.

Opening for Senior Staff Engineer at BD Corporate CAE Group

The Corporate CAE group for Becton Dickinson is looking for a CAE Senior Staff Engineer at the Research Triangle Park, NC USA location (Raleigh-Durham area).

1073741819 error code in ABAQUS

Dear all,

I'm using UEL in ABAQUS. The UEL works perfectly as far as I have 256 time increments (each 1e-6 sec). When I'm trying to increase the time increments (let's say 512 with the same 1e-6 sec per increment) Abaqus gives me error code 1073741819.

I'm running Abaqus 6.14.2 with Intel Fortran Composer XE 2013 on a Windows 7. CPUs are 3rd generation.

I would appreciate if you could help me to figure it out.

Best Regards,

1073741819 error code in ABAQUS

Dear all,

I'm using UEL in ABAQUS. The UEL works perfectly as far as I have 256 time increments (each 1e-6 sec). When I'm trying to increase the time increments (let's say 512 with the same 1e-6 sec per increment) Abaqus gives me error code 1073741819.

I'm running Abaqus 6.14.2 with Intel Fortran Composer XE 2013 on a Windows 7. CPUs are 3rd generation.

I would appreciate if you could help me to figure it out.

Best Regards,

Job position in numerical biomechanics

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Strain calculation in ABAQUS

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Hello,

I have some troubles in calculating the strain in ABAQUS. I have the following Model with one element (see picture) and a linear elastic isotropic Material (Steel), which is sheared in the x-direction. The analytical result of the strain tensor gives me in xz-direction 0.25 (see picture). The result in ABAQUS is 0.5. I ran the same simulation in CalculiX CrunchiX and got the expected strain of 0.25 in the xz-direction

Can anyone tell me how ABAQUS calculates the strain for a linear static analysis? Why is the ABAQUS result exactly 50% higher?

Dario Schiano Moriello's picture

Application of Corotational Formulation

Hello,  I am a PhD student in Mechanical Engineering, and at the moment I am studying the co-rotational formulation from Criesfield's books.

I am looking for applications of the corotational formulation in ABAQUS or MATLAB; my supervisor suggested me it could be done in ABAQUS through a User Defined Element Subroutine, but being a new user to this software I don't really know from where I should start.

Dario Schiano Moriello's picture

Implementation of Corotational Formulation

Hello,
I am a PhD student in Mechanical Engingeering.

I am currently studying the co-rotational formulation, following the theory on Crisfield's books. The next step in my project would be to apply the corotational formulation for the simulation of a beam, and my supervisor suggested me this could be done in ABAQUS through a User Defined Element Subroutine.

Second derivatives of displacement field ABAQUS

 

Hello everyone,

 

I need to compute the second derivatives of displacement field in ABAQUS, in the integration point of quadratic elements if it is possible. I thought about using USDFLD subrutine, but I am stuck with getting the Jacobian matrix that couples the isoparametric space with the physical space in ABAQUS. GETVRM is what everyone suggests to get variables from abaqus, however I did not find the definitions of JMAC, JMATYP... so I do not know what I can get from that subrutine exactly.

 

computational nonlinear elasticity references

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I will be developing constitutive material models into commercial FE codes for nonlinear elasticity and searching for good books to get started for computational aspects. There are many good books for computational plasticity but I did not find any for nonlinear elasticity. Suggestion for good books or references is welcome.

ABAQUS - increase the size of the interior elements

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Hello everyone,

I am currently working on modelling ITZ zones in concrete 2D microstructure. ITZ is the cement paste zone near the surface of aggregate which differs in properties from bulk cement paste. The thichness of ITZ zone ranges from 10-50 micrometer (0.01 - 0.05 mm). The size of RVE I am using is 100X100 mm which makes ITZ a very fine detail in my microstructure. I have created a instance in abaqus merging all parts, Aggregate, ITZ and Matrix( Cement Paste).

I seeded the instance with using these parameter:

Global Size: 2

ABAQUS XFEM error message: std_findcutoneedge3d8_xfem

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Hi everyone,

After switching from a working 2D model to 3D, I'm facing the following error message after about 20 iteration steps:

The system error in std_findcutoneedge3d8_xfem -- nodal level set values might not be correct for element 12345 instance FEM_MODEL_V1

Xinlei_Wu's picture

Periodic displacement loads decompose with 4 load steps in Abaqus

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 I want to simulate a dynamic motion of a pipe under periodic displacement loads.

Hidroxid's picture

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

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

 

Using libraries in Abaqus subroutines

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Hi,
Can someone comment on using libraries in Abaqus subroutines?

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