UMAT

Hi all,

I'm using ABAQUS and UMAT for structural simulation. I used quadratic element (CPS4) with 4 integration points (IP).

During the calculation (which calling my UMAT), at each time step, for each element, I need to calculate the average stress of these IPs and produce a state variable for these IPs from this average stress. Then, I would need to update this state variable back to these IPs in that element. But as far as I know, the ABAQUS call UMAT for every IP and calculate everything within this current IP.

Hello All,

I am working on stochastic upscalling of damage in concrete microstructure. Can someone provide a UMAT for Mazar's damage model or any resource to help me create UMAT on my own.

Thank you.

Vasav Dubey

Texas A&M University

Texas, USA

Dear iMechanica community,

you can find the UMAT-implementation of a Zener model, i.e. a Maxwell model parallel to a spring, in my PhD thesis:

“Upsetting and Viscoelasticity of Vitreous SiO2: Experiments, Interpretation and Simulation“
Technische Universitaet Berlin, Germany, 2006
https://depositonce.tu-berlin.de/handle/11303/1574
http://dx.doi.org/10.14279/depositonce-1277

We performed a comprehensive study of a large class of Implicit and Explicit integration algorithms for Elastic-Plastic behaviors in Finite Element Analysis (FEA) developed in UMAT and VUMAT for ABAQUS and presented various unique results. We also showed detailed integration algorithms for both Associated and Non-Associated Flow Rules with mixed isotropic and kimenatic hardening with expandable number of internal variables (damage and etc).

Full bibliographic details:

Dear researchers,

I’m Joseba Mendiguren, researcher at the Advanced Manufacturing Group of Mondragon Unibertsitatea. I’m currently working on advanced yielding/hardening models for metals.
I’m in the middle of a paper writing work but I cannot find time to sit down and program the VMAT that I need to run some simulations for the paper. I’m looking for a VUMAT programmer researcher willing to work on the topic and share the publication authorship on return.

Dear Colleagues,

I have done some analysis with nonlinear geometry. I use quadratic 3D solid elements. I have learned the way to calculating DSTRAN and DROT from ABAQUS documentation as follows:

Job Summary:
The postdoctoral research associate is expected to
provide research support within the frame of a multi-year engineering
research project undertaken by faculty from the departments of
Mechanical Engineering and Applied Math and Sciences at Khalifa
University. Limited teaching or other academic duties may be assigned to
the successful candidate under the supervision of the Advisor as
required by the University.
The successful candidate will be

Hello All,

I want to use an external subroutine in my umat but I have not been able to do that so far. Having created a dynamic library project in Visual Studio 2008, I have created a .dll and .lib files and copied the .lib file into the working directory of my abaqus job and the .dll file to exec folder. I have also added the directory of the .lib file in the LIB environmental variable. But I get these errors from ABAQUS: 

Here you can find a sample codes along with documentation:

 http://www.columbia.edu/~jk2079/Kysar_Research_Laboratory/Research.html

 At the end of the page there is the link. 

Hello everyone,

I am currently in the process of implementing a multiscale modeling approach in ABAQUS/Standard.

Here is what I am doing.

Macroscale ABAQUS model <--> UMAT <--> Python script <--> Microscale ABAQUS model

So basically the microscale model is being called at every macroscale integration point. The UMAT passes the required data to python as command line arguments and the python script returns the stress and tangent modulus in a text file.

Hello,

Hi all,

Hi everyone 

I am learning the polycrystalline crystal plasticity and testing material in ABAQUS and UMAT. Now I am trying to build a RVE by using the truncated octahedrons as the grain shape or Voronoi tessellations.

For truncated octahedrons, I built a truncated octahedrons and assembled them into the grain aggregate in the .inp file, and assign orientations in the UMAT based on the part's name. However, I found it hard to define their interaction between grains. What is their interaction properties and how to define the contact pair in an automatic way?